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Sweet Potato Production Sweet Potato Production

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                             B est
                         M anagement
                          P ractices
                            endorsed by

SWEET POTATO BMPS 2000                    1
                                              WHY BMPS ARE
    TABLE OF                                  IMPORTANT TO LOUISIANA
                                                    In Louisiana we are blessed with beautiful and
    Introduction ...................... 3     abundant waters to enjoy fishing, hunting, boating or just
                                              relaxing on the shore of a lake, river or bayou. Most of
    Soil and Water                            the water in Louisiana’s rivers and lakes comes from
    Management ...................... 4       rainfall runoff. As this runoff travels across the soil
                                              surface, it carries with it soil particles, organic matter and
    Pesticide Management and                  nutrients, such as nitrogen and phosphorus. Agricultural
    Pesticides ......................... 12   activities contribute to the amount of these materials
                                              entering streams, lakes, estuaries and groundwater. In
    Nutrient Management .. 17
                                              addition to assuring an abundant, affordable food supply,
    General Farm BMPs ...... 23               Louisiana farmers must strive to protect the environment.

    Research Overview ....... 25                    Research and educational programs on environ-
                                              mental issues related to the use and management of natu-
                                              ral resources have always been an important part of the
                                              LSU AgCenter’s mission. Working with representatives
                                              from the agricultural commodity groups, the Natural
                                              Resources Conservation Service (NRCS), the Louisiana
                                              Department of Environmental Quality (LDEQ), the Louisi-
                                              ana Farm Bureau Federation (LFBF) and the Louisiana
                                              Department of Agriculture and Forestry (LDAF), the LSU
                                              AgCenter has taken the lead in assembling a group of Best
                                              Management Practices (BMPs) for each agricultural com-
                                              modity in Louisiana.

                                                    BMPs are practices used by agricultural produc-
                                              ers to control the generation and delivery of pollutants
                                              from agricultural activities to water resources of the state
                                              and thereby reduce the amount of agricultural pollutants
                                              entering surface and ground waters. Each BMP is a culmi-
                                              nation of years of research and demonstrations conducted
                                              by agricultural scientists and soil engineers. BMPs and
                                              accompanying standards and specifications are published
                                              by the NRCS in its Field Office Technical Guide.
2                                                                                    SWEET POTATO BMPS 2000

     Sweet potatoes are an               The runoff from sweet                 References are made to
important commodity in Louisi-      potato fields can have a potential   specific Natural Resources
ana. The total acreage planted in   impact on the surface water          Conservation Service (NRCS)
1999 was approximately 24,925       quality throughout the regions       production codes in this publica-
acres. Most are grown in 11         where sweet potatoes are grown.      tion. These production codes are
parishes: West Carroll,             The quality of water in the          explained in the text. More
Morehouse, Franklin, Avoyelles,     streams, rivers, bayous, lakes and   detailed information about these
St. Landry, Evangeline, Acadia,     coastal areas of Louisiana is        practices can be found in the
St. Martin, Rapides, Grant and      extremely important to all resi-     NRCS Field Office Technical
Richland. The gross farm value      dents.                               Guide (FOTG). The FOTG can

of Louisiana-grown sweet pota-            The intent of Best Manage-     be found in all Soil and Water
toes in 1999 was about $72          ment Practices (BMPs) is to          Conservation District Offices, all
million. Value added of fresh       provide the growers of sweet         NRCS field offices and on the
market potatoes is determined by    potatoes some guidelines on          NRCS web page. Additionally,
the increase in value of the        what practices they can imple-       under voluntary participation by
harvested potatoes that are         ment to reduce the impact these      the producer, technical assistance
washed, graded, packed and          agricultural practices may have      to develop and implement a
shipped. The estimated value        on the environment. If properly      farm-specific conservation plan
added for the 1999 crop was $53     implemented, with appropriate        is available through the Conser-
million, for a total economic       incentives where needed, the         vation Districts, NRCS field
value to the state of more than     practices described in this publi-   offices and the LSU AgCenter
$125 million. Sweet potatoes are    cation will help to improve water    parish offices.
the single most important veg-      quality without placing unrea-

etable crop in Louisiana in terms   sonable burdens on the agricul-
of acreage planted and economic     tural industry of Louisiana.

SWEET POTATO BMPS 2000                                                                                    3

                                              SOIL             AND            WATER MANAGEMENT
                                Irrigation Management
                                (NRCS Code 449)

                                Furrow Irrigation Systems                            Furrow Irrigation

                                      Crop residue cover and tillage practices
                                play important roles in the way crops use
                                water and also affect the ability of irrigation
                                systems to replace that water. Tillage prac-
                                tices (NRCS Code 329) and crop residue
                                management (NRCS Code 344) play impor-
                                tant roles in the way irrigation systems
                                perform and are managed. Tillage practices
                                affect the way that water moves into and off
                                of the soil (infiltration and runoff).

                                      Many factors affect the               Tillage practices affect         Center Pivot
                                performance of furrow irrigation      furrow irrigation systems by
                                systems. Physical conditions,         altering the infiltration character-   Irrigation Systems
                                such as soil texture, soil struc-     istics of the soil and by altering     (NRCS Code 442)
                                ture, field slope, field length,      crop residue in the furrow. Both
                                furrow shape and the amount of        factors affect the ability of the           Crop residues serve a
                                crop residue cover, all have some     furrow to convey water down the        largely positive role in center
                                impact on the performance of the      field. As tillage practices become     pivot irrigation management.
                                irrigation system. The way the        less intensive, infiltration rates     Selecting a tillage system that is
                                system is managed, including the      often increase.                        best suited for a particular field
                                furrow flow rate, length of                                                  situation can be a very important
                                                                            The need to match manage-        decision. Disregard for the
                                application time and irrigation       ment factors with the physical
                                frequency, also affects system                                               importance of this decision could
                                                                      conditions present at the time of      directly affect the effectiveness
                                performance. Irrigation system        irrigation is critical. In some
                                performance is often measured in                                             of the water application system,
                                                                      cases, a change in tillage practice    as well as other crop production
                                terms of the percentage of the        may cause changes in infiltration
                                water applied that remains in the                                            practices.
                                                                      rates that are too severe to over-
                                active root zone after the irriga-    come with management factors                 In general, concerns associ-
                                tion (application efficiency).        alone. In some cases physical          ated with tillage practices selec-
                                Thus, deep percolation (water         changes to the system may be           tion and center pivot operation
                                passing through the root zone)        necessary. The field slope or          are related to the potential for
                                and runoff (tailwater)(NRCS           length of run may need to be           runoff and erosion. The potential
                                Code 447) should be held to a         changed or furrow packing may          for runoff exists whenever the
                                minimum while supplying               be used to help overcome prob-         water application rate of the
                                adequate water to the crop along      lems associated with extreme           irrigation system exceeds the
                                the length of the furrow.             increases in infiltration character-   infiltration rate of the soil.
                            4                                                                                          SWEET POTATO BMPS 2000
                                                                                                                             SOIL AND WATER MANAGEMENT
                                                                                    (NRCS) or Soil and Water
                                             The potential for runoff exists
                                             whenever the water application rate
                                                                                    Conservation District for compli-
                                             of the irrigation system exceeds the   ance with conservation plans in
                                             infiltration rate of the soil.
                                                                                    making these decisions.
                                                                                          Crop residues also act like
                                                                                    small dams for temporary soil
                                                                                    surface storage of excess water.
                                                                                    Water applied in excess of the
                                                                                    soil infiltration rate will be
                                                                                    blocked from running off the
                                                                                    field long enough for infiltration
                                                                                    to occur. This results in more
                                                                                    uniform water application. In the
                                                                                    process, soils that would have
                                                                                    been transported with the runoff
                                                                                    water remain near their point of
                                                     Center Pivot Irrigation              Another option is to alter
                                                                                    the operating characteristics of
      To lower pumping costs,           tillage or water application, can           the irrigation system. For ex-
some row crop farmers fit their         reduce infiltration. For example,           ample, by selecting a sprinkler
machines with low to medium             as the size and number of water             package based on soil type and
pressure sprinkler packages. On         droplets increase, fine soil par-           field topography, you can match
occasion, sprinkler packages may        ticles are consolidated on the              more closely the water applica-
be improperly matched with the          surface to form a thin crust. As            tion rate of the center pivot with
soil infiltration rate. Irrigation      the soil crust develops, the water          the soil infiltration rate. By
system management and tillage           infiltration rate tends to decrease.        considering the interaction
practices may be used to control        Soil surface crusts can result in           between the sprinkler package
runoff if changes in the irrigation     infiltration rate reductions of up          and soil, selection of an unsuit-
system itself are desirable.            to 75 percent. One way to com-              able sprinkler package can be
                                        bat the negative effect of water            avoided.
      One option is to reduce the
                                        droplets is to be sure crop resi-
application depth per irrigation.
                                        dues are distributed evenly over
In doing so, the operator reduces
                                        the soil surface. Crop residues
the potential for runoff but
                                        spread in this manner protect the
increases the opportunity for soil
                                        soil by absorbing energy carried
evaporation over the course of
                                        by falling water droplets. This
the growing season. Although
                                        limits soil crust development,
crop residues can help reduce the
                                        resulting in a more consistent
magnitude of soil evaporation
                                        infiltration rate throughout the
losses, repeated wetting of the
                                        growing season.
soil surface will limit the water
savings attributed to crop resi-              Tillage practices that result
dues.                                   in minimal soil disturbance
                                                                                       Sweet potato residues, which
                                        should be used when topography
     Runoff also may be gener-                                                         are produced in less quantity,
                                        is rolling. On highly erodible                 are considerably more fragile
ated if the soil infiltration rate is
                                        land, it is important to check                 than small grain or corn
reduced over a period of time. A                                                       residues.
                                        with your local Natural Re-
number of factors, such as soil
                                        sources Conservation Service
texture and structure, surface

SWEET POTATO BMPS 2000                                                                                                   5
                                      The combination of improved water application uniformity                  “Irrigation return flow” is
                                resulting from more consistent infiltration rates, less runoff and         that portion of water which
                                reduced soil evaporation losses make crop residues a major factor in       returns to its source after being
                                the water conservation effort. Residue management (NRCS Code               used to irrigate crops. With
                                344) also can be a crucial component to minimizing the effect of           increasing environmental con-
                                irrigation on surface water quality.                                       cern, the term “irrigation return
                                                                                                           flow” has been extended to
                                  IRRIGATION          PRACTICES THAT CAN REDUCE                            include irrigation water that
                                                                                                           makes its way to any body of
                                  OR PREVENT EROSION INCLUDE:                                              water after its use on a crop.
                                  Manage crop residues to reduce surface water contamination                     Tailwater from furrow
                                  (NRCS Code 344).                                                         irrigation and runoff caused by
                                        Living vegetation and crop residues left on                        excessive irrigation or poor
                                  the soil surface are important in:                                       system design can make its way
                                         intercepting rainfall and reducing the                            into drainage ditches which
                                  impact of raindrops on the soil surface                                  eventually lead to bayous, rivers
                                                                                                           and lakes. Water from irrigated
                                         reducing erosion and sedimentation by
                                  decreasing runoff velocity
                                                                                                           land that is artificially drained
                                                                                                           must go somewhere, often into
                                         increasing structural stability of soil aggregates                the same water body it was taken
                                         increasing biological activity in the soil                        from.
                                         screening out soil particles from runoff water                          Irrigation return flow is
                                                                                                           becoming an important issue
                                  Conservation Cropping Sequence - (NRCS Code 328)                         because of its potential to be a
                                  Systems in which crops are alternated.                                   nonpoint source of pollution.
                                        May reduce weed pressure in sweet potatoes.                        This is not the only reason sweet
                                         May reduce some disease problems.                                 potato producers should use
                                          Where erosion is a problem, high residue crops included in the   return flow management prac-
                                  rotation reduce soil loss.                                               tices, however. Excessive runoff
                                                                                                           is a symptom of poor irrigation
                                                                                                           system design or poor manage-
                                  Cover and green manure crops - (NRCS                                     ment of irrigation water. It is also
                                  Code 340) Such crops are usually planted                                 water that is wasted. Wasting
                                  when the primary commodity crop is not                                   water not only has immediate
                                  growing.                                                                 financial ramifications, but it also
                                        Protect soils from erosion and reduce
                                                                                                           threatens the long-term availabil-
                                                                                                           ity of water for irrigation. Sound
                                         Filter runoff waters to reduce pesticide and nutrient losses.     management practices can reduce
                                                                                                           irrigation return flow while
                                  Precision level the land to optimize
                                                                                                           ensuring the most efficient use of
                                  furrow slopes to reduce soil erosion
                                                                                                           our water resources.
                                  (NRCS Code 462)
                                                                                                                 The major concern is the
                                                                                                           direct runoff that may occur from
                                                                                                           irrigated land. Many of the
                                  TREATMENT OF IRRIGATION                                                  fertilizer nutrients and chemicals
                                                                                                           used in agriculture are easily
                                  RETURN FLOW                                                              adsorbed onto soil particles.
                                  Install vegetative buffering (filter) strips                             When runoff occurs, soil par-
                                  (NRCS Code 393)                                                          ticles containing these adsorbed
                            6                                                                                        SWEET POTATO BMPS 2000
                                                                                                                  SOIL AND WATER MANAGEMENT
materials are picked up and transported out of the field. Eroded
sediments constitute the major potential for pollution from surface
return flows. In addition, soluble chemicals are dissolved by runoff
and carried with the water as it flows over the soil.

   There are three basic approaches to reducing
   pollutants in surface return flows (NRCS Code 570):
         eliminating or reducing surface runoff
             eliminating or reducing soil loss                            Residue
             reducing pollutants from irrigation return flow
     The first two approaches are achieved by properly designing,         (NRCS Code 344)
operating and managing irrigation systems. Following the directions            Living vegetation and crop
on the pesticide label will usually solve any problems associated with    residues left on the soil surface
applying agricultural chemicals.                                          are important in:
     The third approach involves using grass buffer strips (NRCS                 intercepting rainfall and
Code 386), artificial wetlands (NRCS Code 645), settling basins and       reducing the impact of raindrops
ponds (NRCS Code 350) and similar structures to reduce pollutant-         on the soil surface
bearing sediments. Treating return flow is more costly and trouble-
some than preventing it.                                                         reducing erosion and
                                                                          sedimentation by decreasing
                                                                          runoff velocity
                                                                                  increasing structural
                                                                          stability of soil aggregates
                                                                                  increasing biological
                                                                          activity in the soil
                                                                                  screening out soil par-
                                                                          ticles from runoff water.

  Buffer strips                        Wetlands
                                                                                Crop residues protect the
                                                                          soil surface from the impact of
                                                                          raindrops and act like a dam to
      Proper irrigation water management (NRCS Code 449) means            slow water movement. Rainfall
timing and regulating water applications in a way that will satisfy the   stays in the crop field, allowing
needs of a crop and efficiently distribute the water without applying     the soil to absorb it. The decom-
excessive amounts of water or causing erosion, runoff or percolation      position of these residues also
losses. Good irrigation water management can reduce moisture              increases the soil organic matter.
extremes. The sweet potato producer should have a good understand-        Soils with high organic matter
ing of the factors influencing proper irrigation scheduling and water     content are less likely to erode
management. The timing of                                                 than soils with low organic
irrigation and the total amount                                           matter content.
applied per irrigation should be
based on both the crop’s water
use and the moisture content of
the soil, as well as on expected

SWEET POTATO BMPS 2000                                                                                        7
                                     The table below shows the effects of residue cover on surface       Field Borders
                                runoff and soil loss. An increase in residue cover significantly de-
                                creases runoff and sediment from a field. Typically, 30 percent          (NRCS Code 386)
                                residue cover reduces soil erosion rates by 50 percent to 60 percent     and Filter Strips
                                compared to conventional tillage practices.
                                                                                                         (NRCS Code 393)
                                 Sediment directly damages            In addition, sediment is often
                                 water quality and reduces the        rich in organic matter.                  Field borders and filter
                                 usefulness of streams and lakes      Nutrients such as nitrogen and     strips are strips of grasses or
                                 in many ways. These may              phosphorus and certain             other close-growing vegetation
                                 include:                             pesticides may enter streams       planted around fields and along
                                   Impaired fish spawning areas       with sediment. The                 drainageways, streams and other
                                   Reduced light penetration for
                                                                      detrimental effects of these       bodies of water. They are de-
                                 aquatic life
                                                                      substances accompanying the        signed to reduce sediment,
                                   Increased water purification
                                                                      sediment may include:              organic material, nutrients and
                                 costs                              Rapid algae growth                   chemicals carried in runoff.
                                   Lower recreational value         Oxygen depletion as organic                In a properly designed filter
                                   Clogged channels and           matter and algae decompose             strip, water flows evenly through
                                 increased flooding                 Fish kills from oxygen               the strip, slowing the runoff
                                   Increased dredging to maintain depletion                              velocity and allowing some
                                 navigation                         Toxic effects of pesticides on       contaminants to settle from the
                                   Reduced storage capacity for   aquatic life                           water. In addition, where filter
                                 reservoirs                         Unsafe drinking water                strips are seeded, fertilizers and
                                                                  because of nitrate or pesticide        herbicides no longer need to be
                                                                  content                                applied right next to susceptible
                                                                                                         water sources. Filter strips also
                                 Effects of surface residue cover on runoff and soil loss                increase wildlife habitat.
                                                                                                               Soil particles (sediment)
                                 Residue                      Runoff        Sediment in    Soil          settle from runoff water when
                                 Cover        Runoff          Velocity      Runoff         Loss
                                                                                                         flow is slowed by passing
                                 %            % of rain       ft./minute    % of runoff    tons/acre
                                                                                                         through a filter strip. The largest
                                    0            45              26              3.7            12.4     particles (sand and silt) settle
                                    41           40              14              1.1            3.2      within the shortest distance.
                                    71           26              12              0.8            1.4      Finer particles (clay) are carried
                                    93           0.5             7               0.6            0.3      the farthest before settling from
                                                                                                         runoff water, and they may
                                                                                                         remain suspended when runoff
                                                                                                         velocity is high. Farming prac-
                                                                                                         tices upslope from filter strips
                                                                                                         affect the ability of strips to filter
                                                                                                         sediment. Fields with steep
                                                                                                         slopes or little crop residue will
                                                                                                         deliver more sediment to filter
                                                                                                         strips than more gently sloping
                                                                                                         fields and those with good
                                                                                                         residue cover. Large amounts of
                                                                                                         sediment entering the filter strip
                                                                                                         may overload the filtering capac-
                                                                                          Field border
                                                                                                         ity of the vegetation, and some
                                                                                                         may pass on through.

                            8                                                                                       SWEET POTATO BMPS 2000
                                                                                                                    SOIL AND WATER MANAGEMENT
 Filter strip effectiveness depends on five factors:                        3. Infiltration rate of the soil
 1. The amount of sediment reaching the filter strip. This is                     Soils with higher infiltration
 influenced by:                                                             rates will absorb water and the
          type and frequency of tillage in cropland above the filter strip. accompanying dissolved nutri-
 The more aggressive and frequent tillage is above filter strips, the       ents and pesticides faster than
 more likely soil will erode.                                               soils with low infiltration rates.
          soil organic matter content.                                      Parish soil survey reports include
                                                                            a table listing the infiltration rate
          time between tillage and a rain. The sooner it rains after a
                                                                            group for the soils identified in
 tillage operation, the more likely soil will erode.
                                                                            each parish.
          rain intensity and duration. The longer it rains and thus the
 more sediment is deposited, the less effective filter strips become as
 they fill with soil.                                                       4. Uniformity of water flow
          slope and the length of run above the filter strip. Water flows through the filter strip
 faster down steeper slopes. Filter strips below steep slopes need to be          Shallow depressions or rills
 wider in relation to the cropland drained above to slow water and          need to be graded to allow uni-
 sediment movement adequately.                                              form flow of water into the filter
                                                                            strip along its length. Water
       In general, a wider, uniformly shaped strip is more effective at concentrated in low points or rills
 stopping or slowing pollutants than a narrow strip. As a field’s slope will flow at high volume, so little
 and/or watershed size increases, wider strips are required for effec-      filtering will take place.
 tive filtering. The following table gives the suggested filter strip
 width based on slope. For a more accurate determination of the size
 filter strip you will need for your individual fields, consult your local 5. Maintenance of the filter
 NRCS or Soil and Water Conservation District office.                       strip
                                                                                  When heavy sediment loads
 Suggested Vegetated Filter Strip Widths on Percent Slope                   are deposited, soil tends to build
                                                                            up across the strip, forming a
 Land Slope, %                          Strip Width, Feet                   miniature terrace. If this becomes
           0-5                                   20                         large enough to impound water,
           5-6                                   30                         flow will eventually break over
           6-9                                   40                         the top and become concentrated
           9 - 13                                50                         in that area. Strips should be
           13 - 18                               60                         inspected regularly for damage.
 *Widths are for grass and legume species only and are not                  Maintenance may include minor
 intended for shrub and tree species. Adapted from the                      grading or re-seeding to keep
 NRCS Field Office Technical Guide, 1990                                    filter strips effective.
                                                                            In summary:
 2. The amount of time that water is retained in the filter
                                                                                   Vegetative filter strips can
 strip. This is influenced by:
                                                                            reduce sediment effectively if
        width of the filter area. Filter strips should vary in width,       water flow is even and shallow.
 depending on the percent slope, length of slope and total drainage
 area above the strip.                                                             Filter strips must be
                                                                            properly designed and con-
          type of vegetation and quality of stand. Tall, erect grass can
                                                                            structed to be effective.
 trap more sediment than can short, flexible grass. The best species
 for filter strips are tall perennial grasses. Filter strips may include            Filter strips become less
 more than one type of plant and may include parallel strips of trees       effective as sediment accumu-
 and shrubs, as well as perennial grasses. In addition to potential for     lates. With slow accumulation,
 improving water quality, these strips increase diversity of wildlife       and/or dissolved pesticides into
 habitat.                                                                   surface waters.
SWEET POTATO BMPS 2000                                                                                          9
                             RELATED        CONSERVATION PRACTICES:

                             Land Smoothing
                             (NRCS Code 466):
                                  The removing of irregularities on the land surface by use of
                             special equipment. This improves surface drainage, provides for
                             more effective use of precipitation, obtains more uniform plant-
                             ing depths, provides for more uniform cultivation, improves
                             equipment operation and efficiency, improves terrace alignment
                             and facilitates contour cultivation.

                             Chiseling and Subsoiling (NRCS Code
                                  Loosening the soil, without inverting (plowing) and with a
                             minimum of mixing of the surface soil, to shatter restrictive
                             layers below normal plow depth that inhibit water movement or
                             root development.

                             Surface Drainage - Field Ditch
                             (NRCS Code 607):
                                   A graded ditch for collecting excess water in a field or for
                             irrigation water drainage. This practice intercepts or collects
                             surface water and carries it to an outlet.

                             Grassed Waterways (NRCS Code 412):
                                  Natural or constructed channels that are shaped or graded
                             to required dimensions and established in suitable vegetation for
                             the stable conveyance of runoff. They are designed to convey
                             runoff without causing erosion or flooding and to improve water

                             Buffer Zones
                             (NRCS Code 342)
                                  Similar to vegetated filter strips, buffer zones provide a
                             physical separation between adjacent areas, such as between a
                             crop field and a body of water. Unlike filter strips, buffer zones
                             may not necessarily be designed to filter water that flows
                             through them.

                            10                                                                    SWEET POTATO BMPS 2000
                                                                                                   WEET OTATO     S
                                                                                                 SOIL AND WATER MANAGEMENT
  Riparian Zones (NRCS Code 644)
        A riparian zone consists of the land adjacent to and includ-
  ing a stream, river or other area that is at least periodically influ-
  enced by flooding in a natural state. Similar to vegetated filter
  strips, plants in riparian areas effectively prevent sediment,
  chemicals and organic matter from entering bodies of water.
  Unlike filter strips, riparian zones use plants that are of a higher
  order, such as trees or shrubs, as well as grasses or legumes.
  Vegetated filter strips are often used in riparian areas as initial
  filtering components next to crop field borders.

                                       For more information on these practices and how to
                                   implement them, contact your local NRCS or Soil and
                                   Water Conservation District Office or call your county

 WEET OTATO     S                                                                           11
                                              PESTICIDE MANAGEMENT
                                              AND PESTICIDES
                                       Introduction                                                                            Rain or irrigation
                                                                                                                               starts pesticides
                                                                                                                               moving into and
                                                                                                                                                    systemic pesticide

                                                                                                                               through soil.

                                             To preserve the availability of                   Pesticide is taken up
                                                                                               by plants, broken
                                       clean and environmentally safe                          down by organisms,
                                       water in Louisiana, contamination of                    sunlight or chemical
                                                                                               reactions.                                            Pesticide is carried
                                       surface and groundwater by all                                                                                into and through
                                       agricultural and industrial chemicals                  Rainfall runoff                                        soil. Movement
                                                                                                                                                     through soil is
                                                                                              will also move
                                       must be prevented. Some sources of                     pesticides across                                      affected by soil and
                                       contamination are easily recogniz-                     the soil surface.                                      pesticide
                                                                                                                                                     properties and
                                       able from a single, specific location.                                                                        amount and
                                       Other sources are more difficult to                                                                           timing of water.
                                                                                                                                                     Pesticide residue
                                       pinpoint. Nonpoint-source pollution                   Pesticides can directly enter                           and by-products
                                       of water with pesticides is caused by                 groundwater by spills around poorly
                                                                                                                                                     not absorbed are
                                                                                                                                                     broken down into
                                       rainfall runoff, particle drift or                    constructed or sealed wells, or wells                   the groundwater.
                                                                                             with improper casting, or by back-
                                       percolation of water through the                      siphoning during spray tank filling.
                                       soil. Pest management practices will                                                                          Movement with
                                                                                                                                                     groundwater –
                                       be based on current research and                                                        WATER TABLE           additional
                                       extension recommendations. By                                                                                 breakdown
                                                                                                                                                     generally slowed,
                                       using these recommendations,                                                                                  but depends on
                                       pesticide usage will follow environ-                  Groundwater flow                                        chemical nature
                                                                                                                                                     and groundwater.
                                       mentally sound guidelines.

                                       Pest Management Procedures
                                            Pesticides will be applied only when they are necessary for the protection

                                       of the crop. The pesticide will be chosen following guidelines to assure that the
                                       one chosen will give the most effective pest control with the least potential
                                       adverse effects on the environment.
                                            Water quality, both surface and ground, will be protected by following all
                                       of the label recommendations and guidelines dealing with water
                                               All label statements and use directions designed specifi-
                                       cally to protect groundwater will be followed closely.
                                              Specific Best Management Practices designed to protect
                                       surface water will be followed closely.
                                              Erosion control practices (such as pipe drops, etc.) will
                                       be used to minimize runoff that could carry soil particles with
                                       adsorbed pesticides and/or dissolved pesticides into surface

                                      12                                                                                       SWEET POTATO BMPS 2000
Pesticide                                     These practices will be

Application                                     Select the pesticide to give
                                         the best results with the least
     Management practices such           potential environmental impact
as the pesticide selected, the           outside the spray area.
application method, the pesticide               Select with care and care-
rate used and the application            fully maintain application equipment.
timing influence pesticide move-                Carefully calibrate the
ment. Pesticides should be               application equipment at the
applied only when needed to              beginning of the spray season and
prevent economic loss of a crop.         periodically thereafter. Spray
     Using chemicals at rates            according to recommendations.
above those specified by the                     Minimize spray drift by
label is ILLEGAL and an envi-            following the label instructions and
ronmental hazard because more            all rules and regulations developed
pesticide is exposed to erosion,         to minimize spray drift (the physical movement of spray particles
runoff or leaching. In pesticide         at the time of or shortly after application).
application, “the label is the
law.” Poor timing of a pesticide                Before applying a pesticide, make an assessment of all of
application also can result in           the environmental factors involved in all of the area surrounding
pesticide movement into water            the application site.
sources, as well as give little                  Carefully maintain records of all pesti-
control of the targeted pest.            cide applications, not just a record of Re-
     Certain areas on your farm          stricted Use Pesticides.
such as streams and rivers,
wellheads, and lakes or ponds
are sensitive to pesticides. You
should create buffer zones
around these areas where pesti-
cide use will be reduced or
eliminated. By buffering these                       Pesticide Selection

                                                                                                                     PESTICIDE MANAGEMENT AND PESTICIDES
areas, you may reduce water
                                                          When selecting pesticides, a farmer should consider
quality problems. Areas such as
                                                     chemical solubility, adsorption, volatility and degradation
roads, off-site dwellings and
                                                     characteristics. Chemicals that dissolve in water readily
areas of public gatherings should
                                                     can leach through soil to groundwater or be carried to
be identified. You may want to
                                                     surface waters in rainfall or irrigation runoff. Some chemi-
limit the use of pesticides near
                                                     cals hold tightly to, or are adsorbed on, soil particles, and
these types of areas, too.
                                                     do not leach as much. But even these chemicals can move
                         The water table separates
                         the unsaturated zone
                                                     with sediment when soil erodes during heavy rainfall.
                         from the saturated zone     Runoff entering surface waters may ultimately recharge
                         (groundwater)               groundwater reserves. Chemicals that are bound to soil
                                                     particles and organic matter are subject to the forces of
                           Rainfall runoff
                                                     leaching, erosion or runoff over a longer period, thus
                           Unsaturated zone          increasing the potential for water pollution.

                           WATER TABLE
                           Saturated zone
SWEET POTATO BMPS 2000                                                                                          13
                                            These practices will be followed:                                      Exceptions for
                                              Selection will be based upon recommendations by qualified
                                       consultants, crop advisors and upon the published recommendations
                                       of the LSU AgCenter, Cooperative Extension Service.                               Farmers disposing of used
                                              The selection of the pesticide to be used will be based upon its     pesticide containers for their own
                                       registered uses and its ability to give the quality of pest control         use are not required to comply
                                       required.                                                                   with the require-
                                                                                                                   ments of the
                                              The selection will also be based upon its impact on                  hazardous waste
                                       beneficials, other non-target organisms and on the general environ-         regulations
                                       ment.                                                                       provided that
                                                                                                                   they triple rinse
                                       Pesticide Storage and                                                       or pressure wash
                                                                                                                   each container

                                                                                                                   and dispose of the residues on
                                                                                                                   their own farms in a manner
                                                                                                                   consistent with the disposal
                                                                                                                   instructions on the pesticide
                                                          storage shed                                             label. Note that disposal of
                                                                                                                   pesticide residues into water or
                                                                                                                   where they are
                                                                                                                   likely to reach
                                             Farmers and commercial            ronment. Pesticides should not      surface or
                                       pesticide applicators are subject       be stored in an area susceptible    groundwater
                                       to penalties if they fail to store or   to flooding or where the charac-    may be consid-
                                       dispose of pesticides and pesti-        teristics of the soil at the site   ered a source of
                                       cide containers properly. Each          would allow escaped chemicals       pollution under
                                       registered pesticide product,           to percolate into groundwater.      the Clean Water
                                       whether general or restricted use,      Storage facilities should be dry    Act or the Safe
                                       contains brief instructions about       and well-ventilated and should      Drinking Water Act and therefore
                                       storage and disposal in its label-      be provided with fire protection    illegal.
                                       ing. The Louisiana Pesticide Law        equipment. All stored pesticides          After the triple rinse proce-
                                       addresses specific requirements         should be labeled carefully and     dure, the containers are then

                                       for storage and disposal. The           segregated and stored off of the    “empty” and the farmer can
                                       applicator must follow these            ground. Pesticides should not be    discard them in a sanitary waste
                                       requirements carefully and              stored in the same area as animal   site without further regard to the
                                       ensure that employees follow            feed. The facility should be kept   hazardous waste regulations. The
                                       them as well.                           locked when not in use. Further     empty containers are still subject
                                            The recommended proce-             precautions include appropriate     to any disposal instructions
                                       dures do not apply to the disposal      warning signs and regular in-       contained within the labeling of
                                       of single containers of pesticides      spection of containers for corro-   the product, however. Disposal in
                                       registered for use in the home          sion or leakage. Protective         a manner “inconsistent with the
                                       and garden, which may be dis-           clothing should be stored close     labeling instructions” is a viola-
                                       posed of during municipal waste         by but not in the same room as      tion of EPA guidelines and could
                                       collection if wrapped according         the pesticides because they may     lead to contamination of water,
                                       to recommendations.                     become contaminated. Decon-         soil or persons and legal liability.
                                                                               tamination equipment should be
                                            Storage sites should be            present where highly toxic
                                       carefully chosen to minimize the        pesticides are stored.
                                       chance of escape into the envi-
                                      14                                                                                     SWEET POTATO BMPS 2000
Agricultural Chemicals and Worker Safety
      The EPA has general author-      and exposure to pesticides. The
ity to regulate pesticide use in       rule sets forth minimum stan-       The Occupational
order to minimize risks to human       dards for the protection of farm    Safety and Health
health and the environment. This       workers and pesticide handlers      Act (OSHA)
authority extends to the protec-       that must be followed. The                The federal govern-
tion of farm                           regulations include standards       ment also regulates farm
workers                                requiring oral warnings and         employee safety under the
exposed to                             posting of areas where pesticides   Occupational Safety and
pesticides. All                        have been used, training for all    Health Act (OSHA).
employers                              handlers and early re-entry         OSHA applies to all
must comply                            workers, personal protective        persons (employers)
with ALL                               equipment, emergency transpor-      engaged in business affect-
instructions of the Worker Pro-        tation and decontamination          ing interstate commerce.
tection Standard concerning            equipment.                          The federal courts have
worker safety or be subject to               The EPA                       decided that all farming
penalties. Labels may include,         regulations                         and ranching operations,
for example, instructions requir-      hold the                            regardless of where goods
ing the wearing of protective          producer of                         produced are actually sold
clothing, handling instructions        the agricul-                        or consumed, affect inter-
                     and instruc-      tural plant on a farm, forest,      state commerce in some
                     tions setting a   nursery or greenhouse ultimately    respect, and thus are
                     period of time    responsible for compliance with     subject to OSHA’s require-
                     before work-      the worker safety standards. This   ments. In general, every
                     ers are al-       means the landowner must            employer has a duty to
                     lowed to re-      ensure compliance by all em-        provide employees with an
enter fields after the application     ployees and by all independent      environment free from
of pesticides (Restricted Entry        contractors working on the          hazards that are causing or
Interval).                             property. Contractors and em-       are likely to cause death or
     Employers should also read        ployees also may be held respon-    serious injury.
the Worker Protection Standard         sible for failure to follow the
regulations governing the use of       regulations.

                                                                                                               PESTICIDE MANAGEMENT AND PESTICIDES

SWEET POTATO BMPS 2000                                                                                    15
                                       In summary:                            a container free of leaks, abiding       bags to the fullest extent possible.
                                                                              by any specific recommendations          The sides of the container will cut
                                            A. All label directions will be
                                                                              on the label. The storage area must      and opened fully, without folds or
                                       read, understood and followed.
                                                                              be maintained in good condition,         crevices, on a flat surface; any
                                             B. The Louisiana Department      without unnecessary debris. This         pesticides remaining in the opened
                                       of Agriculture and Forestry            enclosure will be at least 150 feet      container will be transferred into
                                       (LDAF) is responsible for the          away and down slope from any             the spray mix. After this procedure
                                       certification of pesticide applica-    water wells.                             the containers will be disposed of
                                       tors. All applicators of restricted                                             in a sanitary landfill.
                                                                                    E. All uncontained pesticide
                                       use pesticides in Louisiana must
                                                                              spills of more than one gallon                 H. Application equipment
                                       successfully complete a certifica-
                                                                              liquid or four pounds dry weight         will be triple rinsed and the rinsate
                                       tion test administered by the
                                                                              will be reported to the director of      applied to the original application
                                       LDAF. The LSU AgCenter con-
                                                                              Pesticide and Environmental              site or stored for later use to dilute
                                       ducts training sessions and pub-
                                                                              Programs, Louisiana Department           a spray solution
                                       lishes study guides in various
                                                                              of Agriculture and Forestry within
                                       categories covered by the test.
                                                                              24 hours by telephone (225-925-
                                       Contact your county agent for
                                                                              3763) and by written notice within
                                       dates and times of these trainings.
                                                                              three days. Spills on public road-
                                             C. All requirements of the       ways will be reported to the
                                       Worker Protection Standard (WPS)       Louisiana Department of Transpor-                          Wash pad with
                                       will be followed, including, but not   tation and Development. Spills into                        collection pond
                                       limited, to:                           navigable waters will be reported
                                             • Notifying workers of a         to LDEQ, Coast Guard, USEPA.                   I. Mix/load or wash pads
                                       pesticide application (either oral           F. Empty metal, glass or           (NRCS production code Interim)
                                       or posting of the field), abiding by   plastic pesticide containers will be     will be located at least 150 feet
                                       the restricted entry interval (REI).   either triple rinsed or pressure         away and down slope from any
                                             • Maintaining a central          washed, and the rinsate will be          water wells and away from surface
                                       notification area containing the       added to the spray solution to           water sources such as ponds,
                                       safety poster; the name, address       dilute the solution at the time or       streams, etc. The pads will be
                                       and telephone number of the            stored according to the LDAF rules       constructed of an impervious
                                       nearest emergency medical facility;    to be used later. Rinsed pesticide       material, and there will be a system
                                       and a list of the pesticide applica-   containers will be punctured,            for collecting and/or storing the
                                       tions made within the last 30 days     crushed or otherwise rendered            runoff.
                                       that have an REI.                      unusable and disposed of in a                 J. Empty containers will not
                                                                              sanitary landfill. (Plastic containers

                                            • Maintaining a decontami-                                                 be kept for more than 90 days after
                                                                              may be taken to specific pesticide       the end of the spray season.
                                       nation site for workers and han-       container recycling events. Contact
                                       dlers.                                 your county agent for dates and               K. Air gaps will be main-
                                            • Furnishing the appropriate      locations in your area.)                 tained while filling the spray
                                       personal protective equipment                                                   tank to prevent back-siphoning.
                                                                                  G. All pesticides will be
                                       (PPE) to all handlers and early        removed from paper and plastic
                                       entry workers, and ensuring that
                                       they understand how and why they                                 Air gap

                                       should use it.
                                            • Assuring that all employees                         backflow                                  ...Not This
                                       required to be trained under the                           protection                                chemicals
                                       Worker Protection Standard have                                                                      siphoned back
                                                                                                                                            into water supply
                                       undergone the required training.
                                             D. Pesticides will be stored
                                       in a secure, locked enclosure and in

                                      16                                                                                          SWEET POTATO BMPS 2000
                                                                                                                   NUTRIENT MANAGEMENT

                                      Similarly, practices that limit the   provide optimum economic
                                      buildup of nutrients in the soil,     yields.
                                      which can leach to groundwater             Decomposition of organic
                                      or be picked up in runoff, and        matter results in simpler inor-
                                      practices that ensure the safe use    ganic N forms such as ammo-
                                      of agricultural chemicals also are    nium (NH4+) and nitrate (NO3-).
                                      considered BMPs. In general,          These are soluble in soil water
                                      soil conservation and water           and readily available for plant
                                      quality protection are mutually       uptake. The ammonium form is
                                      beneficial; therefore the BMPs        attracted to and held by soil
                                      described here are the best means     particles, so it does not readily
                                      of reducing agricultural              leach through the soil with
                                      nonpoint-source pollution result-     rainfall or irrigation water.
                                      ing from fertilizer nutrients.        Nitrates, on the other hand, are
                                                                            not attached to soil particles and
Introduction                                Nitrogen (N) is a part of all
                                                                            do move downward with soil
                                                                            water and can be leached into
      A sound soil fertility pro-     plant and animal proteins. There-     groundwater or run off into
gram is the foundation upon           fore, human survival depends on       surface waters.

which a profitable farming            an abundant supply of N in
                                                                                 Excessive nitrate concentra-
business must be built. Agricul-      nature. Approximately 80 percent
                                                                            tions in water can accelerate
tural fertilizers are a necessity     of the atmosphere is nitrogen
                                                                            algae and plant growth in streams
for producing abundant, high          gas, but most plants cannot use
                                                                            and lakes, resulting in oxygen
quality food, feed and fiber          this form of nitrogen. Supple-
                                                                            depletion. Nitrate concentrations
crops. Using fertilizer nutrients     mental nitrogen must be supplied
                                                                            above a certain level in drinking
in the proper amounts and             through the soil. A crop well
                                                                            water may injure some animals
applying them correctly are both      supplied with N can produce
                                                                            or human infants.
economically and environmen-          substantially higher yields, on
tally important to the long-term      the same amount of water, than        Phosphorus
profitability and sustainability of   one deficient for N. Properly
                                                                                  Phosphorus (P), like nitro-
crop production. The fertilizer       fertilized crops use both N and
                                                                            gen, is essential for plant growth.
nutrients that have potential to      water more efficiently, thus
                                                                            Naturally occurring P exists in a
become groundwater or surface         improving environmental quality
                                                                            phosphate form either as soluble
water pollutants are nitrogen and     and profitability.

                                                                            inorganic phosphate, soluble
phosphorus. In general, other               Supplemental N will be          phosphate, particulate phosphate
commonly used fertilizer nutri-       necessary on almost all non-          or mineral phosphate. The min-
ents do not cause concern as          legume crops in Louisiana for         eral forms of phosphorus (cal-
pollutants.                           maximum profits. Rely on N            cium, iron and aluminum phos-
     Because erosion and runoff       recommendations based on              phates) are low in solubility. The
are the two major ways                Louisiana research. These recom-      amount of these elements (cal-
nonpoint-source pollutants move       mendations take into account          cium, iron and aluminum)
into surface water resources,         maximum economic yield poten-         present in reactive forms varies
practices that reduce erosion or      tials and soil texture. Nitrogen      with different soils and soil
runoff are considered Best            recommendations from the LSU          conditions. They determine the
Management Practices (BMPs).          AgCenter are usually ample to

SWEET POTATO BMPS 2000                                                                                        17
                       amount of phosphorus that can         to living organisms, but
                       be fixed in the soil.                 becomes available as it
                             The immediate source of         detaches from sedi-
                       phosphorus for plants is that         ment. Only a small part
                       which is dissolved in the soil        of the phosphate
                       solution. A soil solution contain-    moved with sediment
                       ing only a few parts per million      into surface water is
                       of phosphate is usually consid-       immediately available
                       ered adequate for plant growth.       to aquatic organisms.
                       Phosphate is absorbed from the        Additional phosphate
                       soil solution and used by plants.     can slowly become
                       It is replaced in the soil solution   available through bio-                                       Algae bloom

                       from soil minerals, soil organic      chemical reactions, however. The     groundwater (NRCS Production
                       matter decomposition or applied       slow release of large amounts of     Code 590). A nutrient manage-
                       fertilizers.                          phosphate from sediment layers       ment plan should be developed
                                                             in lakes and streams could cause     for the proposed crop by using
                            Phosphate is not readily
                                                             excessive algae blooms and           soil analyses from approved
                       soluble. Most of the ions are
                                                             excessive growth of plants,          laboratories.
                       either used by living plants or
                                                             thereby affecting water quality.
                       adsorbed to sediment, so the
                       potential of their leaching to             Nutrients will be used to
                       groundwater is low. That portion      obtain optimum crop yields
                       of phosphate bound to sediment        while minimizing the movement
                       particles is virtually unavailable    of nutrients to surface and

                       Nutrient Application Rates
                             Nutrient application rates           Soil testing is the founda-
                       will be based on the results of a     tion of a sound nutrient man-
                       soil analysis. Select only those      agement program.
                       materials recommended for use              A soil test is a series of
                       by qualified individuals from the     chemical analyses on soil that
                       Louisiana Cooperative Extension       estimates whether levels of
                       Service, Louisiana Agricultural       essential plant nutrients are
                       Experiment Station, certified         sufficient to produce a desired      predict which nutrient(s) and
                       crop advisors and certified           crop and yield. When not taken       how much of that nutrient(s)
                       agricultural consultants and/or       up by a crop, some nutrients,        should be added to produce a
                       published LSU AgCenter data.          particularly nitrogen, can be lost   particular crop and yield. Take
                                                             from the soil by leaching, runoff    soil tests at least every three
                                                             or mineralization. Others, like      years or at the beginning of a
                                                             phosphorus, react with soil          different cropping rotation.
                                                             minerals over time to form
                                                             compounds that are not available
                                                             for uptake by plants. Soil testing
                                                             can be used to estimate how
                                                             much loss has occurred and
                      18                                                                                   SWEET POTATO BMPS 2000
                                                                                                            WEET OTATO     S
                                                                                                                   NUTRIENT MANAGEMENT
                         Recommended Practices

    1. Soil test for nutrient status and pH to:          5. Inject fertilizers or incorporate surface
         • determine the amounts of additional           applications when possible to:
    nutrients needed to reach designated yield goals          • increase accessibility of fertilizer nutri-
    and the amount of lime needed to correct soil        ents to plant roots
    acidity problems                                         • reduce volatilization losses of ammonia
         • learn the Cation Exchange Capacity            N sources
    (CEC) and the organic matter concentration so             • reduce nutrient losses from erosion and
    as to determine how much of these nutrients the      runoff
    particular soil is capable of holding
                                                         6. Rotate crops when feasible to:
         • optimize farm income by avoiding exces-
                                                              • improve total nutrient recovery with
    sive fertilization and reducing nutrient losses by
                                                         different crop rooting patterns
    leaching and runoff
                                                              • reduce erosion and runoff
          • identify other yield-limiting factors such
    as high levels of salts or sodium that may affect         • reduce diseases, insects and weeds
    soil structure, infiltration rates, surface runoff   7. Control nutrient losses in erosion and
    and, ultimately, groundwater quality                 runoff by:
    2. Base fertilizer applications on:                      • using appropriate structural controls
        • soil test results                                  • adopting conservation tillage practices
         • realistic yield goals and moisture pros-      where appropriate
    pects                                                     • properly managing crop residues
         • crop nutrient requirements                         • land leveling
         • past fertilization practices                       • implementing other soil and water con-
         • previous cropping history                     servation practices where possible
    3. Manage low soil pH by liming according                 • using filter strips
    to the soil test to:                                 8. Skillfully handle and apply fertilizer by:
         • reduce soil acidity                                • properly calibrating and maintaining
         • improve fertilizer use efficiency             application equipment
         • improve decomposition of crop residues             • properly cleaning equipment and dispos-
                                                         ing of excess fertilizers, containers and wash
         • enhance the effectiveness of certain soil
    applied herbicides
                                                              • storing fertilizers in a safe place
    4. Time nitrogen applications to:
         • correspond closely with crop uptake
         • increase nutrient use efficiency
         • minimize leaching and runoff losses

 WEET OTATO     S                                                                                             19

                       Nutrient Management
                       Plans (NMPs)
                             Both the U.S. Environmental Protection Agency (EPA) and the
                       U.S. Department of Agriculture (USDA) are encouraging a volun-
                       tary approach to handling nonpoint-source issues related to agricul-
                       ture.                                                                          Another important part of a
                             The implementation of Nutrient Management Plans (NMP) by           successful NMP are BMPs.
                       all agricultural producers will ensure that fertilizers are managed in   BMPs, such as soil testing, help
                       an environmentally friendly fashion.                                     you select the right nutrient rate
                                                                                                and application strategy so that
                                                                                                crops use nutrients efficiently.
                                                                                                This not only reduces nutrient
                                                                                                losses and protects the environ-
                       Developing a Nutrient Management Plan                                    ment but also increases farm
                             An NMP is a strategy for making wise use of plant nutrients to     profitability. BMPs may include
                       enhance farm profits while protecting water resources. It looks at       managing the farm to reduce soil
                       every part of your farming operation and helps you make the best         erosion and improve soil tilth
                       use of manures, fertilizers and other nutrient sources. Successful       through conservation tillage,
                       nutrient management requires thorough planning and recognizes            planting cover crops to use
                       that every farm is different. The type of farming you do and the         excess nutrients or using filter
                       specifics of your operation will affect your NMP. The best plan is       strips and buffers to protect water
                       one that is matched to the farming operation and the needs of the        quality.
                       person implementing the plan.

                       The Parts of an NMP
                             An NMP looks at how nutrients are used and managed through-
                       out the farm. It is more than a nutrient management plan that looks
                       only at nutrient supply and needs for a particular
                       field. Nutrients are brought to the farm through
                       feeds, fertilizers, animal manures and other off-farm
                       inputs. These inputs are used, and some are recycled
                       by plants and animals on the farm. Nutrients leave
                       the farm in harvested crops and animal products.
                       These are nutrient removals. Ideally, nutrient inputs
                       and removals should be roughly the same. When
                       nutrient inputs to the farm greatly exceed nutrient
                       removals from the farm, the risk of nutrient losses to
                       groundwater and surface water is greater. When you
                       check nutrient inputs against nutrient removals, you
                       are creating a mass balance. This nutrient mass
                       balance is an important part of an NMP and impor-
                       tant to understand for your farming operation.
                      20                                                                                  SWEET POTATO BMPS 2000
                                                                                                           WEET OTATO     S
                                                                                                               NUTRIENT MANAGEMENT
The Basic Steps
     NMPs consist of four major
parts: evaluation of nutrient       where nutrient use will be
needs, inventory of nutrient        reduced or eliminated. By
supply, determination of nutrient   buffering these areas, water
balance, and preventive mainte-     quality problems may be de-
nance and inspection.               creased.
                                                                         nitrogen, phosphorus
                                                                         and potassium should be
                                    Soil Testing                         listed in the plan for each field.
                                          Complete and accurate soil
Evaluation of                       tests are important for a success-
                                                                         Most soil and plant analysis labs
                                                                         will give you recommended
Nutrient Needs                      ful nutrient management plan.        application rates based on the
                                    You will need soil tests every       soil test results. Your county
Maps and Field Information
                                    three years to determine how         agent can help you with this.
    You will need a detailed        much nutrient addition is
map of your farm. The map           needed. The needed nutrients
should include:                     can be supplied from commer-         Inventory of
     • farm property lines          cial fertilizer and/or organic
     • your fields with the field   sources. Be sure to take repre-      Nutrient Supply
identification                      sentative soil samples and have            Many of the nutrients
                                    them tested by a reputable           needed to grow your crops are
    • the location of all surface   laboratory familiar with Louisi-
waters such as streams, rivers,                                          already present on your farm in
                                    ana soils and crop production.       the soil, in animal manures or in
ponds or lakes                      Your county agent can help you       crop residues. Knowing the
     • direction of surface flows   submit samples to the LSU Soil       amounts of nutrients already
      • arrows showing the direc-   Testing Laboratory.                  present in these sources is impor-
tion that streams or rivers flow                                         tant so that you do not buy or
     • a soils map, if available                                         apply more nutrients than
      This map will serve as the
basis for the entire plan, so each
field should have a unique                                               Determine the Quantity of
identification. In addition to the                                       Nutrients Available on Your
map, prepare a list of the crops to                                      Farm
be grown in each field with a                                                 Supply planning starts with
realistic yield goal for each crop.                                      an inventory of the nutrients
Most of this information is                                              produced on the farm. This
available at your local USDA                                             information will allow you to
Farm Service Center.                Determine Nutrients                  balance your nutrient purchases
                                    Needed for Each Field                with what is available on your
                                          Once you have set realistic    farm for the realistic production
Locate Critical Areas               yield goals and you have your        potential of the crops grown.
      Certain areas on your farm    soil test results, you can deter-
such as streams and rivers,         mine the nutrients your crops
wellheads and lakes or ponds are will need. The amount of nutri-
sensitive to nutrient overload.     ents needed should be based on
You should create buffer zones      your local growing conditions. At
around these areas on your map      a minimum, the amounts of lime,

 WEET OTATO     S                                                                                         21
                       Nutrient Balance
                       Balance Between Supply and
                             Once you have determined
                       both the supply and need of          Where Can You Obtain
                       nutrients for each of your fields,
                       a critical aspect of NMPs is         Information Needed for Your
                       balancing the two. This can be       NMP?
                       done in several ways. Most
                       NMPs are developed based on                The LSU AgCenter, the USDA Natural
                       nitrogen, but other factors such     Resources Conservation Service, the Louisi-
                       as phosphorus or metals could        ana Department of Agriculture and Forestry,
                       control how much you can put         certified crop advisors or other private con-
                       out under certain conditions. A      sultants will be able to assist you in develop-
                       phosphorus index is being            ing parts of a comprehensive nutrient manage-
                       developed to help producers          ment plan.
                       determine when nutrient man-              An NMP is a good tool to help you use
                       agement based on phosphorus          your on- and off-farm resources more effi-
                       would be advisable.                  ciently and prevent future problems. A suc-
                                                            cessful NMP will help you obtain the maxi-
                                                            mum profit while protecting the environment.
                       Maintenance and
                             Keeping good, detailed
                       records that help you monitor
                       your progress is essential to
                       know if your NMP is to accom-
                       plish the goals you have set. You
                       should keep all results from soil
                       and plant and examine how they
                       change with time with your
                       management practices. Records
                       should be kept on crop yields,
                       nutrient application rates, timing
                       and application methods. Keep
                       detailed schedules and records
                       on calibration of spraying and
                       spreading equipment. When you
                       have a major change in produc-
                       tion, update your plan to reflect
                       these changes.

                      22                                                                       SWEET POTATO BMPS 2000
              GENERAL FARM BMPS

Water well                           Used engine oil,                       Irrigation water
protection -                         grease, batteries,                     quality
      Farm*A*Syst/                   tires, etc.                                 Irrigation water (surface
Home*A*Syst                                                                 and/or well) should be tested in
                                          • Used engine oil should be
should be used                                                              the spring to determine the
                                     stored in a waste oil container
every three                                                                 salinity (salt) level before irrigat-
                                     (tank or drum) until recycled.
years to deter-                                                             ing fields. Take samples to an
mine potential                            • Empty paint cans, anti-         approved laboratory for analysis.
threats to water                     freeze containers, used tires, old
wells. Threats                       batteries, etc., will be stored in a
identified will                      secure area until they can be
be ranked and                        disposed of properly.
measured to
correct the
most serious.

Fuel storage tanks
      Above-ground fuel storage tanks in Louisiana are regulated
by the State Fire Marshal and by the EPA if surface water is at risk.
Above-ground tanks containing 660 gallons or more require
secondary containment. The State Fire Marshal recommends that
some sort of secondary containment be used with all fuel storage
tanks. This could include the use of double-walled tanks, diking
around the tank for impoundment or remote impoundment facili-
     These practices are to be followed:
                                                                                                                     GENERAL FARM BMPS

       Any existing above-ground fuel storage tank of 660 gallons or                It is recommended that the
more (1320 gallons if more than one) must have a containment wall           storage tank be on a concrete
surrounding the tank capable of holding 100 percent of the tank’s           slab to prevent any spillage from
capacity (or the largest tank’s capacity if more than one) in case of       entering surface and groundwa-
spillage.                                                                   ter.
      The tank and storage area should be located at least 40 feet                 The storage area should
from any building. Fuel storage tanks should be placed 150 feet and         be kept free of weeds and other
downslope from surface water and water wells.                               combustible materials.
SWEET POTATO BMPS 2000                                                                                          23
                            The tank should be                  All tanks that catch on fire
                     conspicuously marked with the        must be reported to the State Fire
                     name of the product that it          Marshal within 72 hours of the
                     contains and “FLAMMABLE –            fire.
                     KEEP FIRE AND FLAME                          Underground storage
                     AWAY.”                               tanks are defined as containing
                            The bottom of the tank        more than 10 percent of their
                     should be supported by concrete      total volume beneath the soil
                     blocks approximately 6 inches        surface. Underground tanks
                     above the ground surface to          represent more of a problem than
                     protect the bottom of the tank       above-ground tanks because
                     from corrosion.                      leaks can often go for long
                                                          periods without being detected.
                             If a pumping device is
                                                          This poses a serious threat to
                     used, it should be tightly and
                                                          groundwater sources in the
                     permanently attached and meet
                                                          vicinity of the tank. If you have
                     NFPA approval. Gravity dis-
                                                          an underground fuel storage tank,
                     charge tanks are acceptable, but
                                                          you need to contact the State Fire
                     they must be equipped with a
                                                          Marshal’s Office for regulations
                     valve that will automatically
                                                          affecting these storage tanks.
                     close in the event of a fire.
                             Plans for the installation
                     of all storage tanks that will                                                  10% of tank is below
                     contain more than 60 gallons of                                                 ground level

                     liquid must be submitted to the
                     State Fire Marshal for approval.

                                                                                               This tank would be classified as
                                                                                               an underground fuel tank.

                    24                                                                         SWEET POTATO BMPS 2000
                                                                                                WEET OTATO     S
                                                                                                                                      RESEARCH OVERVIEW
William H. Brown
       The word “environment”                     The stage was set for contem-
means different things to different        porary LSU AgCenter environmental
people. To some it stirs visions of        research programs when “Focus
clear, pristine streams and lakes; to      2000: Research for the 21st Cen-
others vistas of forests or prairies; to   tury,” a strategic plan for the Louisi-
                                                                                      William H. Brown, Associate Director and
still others, clean, fresh mountain air.   ana Agricultural Experiment Station        Associate Vice Chancellor, LSU AgCenter
To agriculturalists, who produce           (LAES), was adopted in 1990. One
food and fiber for the citizens of the     thrust of this plan was to protect the    for the LAES environmental re-
United States and a substantial part       environment by “ developing               search programs conducted since.
of the rest of the world, a quality        production systems that protect the
environment means acres of produc-                                                         AgCenter environmental
                                           soil and minimize the need for
tive soil, clean air and an adequate                                                 research programs can be grouped as
                                           fertilizer, water, tillage, and other
supply of quality water for irriga-                                                  follows: conservation tillage,
                                           inputs.” Adoption of Focus 2000 led
tion, livestock consumption and                                                      management of wastes and residues
                                           to establishment of the Soil, Water
human use. All these visions are                                                     for beneficial uses, water quality,
                                           and the Environment Research
both accurate and incomplete. To                                                     integrated pest management and
                                           Advisory Committee (RAC), which
complete the picture, one must                                                       nutrient management.
                                           provided researchers a forum for
appreciate the array of agricultural       exchanging information on environ-
research conducted in Louisiana and        mental programs and for forming           CONSERVATION         TILLAGE
at other agricultural experiment           new collaborations with colleagues.
stations across the country. Many of                                                        AgCenter programs in conser-
these topics are not commonly                                                        vation tillage for cotton production
thought of as environmental, yet                                                     on Macon Ridge soils demonstrated
they have a major impact on the              Agricultural                            not only that cotton could be suc-
quality of our air, soil and water                                                   cessfully produced with little or no
                                             scientists were                         tillage, but, when combined with a
                                             among the                               winter cover crop, soil erosion could
AIR,   SOIL AND WATER                                                                be reduced by up to 85 percent, soil
                                             original                                organic matter could be slowly but
       Agricultural scientists were                                                  steadily rebuilt, and that nitrogen
among the original environmental-            environmentalists.                      fertilizer requirements could be
ists. For most of this century,                                                      stabilized at about 70 pounds or less
agricultural researchers have recog-                                                 per acre, depending on the cover
nized the importance of sustaining               One product of the Soil, Water      crop grown. This pioneering re-
the natural resource base on which         and Environment RAC was sponsor-          search, along with advances in
agricultural production relies. For        ship of an environmental conference       herbicide technology, paved the way
example, the 1930s saw the initia-         in 1995. This conference included         for the adoption of practical conser-
tion of widespread programs at land-       LAES research presentations on land       vation tillage production systems
grant universities and at the federal      use management, waste manage-             (sometimes called “stale seedbed”
level to reduce soil erosion, to keep      ment, forestry, pest management,          systems) now widely used on
the soil covered with vegetation and       water quality and conservation            Louisiana cropland, resulting in
to improve drainage to enhance soil        tillage and presentations from            major soil erosion reductions.
productivity. Through the ensuing          numerous state and federal agencies              Another area in which
years, many research programs have         including the Louisiana Department        AgCenter scientists have pioneered
been conducted to provide informa-         of Environmental Quality, the             has been in the development of
tion for improving the environmental       Barataria-Terrebonne National             conservation tillage systems for rice
“friendliness” of food and fiber           Estuary Program and the Natural           in southwest Louisiana. Although
production and processing.                 Resources Conservation Service.           still being developed and refined,
                                           Conference participants set the stage     conservation tillage promises to
 WEET OTATO     S                                                                                                                25
                     offer rice producers a practical way      can be incorporated into the soil to
                     of growing rice while reducing the        enhance soil structure and plant
                     sediment load of the water leaving        growth. The LSU AgCenter’s
                     their fields.                             Callegari Organic Recycling Center
                                                               provides the facilities for both
                                                               research and training in the com-
                     WASTE    MANAGEMENT                       posting process. The AgCenter has                 Water table management is a
                                                               conducted 12 one-week programs           technology that uses underground
                              Waste management pro-                                                     tubes to drain excess water from
                     grams deal with the manures and           which have trained more than 200
                                                               people from 29 states and five           fields to prevent water logging
                     residues that result from animal                                                   damage to crops during wet weather
                     production and processing and the         countries in the proper techniques of
                                                               composting organic residues.             and also to irrigate from below the
                     development of methods to benefi-                                                  surface during drought. Cooperative
                     cially use the solid wastes that                                                   studies with USDA scientists focus
                     originate from both agricultural                                                   on how water table management can
                                                               WATER    QUALITY
                     operations and urban activities. A                                                 enhance crop production (sugarcane
                     program is under way to determine                  Water quality research          especially) while improving the
                     the extent to which dairy manures         studies cut across many crops and        quality of the water drained from the
                     and related fecal coliform indicator      soil types. These studies provide        field.
                     organisms move into water bodies          basic information on how precipita-
                     when irrigated onto pastureland in        tion moves off the land, through the
                     “no discharge” systems. Further           soil and what it carries with it. This   INTEGRATED    PEST MANAGEMENT
                     knowledge about how to minimize           information is fundamental to our
                                                               understanding of how water trans-                 Integrated pest management
                     the environmental impacts of
                                                               ports nutrients and chemicals            (IPM) refers to the integrated use of
                     dairying is vital for Louisiana’s
                                                               through the soil and how rainfall or     all appropriate methods to control
                     economically important dairy
                                                               irrigation water can be managed to       agricultural pests such as weeds,
                     industry in the environmentally
                                                               improve both crop production and         insects, diseases and nematodes.
                     sensitive Lake Pontchartrain drain-
                                                               the environment.                         IPM systems employ judicious use
                     age basin.
                                                                                                        of pesticides along with cultural
                                                                        AgCenter soil scientists and    practices, genetic resistance and
                                                               agricultural engineers have teamed       other available means to reduce
                                                               with USDA researchers to determine       dependence on pesticides. Reduced
                                                               the complex mechanisms by which          pesticide usage is based on careful
                            Another area of intense re-        water moves through Louisiana’s          scouting and precision application
                     search activity deals with establish-     alluvial soils, how rapidly it moves     methods. Although most pesticides
                     ing benchmarks for poultry litter         and the extent to which it transports    used today are much less toxic to
                     disposal in north Louisiana. Poultry      certain nutrients and pesticides.        non-target organisms and used in
                     litter, a byproduct of broiler produc-    Other studies have shown that            much smaller quantities (ounces
                     tion, is a valuable source of nutrients   subsurface drainage can reduce soil      rather than pounds per acre), the end
                     for pasture and forest lands, but         erosion and improve water dis-           result of IPM is that relatively fewer
                     excessive application can overload        charges into drainage systems.           pesticides are introduced into the
                     the soil’s ability to assimilate          Studies of corn production over five     environment. Some crops are now
                     phosphorus. And, if allowed to move       years showed that subsurface             resistant to selected herbicides or to
                     into water bodies, phosphorus could       drainage reduced soil loss by 30         certain insect pests because of recent
                     cause eutrophication problems.            percent, nitrogen loss by 20 percent     advances in plant genetic engineer-
                     Several studies are under way that        and phosphorus loss by 36 percent.       ing. The fruits of several decades of
                     will define safe application levels,      A similar nine-year study with           intensive molecular biology research
                     the fertility value and alternative       soybeans showed 48 percent less          have provided LAES entomologists
                     beneficial uses for poultry litter.       soil loss, 39 percent less nitrogen      and weed scientists with additional
                                                               loss, 35 percent less phosphorus loss    tools to develop practical production
                             Many agricultural and urban
                                                               and 36 percent less potassium loss.      systems that use these special plants
                     residues can be treated by com-
                     posting to reduce volume, eliminate                                                to combat competing or damaging
                     odors and neutralize undesirable                                                   pests while minimizing pesticide
                     components. The resulting compost                                                  use.

                    26                                                                                             SWEET POTATO BMPS 2000
                                                                                                                            RESEARCH OVERVIEW
NUTRIENT    MANAGEMENT                    extension specialists, in cooperation    the production of food and fiber for
                                          with farmers representing the            a growing world population will
         Nutrient management,
                                          Louisiana Farm Bureau Federation,        have environmental consequences.
actually one of the oldest of the
                                          and representatives of state and         Agriculture and cities must co-exist,
agricultural sciences, determines the
                                          federal agencies such as the Natural     however, if society, as we know it, is
need for supplementing the soil’s
                                          Resources Conservation Service           to continue and to prosper. Some
natural fertility with the appropriate
                                          (NRCS), Louisiana Department of          forecasts suggest that the world’s
types and amounts of nutrients to
                                          Agriculture and Forestry (LDAF),         food demand will triple over the next
achieve the genetic potential of
                                          Louisiana Department of Environ-         40 years. To meet that demand, we
today’s improved seeds. It is impor-
                                          mental Quality (LDEQ), Department        must continue to invest in science
tant, both environmentally and
                                          of Natural Resources (DNR),              and technology so that we can learn
economically, that nutrients not be
                                          Agricultural Research Service            how to use reasonable and effective
applied to producers’ fields in
                                          (ARS) and others launched an effort      measures to blend sustainable
excessive amounts.
                                          to integrate the best information        economic growth with acceptable
          Nutrient management             available into a series of “best         environmental impacts.
research starts with LAES agrono-         management practices” or BMPs.
mists who determine the nutrient          The BMPs cover all of the major
needs for the many crops produced         plants and animals produced in
on the diverse soil types of Louisi-      Louisiana.
ana. Soil scientists determine
nutrient interactions and availability              Two research stations,
in the various soil types and textures.   Southeast and Iberia, have operated               Compiled by:
The Soil Testing Laboratory pro-          sites for the National Atmospheric
                                                                                       Fred Sanders, Ph.D., and
vides individual field analyses that      Deposition Program (NADP) since
                                          the early 1980s. This program,
                                                                                         Mike Cannon, Ph.D.
determine the nutrients that need to
be added and their amounts for            supported in part by state agricul-
                                          tural experiment stations nationwide,      Other AgCenter contributors
specific crops and locations. This
                                          has provided measurements of                         were:
information is provided to extension
agents so they can make specific          precipitation acidity and atmo-             Eddie Funderburg, Ph.D.
fertility recommendations to farm-        spheric nutrient deposition at more           Mary Grodner, Ph.D.
ers. Finally, new technologies are        than 200 sites for 20 years. The              Dearl Sanders, Ph.D.
now being investigated, usually           NADP is now developing a national                 Bill Branch
called “precision farming systems,”       mercury deposition network, and the
that will allow variable, on-the-go       AgCenter will provide two monitor-          Sweet Potato BMP review
precision nutrient applications           ing sites, the Hammond and the
within fields based on intensive soil     Sweet Potato research stations, that
testing, crop production history and      will be operated by the Louisiana
                                          DEQ. The AgCenter also operates a               Jack Bagent, Ph.D.
other pertinent factors.
                                          network of meteorological recording                 Bill Hadden
         Taken together, today’s          sites at the research stations called           Chris Clark, Ph.D.
producers are armed with an array of      the Louisiana Agriclimatic Informa-           Michael Jordan, NRCS
science-based data, sophisticated         tion System (LAIS). The LAIS                     Sam Rogers, ARS
testing services and the latest           provides research scientists with an            Gary Goay, LDEQ
technology to enable them to apply        extensive database of the state’s                Ed Britton, DNR
only the required nutrients in only       recent meteorology in support of
the needed amounts at only the                                                           Lamar Bush, Grower
                                          their research programs.                        Irv Daniel, Grower
proper locations for optimum crop
performance.                                                                             Mark Fields, Grower
                                          FUTURE   FOOD DEMANDS                         Larry Fontenot, Grower
                                                                                          Ray Poret, Grower
OTHER                                              The earth’s environment has
         ACTIVITIES                                                                       Jerry Self, Grower
                                          never been static. It has been subject
         Integrating the best science                                                    Jim Sowell, Grower
                                          to both dramatic upheavals and slow,
with economic constraints and             evolutionary changes. Our crowded              Mitch Stelly, Grower
environmental concerns is challeng-       cities and sprawling suburbs have             Ken Thornhill, Grower
ing. In 1993, AgCenter scientists and     environmental impacts. Likewise,
SWEET POTATO BMPS 2000                                                                                                 27
                       T   he complex nature of nonpoint pollution means programs designed to
                       reduce its impact on the environment will not be easy to establish or
                       maintain. Controlling these contaminants will require solutions as diverse
                       as the pollutants themselves. Through a multi-agency effort, led by the
                       LSU AgCenter, these BMP manuals are targeted at reducing the impact
                       of agricultural production on Louisiana’s environment. Agricultural
                       producers in Louisiana, through voluntary implementation of these
                       BMPs, are taking the lead in efforts to protect the waters of Louisiana.
                       The quality of Louisiana’s environment depends on each of us.

                                                    Visit our website:

                                         Produced by LSU AgCenter Communications

                      Louisiana State University Agricultural Center, William B. Richardson, Chancellor
                   Louisiana Agricultural Experiment Station, R. Larry Rogers, Vice Chancellor and Director
                    Louisiana Cooperative Extension Service, Jack L. Bagent, Vice Chancellor and Director

                                                 Pub. 2832       (1M)       12/00

     Issued in furtherance of Cooperative Extension work, Acts of Congress of May 8 and June 30, 1914, in cooperation with the
       United States Department of Agriculture. The Louisiana Cooperative Extension Service provides equal opportunities in
                                                    programs and employment.

          Originally developed through a cooperative agreement with the Louisiana Department of Environmental Quality,
                                                        Contract 522100.

28                                                                                                 SWEET POTATO BMPS 2000

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