Lint Yield and Fiber Quality of Cotton Fertilized with Broiler Litter

Poultry litter is generated in large quantities in the same southeastern U.S. states where cotton ( Gossypium hirsutum L.) is a dominant field crop, but is rarely used as a primary cotton fertilizer partly because of lack of adequate management recommendations. This research was conducted to determine adequate rates of broiler litter and whether supplementation with inorganic N would be necessary for optimum cotton lint yield and fiber quality. The research was conducted from 2002 to 2004 on two commercial farms representing conventional‐till (CT) and no‐till (NT) systems. The treatments consisted of an unfertilized control, a farm standard (STD) fertilized with inorganic fertilizers, and broiler litter of 2.2, 4.5, and 6.7 Mg ha −1 in an incomplete factorial combination with 0, 34, or 67 kg ha −1 N as urea–ammonium nitrate solution (UAN). Litter without supplemental UAN–N increased yield by 23 to 110 kg lint ha −1 for every 1.0 Mg ha −1 litter under both CT and NT. The often‐recommended litter rate of 4.5 Mg ha −1 was not adequate to increase yield to be equivalent to that of the STD that received 101 to 135 kg ha −1 as UAN. It was necessary to supplement this or the other litter rates with 34 or 67 kg ha −1 . UAN–N to support yield equal to or greater than the yield of the STD. The most consistently well‐performing treatment under both tillage systems in all years was the 4.5 Mg ha −1 litter supplemented with 67 kg ha −1 . UAN–N. Lint yield was highly correlated ( r 2 = 0.83–0.97) with applied total plant‐available N (N TPA ) under both systems. Fiber quality, fiber length and micronaire in particular, also responded to N TPA , but the responses were smaller than lint yield. Litter when adequately supplemented with UAN–N did not adversely affect fiber quality. These results show broiler litter as much as 4.5 Mg ha −1 should be supplemented with inorganic N fertilizers when used as a primary cotton fertilizer and when the expected yield is ≈1700 kg ha −1 under CT and ≈1500 kg ha −1 under NT.