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Reducing Soil Phosphorus Buildup From Animal Manure Applications

Reducing Soil Phosphorus Buildup From Animal Manure Applications. Gerald W. Evers Texas A&M University Agricultural Research and Extension Center Overton. Benefits of Animal Manure on Agricultural Land. Complete fertilizer – contains all plant nutrients Organic matter improves soil quality

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Reducing Soil Phosphorus Buildup From Animal Manure Applications

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  1. Reducing Soil Phosphorus Buildup From Animal Manure Applications Gerald W. Evers Texas A&M University Agricultural Research and Extension Center Overton

  2. Benefits of Animal Manure on Agricultural Land • Complete fertilizer – contains all plant nutrients • Organic matter improves soil quality • Slow release of soluble nutrients (N, S, B) • Usually more economical than commercial fertilizer

  3. Soil Phosphorus Buildup – A Major Problem • Difference in nitrogen:phosphorus (P2O5) ratio in mature (1:1) and plant requirements (4:1) • Only about 20 to 30% of the phosphorus is taken up by the agricultural crop • Excess soil phosphorus can move into surface water through runoff and soil erosion • Elevated water phosphorus levels result in eutrophication and blue-green algae blooms.

  4. Theory • If moderate levels of animal manure are applied (to meet 60 to 70% of N requirements of the crop), nitrogen becomes the most limiting nutrient. • If additional nitrogen is applied, plant growth and uptake of excess phosphorus should be enhanced and residual soil phosphorus reduced.

  5. Study Outline • A Coastal bermudagrass hay meadow was overseeded in October of 1998-2001 with annual ryegrass or crimson clover. • Broiler litter was applied at 9.0 Mg/ha in 1998 and 1999 and 4.5 Mg/ha in 2000 and 2001. • Broiler litter was applied to the ryegrass – bermudagrass system in October and to the clover – bermudagrass system in April.

  6. Study Outline • In the ryegrass – bermudagrass system, 56 kg N/ha was applied 1 to 4 times/year in December, March, May, and/or July. • In the clover – bermudagrass system, 56 kg N/ha was applied 1 to 3 times/year in April, June, and/or July. • After 4 years, soil samples from 0-15, 15-30, and 30-60 cm depths were analyzed for P.

  7. Annual Ryegrass – Coastal Bermudagrass System

  8. Nutrients applied to ryegrass-bermudagrass

  9. Ryegrass-bermudagrass yield when fertilized with broiler litter and N fertilizer. Yield of Ryegrass-Bermudagrass (Mg/ha) a a Years 1 and 2 b b c cd cd cd d e

  10. Ryegrass-bermudagrass yield when fertilized with broiler litter and N fertilizer. Yield of Ryegrass-Bermudagrass (Mg/ha) Year 3 a a a,b a,b b,c c c cd cd d e

  11. Ryegrass-bermudagrass yield when fertilized with broiler litter and N fertilizer. Yield of Ryegrass-Bermudagrass (Mg/ha) a a Year 4 b b bc b-d c-e de e f g

  12. Ryegrass-bermudagrass P uptake when fertilized with broiler litter and N fertilizer. Phosphorus Uptake of Ryegrass-Bermudagrass (kg/ha) a a Years 1 and 2 a a b bc b-d c-e ed e

  13. Ryegrass-bermudagrass P uptake when fertilized with broiler litter and N fertilizer. Phosphorus Uptake of Ryegrass-Bermudagrass (kg/ha) Year3 a a a ab ab ab ab ab ab b c

  14. Ryegrass-bermudagrass P uptake when fertilized with broiler litter and N fertilizer. Phosphorus Uptake of Ryegrass-Bermudagrass (kg/ha) Year 4 a ab bc cd ef c-e de de c-e f g

  15. Soil P levels after applying broiler litter and N fertilizer for 4 years to annual ryegrass-bermudagrass.

  16. SUMMARY Ryegrass-Bermudagrass • Maximum yield was reached with 168 kg N/ha three years and 112 kg N/ha one year. • Maximum phosphorus uptake occurred at 56 kg N one year, 112 kg N two years, and 168 kg N one year. • After four years, combining N fertilizer with broiler litter resulted in lower residual soil P than broiler litter alone.

  17. Crimson Clover – Coastal Bermudagrass System

  18. Nutrients applied to clover-bermudagrass

  19. Crimson clover-bermudagrass yield when fertilized with broiler litter and N fertilizer. Yield of Crimson-Bermudagrass (Mg/ha) Years 1 and 2 a ab ab a-c bc bc c bc

  20. Yield of Crimson-Bermudagrass (Mg/ha) Crimson clover-bermudagrass yield when fertilized with broiler litter and N fertilizer. a ab a a-c Years 3 and 4 bc c c c d

  21. Crimson clover-bermudagrass P uptake when fertilized with broiler litter and N fertilizer. Phosphorus Uptake of Crimson-Bermudagrass (kg/ha) Years 1 and 2 a a a a a a a a

  22. Phosphorus Uptake of Crimson-Bermudagrass (kg/ha) Crimson clover-bermudagrass P uptake when fertilized with broiler litter and N fertilizer. ab a a-c bc a-c a-c c c Years 3 and 4 d

  23. Soil P levels after applying broiler litter and N fertilizer for 4 years to crimson clover-bermudagrass.

  24. SUMMARY Crimson Clover-Bermudagrass • When 9 Mg/ha of broiler litter was applied, there was no yield response to N fertilizer. When 4.5 Mg/ha of broiler litter was applied, there was a yield increase up to 112 kg N/ha. • Combining N fertilizer with broiler litter do not increased P uptake and seldom decreased residual soil P. • The crimson clover-bermudagrass system was as effective as applying N fertilizer to the annual ryegrass-bermudagrass system for reducing residual soil P.

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