Trends in Feed and Manure Phosphorus. John Peters Soil Science Department UW-Madison

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1 Trends in Feed and Manure Phosphorus John Peters Soil Science Department UW-Madison

2 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

3 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.

4 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) Dietary Phosphorus (% DM)

5 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

6 Phosphorus (P) story

7 Average soil P levels of Wisconsin cropland fields over time

8 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

9 Debunking the myth: Milk production is not harmed by lower P diets Summary of 8 studies Milk Production (lbs/day) Studies Low dietary P High dietary P

10 National Research Council (NRC) feed-p recommendations Milk Production Dietary P Level (lbs/day) (%) Adapted from Nutrient Requirements for Dairy Cattle, Seventh Revised Edition, National Academy Press Washington, D.C., January 2001

11 New Assessment Tool: TMR Sample

12 Dietary P data from 89 high-producing dairy herds UW Soil & Forage Analysis Lab Marshfield, WI % of herds studied NRC, Total Dietary P Level (wet chemistry analysis)

13 TMR Quality Control Dietary Phosphorus Results y = x R 2 = % P (DM basis) /02 10/02 04/03 11/03 05/04 12/04

14 Rock River Laboratory TMR Data % P Jan-01 Jul-01 Feb-02 Sep-02 Mar-03 Oct-03 Apr-04 Nov-04 Date

15 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

16 TMR Quality Control Dietary Calcium Results y = x R 2 = % Ca (DM basis) /02 10/02 04/03 11/03 05/04 12/04

17 TMR Quality Control Dietary Magnesium Results 3.50 % Mg (DM basis) y = x R 2 = /02 02/03 09/03 03/04 10/04

18 TMR Quality Control Dietary Potassium Results % K (DM basis) y = x R 2 = /02 02/03 09/03 03/04 10/04

19 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

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21 Effect of P intake on P in manure Fecal P, lb/cow/year % 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!

22 Effect of P intake on form of P in manure Dietary P intake, % soluble P insoluble P A high P diet produces manure that is more likely to cause environmental problems.

23 Land required for recycling fecal P from one cow fed various dietary P levels Acres % 0.38% 0.48% 0.55% Dietary P level Alfalfa, corn, soybean rotation with 27 lb P/a removal

24 UW Soil & Forage Analysis Laboratory Dairy Manure Summary P as P 2 O Average lbs/1000 gal. (liquid) Average lbs/ton (solid) Solid Liquid

25 Rock River Laboratory Dairy Manure Summary 10 P as P 2 O 5 Average lbs/1000 gal. (liquid) Average lbs/ton (solid) Liquid Solid 0 May-Jun 2003 Jul-Sep 2003 Oct-Dec 2003 Jan-Mar 2004 Apr-Jun 2004 Jul-Sep 2004 Quarter

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27 An Alternative Manure Handling Practice

28 Digested and Separated Manure Gordondale Farms, Nelsonville, WI % Dry Matter Digester - in Digester- out Separator liquid Separator solid

29 Digested and Separated Manure Gordondale Farms, Nelsonville, WI Digester - in Digesterout Total P2O5 (lbs/ton) 83% 17% Separator liquid Separator solid

30 Digested and Separated Manure Gordondale Farms, Nelsonville, WI Total N (lbs/ton) % 17% 2 0 Digester - in Digesterout Separator liquid Separator solid

31 Digested and Separated Manure Gordondale Farms, Nelsonville, WI Ammon. N (lbs/ton) % 17% Digester - in Digesterout Separator liquid Separator solid

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33 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.