Distribution of phosphorus forms in soil amended with poultry litter of different ages and application rates: Agronomic and environmental perspectives

Abstract

AbstractPoultry litter (PL) can be used as a viable alternative to phosphate fertilizers. However, there is a lack of information about phosphorus (P) distribution in inorganic (Pi) and organic (Po) forms and its transformation in soils amended with PL of varying age (based on litter clean‐out frequency) and application rate. This study aimed to determine the effect of PL age and application rate on soil P forms and their bioavailability. Soils were amended with 5 and 10 Mg ha−1 PL using 6‐, 18‐, and 30‐month‐old litter and incubated for 6 months. Soil P fractionation was performed following the Hedley protocol. Soil P availability and soil P storage capacity (SPSC) were determined using Mehlich 3 (M3) extraction. Results indicated that P transformation from labile to stable P forms occurred over 150‐day incubation. Litter age had no significant effect on the distribution of soil P forms. However, the highly reactive Pi (HRPi) form was higher for treatments with 10 Mg ha−1 PL on Day 0, indicating a risk for P loss, which was also revealed by negative SPSC for those treatments. At Day 0, M3‐P was positively correlated to HRPi. However, from Day 30 to 150, M3‐P was strongly correlated to both HRPi and moderately reactive Pi (MRPi) forms, indicating MRPi contribution to soil P availability. The negative relationship between HRPi and SPSC further confirms that high HRPi on Day 0 may be an environmental concern.