BACKGROUNDThe total selenium content in the selenium-rich red soils in Fengcheng City of Jiangxi Province was relatively high, but the available selenium content directly absorbed and utilized by plants was low. The bioavailability of selenium in soils is a key factor affecting selenium in crops.

OBJECTIVESTo find safe and effective ameliorants for improving the availability of selenium in selenium-rich soils.

METHODSBiomass carbon and steel slag were used as modifiers, and 8 different experiments were set up. Through indoor soil test and pot experiment, the content of available selenium in the selenium-rich red soils in Fengcheng was determined by atomic fluorescence spectrometry, and the regulation effect of two kinds of ameliorants on available selenium under different treatment levels was investigated.

RESULTSThe results of the soil tests showed that different amounts of biomass carbon and steel slag can increase the soil pH in the study area by 0.1-3.79 units. The results of elemental speciation analysis indicated that the ameliorant mainly controlled the soil available selenium by affecting the organically bound selenium. The soil organic matter content increased significantly after the application of biochar in the soil, but the organic matter showed a fixed effect on selenium. The available selenium content decreased by 8.4%-15.1%, resulted in the overall lower available selenium content in soils. The significant effect of steel slag on soil pH was beneficial to the activation of selenium in soils, and the soil available selenium content can be increased by 1.4 to 2.0 times. The results of the pot experiment showed that the selenium content of Chinese cabbage increased by more than 30% after treatment with steel slag, while the selenium content of Chinese cabbage decreased by 7.14%-42.8% after treatment with biochar.

CONCLUSIONSThis study shows that biochar is not suitable for regulating the availability of selenium in the soil of the study area. Steel slag can be used as a control material for soil selenium availability in the study area, which not only realizes solid waste recycling, but also improves the availability of selenium in soil.