Abstract:

Newly cultivated red soil has many defects, such as strong acid and poor nutrient content, and needs to be improved by many measures. To understand the effect of phosphogypsum and limestone powder on reducing acidity and increasing mineral nutrients in the newly cultivated red soil, a pot experiment was designed to study the effect of applying different amounts and combinations of phosphogypsum and limestone powder on soil acidity, available nutrients and crop growth. The results showed that both phosphogypsum and limestone powder could significantly reduce soil acidity and increase soil available calcium, and the effect increased with the increasing dosage of amendments. Under the condition of equal mass application of the amendments, the effect of the single application of limestone powder or the combined application of phosphogypsum and limestone powder on the reduction of soil acidity was higher than that of the single application of phosphogypsum. The effects of the combined application of phosphogypsum and limestone powder or single application of phosphogypsum on the improvement of soil mineral nutrients, physical properties and vegetable growth were higher than those of single application of limestone powder. Under the experimental condition, the application of phosphogypsum did not significantly increase the accumulation of heavy metals in the soil, and the content of Cd, Cr and Pb in vegetables decreased due to the increase of soil pH, but the content of As increased slightly, which had no obvious effect on the accumulation of other heavy metals in vegetables. The results showed that the newly cultivated red soil with obvious acidification and low nutrients could be improved by the combined application of phosphogypsum and limestone powder instead of limestone powder alone, but the application amount of phosphogypsum should be controlled properly.

Key words: newly cultivated red soil, phosphogypsum, limestone powder, acidity, nutrient, soil improvement