Submitted to: American Society of Agricultural Engineers Meetings Papers
Publication Type: Other
Publication Acceptance Date: 7/19/1999
Publication Date: N/A
Interpretive Summary: Economic, environmental and legislative issues faced by farmers are changing traditional agriculture. Conservation tillage and use of animal waste as alternative nutrient source are getting attention nationwide as avenues towards sustainable agriculture. Farmers need information on how to adapt new technology without undue risks. Recent rapid growth in cotton acreage, continuing expansion of poultry litter use as an alternative fertilizer, and increasing adoption of alternative tillage methods have the potential for significantly affecting the quality of water runoff and leachate in the Southeast. Little is known about the interactions of tillage and poultry litter in determining nutrient movement to ground and surface water in the southeast. We conducted an experiment in 1997 and 1998 on instrumented and tile-drained plots, near Watkinsville, GA, to quantify nitrate losses from cotton with a rye cover crop, managed under no-till and dconventional-till, fertilized with poultry litter and conventional fertilizer. So far, no-till did not increase nitrate leaching when compared to conventional-till. Although poultry litter led to a larger nitrate loss than conventional fertilizer, the difference was relatively small (3.5 kg/ha) and biologically considered to be unimportant. These are encouraging results for those growing cotton under no-till with poultry litter.
Technical Abstract: Concern about nitrate-nitrogen (NO3-N) contamination of water resources from non-point sources is high world wide. We conducted an experiment near Watkinsville, GA, in 1997 and 1998, to quantify NO3-N losses by drainage from a cotton/rye cropping system managed under different tillage and nutrient sources on a Cecil soil of the Southern Piedmont. The study was done on twelve 10 m x 30 m instrumented, tile-drained plots as a randomize complete block design in a 2 x 2 factorial arrangement of no-till (NT) and conventional-till (CT) with poultry litter (PL) and conventional fertilizer (CF). Treatments were replicated three times. There was no difference in total NO3-N loss between CT and NT (mean 8.9 and 8.2 kg NO3-N/ha, respectively; P>0.73)during the 1997 cotton season. However, PL ans CF plots showed differences (10.3 and 6.5 kg NO3-N/ha, respectively; P=0.007)which were relatively small, and biologically considered to be unimportant. The differences may have been due, partly, to a larger than expected N mineralization from PL. Concentrations peaked at 20-27 mg NO3- N/L for CT, 10-15 mg NO3-N/L for NT, 15-20 mg NO3-N/L for CF and PL during the first two months after N application, and then fell to below 5 mg NO3- N/L late in the season. There was no drainage in the 1998 cotton season due limited rainfall. These are encouraging results for producers engaged in cotton production under no-till with poultry litter.