No-till and conventional-till cotton response to broiler litter fertilization in an upland soil: lint yield
The effectiveness of poultry litter as cotton (Gossypium hirsutum L.) fertilizer is not well documented for upland soils in the southern and southeastern United States. The objective of this research was to measure cotton yield response to broiler litter fertilization in contrast to inorganic N fertilization and to quantify yield reduction due to lack of incorporation under no-till and conventional-till systems in an upland soil. Six treatments were tested in two unreplicated adjacent fields, one under no-till (NT) and the other under conventional-till (CT) management, from 2003 to 2006 near Pontotoc, MS. The treatments consisted of an unfertilized control (UTC), a standard fertilization (STD) with urea-ammonium nitrate solution (UAN), fertilization with 5.2 Mg ha–1 incorporated or unincorporated broiler litter to supply 67% of the N need plus 34 kg ha–1 UAN-N to supply 33% of the N need, and fertilization with 7.8 Mg ha–1 incorporated or unincorporated broiler litter. Lint yield results showed broiler litter was a more effective cotton fertilizer than inorganic fertilizers under both NT and CT systems. The UTC produced an average across years of 870 kg ha–1 lint under NT and 1105 kg ha–1 under CT. The STD treatment increased yield over the UTC by only 121 kg ha–1 (14%) under the NT and did not affect yield under the CT. Fertilization with litter-only when incorporated, relative to the UTC, increased lint yield by 260 kg ha–1 (30%) under NT and by 137 kg ha–1 (12%) under CT. The yield of this incorporated litter-only treatment exceeded the yield of the STD treatment by 139 kg ha–1 (14%) under NT and by 115 kg ha–1 (10%) under CT. Fertilization with litter also resulted in greater leaf area index but less chlorophyll index than the STD treatment. Lack of litter incorporation reduced yield by up to 84 kg ha–1 under NT but did not affect yield under CT. Overall, broiler litter appears to be a more effective cotton fertilizer than conventional inorganic N fertilizers for this upland soil, but the inherent inability to incorporate under no-till may reduce this benefit.