Phosphorus runoff from sandy soils under conservation tillage with surface broadcasted recovered phosphates

Potential new sources of phosphorus (P) fertilizers are the recovered P from livestock wastewater through chemical precipitation and the ash from combusting animal manures. These P-rich materials have low water solubility. Most of the research on P losses from conservation tillage include commercial fertilizer sources that have a high-water soluble P content but information on the use of non-conventional, low water soluble, recycled P sources is scarce. The objective of this study was to investigate the potential P runoff from conservation tillage fertilized with phosphates recovered from turkey litter ash and liquid swine manure in comparison with commercial P fertilizer triple superphosphate (TSP). Simulated rain corresponding to the annual 30-minute rainfall in the study site (Florence, South Carolina) was applied to plots treated with three P fertilizer sources and one control. The P fertilizer sources included turkey litter ash (a bio-energy byproduct), granulated recovered P from liquid swine manure, and TSP. The runoff was monitored and sampled every 5 minutes during the test. Laboratory analyses were conducted to quantify the P wash-off in runoff samples. Results show that the quantity of P wash-off from the plots treated with turkey litter ash and the recovered P from swine manure were respectively 10 and 15 times lower than the triple super phosphate plots. These results sustain the use of the turkey litter ash and recovered P from swine manure as crop P fertilizer through surface broadcast application.