Nitrogen fertilization of no-till cotton on loess-derived soils

Information on nitrogen (N) fertilization of no-till (NT) cotton (Gossypium hirsutum L.) is needed to optimize lint yields and earliness. We evaluated five N rates and three application methods for NT cotton production on Lor ing silt loam (fine-silty, mixed, active, thermic Oxyaquic Fragiudalfs) wit h natural winter annuals as a cover; and on Memphis silt loam (fine-silty, mixed, active, thermic Typic Hapludalfs) having corn (Zea mays L.) stover a s a cover and on Lexington silt loam (fine-silty, mixed, active, thermic Ut lic Hapludalfs) having winter wheat (Triticum aestivum L.) as a cover. Nitr ogen rates of 0, 34, 67, 101, and 134 kg ha(-1) were either broadcasted as ammonium nitrate (AN) or injected as urea-ammonium nitrate (UAN) at plantin g. Additional treatments included broadcasting 67 kg N ha(-1) as AN at plan ting with either 34 or 67 kg N ha(-1) banded 6 wk later. Relative to no N, broadcasting 67 kg N ha(-1) as AN increased 4-yr average NT lint yields on Loring silt loam from 739 to 1281 kg lint ha(-1) and 2-yr average yields on Lexington silt loam from 1086 to 1535 kg ha(-1). A higher N rate (101 kg N ha(-1)) was needed to increase 2-yr average yields on Memphis silt learn f rom 821 to 1169 kg ha(-1). Broadcasting AN was a satisfactory placement met hod producing yields equal to or higher than injecting UAN or splitting AN for NT cotton produced on these loessial soils despite different covers and residues.