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 Slow release of soluble nutrients (N, S, B) Usually more economical than commercial fertilizer

Soil Phosphorus Buildup – A Major Problem Difference in nitrogen:phosphorus (P 2 O 5 ) 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.

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.

Study Outline A Coastal bermudagrass hay meadow was overseeded in October of 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 Broiler litter was applied to the ryegrass – bermudagrass system in October and to the clover – bermudagrass system in April.

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 cm depths were analyzed for P.

Annual Ryegrass – Coastal Bermudagrass System Year 1Year 2Year 3Year 4 Broiler Litter Application, Ryegrass Planting, and Harvest Dates Oct. 15, 1998Oct. 21, 1999Oct. 20, 2000Oct. 1, 2001 Oct. 23, 1998Oct. 22, 1999Oct. 25, 2000Oct. 31, 2001 Jan. 19, 1999 Mar. 17, 1999 Apr. 19, 1999 June 7, 1999 July 1, 1999 Aug. 10, 1999 Oct. 13, 1999 Nov. 30, 1999 Mar. 14, 2000 Apr. 21, 2000 May 31, 2000 June 28, 2000 Aug. 15, 2000 Oct. 9, 2000 Apr. 3, 2001 Apr. 30, 2001 June 19, 2001 July 18, 2001 Sept. 26, 2001 Mar. 22, 2002 Apr. 19, 2002 June 19, 2002 Aug. 15, 2002 Oct. 14, 2002

9.0 Mg/ha4.5 Mg/ha Year 1Year 2Year 3Year kg / ha N P 2 O 5 K 2 O Ca Mg Na Zn Fe Cu Mn Nutrients applied to ryegrass-bermudagrass

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

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

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

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

Ryegrass-bermudagrass P uptake when fertilized with broiler litter and N fertilizer. Year 3 Phosphorus Uptake of Ryegrass-Bermudagrass (kg/ha) c b ab a a a

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

Soil P levels after applying broiler litter and N fertilizer for 4 years to annual ryegrass-bermudagrass. 56 kg N/ha 0-15 cm15-30 cm30-60 cm P (ppm) No BL or N No N Dec Mar May July Dec, Mar May, July Mar, May Mar, May, July Dec, Mar, May, July 6.8e 44.3a 21.1cd 19.9cd 32.2b 21.3cd 34.1b 21.9cd 23.7c 22.7cd 19.0d 2.3d 11.0a 7.4b 5.7bc 7.4b 5.5bc 4.9c 5.5bc 5.1c 7.4b 5.6bc 2.5c 5.2a 3.4bc 2.7c 2.9bc 2.4c 2.3c 3.3bc 4.5ab 3.8a-c 3.3bc

SUMMARYRyegrass-Bermudagrass Maximum yield was reached with 168 kg N/ha three years and 112 kg N/ha one year. 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. 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. After four years, combining N fertilizer with broiler litter resulted in lower residual soil P than broiler litter alone.

Crimson Clover – Coastal Bermudagrass System Year 1Year 2Year 3Year 4 Broiler Litter Application, Clover Planting, and Harvest Dates April 22, 1999April 24, 2000May 4, 2001May 10, 2002 June 7, 1999 June 30, 1999 Aug. 10, 1999 Oct. 13, 1999 Oct. 21, 1999 Nov. 30, 1999 Mar. 20, 2000 Apr. 21, 2000 May 31, 2000 June 28, 2000 Aug. 15, 2000 Oct. 9, 2000 Oct. 20, 2000 Apr. 3, 2001 Apr. 30, 2001 June 19, 2001 July 18, 2001 Sept. 26, 2001 Oct. 1, 2001 Apr. 30, 2002 June 19, 2002 Aug. 15, 2002 Oct. 14, 2002 Oct. 17, 2002 Apr. 25, 2003

9.0 Mg/ha4.5 Mg/ha Year 1Year 2Year 3Year kg / ha N P 2 O 5 K 2 O Ca Mg Na Zn Fe Cu Mn Nutrients applied to clover-bermudagrass

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

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

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

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

Soil P levels after applying broiler litter and N fertilizer for 4 years to crimson clover-bermudagrass. 56 kg N/ha 0-15 cm15-30 cm30-60 cm P (ppm) No BL or N No N April June July Apr, June Apr, July June, July Apr, June, July 9.2 c 26.7 ab 23.5 ab 25.9 ab 19.3 b 31.4 a 23.3 ab 26.7 ab 29.8 a 3.0 d 10.5 a 9.1 ab 9.8 a 6.2 c 10.2 a 8.4 a-c 9.7 a 6.7 bc 2.4 a 3.3 a 3.8 a 3.4 a 4.1 a 3.8 a 2.7 a 3.6 a 3.5 a

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. 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. 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. The crimson clover-bermudagrass system was as effective as applying N fertilizer to the annual ryegrass- bermudagrass system for reducing residual soil P.