Alabama is a major cotton production state in the USA. In this study, we assessed the impact of soil management practices on phosphorus (P) forms and lability in Alabama Decatur silt loam cropped with cotton. The data indicated that inorganic P in the soils studied was mainly associated with Fe and Al oxides and was not readily bioavailable. On the other hand, elevated levels of water plus Fe and Al inorganic P fractions were observed in soils treated with poultry litter compared to the control and other inorganic fertilized soils. Most of the soil organic P was associated with Al oxide (> 40%) with the exception of the no-till and control treatments where the bulk of the soil organic P was organic matter bound. Water soluble organic P increased after poultry litter applications whereas no increase was observed with inorganic fertilization. Statistical analysis (mean separation) revealed that the phosphatase and phytase hydrolyzed water soluble organic P within each treatment was not significantly different at P < 0.05. More than 50% of organic P in the sequentially-extracted NaOH fraction was hydrolyzable by the various phosphatase enzymes, indicating that NaOH-extractable organic P is labile. Any portion of the organic P extracted in the fractions that was not hydrolyzed by the enzymes is considered to be in the complex forms tightly bound to colloidal and other materials.
1Department of Biological and Environmental Sciences, College of Agricultural, Life and Natural Sciences, Alabama A&M University, Normal, AL.
2USDA-ARS Southern Regional Research Center, 1100 Robert E Lee Blvd, New Orleans, LA.
Address for correspondence: Irenus A. Tazisong, Department of Biological and Environmental Sciences, College of Agricultural, Life and Natural Sciences, Alabama A&M University, Normal, AL 35762; E-mail: Irenus.email@example.com
Financial Disclosures/Conflicts of Interest: Trade or manufacturers’ names mentioned in the article are for information only and do not constitute endorsement, recommendation, or exclusion by Alabama A&M University and/or USDA-ARS. The research was supported in part by USDACSREES, Evans-Allen Grant # ALAX011.
Financial Disclosures/Conflicts of Interest: None reported.
Received November 29, 2012.
Accepted for publication May 21, 2013.