Should cotton growers apply full nitrogen rate when using broiler‐litter as soil amendment?

Nitrogen plays a critical role in cotton ( Gossypium hirsutum L.) production. Interest in using broiler ( Gallus gallus domesticus ) litter has increased in recent years due to its nutrient and soil health benefits. However, growers typically do not discount the N present in broiler litter and apply a full dose of fertilizer N. A five site‐years field study was conducted to assess the effects of supplemental fertilizer N rate (0, 25, 45, 55, 70, and 85 lbs acre − 1 ) on broiler‐litter–fertilized cotton lint yield, above‐ground biomass, nutrient uptake, lint turnout, and fiber quality. Broiler litter was applied at a rate of 2 tons acre − 1 yr − 1 before planting. Six treatments were arranged in a randomized complete block design with four replications. Cotton receiving only broiler litter (i.e., zero fertilizer N treatment) did not exhibit lint yield declines relative to the combination of broiler litter and fertilizer N at low lint yield levels (864 to 1313 lbs acre − 1 ). However, a positive crop response to fertilizer N (up to 55 lbs acre − 1 ) was observed at higher mean lint yield levels (1775 to 2270 lbs acre − 1 ). Fertilizer N had no significant effect on above‐ground biomass, lint turnout, or fiber quality measurements in any growing season. Overall, these results suggest that supplementing broiler‐litter–fertilized cotton with fertilizer N is required for high production potential. Low‐yielding broiler‐litter–fertilized cotton did not respond to supplemental N.