Effect of Alkalized Phosphogypsum on Soil Chemical and Biological Properties

Abstract

Phosphogypsum (PG) was mixed with calcium hydroxide [Ca(OH)(2)], ranging from 0 to 5%, to determine the optimal amount of Ca(OH)(2) required to alkalize the acidity of PG. The alkalized PG by 4% of Ca(OH)(2) addition was selected for field tests to evaluate the effects of alkalized PG on soil microbial, chemical properties, and yield of Chinese cabbage. Soil pH increased with increasing application rate of the alkalized PG and decreased with the unmodified PG application. Available phosphorus (P), water-soluble sulfate (SO42-), and exchangeable potassium (K), calcium (Ca), and magnesium (Mg) increased significantly with increasing application rate of alkalized and unmodified PG. Microbial biomass carbon (C) and nitrogen (N) concentrations, soil enzyme activities, and the yield of Chinese cabbage in the alkalized PG application were greater than those of unmodified PG application. We concluded that alkalizing PG by mixing it with an alkaline material such as Ca(OH)(2) can turn it into a useful material for agricultural utilization.