Doctor of Philosophy (PhD)


School of Plant, Environmental, and Soil Sciences

Document Type



Lower solubility of P in poultry litter ash (PLA) than conventional phosphorus (P) fertilizers such as triple superphosphate (TSP) may reduce P losses in drainage and runoff; however, lower P solubility may reduce its efficacy as a P source. A laboratory experiment was conducted to examine the effect of acidity on P release and the effect of different combustion temperatures on P solubility as a prerequisite to the following studies. The first research objective was to determine the effect of soil pH on the efficiency of PLA relative to TSP for establishment of common bermudagrass (Cynodon dactylon L.) and P loss on representative coastal plain soil and. In the study, yields and tissue concentrations were greater where fertilized. Yields were minimally greater with TSP but there were no consistent differences in tissue concentrations between PLA and TSP. Leaching of P was negligible regardless of P fertilizer solubility, however, P runoff losses significantly decreased TSP>PLA>control. The second research objective was to evaluate PLA compared to triple superphosphate in ratios of PLA:TSP of 0:100, 25:75; 50:50; 75:100 as a pre-plant fertilizer incorporated into a 90:10 (v/v) sand and peat mixture seeded with bermudagrass. Compared to TSP, PLA reduced P, K, Ca, and Mg leaching losses during the first two weeks after planting. As the percentage of PLA increased relative to TSP, nutrient leaching decreased incrementally. The objective of the third study was to determine whether P supplied as PLA produced an effect equal to that of TSP on loblolly pine (Pinus taeda L.) growth and nutrient uptake at mid-rotation of two genotypes (eastern and western) on a coastal plain soil. Effects on soil parameters and runoff P were also examined. Through 2+ years, P fertilization and source had no effect on tree growth, but foliar P concentrations were greatest with TSP, and short-term increase in stem diameter was greater for the eastern genotype. There was numerically less P in runoff with PLA than TSP, however, variability among replicates precluded significance. Based on the data from these studies, PLA has the potential to reduce P loss and serve as an alternative to conventional P fertilizers.



Committee Chair

Gaston, Lewis