Poultry Manure Nutrient Effects on Cotton, Corn, and Residual Soil with Conventional and Conservation Tillage.

Three poultry manure sources (broiler litter, BL; layer manure, LM; and composted layer manure, CLM) were evaluated in four-year cotton-corn rotational plots at North Carolina coastal plain and tidewater region sites.  During the first year of the study, residual N levels were sufficiently high so that no response of cotton to inorganic or poultry manure N sources were observed.  In the second year, significant corn responses to poultry manure N additions were observed with both conventional and strip-tillage at the coastal plain site, and with no-till but not with conventional tillage at the tidewater site.  Crop yield and plant tissue analyses from samples collected from inorganic N fertilizer plots and poultry manure plots were used to calculate fertilizer N equivalence of manures.  Values have ranged from 15 to 100% in the first year, and from 0 to 56% in the second year after application.  Initial year soil samples documented soil pH, P, K, and Zn changes in response to poultry manure additions.  Crop responses, N fertilizer equivalency, and summaries of residual soil effects from additional years will also be presented.