I. A field-based assessment tool for phosphorus losses in runoff in Kansas. II. Effects of phosphorus and manganese oxides on soil lead bioavailability. III. Assessment of bioavailability of zinc by diffusive gradients in thin films (DGT)

Nonpoint P sources from the agricultural landscape are a significant environmental problem for surface water bodies due to the promotion of eutrophication. Many states have developed P assessment tools to help differentiate land uses and their potential for P losses to surface water. Kansas has developed such a P index (PI) and the purposes of this paper are to report on the calibration of that index against data collected from four runoff studies and to explore the modification of the PI inputs and weighting factors as means to improve the predictive capability of the PI. The PI includes soil test P, rate and application method for P from fertilizers and manure, soil erosion, runoff class, distance from surface water bodies, and irrigation erosion as inputs.; Lead (Pb) is toxic to humans, especially to young children, and animals. Toxicity is strongly related to the bioavailability of Pb. A reduction in soil Pb bioavailability can be accomplished by either the formation of insoluble Pb compounds or adsorption of Pb, or both processes simultaneously. Manganese (Mn) oxides are a strong adsorbent for soil Pb compared to any other metal (hydr)oxides. This study was conducted to evaluate the effects of Mn oxides and phosphorus (P) on Pb bioavailabilty in five Pb contaminated soils or mine spoils from Kansas and Missouri. A total of fifteen treatments were used which consisted of four Mn oxides (two commercial, Brazilian (BMN) and Amonone #4 (AM#4), and two synthetic, birnessite (BIR) and cryptomalene (CRYP)) with two P sources (phosphate rock (PR) and triple superphosphate (TSP)) and their combinations.; Assessment of Zn phytoavailability can be predicted with routine soil extractants, however, these methods generally do not perform well across a wide range of soils. The newly developed technique of diffusive gradients in thin films (DGT) can be employed for variety of soils. A greenhouse study was conducted to assess the phytotoxicity thresholds and the phytoavailability of Zn to sorgham-sudan (Sorgham vulgare var. sudanese) grass by DGT as compared to CaCl2-extraction. Varying levels of Zn phytoavailability were created by amending sand with ZnSO4 or two different Zn mine wastes. Plant nutrients were added as Hoadgland solution. (Abstract shortened by UMI.)...