THE INFLUENCE OF BRINE CONTAMINATION AND PHOSPHOGYPSUM AMENDMENTS ON SOIL CHEMICAL-PROPERTIES AND PLANT-RESPONSE

Phosphogypsum (PG), the by-product of wet acid production of phosphoric acid from rock phosphate, was found to be effective as a soil conditioner for sodic, solonets, and solonetzic soils. Unlike mine gypsum, PG contains impurities whose release into soil and ground water need to be monitored. PG was incorporated with soils contaminated with oilfield brine to determinate the influence of PG amendments and brine contamination on soil chemical properties and plant response in a growth chamber. Application rates of PG were 0, 25, 50, 100, 200, and 400 Mg ha(-1) and the testing crop was Barley (Hardeum vulgare L.). Phosphogypsum provides a means of remediating brine spills and can result in benefits expressed as increased plant growth. Soil salinity of brine contaminated soils was ameliorated as evidenced by reduced the electrical conductivity, SAR and exchangeable Na levels in 0-15 cm depth of the columns. There is no evidence that application of PG increased the level of trace elements in plants. Contamination of soil with brine spill is the major factor dominating plant growth and soil-plant element content. From plant growth point of view, two elements could be excessive, namely Boron (B), and Cadmium(Cd). The high level of B in the plant arose from brine spill and the cause for the excessive Cd level in barley grain is unknown and currently under investigation. The distribution of trace elements in soil profiles demonstrated that there was little, if any, potential for movement of trace elements into greater depths.