Sequential fractionation and water soluble phosphorus methods to investigate soil phosphorus in a long-term manure applicatio

Scope and Method of Study: The objectives of this study were to investigate soil P using sequential fractionation, and to evaluate how long-term manure applications affect the amount and of bioavailable P and water soluble P (WSP) levels at multiple depths (0-120 cm) in the soil when different N sources (beef manure, swine effluent and anhydrous ammonia) are utilized as sources of plant nutrients.;Findings and Conclusions: The results showed that 13 years of animal manure application has increased soil P pools in the soil profile Gruver clay loam. The soil P fractionation results suggest that continuous application of beef manure on the basis of crop N requirements significantly increased all P fractions. A possible solution to this problem is applying animal manure based on crop P rather than N requirements. Thus, animal waste management practices are an important nutrient source that can be a viable alternative to a commercial fertilizer. However, soil and weather condition as well as animal manure composition should be considered for a sustainable model in the agricultural production.