Cotton Response to Residual Poultry Litter: Leaf Area, Nitrogen Removal, and Yield

Core Ideas A low to moderate N rate is a best management practice after cessation of pelletized poultry litter. This best management practice optimized leaf area, N removal, and lint yield, while reducing input costs. This best management practice reduced soil nitrate levels in the top 30 cm after harvest by approximately 61%.Nitrogen carryover from pelletized poultry litter (PPL) can partially meet cotton ( Gossypium hirsutum L.) N demands. A 3‐yr study determined yield effects of 6.7 Mg ha −1 PPL applied in 2010 to 2013 on cotton leaf area, nitrogen use efficiency (NUE) and yield. Treatments in 2014 and 2015 were no N (control), residual PPL, residual PPL with 84 kg ha −1 N (urea ammonium nitrate) at squaring, and 56 and 84 kg ha −1 N at planting and squaring, respectively. Treatments in 2016 were control, residual PPL with 56 kg ha −1 N, residual PPL with 56 kg ha −1 N at planting and squaring, and split application of 112 kg ha −1 N. Applying 84 kg ha −1 N to residual PPL plots increased ( P < 0.05) leaf area index during the boll‐filling period. Across years, N removal did not differ between residual PPL with 84 kg N ha −1 and fertilizer N only (112 vs. 116 kg N ha −1 ), but was considerably less with residual PPL (40 kg N ha −1 ). Lint yield was greater ( P < 0.01) in PPL with fertilizer N than fertilizer N only by 10% in 2014 (1795 vs. 1633 kg ha −1 ), 5% in 2015 (1898 vs. 1809 kg ha −1 ), and 20% in 2016 (1860 vs. 1554 kg ha −1 ), suggesting residual PPL enhanced NUE. Following cessation of PPL, side‐dress N applications of 56 or 84 kg ha −1 appeared to meet cotton N requirement and enable optimization of fertilizer use.