THE FORMS AND FATE OF PHOSPHORUS UNDER VARIOUS FERTILIZATION AND TILLAGE PRACTICES

Abstract

The use of phosphorus (P) in agricultural systems is necessary for proper plant growth and development. Proper management of P is critical to avoid surface and sub-surface water contamination. Studies have indicated that application rates of P and tillage can influence soil P forms and losses from agricultural land. Study 1 of this thesis considered how tillage could influence P concentrations in water after spring and fall applications of liquid swine manure. It was determined that incorporation of manure is the least resource intensive and most environmentally suitable tillage system in terms of reducing P losses. Study 2 examined how the application of various P amendments applied at rates near or below plant removal for 4 years could influence soil P forms. Conclusions were that only inorganic fertilizers influenced soil test P (STP). In addition, labile soil P forms were affected by treatment, while organic and resistant fractions were not.