Feedlot Manure Management - PowerPoint

							The Iowa P index
and Manure
Management

    Jeremy Klatt
Manure Management
Planning in Iowa
 Manure Management Plan (MMP) –
  required of confinement feeding
  operations with >500 animal units

 Nutrient Management Plan (NMP) –
  required of open feedlots with >1000
  animal units or feedlot that needs an
  NPDES permit
                                     March 14, 2007
Manure Management
Planning in Iowa
  MMP and NMP
   use P index to
   determine
   application rates




                       March 14, 2007
  Why Focus on P?

 Iowa's waters are high in
  nutrients
 P limited waters
 Stimulates algae growth
   turbid water
   frequent blooms of
    potentially toxic algae
   low dissolved oxygen
   shift of aquatic species
    towards more pollution           DNR photo

    tolerant
                               March 14, 2007
   Phosphorus and Manure

 N-based manure
  plans often build
  soil P
 Very high soil tests
  increase risk of P
  loss
 Need to assess
  risk of P loss

                         March 14, 2007
 Feedlot Manure Example

 Open Feedlot manure (ISU)
 N – 22 lbs/ton; P2O5 – 16 lbs/ton
 40% N available in first year
  Manure Rate   Avail. N Rate   P2O5 Rate      Years of Corn
   (ton/acre)     (lb/acre)      (lb/acre)       Removal*
      10             80           160                 2.7
      20            160           320                 5.3

      30            240           480                  8
                                             * Assuming 160 bu/ac

                                                      March 14, 2007
     Feedlot Manure Example

         10 ton/acre                       20 ton/ac                    30 ton/ac




 100 lbs P205     60 lbs P205
                                     260 lbs P205   60 lbs P205   420 lbs P205       60 lbs P205




*Manure content: 22 lbs. TN, 16 lbs. P205 ton-1               lbs P205 ac-1 removed by harvest
*Manure incorporated w/in 24 hours
*Yield: 160 bu acre-1                                         excess lbs P205 ac-1
4500
                                                            75
4000
3500                                                       58
3000
2500                                                       42
2000
1500                                                        25
1000
500                                                         8
  0
       1       2   3   4   5   6   7   8   9         10
   10 ton/ac
                                               Open Feedlot Manure
   20 ton/ac                                   TN 22, P2O5=16 lbs/ton
   30 ton/ac                                   CN=160 bu/ac,
  Phosphorus Loss

 What does “Very
  High” soil test mean?
   Agronomy: No P is
    needed to grow a
    crop
 Does “Very High”
  equal high
  environmental risk?

                          March 14, 2007
 Phosphorus Loss

Very High soil P but low
runoff and erosion potential
could = low P loss




                           Low soil P doesn’t necessarily
                          indicate low P loss



                                                March 14, 2007
Iowa P index

 Considers all factors that influence P loss
   Soil
   Landscape
   management practices
 Provides a risk rating and interpretation
 Producers can use P index
   to identify causes of high P loss
   provide options to reduce P loss

                                        March 14, 2007
Iowa P index

 Developed by
   Iowa State University
   Iowa USDA-NRCS
   USDA-ARS National Soil Tilth Laboratory
 Based on available Iowa research and
  scientific judgment
   NRCS Iowa Technical Note No. 25 - Iowa
    Phosphorus Index (Jan. 2001)
   NRCS Standards and Specifications for Nutrient
    Management (590 Standard)

                                              March 14, 2007
  Iowa P index

 Three components
   Erosion
   Surface runoff
   Subsurface drainage
 Sum gives an
  estimate of P loss
  from the field


                          March 14, 2007
Erosion component
 Total gross soil erosion
  estimates
    RUSLE
    Ephemeral erosion
    gully erosion
 Sediment trap factor
 Sediment delivery ratio (SDR)
  factor
 Buffer strip factor
 Total soil P factor
 Sediment enrichment factor

                                  March 14, 2007
Erosion Component

Soil reaching stream (ton/ac)
             X
Concentration P in soil (lbs P/ton)
             =
P reaching stream with soil (lbs P/ac)



                                     March 14, 2007
Surface Runoff Component

  NRCS Runoff Curve
   Number
  County average
   precipitation
  Soil-test P runoff factor
  P application factor
     Rate effect on soil-test P
      increase
     Method and time of
      application                  March 14, 2007
Surface Runoff Component

       Volume of runoff (gal/ac)
                  X
     Concentration of P (lbs P/gal)
                  =
P reaching stream with runoff (lbs P/ac)



                                       March 14, 2007
Subsurface Drainage
Component
            A 10% flow estimate
            Presence of tiles or
             sandy subsoil
             recharge to surface
             water
            County average
             precipitation
            Soil-test P drainage
             factor

                            March 14, 2007
Subsurface Drainage
Component
Volume of subsurface drainage (gal/ac)
                    X
     Concentration of P (lbs P/ac)
                    =
P reaching stream with subsurface
drainage (lbs P/ac)


                                    March 14, 2007
Phosphorus Loss

P reaching stream with soil (lbs P/ac)
               +
P reaching stream with runoff (lbs P/ac)
               +
P reaching stream with subsurface      drainage
  (lbs P/ac)

   Total P loss from field (i.e. P index Value)

                                           March 14, 2007
Phosphorus Loss

 P index value determines application
  rates.
 Field ranked as:
     Very Low
     Low
     Medium
     High
     Very High

                                    March 14, 2007
“Optimum” soil test 20 ppm                     VH

                             No application

                                               H

                                  P-based
                                  until 2009


                             < 2X P-based      M
                                                L
                                 N-based
                                               VL




                                     March 14, 2007
   Reducing the P index

 Erosion is typically the dominant factor
 P index can be reduced by adopting
  additional conservation practices
     Reduced tillage
     Buffers
     Terraces
     Grass Waterways

                        NRCS


                                             March 14, 2007
  Iowa P index

 Inputs needed to
   run index
     Erosion estimates
     Distance from center of field to a stream
     P value from a recent soil test
     Soil type
 NRCS provides an Excel
  spreadsheet to do calculations
                                                  March 14, 2007
Benefits of P index

 Comprehensive
   Erosion
   Runoff
   Subsurface drainage
 Flexible
   P index can be reduced
   High “risk” areas managed separately


                                       March 14, 2007