Phosphorus Sorption and Desorption Properties of Surface and Subsurface Horizons at Three Vegetative Treatment Areas in New York

摘要

Phosphorus (P) loss from intensive animal production farms to surface waters has drawn much attention in New York and elsewhere in the U.S. due to the role of P in surface water eutrophication. Vegetative treatment areas (VTAs) are alternative systems to treat farm wastewaters. P retention in the VTAs is partially dependent on soil properties. P sorption and desorption properties of surface and subsurface horizons of New York soils (Langford, Volusia, and Mardin) in three VTAs receiving dairy farm wastewaters were studied using batch experiments. Pearson correlation and stepwise linear regression show that soil organic matter (OM) is the most prominent soil property correlating with P sorption parameters. While OM is positively correlated with theP sorption maxima (S_(max)), it is also positively related to the sorbed legacy P (S_0, the labile soil P from historical P additions), the zero-sorption equilibrium concentration (EPC_0), and negatively correlated to the bonding energy constant (k). Relative to the surface soils, the subsurface soils generally had lower S_(max) and EPC_0 as well as greater k. P desorption is related to similar soil properties correlating with S_0 and EPC_0, tapping the same labile soil P. The desorption can be lessened by decreasing soil moisture content or increasing contact time of the sorbed P with soils, following P sorption. Comparison between measured field P concentration and predicted EPCo from the regression equation suggests that the P sorption study is a viable technique for qualitatively characterizing soil P loss, but not adequate in estimating field P concentrations. Implications on VTA design and management are discussed.