Broiler Litter Timing and Cover Crop Affect Cotton Yield and Residual Soil N.

Timing of broiler litter applications has critical effect on the availability of litter derived nutrients and should affect cotton (Gossyptium spp.) growth and yield. This experiment was conducted on a Leeper silty clay loam (fine, montmorillionitic, nonacid, thermic Vertic Haplaquepts) soil at Mississippi Plant Science Research Center to quantify the effects of cropping system [(winter rye (Secale cereale L.) cover crop vs. winter fallow)] and time of broiler litter application (fall vs. spring) on cotton yield and soil residual NO₃ during 2006-2008 time period.  Broiler litter was applied at the rate of 0, 4.5, 9, and 13.4 Mg h a^-1 and incorporated immediately. Fall applied broiler litter coupled with winter rye cover crop increased cotton lint yield by 8 and 17% in 2007 and 2008, respectively compared to winter fallow. However, spring applied broiler litter provided the best agronomic response and resulted in greater cotton lint yield and N use efficiency than those of fall applied litter. Mean NO₃-N concentration in the leachat samples collected at 60 cm depth during late fall, winter and early spring was significantly reduced by 86% in winter rye cover crop treatment compared to winter fallow. This indicates over seeding a catch crop to fall applied broiler litter appears to reduce leaching losses of NO₃-N and increase N recycling for subsequent crops in the spring.