Submitted to: Agronomy Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 10/2/2000
Publication Date: N/A
Technical Abstract: This research compared orthophospate-P (PO4) losses in runoff from cotton managed under no-till (NT) and fertilized with poultry litter (PL) versus that from conventionally tilled (CT) and fertilized (CF as NH4NO3) cotton from a Cecil sandy loam soil of the Southern Piedmont. The study was conducted in 1996, 1997 and 1998 near Watkinsville, GA. The site consisted of twelve 10 m x 30 m plots instrumented to measure and sub-sample runoff. Cotton was grown in summer followed by rye as cover crop in winter. Nitrogen fertilizer was applied at the rate of 60 kg ha-1 available N (4.5 Mg ha-1 for PL) and incorporated into the soil by light disking in CT and surface applied in NT. Treatments were replicated three times. Because of instrumentation problem in 1996 and dry conditions in 1998, runoff data were limited to 1997. Mean PO4 concentration from April to June 1997 from seven runoff events was 0.31 and 0.38 mg L-1 in CTCF and CTPL, and 0.94 and d1.74 mg L-1 in NTCF and NTPL respectively. Total PO4 load in runoff was 0.20 and 0.18 kg ha-1 in CTCF and CTPL and 0.45 and 0.56 Kg ha-1in NTCF and NTPL respectively. Incorporation of the fertilizer in CT appears to have reduced the PO4 loss in the runoff. The PL led to higher PO4 concentration in both tillage treatments. Overall, the PO4 losses do not appear to be excessive.