1. My Field has High Soil Test P. Now what? John A. Lory, Ph.D. Division of Plant Sciences Commercial Agriculture Program University of Missouri

2. Nutrient Management Scale Farm P Assessment Scale Field

3. Water Quality Scale Watershed

4. Water Quality Scale Watershed Nutrient Management Scale Farm P Assessment Scale Field

6. Lake 3 – MU Dairy Farm Lake: 6 acres Watershed: 77 acres Mean soil test P: 94 lbs/a 197 ppb P

7. Missouri Reservoirs Jones and Knowlton 1993 Water Clarity as measured by Secchi depth (m) Missouri reservoirs Lake 3

8. Lake 1 – MU Dairy Farm Lake: 15 acres Watershed: 135 acres Mean soil test P: 69 lbs/a 223 ppb P

9. Lake 2 – MU Dairy Farm Lake: 2.4 acres Watershed: 22 acres Mean soil test P: 91 lbs/a Lake 2 68 ppb P

10. Understanding Edge of field P losses

11. Bray-1 Soil Test P (lbs/acre) Dissolved Reactive P in runoff (ppb) Effect of soil test P on runoff P in forage systems (small plot runoff) Creldon Soil

12. What are my options? 223 ppb P

13. What are my options? Improve timing of application 223 ppb P

14. Water Soluble P in Runoff (ppm) Days After Treatment 200 lbs./acre phosphate applied 3/22/00 to forages Mt. Vernon, MO Improve timing of surface application

15. Days after application Dissolved Reactive P (mg kg -1 ) DAPPoultry Litter Effect of recently applied P on runoff P in forage systems

16. Aug.Oct. Nov. Dec.Jan. Volumetric Water Content (%) Soil moisture at Mt. Vernon, MO 2003 Saturated soil Feb.Mar.Apr.MayJun.Jul.Sep. 2 inches 4 inches Precipitation (in)

17. Aug.Oct. Nov. Dec.Jan. Volumetric Water Content (%) Soil moisture at Mt. Vernon, MO 2004 Saturated soil Feb.Mar.Apr.MayJun.Jul.Sep. 2 inches 4 inches Precipitation (in)

18. Nitrogen for Tall Fescue Hay AprilAugustOctoberJune Forage yield Herd feed requirement

19. Litter is an excellent fertilizer for fall fescue growth

20. What are my options? Lower P index on fields 223 ppb P

21. The importance of erosion TreatmentSTP Soluble P in runoff Erosion Runoff volume ppm kg/hamm Pasture1551.013 Tillage w/residue 1030.215315 Tillage w/o residue 1180.2172622

23. What are my options? Lower P balance watershed 223 ppb P Export more manure Import less manure and fertilizer

24. What are my options? Lower P balance watershed 223 ppb P Should I raise STP on this field?

25. Raise soil test P 10 units with manure Low testing field: 5 ppm to 15 ppm Very high testing field: 50 to 60 ppm Very high testing field: 500 to 510 ppm Is there a water quality benefit from choosing one field over another?

26. Raise soil test P 10 units with manure Low testing field: 5 ppm to 15 ppm –Improved yield and forage quality –Reduced erosion –Lower runoff volume Very high testing field: 50 to 60 ppm Very high testing field: 500 to 510 ppm

27. What are my options? Follow the rules. 223 ppb P No application on frozen or saturated soils No application on >10% slope Adhere to setback requirements

28. What are my options Improve timing of applications Lower field P index Import less and export more P Follow the rules

29. Some philosophy It is a lot easier to avoid a problem then to fix a problem. The P index is best used as a educational tool, not a justification for more manure applications