IMPROVING CROP AND ANIMAL PRODUCTION SYSTEMS FOR SOUTHERN PRODUCERS
Location: Athens, Georgia
Title: Sequential P Extracts in Cecil soil during ten years of conventional and conservation tillage cropping management with and without poultry litter
Submitted to: ASA-CSSA-SSSA Annual Meeting Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: August 3, 2009
Publication Date: November 1, 2009
Citation: Endale, D.M., He, Z., Schomberg, H.H., Zhang, H., Jenkins, M., Honeycutt, C.W. 2009. Sequential P Extracts in Cecil soil during ten years of conventional and conservation tillage cropping management with and without poultry litter [abstract]. ASA-CSSA-SSSA Annual Meeting, November 1-5, 2009, Pittsburg, Pennsylvania.
Soil phosphorus (P) buildup from long-term applications of poultry litter presents a potential environmental problem. Knowledge of soil P distribution among its chemical forms is useful for assessing risk levels. We measured sequentially-fractioned H2O, NaHCO3, NaOH, and HCl extractable P in a Cecil soil from 1996 to 2005 near Watkinsville, GA, from samples taken in the second of a 5-yr cotton phase, at the end of the cotton phase, and at the end of a 5-yr corn phase following cotton. Each crop was managed in either conventional tillage or no-till, with either conventional fertilizer (CF) or poultry litter (PL). Rye was the winter cover crop. For cotton, PL application rate was 4.5 Mg ha-1 based on nitrogen (N) requirement. For corn, PL application rates were 2 to 4 times that of cotton, partly because of corn’s greater N requirement. Inorganic P fractions extracted were 53 to 79%, with NaOH, 16 to 22% each with NaHCO3 and HCl, and < 5% with H2O. Total P (Pt) fractions extracted were 60 to 80% with NaOH, 15 to 23% with NaHCO3, 3 to 18% with HCl and < 5% with H2O. The residue fraction accounted for 23 to 43% of Pt. With conventional fertilizer, P fractions remained essentially the same throughout or slightly increased (~ x 2) by October 2005. With PL, fractions essentially remained the same during cotton but increased 2 to 5 times by October 2005. Sequentially, total P in mg kg-1 from the PL fields in October 2005 was approximately 17, 85, 214, 61, and 114 for H2O, NaHCO3, NaOH, and HCl extracts and residual, respectively. In Cecil soil, application of PL at levels to meet N needs of corn increases the risk of increasing soil P to environmentally unacceptable levels.