Residual effect of poultry litter applied to cotton in conservation tillage systems on succeeding rye and corn

The burgeoning poultry industry in the southeastern US is presenting a majo r environmental problem of safe disposal of poultry litter (PL). In a compr ehensive study, we explored ways of PL use in conservation tillage-based co tton (Gossypium hirsutum L.) production systems on a Decatur silt loam soil in north Alabama, from 1996 to 1999. The study reported here-in presents t he residual effects of PL applied to cotton in mulch-till (MT) and no-till (NT) conservation tillage systems in 1997 and 1998 cropping seasons on N up take, growth, and yield of rye (Secale cereale, L.) cover crop and rotation al corn (Zea mays L.) in 1999. Rye was grown without additional N, whereas corn was grown at three inorganic N levels (0, 100, and 200 kg N ha(-1)). P oultry litter was applied to cotton in 1997 and 1998 at 0, 100, and 200 kg N ha(-1). Residual N from PL applied to cotton in 1997 and 1998 produced up to 2.0 and 17.3 Mg ha(-1), respectively, of rye cover crop and corn biomas s (includes 7.1 Mg ha(-1) of corn grain yield) without additional fertilize r. Therefore, in addition to supplying crop residues which reduce soil eros ion, increase soil organic matter, and conserve soil moisture, the rye cove r crop was able to scavenge residual N left by the cotton crop, which would otherwise, be at risk of being leached and pollute groundwater resources. Poultry litter applied to cotton also increased corn grain quality as shown by up to 100% increase in grain N content compared to the ON treatment. Us ing PL with a slower rate of N release compared to inorganic fertilizer to meet some of the N requirements of corn, will not only reduce N fertilizer costs for corn, but will also reduce the risk of nitrate N leaching into gr oundwater. The maximum amount of crop residues added to the cotton based cr opping system by residual N from PL and inorganic N was 21.3 Mg ha(-1). Thi s will lead to an increase in soil organic carbon and soil structure in the longs term and a reduction in soil erosion, thereby further improving soil productivity, while at the same time, protecting the environment from nitr ate pollution and soil degradation. Our study demonstrates that cotton unde r conservation tillage system in combination with rye cover crop and rotati onal corn cropping could use large quantities of PL thereby avoiding seriou s potential environmental hazards. (C) 2001 Elsevier Science B.V. All right s reserved.