Supplemental Nitrogen Effect on Broiler‐Litter–Fertilized Cotton

Nitrogen nutrition plays a critical role in cotton ( Gossypium hirsutum L.) production. However, increasing N fertilization may not always be desirable because production problems occur when N supply exceeds the crop requirement. A field experiment was conducted during 2000–2002 to study the optimal quantity of N needed from litter or combination of litter N and supplemental inorganic N for optimum cotton yield production. Poultry litter (2.24 Mg ha −1 equivalent to 1 ton acre −1 ) has been applied to the site annually for the past 20 yr. The experiment included four inorganic N rates (0, 34, 67, and 101 kg N ha −1 ) as sidedress in addition to litter application. The smallest overall average cotton lint yield of 562 kg ha −1 was obtained during 2000 (an exceptionally dry year) followed by 1551 kg ha −1 in 2001 and 880 kg ha −1 in 2002. The supplemental N application did not impact the cotton yield in 2 out of 3 yr. In the 2000 growing season, cotton yield was significantly greater for 0 and 34 than 67 and 101 kg N ha −1 rates. This indicates the negative effect of excess N application on cotton yield under drought conditions. However, under more favorable soil moisture conditions, no significant yield differences were observed by increasing the supplemental N rate up to 101 kg N ha −1 . The 2.24 Mg ha −1 broiler litter application to all plots before planting each year provided approximately 80 kg N ha −1 , which proved to be adequate in three consecutive years for optimum cotton production under a no‐till system.