Transport preferences of P forms in wind-blown sediments of two susceptible soils

Abstract

Wind erosion of agricultural soils affects their stock of essential elements for plants, like phosphorus (P). It is known that the composition of the eroded sediments varies with height, according to the size and density of the transported substances. Aim of this study was to analyze the concentration and enrichment ratios of P forms in sediments transported by the wind. A wind-tunnel study was performed on a sandy- and a sandy loam soil in order to measure P forms concentrations in the saltating sediments. P concentrations were also measured in the particulate matter (PM) of each soil, gained with the Easy Dust Generator. In both soils, inorganic- (P_i) and organic P (P_o) were preferentially transported in PM, with enrichment ratios of 1.8 and 5.5, respectively. Nevertheless, a P_i/P_o of 0.9 indicated that the accumulation of the minor P_o in PM was more pronounced than P_i. This agrees with P-rich light and easily erodible organic compounds, almost exclusively accumulated in PM, and in relatively heavy and less erodible minerals, like apatites, in lower height sediments. Labile P (P_l) was preferentially transported in saltating sediments of both soils. This was attributed to the selective Bray & Kurtz I’s extraction of the abundant inorganic P forms of these sediments. Total P (P_t) copied the transport trends of P_i, the major form. According to the transporting trends, P_i and P_o would be re-sedimented at longer distances from the source than P_l. Outcomes become useful for modeling the influence of wind erosion on P cycling.