Submitted to: Meeting Abstract
Publication Type: Proceedings
Publication Acceptance Date: April 19, 2007
Publication Date: July 25, 2007
Citation: Read, J.J., Brink, G.E., Adeli, A., Thomas, J.G. 2007. Effects of swine effluent application rate and timing on nitrogen utilization and residual soil nitrogen in common bermudagrass. Proceeedings 17th Annual Mississippi Water Resources Conference. p. 35-41. Technical Abstract: Frequent summer precipitation in the southeastern USA may delay the application of swine effluent to bermudagrass [Cynodon dactylon (L.) Pers.] hay fields until late summer or early fall. Due to declining growth of this warm-season forage in the fall, there is potential for excessive N accumulations in soil and hence, nitrate leaching. Field studies were conducted on a Prentiss soil (coarse-loamy, siliceous, semiactive, thermic Glossic Fragiudult) to determine if irrigation rate and timing influence N recovery and soil residual nitrate-N in common bermudagrass. Effluent was applied at 10 and 20 cm/ha (270 and 480 kg N/ha, respectively) in four irrigation seasons: April to September, April to May, June to July, and August to September. Total N uptake averaged 306 kg/ha in 2000 and 335 kg/ha in 2001, and was associated with significantly lower forage biomass yield in 2000 than 2001 (8.1 vs. 11.4 mg/ha). Averaged across timing treatments, doubling the effluent rate significantly decreased N recovery in 2001 from about 64.2 to 55.8% (LSD =5.4%). In the Aug-Sep treatment irrigated with 20 cm effluent, N recovery by bermudagrass was about 54% in 2000 and 31% in 2001. Soil nitrate levels at 0-10 cm depth in November were elevated above the control (no effluent) when 20 cm/ha was applied from Jun-Jul, Apr-Sep, and Aug-Sep (mean of 70 mg/kg nitrate). Nitrogen in effluent applied late in the growing season, particularly at high rates, is thus less likely to be utilized by bermudagrass due to dry summer conditions or declining growth during the fall.