Trends in Feed and Manure Phosphorus John Peters Soil Science Department UW-Madison
Acknowledgments Laboratory manure and TMR data provided by: Dairyland Laboratories, Inc. Rock River Laboratory, Inc. Digester/separator data provided by Gordondale Farms, Nelsonville, WI Dairy dietary P information provided by Mark Powell, USDA-ARS
Phosphorus story More than half of Wisconsin dairy farmers feed more P than cows need According to National Research Council recommendations Source: Powell et al., 2002 survey of 93 farms.
How much P is being fed? NRC 1989 What dairy producers fed (1999) Beginning Signs of P Deficiency NRC 2001 What dairy producers feed (today) 0.30 0.35 0.40 0.50 Dietary Phosphorus (% DM)
Potential annual phosphorus inputs and outputs from a 100 cow Wisconsin dairy farm P inputs P outputs (lb) (lb) Protein supplement 1219 Milk 1806 Dicalcium phosphate 1627 Cull cows/calves 300 Grain 0 Surplus Feed 0 Forage 0 Manure 0 Fertilizer 1181 Runoff 201 TOTALS 4027 TOTALS 2307 Farm P balance = +1,720 lb P
Phosphorus (P) story
Average soil P levels of Wisconsin cropland fields over time
Why is P overfed? Myth that increasing P improves reproductive performance Little research on the absolute minimum P content required to support moderate to high levels of milk production Aggressive marketing of P supplements Cheap and available protein feed sources that are high in P content
Debunking the myth: Milk production is not harmed by lower P diets Summary of 8 studies Milk Production (lbs/day) 90 80 70 60 50 40 30 20 10 0 1 2 3 4 5 6 7 8 Studies Low dietary P High dietary P
National Research Council (NRC) feed-p recommendations Milk Production Dietary P Level (lbs/day) (%) 55 0.32 77 0.35 99 0.36 120 0.38 Adapted from Nutrient Requirements for Dairy Cattle, Seventh Revised Edition, National Academy Press Washington, D.C., January 2001
New Assessment Tool: TMR Sample
Dietary P data from 89 high-producing dairy herds UW Soil & Forage Analysis Lab Marshfield, WI-2002 35 30 % of herds studied 25 20 15 10 5 NRC, 2001 0 0.25-0.30 0.31-0.35 0.36-0.40 0.41-0.45 0.46-0.50 0.51-0.55 0.56-0.60 Total Dietary P Level (wet chemistry analysis) 0.61-0.65
TMR Quality Control Dietary Phosphorus Results 1.00 0.90 0.80 y = -0.0001x + 4.223 R 2 = 0.0913 % P (DM basis) 0.70 0.60 0.50 0.40 0.30 0.49 0.39 0.20 0.10 0.00 03/02 10/02 04/03 11/03 05/04 12/04
Rock River Laboratory TMR Data 0.5 0.45 0.4 % P 0.35 0.3 0.25 Jan-01 Jul-01 Feb-02 Sep-02 Mar-03 Oct-03 Apr-04 Nov-04 Date
Dairyland Labs TMR Data 1.00% 0.90% 0.80% 0.70% 0.60% % P 0.50% 0.40% 0.30% 0.20% 0.10% 0.00% 10/6/03 11/25/03 1/14/04 3/4/04 4/23/04 6/12/04 8/1/04 9/20/04 11/9/04 Date
TMR Quality Control Dietary Calcium Results 3.00 2.50 y = 0.0001556x - 4.9311247 R 2 = 0.0277642 % Ca (DM basis) 2.00 1.50 1.00 0.88 1.03 0.50 0.00 03/02 10/02 04/03 11/03 05/04 12/04
TMR Quality Control Dietary Magnesium Results 3.50 % Mg (DM basis) 3.00 2.50 2.00 1.50 1.00 y = 0.0000123x - 0.1064697 R 2 = 0.0005549 0.50 0.35 0.36 0.00 08/02 02/03 09/03 03/04 10/04
TMR Quality Control Dietary Potassium Results % K (DM basis) 16.00 14.00 12.00 10.00 8.00 6.00 4.00 2.00 y = -0.0000232x + 2.4244994 R 2 = 0.0001248 1.53 1.54 0.00 08/02 02/03 09/03 03/04 10/04
Dietary P conclusions Performance (reproductive efficiency and milk production) is not adversely affected by reducing P to NRC recommendations Recent TMR tests indicate a trend toward reduced P levels in dairy rations
Effect of P intake on P in manure Fecal P, lb/cow/year 80 70 60 50 40 30 20 10 0 0.35 0.38 0.48 0.55 % P in diet Increasing P content from 0.35% to 0.55% of diet dry matter increases P output from 42 to 78 lbs/cow/year!
Effect of P intake on form of P in manure 100 90 80 70 60 50 40 30 20 10 0 0.3 0.35 0.4 0.45 0.5 0.55 Dietary P intake, % soluble P insoluble P A high P diet produces manure that is more likely to cause environmental problems.
Land required for recycling fecal P from one cow fed various dietary P levels 3 2.5 Acres 2 1.5 1 0.5 0 0.35% 0.38% 0.48% 0.55% Dietary P level Alfalfa, corn, soybean rotation with 27 lb P/a removal
UW Soil & Forage Analysis Laboratory Dairy Manure Summary P as P 2 O 5 12 10 Average lbs/1000 gal. (liquid) Average lbs/ton (solid) 8 6 4 2 1998 1999 2000 2001 2002 2003 2004 0 Solid Liquid
Rock River Laboratory Dairy Manure Summary 10 P as P 2 O 5 Average lbs/1000 gal. (liquid) Average lbs/ton (solid) 9 8 7 6 5 4 3 2 1 Liquid Solid 0 May-Jun 2003 Jul-Sep 2003 Oct-Dec 2003 Jan-Mar 2004 Apr-Jun 2004 Jul-Sep 2004 Quarter
An Alternative Manure Handling Practice
Digested and Separated Manure Gordondale Farms, Nelsonville, WI 30 25 % Dry Matter 20 15 10 5 0 Digester - in Digester- out Separator liquid Separator solid
Digested and Separated Manure Gordondale Farms, Nelsonville, WI 5 4.5 4 3.5 3 2.5 2 1.5 1 0.5 0 Digester - in Digesterout Total P2O5 (lbs/ton) 83% 17% Separator liquid Separator solid
Digested and Separated Manure Gordondale Farms, Nelsonville, WI 14 12 Total N (lbs/ton) 10 8 6 4 83% 17% 2 0 Digester - in Digesterout Separator liquid Separator solid
Digested and Separated Manure Gordondale Farms, Nelsonville, WI 4.5 4 Ammon. N (lbs/ton) 3.5 3 2.5 2 1.5 1 83% 17% 0.5 0 Digester - in Digesterout Separator liquid Separator solid
Summary An integrated approach to improving P nutrient management on dairy farms seems to be having an impact. TMR samples tested in Wisconsin show a trend toward decreased total P levels, bringing them more in line with NRC guidelines It appears that a trend toward reduced dairy dietary feed P levels is being reflected in average manure P levels as well.