Swine Effluent Application Timing and Rate Affect Nitrogen Use Efficiency in Common Bermudagrass
- J. J. Read *a,
- G. E. Brinkb,
- A. Adelia and
- S. L. McGowenc
- a USDA–ARS, Genetics and Precision Agriculture Research Unit, P.O. Box 5367, Mississippi State, MS 39762
b USDA–ARS, U.S. Dairy Forage Research Center, 1925 Linden Dr. West, Madison, WI 53706
c USDA–Natural Resources Conservation Service, 4900 Oklahoma Ave. Suite 300, Woodward, OK 73801. Journal number J-11205 of the Mississippi Agriculture and Forestry Experiment Station. Mention of a trademark, proprietary product or vendor does not constitute a guarantee or warranty of the product by the USDA and does not imply its approval to the exclusion of other products or vendors that also may be suitable
Bermudagrass [Cynodon dactylon (L.) Pers.] hay production is integral to manure management on southeastern swine farms. But swine effluent timing must be synchronized with crop nitrogen (N) demands to decrease the potential for soil N accumulation and nitrate (NO3) leaching. Field studies were conducted on a Prentiss sandy loam (coarse-loamy, siliceous, semiactive, thermic Glossic Fragiudult) to determine N-use efficiency (NUE) and residual soil NO3–N. Two rates of 10 and 20 cm yr− 1 (∼260 and 480 kg ha−1 N, respectively) were applied in four timing treatments: April to September (full season), April to May, June to July, and August to September. Plots were harvested every 7 to 9 wk beginning in June, and soil was sampled in fall after a killing frost and the following spring. Annual uptake of N and P were least in the August to September timing treatment. Doubling the effluent rate increased N uptake 112% in 2000 (from 130 to 276 kg ha−1) and 53% in 2001 (from 190 to 290 kg ha−1), suggesting 10-cm did not meet crop N demands. Due to low rainfall and decreased forage yield in 2000, doubling the effluent rate led to increased soil NO3–N to 30-cm depth in fall 2000 and spring 2001. Averaged across timing treatments, soil NO3–N at 5-cm depth ranged from 8.5 mg kg−1 in non-irrigated controls to 39.6 mg kg−1 with 20-cm effluent. Results indicate low NUE in the order of 30 to 38% for applications in August to September increase the risk to surface and ground water quality from excess N remaining in soil.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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