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					Pasture Fertility - Internet Inservice Training

                             I.           Nutrient Recycling Overview
                             II.          Uptake by Common Species
                             III.         Urea Volitalization
                             IV.          Forage Quality as Affected by Soil Fertility

                             V.           Poultry and Turkey Litter Application
                                                  Effects of Litter Treatments on Litter Properties
                                                  for Land Application
                             VI.          Legume Nutrient Requirement and Ability to
                                          Supply N to Non-Legumes in a Mixed Pasture
                             VII. Soil Management for Intensive Grazing
                             VIII. Sampling
                             IX.          Soil pH: (1 of 3) [2/28/2002 8:12:18 AM]
Pasture Fertility - Internet Inservice Training

                                                  Optimum Ranges
                                                  Review of Lime Quality Considerations

                                                            Pasture Fertility
                                                       (a multi-state internet training)

                                                      Dates: February 4 to Feb 15, 2002

                                Participating States and Specialists Are:
                                                        Dr. Charles Mitchell - Soil Fertility Specialist
                                                        Dr. Don Ball         - Forage Specialist

                                Georgia:                Dr. John Andrae          - Forage Specialist
                                North Carolina: Dr. Jim Green                    - Forage Specialist
                                South Carolina: Dr. Bruce Pinkerton - Forage Specialist
                                                Dr. Jim Camberato - Soil Fertility Specialist
                                                Dr. Bob Lippert     - Soil Fertility Specialist

                         Return to Clemson Crop and Soil Environmental Science Extension Page

                                                              Visitation is now: (2 of 3) [2/28/2002 8:12:18 AM]
Pasture Fertility - Internet Inservice Training (3 of 3) [2/28/2002 8:12:18 AM]
Pasture Fertility - Nutrient Recycling Overview

                                                              Slide 1 of 29

                              Return to the Pasture Fertility Home Page [2/28/2002 8:12:21 AM]
Pasture Fertility -- Uptake by Common Species

                  Nutrient Uptake and "Removal" by Forages
            Forage crops remove nutrients from the soil just as row crops. If the field is cut for hay and the
       hay transported elsewhere, then those nutrients are indeed removed. Table 1 presents some general
       uptake values by our most common forage species.

                  Table 1. Approximate pounds of nutrients removed by various forage crops at
                  specified yield levels when harvested as hay.1
                                                        Species and assumed hay yield in tons per acre
                                                  Tall fescue Bermudagrass              Sorghum-Sudan   Alfalfa
                                                      3.5          6                          4            5
                  Nitrogen (N)                        135                 258                160         280
                  Phosphate (P2O5)                     65                  60                61           75
                  Potash (K2O)                        185                 288                233         300
                  Magnesium (Mg)                       13                  18                24           25
                  Sulfur (S)                           14                  30                --           25
                  1   Source: Potash & Phosphate Institute

            These figures provide a fair estimate of the fertilizer requirements of these forage crops. These
       values are an under-estimate of actual fertilizer recommendations due to environmental loss and tie-up
       of added fertilizers. Of course, the nitrogen removed by alfalfa is fixed from the air but alfalfa will still
       remove the other nutrients from the soil.

            If the hay is fed on the farm or on a unit where it was produced, then some of "dedicated" hay
       fields. Hay feeding practices can help to recycle nutrients more uniformly although it may not be
       reasonable in some operations.

            The situation is quite different in a grazed pasture. Grazing livestock recycle 80 to 90% of the (1 of 2) [2/28/2002 8:12:24 AM]
Pasture Fertility -- Uptake by Common Species

       nutrients they consume or remove from pastures in their manure and urine. Proper grazing
       management can assist greatly in redistributing the nutrients more uniformly across the pasture. Large
       pastures and continuous grazing will definitely result in nutrient movement and concentration.
       Nutrients will be concentrated at watering points, salt and mineral feeders, and especially under trees
       where the animals lounge.

            A cow, assumed to be that mythical 1000 lb. brood cow, really accounts for no net loss of
       nutrients from a farm until she is sold. Actually, as shown in Table 2, she does not account for much of
       the nutrient uptake by forages, although she processes many 100's of pounds of nutrients in her
       productive life time. The net loss of nutrients in a beef production operation is in the product that is
       sold; i.e., the calf/steer/heifer. A look at Table 2 shows that very little is removed when the calf is sold.

                              Table 2. Approximate amount of nutrients contained in the
                              bodies of two classes of livestock, in pounds.1
                                                            Mature cow                  500 lb Calf
                              Nitrogen                           26                          13
                              Phosphorus                          7                         3.3
                              Potassium                           2                          1
                              Calcium                            15                          7
                                           1    Calculations are approximations based on several
                                                  references of bodily percent composition.

            If the nutrients being consumed by grazing livestock are not really being removed from the farm in
       "product", then we have to assume that they are either lost in another fashion or are poorly distributed
       around the farm. Typically losses are not that great, which leads us to the conclusion that good grazing
       management can have a direct influence on the amount of fertilizer needed in pasture systems by
       increasing the uniformity of nutrient distribution in manure and urine.

                                        Return to Pasture Fertility Home Page (2 of 2) [2/28/2002 8:12:24 AM]

             When considering a good source of nitrogen to use, urea is often the most tempting due to
        its competitive price compared to other nitrogen sources. It is also easy to handle and its high
        analysis means less bulk to transport and distribute. Despite the competitive price of urea, many
        farmers are concerned about nitrogen loss by its conversion to ammonia and subsequent loss to
        the atmosphere. Several factors play a role in the amount of nitrogen lost from urea. If a farmer
        is aware of these factors and how they affect nitrogen volatilization, the broadcasting of urea can
        be timed to minimize loss.

             Acidic soils, especially those with clay on the surface and subsequently a large reservoir of
        stored acidity, are less likely to lose nitrogen from urea. Most soils in the Southeast tend to be
        acidic (pH value less than 7.0) and in the Piedmont where clay is present at the soil surface,
        there is a large reservoir of stored acidity. Therefore, unless a soil is overlimed, it is safe to
        assume that there will be minimal nitrogen loss due to high soil pH values. The higher cation
        exchange capacity (CEC) of clay soils also helps retain the ammonium produced from urea and
        keeps it from escaping as ammonia gas. Sandy soils which have a lesser reservoir of stored
        acidity are more prone to nitrogen loss from urea.

             Urease, an enzyme which can be found in amounts proportional to the organic matter
        content of a soil, is most effective in converting urea to ammonia. Soils in the Southeast tend
        to be low in organic matter but higher than normal levels can be found in soils in Piedmont
        pastures. Urease activity in Piedmont soils could potentially be a problem but the following
        environmental factors will play an even more important role.

             If urea is broadcast when the soil is very dry, there can be no significant enzymatic
        conversion to the more volatile forms since the urea must first dissolve before it can changed. If
        the urea is broadcast on damp or wet soil which then slowly dries over several days, nitrogen
        loss will be significant. This occurs because the urea can now dissolve, be in contact with the
        soil for conversion to volatile nitrogen, and easily escape to the atmosphere due to its proximity
        to the soil surface. If rainfall moves the urea into the soil, nitrogen loss ceases. One-half to 3/4
        inch of rainfall is sufficient for most soils. (1 of 2) [2/28/2002 8:12:26 AM]

             As the soil temperature increases above 50 F, so too the loss of nitrogen from urea will
        increase. As the temperature rises, the enzymatic reactions that breakdown the urea speed up and
        the urease activity will increase with temperature. Higher temperatures also allow more of the
        urea that has been converted to ammonia to escape as a gas.

             The key to minimizing nitrogen loss from urea is to apply it soon before rain is anticipated.
        If the urea moves into the soil below the soil surface, there will be minimal nitrogen loss. If the
        urea must be applied and no rainfall is expected soon, the loss of nitrogen will be in proportion
        to the length of time it stays on the surface of a wet soil.

             These factors should also be considered when using N-30 solution and N-32 solution.
        Research shows that liquid solutions of urea are slightly more susceptible to nitrogen loss than
        the solid form when broadcast on the soil.

                                       Return to Pasture Fertility Home Page (2 of 2) [2/28/2002 8:12:26 AM]
Pasture Fertility -- Forage Quality as Affected by Soil Fertility

                                     Forage Quality and Soil Fertility
        This topic is perhaps one of the most misunderstood in pasture and forage fertility issues. It is best to
        define a few terms before we make too many statements.

        The best measure of forage quality is animal/livestock performance. Since this is only directly
        measured with large scale, expensive, feeding trials, we have to have indicators of forage quality that are
        relatively easy to measure. The old standards are crude protein (CP) which we use to estimate the protein
        feeding value of a feedstuff, and total digestible nutrients (TDN) which provides an estimate of
        digestibility. For the most part few labs determine TDN any longer. Rather, they run acid detergent fiber
        (ADF) and use it to predict TDN. We should be using the ADF directly rather using a predictive value
        but general public acceptance of ADF has been somewhat slow. A more in-depth treatment of forage
        quality is available on the web at: Forage Quality. Forage maturity has, by far, the greatest affect on
        CP and TDN levels in forages.

        Soil potassium level/fertility does not affect crude protein and digestibility (TDN, ADF) of
        forages. Deficient or low potassium fertility levels will most assuredly reduce forage growth, e.g., can
        become first limiting nutrient and decrease overall yields. Potassium is assimilated in luxury amounts by
        most forage species. Forages, typically, will accumulate two to 20 times sufficient/required levels of
        potassium when it is available in the soil.

        Soil phosphorus level/fertility also does not affect crude protein and digestibility (TDN, ADF) of
        forages. Like potassium, low soil phosphorus can be growth limiting. Phosphorus is typically not
        consumed in luxury amounts like potassium and will generally show on forage analysis as 0.2 to 0.3%
        composition on a dry matter basis. Phosphorus may be low enough in forage plant tissue that it becomes
        deficient in the grazing livestock diet. When phosphorus is this low in the soil, plant growth will most
        definitely be reduced/limited. In terms of animal nutrition phosphorus should be fed to the livestock in a
        mineral supplement to correct the deficiency. In the long run however, the soil phosphorus levels must
        be adjusted for adequate forage growth.

        Soil nitrogen level/fertility does not (directly) affect digestibility but does directly affect forage
        crude protein levels in grasses, with much less effect on crude protein levels in legumes. Within
        reason, the greater the nitrogen fertilizer applied the higher the forage grass crude protein; there is, of (1 of 5) [2/28/2002 8:12:34 AM]
Pasture Fertility -- Forage Quality as Affected by Soil Fertility

        course, an upper limit to this affect. Nitrogen fertility levels should be based on realistic yield
        expectations however, and forage crude protein levels should be managed by plant maturity at harvest,
        whether by haying or grazing management.

        From a practical field perspective the fertility levels of the macro and micro-elements do not affect
        crude protein and digestibility either. But once again, if they become deficient they can directly affect
        yield. In perennial pastures and hay fields the major economic impact of inadequate fertility level is
        probably not yield but the persistence/longevity of the stand.

        There are other aspects of forage quality that can be directly affected by soil fertility and fertilizer
        application. We typically refer to these factors as anti-quality components. The two most common are
        nitrate accumulation and the tall fescue toxicosis problem.

             Nitrate Toxicity

        There is no question that nitrogen application to pastures improves production and crude protein
        content of forages. However, moderate to high nitrogen fertilizer rates can elevate the forage nitrate
        concentrations to toxic levels. This is especially true if the plant is a nitrate accumulator or has been
        environmentally stressed.

        Nitrate toxicity is a usually a problem because some plants are "luxury" nitrogen consumers. This
        means that when high levels of nitrogen are available in the soil, plants will take up more than is
        immediately needed. This "luxury" consumption can result in a buildup of nitrate in the plant (especially
        in the lower stem). Toxic nitrate levels are often observed 1-4 weeks following high rates of nitrogen
        fertilizer. Sorghum, sudangrass, soghum-sudangrass hybrids, millets, and corn are all prone to
        accumulating high amounts of nitrates, especially when fertilization occurs in conjunction with plant
        stressors like droughty, cloudy or cool weather. Although nitrate toxicity is usually associated with
        summer annual forages; even tall fescue, cereal grains and bermudagrass can contain toxic nitrate levels
        when grown under heavy nitrogen fertilization (Figure 1; Hojjati et al. 1972). Nitrate levels generally
        peak in plants 1-3 weeks after fertilizer application and gradually decline over time; however, plant
        nitrate concentrations can exceed toxic levels for several weeks after they peak depending on nitrogen
        application rate and plant growth conditions. Several field test kits are available through state extension
        personnel. When in doubt it is wise to sample forages before grazing, cutting or feeding. More
        information is available at: Nitrate Toxicities on the web.

             Fescue Toxicosis

        Animals grazing tall fescue pastures often have lower forage intakes, decreased animal production,
        rough hair coats and higher body temperatures. A fungus contained inside tall fescue was identified in
        the 1970's by USDA researchers. This fungus produces toxic alkaloids which appear to cause the
        symptoms listed above. Several studies have examined the effects of soil fertility on alkaloid production
        in tall fescue. The results are summarized below. (2 of 5) [2/28/2002 8:12:34 AM]
Pasture Fertility -- Forage Quality as Affected by Soil Fertility


        Initial observations of cattle grazing tall fescue indicated that fescue toxicosis was most severe on
        pastures receiving heavy applications of poultry litter. This led researchers to believe that high nitrogen
        rates may increase alkaloid production, which increases the severity of tall fescue toxicosis. The effects
        of nitrogen fertilization on toxic alkaloid production in tall fescue are relatively unclear, but overall
        results indicate that nitrogen application does increase toxic alkaloid production in tall fescue. Several
        research studies have shown that toxic alkaloid levels increase with nitrogen fertilization (Figure 2,
        Rottighaus et al. 1991). Field observations of cattle grazing heavily fertilized tall fescue pastures also
        suggest that high nitrogen application rates increase toxicity of tall fescue. However, other studies have
        reported no alkaloid response to nitrogen fertilization. Inconsistent results may be due to form of
        nitrogen fertilizer, water stress, soil pH and soil calcium concentration.


        The effects of soil phosphorous level on toxic alkaloid production in tall fescue are relatively unknown.
        A recent study examined alkaloid production in tall fescue grown at low, medium and high soil P
        concentrations (Malinowski et al., 1998). Alkaloid content usually increased with higher soil phosphorus
        concentrations. This suggests that high soil phosphorus levels may increase the toxicity of endophyte-
        infected tall fescue. This is particularly important poultry-producing areas of the country where soil
        phosphorus concentrations can be extremely high.

        More information on the fescue endophyte is available at: Tall Fescue on the web.

                   Figure 1. Effect of nitrogen fertilization on nitrate accumulation in forages.
                   (Adapted from Hojjati et al.) (3 of 5) [2/28/2002 8:12:34 AM]
Pasture Fertility -- Forage Quality as Affected by Soil Fertility

                   Figure 2. Effect of nitrogen fertilization and plant part onergot alkaloid content of
                   tall fescue.
                   (Adapted from Rottinghaus et al.)

        Hojjati, S.M., T.H. Taylor, and W.C. Templeton, Jr. 1972. Nitrate accumulation in rye, tall fescue, and
        bermudagrass as affected by nitrogen fertilization. Agron. J. 64:624-627.

        Malinowski, D.P., D.P. Belesky, N.S. Hill, V.C. Baligar, and J.M. Fedders. 1998. Influence of
        phosphorus on the growth and ergot alkaloid content of Neotyphodium coenophialum-infected tall fescue
        (Festuca arundinacea Schreb.) Plant and Soil 198:53-61. (4 of 5) [2/28/2002 8:12:34 AM]
Pasture Fertility -- Forage Quality as Affected by Soil Fertility

        Rottinghaus, G.E., G.B. Garner, C.N. Cornell, and J.L. Ellis. 1991. HPLC method for quantitating
        ergovaline in endophyte-infested tall fescue: Seasonal variation of ergovaline levels in stems with leaf
        sheaths, leaf blades, and seed heads. J. Agric. Food Chem. 39:112-115.

        Prepared by John Andrae and Bruce Pinkerton, Extension Forage Specialists at the University of
        Georgia and Clemson University, respectively.

                                             Return to Pasture Fertility Home Page (5 of 5) [2/28/2002 8:12:34 AM]
Pasture Fertility -- Poultry and Turkey Litter Application

                                                              Jim Camberato

        Land application of poultry manure to forage crop land is an effective way of recycling the nutrients
        back to the land. There are four key steps to utilizing manure in an environmentally and economically
        sound manner:

              q   know the available nutrient content of the manure

              q   know the nutrient needs of the crop, and apply the manure at the correct rate and time to provide
                  the nutrients

              q   use application and conservation practices that minimize movement of the nutrients from the

              q   adjust the use of supplemental fertilizer to compensate for the nutrients applied in the manure

        Applications of manure as a pasture crop nutrient source may provide a portion, or all of the plant
        nutrient requirement, dependent on the rate of application and the relative content of the nutrients.
        Application rate decisions are usually based on either the nitrogen or the phosphorus content of the
        manure and environmental concerns are typically based on the amount of nitrogen, phosphorus, zinc,
        copper, or arsenic added to the soil. Knowing the nutrient content of poultry manure is critical to using it
        as a crop nutrient source. Not knowing the nutrient content of the manure to be applied can result in
        large errors in application rate -- either too much or too little.

                       Table of broiler and turkey manure nutrient content

                       Table of layer manure characteristics and quantity as
                       removed from the house (1 of 10) [2/28/2002 8:12:41 AM]
Pasture Fertility -- Poultry and Turkey Litter Application

                       Estimates of litter production from poultry production houses

        Poultry manure additions are often based on the nitrogen requirement of the crop and the available
        nitrogen content of the poultry manure. Crops that require and remove a lot of nitrogen are favored for
        receiving poultry manure because more manure can be applied to less land. This approach reduces the
        hauling costs of implementing a manure management plan. Soil analysis should be used to ensure that
        soil pH and nutrient conditions are at optimum levels even when manure is applied based on nitrogen.

        Nitrogen fertilizer recommendations for commonly grown crops are listed in Table 1. These rates are
        suggested as the most profitable rate over a period of years with good management. Ranges in nitrogen
        rate recommendations reflect differences in yield and management potential. For example, regarding
        bermudagrass, 240 lb N/acre should be sufficient to produce 4 to 5 tons hay/acre and 400 lb N/acre
        should produce 6 to 7 tons hay/acre with normal rainfall

                   Table 1. Nitrogen fertilizer recommendations for pasture crops.
                   Crop                                                                  Fertilizer N, pound/acre
                   Bermuda grass hay                                                            240 - 400
                   Bermuda grass pasture                                                        about 150
                   Fescue pasture                                                               about 100
                   Annual rye for grazing                                                       about 120

                       Nitrogen Application Timing

        The release of nitrogen from manure should coincide with crop nitrogen accumulation. If the crop is
        not actively accumulating nitrogen then nitrate-nitrogen in the soil will be subject to loss via leaching.
        Pasture and hay crops have more moderate nitrogen requirements over longer periods of time than row
        crops and are not very sensitive to short-term deficits in nitrogen availability. Periods of nitrogen
        accumulation and nitrogen application windows for crops commonly grown in the Southeast are
        presented in Table 2. Most poultry manure is typically applied as a solid. Nitrogen availability from
        poultry litter is greatest and most predictable when incorporated into the soil due to less volatile loss of
        nitrogen and better moisture for organic N mineralization. Manure applications can be made to pasture
        and hay fields as long as that particular grass is actively accumulating nutrients. Delayed nitrogen
        availability and over- or under-estimation of nitrogen availability is not as great a concern with grass
        fields as with annual crops. (2 of 10) [2/28/2002 8:12:41 AM]
Pasture Fertility -- Poultry and Turkey Litter Application

        Although manure application rates are usually based on nitrogen availability, applying poultry manure
        based on its P2O5 or K2O content may also be important. The availability of P2O5 and K2O in manures
        is similar to that of fertilizer sources, so basing application rates on the manure's content of P2O5 and
        K2O should be adequate. Recommended rates of P2O5 or K2O are based on soil analysis, soil type, and
        crop to be grown and are provided with a routine soil test. On soils testing high in P2O5 and K2O, when
        these nutrients are not recommended by soil test, consider using the manure on other fields requiring
        P2O5 and K2O. Manure nutrients are much more valuable when applied to low fertility fields.

             FROM THE FIELD
        Phosphorus movement from the land into surface waters, such as lakes and streams, is considered
        pollution. Phosphorus movement occurs by erosion and runoff. Erosion is the movement of soil from the
        field. Runoff is water movement over the surface of a field containing little sediment. In the Southeast,
        erosion and runoff occur primarily from heavy rainfall or excessive irrigation. Phosphorus in erosion (3 of 10) [2/28/2002 8:12:41 AM]
Pasture Fertility -- Poultry and Turkey Litter Application

        and runoff can be bound to the soil, contained in soil organic matter and manure particles, or dissolved
        in the water.

        Many factors affect the amount of phosphorus that moves from the field to the water. These factors

              q   slope of the land
              q   soil type
              q   distance to the water
              q   rainfall and irrigation intensity and duration
              q   method of manure application
              q   soil phosphorus level
              q   presence of conservation practices-filter
                  strips, contour planting, riparian zones

        Manure application on sloped land is subject to greater loss via runoff and erosion than applications
        made on flat land. The greater the distance between the application area and the surface water the lower
        the chance of phosphorus movement into the water. Hence, the rationale for application setbacks from
        ditches, streams, ponds, and lakes. On tilled soils, incorporated manure results in less phosphorus runoff
        and erosion then when the manure is left on the soil surface. High soil phosphorus is another factor that
        increases the potential for phosphorus pollution of surface waters. The higher the level of phosphorus at
        the soil surface the greater the concentration of phosphorus in the runoff water and erosion sediments.
        When soil test phosphorus is high at the soil surface, application of manure to other fields should be
        considered. Installation of conservation practices that reduce runoff and erosion are beneficial to
        reducing phosphorus pollution of surface waters.

        In most soils with moderate phosphorus application rates, phosphorus remains in the soil where it is
        placed with little downward movement. Phosphorus added to the soil is bound by clay particles so that
        only a portion remains available to the crop. This process reduces the amount of dissolved phosphorus
        in runoff water, but does not affect the loss of phosphorus in erosion sediments. Soils have finite
        capacities to absorb phosphorus. When the capacity is exceeded, added phosphorus remains dissolved in
        the soil water and can be leached downward. Leaching of phosphorus can occur on coarse sandy soils
        with high application rates of phosphorus and on high organic matter soils commonly occurring in
        Carolina Bays. In these soils, phosphorus leaching into the water table and lateral movement of ground
        water can move phosphorus to the stream or lake. In soils with clay subsoils, however, the leaching of
        phosphorus through the soil profile is slow since these soil layers have a substantially greater capacity to
        absorb phosphorus than surface soils.

        Poultry manure applications may be based on crop removal of phosphorus when soil phosphorus levels
        are high to prevent further increases in soil phosphorus. Phosphorus removal for crops commonly grown
        in the Southeast are listed in Table 3. Row crops remove about 30 lb P2O5/acre at typical yield levels
        and hay crops remove more than 50 lb P2O5/acre. (4 of 10) [2/28/2002 8:12:41 AM]
Pasture Fertility -- Poultry and Turkey Litter Application

        Crop accumulation of nutrients from the soil and removal from the field determines the efficiency of
        crop nutrient utilization (Table 3). Nutrient utilization is routinely less than 100% due to inefficiencies
        in nutrient uptake by the crop, soil reactions that render the nutrient unavailable, and loss of the nutrient
        from the soil by leaching, erosion or volatilization. Only a portion of the nutrients in the crop will come
        from that year's application of animal manure or fertilizer. The remainder of nutrient accumulation will
        have come from nutrients already present in the soil. Nutrients in the crop parts that remain in the field,
        such as corn or wheat stover, will be recycled to the soil and available to the next crop. Nitrogen has
        been the plant nutrient most studied. Accumulation efficiency from fertilizer is typically around 60% of
        the nitrogen added and removal efficiency is about 50%. These efficiencies are determined by
        accounting for the amount of nitrogen that came from the soil without added fertilizer. Nitrogen
        efficiency from manures is usually less than that from fertilizer.

        The law in South Carolina regulates animal waste applications by the concentration of Zn, Cu, and As
        in the manure or by the amount of Zn, Cu, and As that can be applied on a cumulative basis. Good
        record-keeping of the amounts of manure applied to a field and the concentration of Zn, Cu, and As in
        the manure is necessary to meet the conditions of the law.

        Zinc (Zn) and copper (Cu) are present in poultry manure in varying amounts and are essential crop
        nutrients. However, long-term use of poultry manure based on providing the total N requirement of the
        crop provides more Zn and Cu than the crop requires, and these nutrients can accumulate to high levels
        in the soil. Crop toxicities may occur in certain situations. Crop removal of Zn and Cu from the field is
        quite small, around 0.03 pounds of Cu per acre per year and about 0.11 pounds of Zn per acre per year
        (see Table 3) and no leaching of these nutrients occurs. Therefore, once applied to the soil they remain
        there. The toxicity of high soil Zn and Cu is reduced by increasing soil pH, however, increased soil pH
        will not completely eliminate Zn and Cu toxicity in some instances. If soil pH is increased too much,
        deficiencies of other micronutrients may be induced by the high pH.

        Arsenic is not an essential plant nutrient. Crop production problems are unlikely to occur from As
        applications typically applied in poultry manure, about 2 pounds of As per acre per year. The main
        concern with As in poultry litter is the potential movement of As from the field to surface and ground

             SOIL ZINC
        Soil Zn levels potentially injurious to crops occur in the Southeast. The sources of excessive Zn in soils
        include poultry manure, Zn containing fungicides, burned tires, and some industrial byproducts. Zinc
        levels in a number of soils receiving poultry manure have been found to exceed 20 pounds of Zn per
        acre with some as high as 90 pounds per acre. Reduced growth and yield of peanuts, soybeans, and
        cotton due to Zn toxicity have occurred in Southeastern fields. (5 of 10) [2/28/2002 8:12:41 AM]
Pasture Fertility -- Poultry and Turkey Litter Application

        Delivering the proper amount of animal waste to the field in uniform fashion is the next step in
        effectively utilizing animal waste. Spreaders must be calibrated to apply the proper rate and be adjusted
        for uniform application.

        When poultry manure is used as the primary N source for crops, supplemental phosphorus, potassium,
        and micronutrient applications are usually not needed. Eliminating unnecessary fertilizer applications is
        a benefit both economically and environmentally. For nutrients other than N, traditional manure, soil
        testing, and plant tissue analysis methods are adequate for determining if further additions of these
        nutrients are required.

          Table 3. Nutrient accumulation and removal by pasture crops commonly
                   in the Southeast.
                                                                                         N P2O5 K2O             Cu          Zn
                  Crop                       Yield level            Plant part
                                                                                         ----- pounds of nutrient per acre -----
         Bermuda grass                       6 tons/acre                hay              300   84   252         ----        0.12
         Fescue                              3 tons/acre                hay              116   56   159         ----        ----
         Annual ryegrass                     3 tons/acre                hay              129   51   144         ----        ----
         Corn                               10 tons/acre                hay              71    24   72          ----        ----
         Sorghum                             5 tons/acre               silage            74    28   141         ----        ----


                       Major Nutrients

        The value of manure nutrients is dependent on soil fertility level, crop nutrient needs, manure nutrient
        content, and the cost of purchased nutrients and manure application. (6 of 10) [2/28/2002 8:12:41 AM]
Pasture Fertility -- Poultry and Turkey Litter Application

        Manure has the greatest nutrient value when applied to low-fertility fields and the least value when
        used on the same field year after year. When soil fertility status is low, high nutrient application rates of
        phosphorus and potassium are recommended in addition to the standard nitrogen application. In this
        situation the crop will benefit from the addition of phosphorus and potassium and the application of
        these nutrients in the manure is valuable. However, most manures when applied based on the crop's
        nitrogen requirement provide more phosphorus and potassium than is required and these nutrients
        accumulate in the soil. When soil fertility status becomes high, supplemental nutrients are not required,
        and the application of phosphorus and potassium is not recommended. In this situation the phosphorus
        and potassium in the manure does not have any value. If manure is continually applied to the same field,
        then the main benefit derived is the nitrogen content of the manure. No benefit is derived from the
        continual application of excess phosphorus and potassium and the potential for phosphorus runoff
        polluting lakes, rivers, and streams is greatly increased. Applying manure to low-fertility fields first and
        having enough land to use manure every second or third growing season are good ways to maximize the
        nutrient value of the manure and minimize the potential for polluting.

        This point is illustrated in Table 4. A producer applies 3 tons of poultry manure per acre to three fields
        varying in soil fertility level to provide 120 lb N/acre in anticipation of growing a 100 bu/acre corn crop.
        The manure also applies 180 lb P2O5/acre, 120 lb K2O/acre, and 30 lb S/acre. One field has a low
        phosphorus and potassium level and 80 lb/acre P2O5 and K2O are recommended, therefore, a significant
        amount of the potassium and phosphorus in the manure has value. In this low soil fertility situation, the
        nutrient content of the 3 tons manure per acre is worth $64.80 or $21.60 per ton. An extra 100 lb
        P2O5/acre was applied. However, when soil test phosphorus and potassium is medium, less P2O5 and
        K2O is recommended and the poultry manure is worth less, $52.20 per acre or $17.40 per ton. At
        medium soil fertility levels an extra 130 lb P2O5/acre was applied. At high soil test phosphorus and
        potassium , no P2O5 or K2O is recommended, and the nutrients in the lagoon water are worth only
        $31.20 per acre or $10.40 per ton. One-hundred eighty lb P2O5/acre, valued at $43.20, was wastefully
        applied to the high fertility soil.

        Excess crop nutrients are not necessarily lost from the soil and without value for the next growing
        season. In most soils some of the excess phosphorus added in one year will be available to future crops
        over several years. If phosphorus applications in future years are reduced or eliminated by the initial
        manure application, then some of the excess phosphorus provided in the initial year has value. Excess
        potassium will also be available to some extent in future years in clayey Piedmont soils and Coastal
        Plain soils with clayey subsoils within 15 inches of the soil surface. In coarse sandy soils with deep
        subsoils, however, much of the potassium may be lost between the first and second cropping season and
        that value will be lost. Even though some of the value of manure nutrients is captured after the first year,
        fertilizing one year for several years is generally not recommended because some of the phosphorus and
        potassium will be wasted.

        The key to getting the most value from manure nutrients after the initial growing season is not to apply
        any more phosphorus and potassium when soil test in subsequent years indicates those nutrients are
        adequate. (7 of 10) [2/28/2002 8:12:41 AM]
Pasture Fertility -- Poultry and Turkey Litter Application

           Table 4. Nutrient value of poultry manure containing 40 pounds
                    available nitrogen, 60 pounds of phosphorus (as P2O5), 40
                    pounds of potassium (as K2O), and 10 pounds of sulfur per ton.
                    The litter was applied to the field at a rate of 3 tons per acre in
                    anticipation of growing a 100 bushel corn crop. The value of the
                    manure nutrients changes dependent on the soil fertility status
                    of the field.
                             Recommended                       Amount Applied
          Fertility                                                                           Value          Nutrients
                    Nutrient  Application                       With Manure
           Status                                                                                            Applied

                                                        Pounds Per Acre                  $ Per Application   lb/Acre

                                                                                           120 x $ .24 =
                               N                  120                120                                        0
                                                                                             $ 28.80

                            P2O5                                                            80 x $ .24
               L                                   80                180                                       100
                                                                                             $ 19.20
               W             K2O                                                            80 x $ .18=
                                                   80                120                                        40
                                                                                              $ 14.40

                                                                                            10 x $ .24=
                               S                   10                 30                                        20
                                                                                              $ 2.40

                                                                                           120 x $ .24=
                               N                  120                120                                        0
                                                                                             $ 28.80
               E            P2O5                                                            50 x $ .24=
                                                   50                180                                       130
               D                                                                              $ 12.00
               I                                                                            50 x $ .18=
               U             K2O                   50                120                                        70
                                                                                              $ 9.00
                                                                                            10 x $ .24=
                               S                   10                 30                                        20
                                                                                              $ 2.40

                                                                                           120 x $ .24=
                               N                  120                120                                        0
                                                                                             $ 28.80

               H            P2O5                                                            0 x $ .24=
                                                    0                180                                       180
               I                                                                                 0
               G                                                                            0 x $ .18=
               H             K2O                    0                120                                       120

                                                                                            10 x $ .24=
                               S                   10                 30                                        20
                                                                                              $ 2.40 (8 of 10) [2/28/2002 8:12:41 AM]
Pasture Fertility -- Poultry and Turkey Litter Application


        The example above did not consider the value of micronutrients (zinc, copper, manganese, etc.)
        because soil testing and plant analysis has shown that micronutrient levels in most fields are adequate
        most of the time. When soil testing or plant analysis identifies micronutrient deficiencies and
        recommend micronutrient additions, however, the value of the micronutrient application in the manure
        should also be considered. Calculate the value of the micronutrient by multiplying the recommended
        application rate by the fertilizer cost of the nutrient.

                       Liming Value or Cost

        Application of manure may decrease or increase the need for liming dependent on the type of manure
        and the rate of application. Liming soils in the Southeast is a very important aspect of crop production.
        Generally, most Southeastern soils will be limed with a ton of dolomitic limestone every two to three
        years to maintain soil pH in the range of 5.8 to 6.5 (for most crops). The use of acid forming nitrogen
        fertilizers is the main reason that soil pH decreases and the estimate of one ton of lime per acre every
        three years is for nitrogen application rates of around 120 pounds of nitrogen per acre per year. Higher
        application rates will cause the soil pH to drop faster and lime will be required more frequently and in
        greater amounts.

        The type of poultry manure determines its effects on soil pH because poultry feed contains varying
        amounts of calcium carbonate. Broiler and turkey feed contains relatively low amounts of calcium
        carbonate, therefore, the litter typically is less than 5% calcium carbonate (100 lb calcium carbonate per
        ton). This amount of calcium carbonate is not enough to offset the acid generated by the nitrogen in the
        litter so broiler and turkey litter generally decrease soil pH. The acidity of these litters is about the same
        as common fertilizer sources such as urea and ammonium nitrate when added at the same rate of
        available nitrogen.

        Laying hens are fed more limestone than broilers and turkeys and consequently have higher amounts
        of calcium carbonate in their manure. Typically hen manures have calcium carbonate contents of 15 to
        18% (300 to 360 lb calcium carbonate per ton). Soil pH may increase substantially with applications of
        hen manure because the amount of liming material added to the soil exceeds the amount of acidity
        released by the conversion of nitrogen. Too high a soil pH due to the over application of lime can be just
        as detrimental to crop production as too low a soil pH. High pH in most Southeastern agricultural soils
        does not occur naturally, but occurs from the over application of commercial limestone or some other
        liming material. Layer manure is a source of liming material that can result in too high a soil pH. Soil
        pH's greater than 7.0 in the upper one foot of soil and nearly 7.0 in the one to two foot sampling depth,
        were found in a number of Piedmont fields receiving repeated applications of hen manure and no
        commercial limestone applications. No crop production problems associated with these unusually high
        soil pH's have been documented in these clay soils; however, pH's this high would likely cause
        problems in sandy Coastal Plain soils. The liming value of layer manure should be considered when (9 of 10) [2/28/2002 8:12:41 AM]
Pasture Fertility -- Poultry and Turkey Litter Application

        layer manure is used as a crop nutrient source. This value is not trivial as one ton of lime per acre every
        three years currently costs about $30 per acre or $10 per acre per year.

                       Stockpiling Manure Solids Lowers Value

        Uncovered stockpiling results in decreases in the nitrogen and potassium content of the manure. Also,
        the manure becomes sticky and difficult to spread uniformly. Leaching and run-off of nitrogen and
        phosphorus from the stockpiled manure may pollute ground and surface water. Covered stockpiles are
        not a problem. If manure is covered while stockpiled, the nutrient content and spreading characteristics
        of the original material will be preserved. The cover will eliminate any pollutant runoff from occurring.
        The proper siting of covered stockpiles on high ground should prevent, movement of the water table into
        the pile and the potential for groundwater pollution.

        Studies have determined conclusively that there are no weed seeds in poultry manure as it is removed
        from the rearing house. However, poultry manure does stimulate the germination of some weed seeds
        already in the soil and the growth of all weeds will be stimulated by the nutrients in poultry manure.

        Weed seeds, particularly pigweed, may be deposited in stockpiled litter and flourish in that
        environment. Application of stockpiled litter to crop land may introduce weed seeds into the field.

                                            Return to Pasture Fertility Home Page (10 of 10) [2/28/2002 8:12:41 AM]
Pasture Fertility -- Effects of Litter Treatments

                                                     James J. Camberato

              Many products are sold as poultry litter treatments with the purpose of lowering ammonia
         levels in the poultry house. These products vary in active ingredient and mode of action. Not
         only do litter treatments affect the air in the house, they may also alter the content and
         availability of ammonium and phosphorus in the litter.

              Effects of litter treatments on litter ammonium will be reflected in a standard manure
         analysis that determines ammonium/ammonia or total nitrogen. A standard manure analysis will
         detect changes in total phosphorus, but not water-soluble phosphorus. Water-soluble phosphorus
         is a better indicator than total phosphorus of the amount of phosphorus that may occur in runoff
         water from fields receiving poultry litter.

              The mode of action, effect on litter ammonium and phosphorus, and precautions for a
         number of common litter active ingredients are discussed below.

                 Active Ingredient: Alum. Also known as aluminum sulfate [A12(SO4)3 . 18H2O].

                 Effects on Litter Nutrients: Increases ammonium nitrogen. Decreases water-
                 soluble phosphorus but does not affect total phosphorus.

                 Mode of Action: Lowers litter pH thereby conserving ammonium-N. Aluminum
                 binds phosphorus reducing its immediate availability to crops.

                 Precaution: Over-application of alum can lower pH too much and increase
                 phosphorus availability in the litter. (1 of 4) [2/28/2002 8:12:44 AM]
Pasture Fertility -- Review of Lime Quality Considerations

                   power as one ton of pure CaCO3.

                     Typical Calcium Carbonate Equivalent (CCE) of Selected
                                       Liming Materials
                                                                                        Tons Required to be
                           Liming Material                   Typical CCE (%)                 Equivalent
                                                                                        to 1.0 Ton of CaCO3

                              Calcite (pure)                       100                          1.0
                           Calcitic limestone                   75 to 100                    1.3 to 1.0
                         Dolomitic limestone                    75 to 108                    1.3 to 0.9
                     Hydrated lime (Ca(OH)2)                    120 to 136                   0.8 to 0.7
                                 Wood ash                        30 to 70                    3.3 to 1.4

                          How is CCE Determined?
                   To determine CCE, a carefully weighed sample of the lime material is reacted
                   with an acid under laboratory conditions prescribed by a standardized procedure.
                   Based on the amount and strength of the acid consumed in the reaction the CCE
                   can be calculated. For example, if a 1 gram sample of limestone was reacted with
                   50 ml of 0.5 N HCl and titrated with 0.25 N NaOH. The titration required 30 ml of
                   0.25 N NaOH. The calculations would be:

                                      %CaCO3 Equivalent = 2.5 x (ml HCl - ml NaOH/2)
                                                                  = 2.5 x (50 - 30/2)
                                                                  = 87.5

                          Is It Possible to Have a CCE Greater than 100?
                   Yes. When a material contains appreciable amounts of magnesium carbonate,
                   calcium hydroxide, calcium oxide, or magnesium oxide, it will have greater
                   neutralizing power than the same weight of calcium carbonate. This will result in
                   a CCE greater than that of pure CaCO3, which is 100.

                   2. How is Particle Size of Aglime Measured and

                   The usual testing procedure is to pass a sample through a series of standard sieves
                   and express the results as percentage passing through, or remaining on the
                   variously sized sieves. Sieves are typically made of wire cloth and are designated
                   by the number of openings per linear inch (mesh) in the cloth. For example, a 60- (4 of 10) [2/28/2002 8:13:03 AM]
Pasture Fertility -- Review of Lime Quality Considerations

                   mesh sieve has 60 openings per linear inch (i.e., 3,600 per square inch). A particle
                   passing through a standard 60-mesh sieve would have a diameter of less than
                   0.0098 inch (less than 0.25 mm). Such material would have the consistency of
                   flour. An aglime will ordinarily be composed of particles of many different sizes,
                   ranging from very fine, dust-like particles to coarse, sand-like ones.

        III. Factors Affecting the Reactivity of Lime
                   1. Purity is expressed as %

                   2. Fineness is based on mesh size

                                       Mesh size                               Reactivity

                               Coarser than 20 mesh very little effect after 18 months
                                                              took 6-18 months to neutralize the acidity
                                          30-60               that was neutralized in 1 month by 80
                                            100               reacts very rapidly

                   3. Neutralizing Value of Different Liming Materials

                                                     Material        CaCO3 equivalent

                               Calcite         CaCO3                          100

                               Dolomite CaCO3                MgCO3            109

                               Hydrated Ca(OH)2                               136
                               Burned          CaO                            179

                             *M.W. = Molecular Weight (5 of 10) [2/28/2002 8:13:03 AM]
Pasture Fertility -- Review of Lime Quality Considerations

                               Example using Ca(OH)2

                   4. Degree of Mixing and Reaction Time

                         Lime is very insoluble, therefore, it needs to be mixed throughout the root
                   zone. If the recommended amount of limestone is properly mixed with the soil,
                   planting may follow without delay because enough fine particles are present in
                   limestone to raise soil pH immediately above toxic Al and Mn levels and to
                   correct a Ca deficiency. In the past it was recommended that limestone be applied
                   2 to 3 months prior to planting. Because of improved tillage equipment for
                   incorporating limestone and improved limestone quality this recommendation is
                   no longer necessary. When limestone is properly incorporated into the soil, liming
                   may be done anytime between the harvesting of one crop and the planting of the

                                                             Click on graph to enlarge (6 of 10) [2/28/2002 8:13:03 AM]
Pasture Fertility -- Review of Lime Quality Considerations

                                                             Click on graph to enlarge

                                                             Click on graph to enlarge

        IV. Effectiveness of Surface Liming For No-Till
        Fields and Pastures
                          In 1985 a study was initiated at Penn State to look at the effects of surface
                   application of lime on a very acid, long-term no-till soil. Since 1977 this field had (7 of 10) [2/28/2002 8:13:03 AM]
Pasture Fertility -- Review of Lime Quality Considerations

                   been in no-till corn production with no limestone applied. The initial pH of "plow
                   layer" was 5.1 and the surface 2 inch pH was 4.5. The limestone recommendation,
                   based on the SMP buffer pH and a target pH of 6.5, was 6000 lb calcium
                   carbonate equivalent (CCE) per acre. The study included four limestone rates (0,
                   3000, 6000, 9000 lb CCE/A) and liming programs ranging from applying lime
                   every year to once every five years. Each year the soil was sampled in the spring
                   in 2 inch increments to a depth of 6 inches. No-till corn was grown from 1985 to
                   1991, no-till soybeans were grown in 1992 and 1993, oats was grown in 1994 and
                   wheat in 1995 and corn in 1996, 1997 and 1998.

                          Soil pH results from soil samples taken in the spring of each year from 1985
                   through 1994 for selected liming programs are given in Figures 1 and 2. The soil
                   pH results for the 6000 lb/A, every third year liming program are shown in Figure
                   1. This treatment was chosen for illustration because this would be the
                   recommended limestone rate based on a plow depth soil sample and this
                   frequency of liming is fairly common in many areas. The pH results in Figure 2
                   are from the every year, 3000 lb/A liming program. The every year program is of
                   interest because there has been speculation that more frequent smaller applications
                   of limestone may be necessary in no-till. Several observations can be made based
                   on these results. First, it is clear that the recommended limestone application
                   changed the soil pH in the surface 2 inches within the first year after application.
                   Soil pH measurements taken within the first year indicated that most of the pH
                   change in the surface layer occurred within the first two months after spring
                   liming. This rapid increase at the surface was expected since this was a high
                   quality finely ground limestone with 90% passing a 100 mesh sieve. Although the
                   0 to 2 inch layer was not subdivided for routine pH determination, spot checks of
                   pH in this layer indicated that most of the pH change was in the surface 1/2 inch.
                   However, there was little change in the soil pH below the surface 2 inches until
                   about the fourth year of the study following subsequent limestone applications.
                   Even after 9 years the soil pH in the 2 to 6 inch layers has not yet reached the
                   target pH of 6.5 that was achieved rather quickly in the surface layer. There is
                   little apparent difference between the standard, every third year liming program,
                   and the more frequent every year liming program. (8 of 10) [2/28/2002 8:13:03 AM]
Pasture Fertility -- Review of Lime Quality Considerations

                              Figure 1. Soil pH vs time for a no-till soil limed at 6000 lb/A
                                        every third year

                              Figure 2. Soil pH vs time for a no-till soil limed at 6000 lb/A
                                        initially and
                                        then every year since 1987 at 3000 lb/A.

                          These pH effects from the liming treatments resulted in slight but generally
                   insignificant increases in corn yield. The greatest yield response was in the wheat
                   crop in 1995. Some negative responses were observed in the years when soybeans
                   were the plots. However, it was speculated that this was due to compaction from
                   the liming operation especially in the more frequent liming programs. A triazine
                   weed control treatment was included in the early years of this study. This work
                   showed that the initial liming which only affected the pH at the soil surface did
                   improve the efficacy of the triazine herbicides. Similar to the effect observed with
                   the triazine activity, there were significant effects on plant tissue concentrations
                   immediately after liming even though the pH effect from the lime was limited to
                   the soil surface. These plant nutrient effects were a significant increase in calcium
                   and a decrease in manganese. From this work it was concluded that surface
                   application of limestone will rapidly change the soil pH at the surface of the soil.
                   It was also observed that even this shallow pH improvement could affect herbicide
                   activity and nutrient availability. A second major conclusion is that a very long
                   time is required to have much effect on the soil pH below the surface 2 inches in
                   no-till crop production. Finally, there seems to be little justification for more
                   frequent liming in no-till systems.

                          Thus, the current recommendation is that where possible on a very acid soil,
                   limestone should be incorporated to adjust the soil pH to the desired level in the
                   entire plow layer before no-till crop production in initiated. Other work has shown
                   that if the soil pH is in the desired range to begin with, it can be maintained by
                   surface applications of limestone in no-till systems. Thus, if a regular liming
                   program is followed and soil pH is not allowed to drop to very low levels further
                   incorporation of limestone should not be necessary. Where incorporation is not (9 of 10) [2/28/2002 8:13:03 AM]
Pasture Fertility -- Review of Lime Quality Considerations

                   possible there are beneficial effects of surface application of limestone to acid no-
                   till soils even though the immediate effect will only be near the soil surface. Also,
                   with surface liming the standard every three year or so liming program based on a
                   regular soil testing program should be adequate.

                             Prepared by:
                             Douglas B. Beegle, Professor of Agronomy
                             Department of Agronomy
                             Penn State University

        V. Individual State Lime Laws
                   NOTE: Each state has its own lime laws. Although the intent of the following text
                   is to discuss the properties of common lime materials, some of the definitions are
                   dependent on Florida state laws. Lime laws for some states can be found at the
                   following links:

                           South Carolina Lime Laws
                                 South Carolina Rules, Regulations and Standards
                                 For a comprehensive list of SC Fertilizer & Lime Law Links.
                           Georgia Lime Code
                           Alabama Lime Laws

                                        Return to Pasture Fertility Home Page (10 of 10) [2/28/2002 8:13:03 AM] [2/28/2002 8:13:04 AM] [2/28/2002 8:13:09 AM] [2/28/2002 8:13:13 AM] [2/28/2002 8:13:15 AM] [2/28/2002 8:13:19 AM] [2/28/2002 8:13:20 AM] [2/28/2002 8:13:21 AM]
Dr. Robert Lippert's Agronomy Web Site

      Dr. Bob Lippert's F.A.Q. Regarding Soil Testing, Plant
      Analysis and Fertilizers (get the pdf)
      Soil Acidity and Liming - Part I - Extension Internet
      Inservice Training (get the pdf)
      Soil Acidity and Liming - Part II - Extension Internet
      Inservice Training (get the pdf)
      Soil Testing Issues for the Southeastern U.S. -
      Extension Internet Inservice Training (get the pdf)
      Pasture Fertility
      Land Application of Animal Manure (get the pdf)
      Cotton Fertility - Internet Inservice Training (get the pdf)
      Department of Crop and Soil Environmental Science (1 of 2) [2/28/2002 8:13:28 AM]
Dr. Robert Lippert's Agronomy Web Site

               Visit the Clemson             University Home Page.

     This page is maintained by Dr. Robert Lippert

                   Phone (864) 656-3502                                        FAX (864) 656-3443

                             This page has been visited                              times. (2 of 2) [2/28/2002 8:13:28 AM] [2/28/2002 8:13:30 AM]

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