土壤中不同形态硫的生物有效性研究

STUDY ON BIOAVAILABILITY OF SULFUR FRACTIONS IN SOILS

在温室条件下连续种植 4茬玉米和水稻幼苗 ,分别研究好气和淹水条件下土壤无机硫(MCP S)和有机硫包括酯键硫 (C O S)、碳键硫 (C S)和未知态有机硫 (UO S)的转化及生物有效性。结果表明 ,植物吸硫总量和植株含硫量从第一茬至第四茬逐渐下降 ,这与土壤MCP S含量下降有关 ,而与土壤有机硫各组分的变化无关。种植期间土壤MCP S的含量也是逐渐下降 ,种植水稻时下降的幅度小于种植玉米 ;土壤有机硫组分如C O S、C S和UO S从第一茬到第四茬逐渐下降 ,种植 4茬后 ,玉米和水稻的吸硫总量远大于土壤MCP S的下降量 ,其高出部分来源于土壤有机硫的矿化。C O S、C S和UO S对植物都是有效的 ,各组分有机硫对玉米和水稻幼苗吸硫的表观贡献为 :C O S >C S >UO S。

Soil S depletion study was conducted in a pot experiment with successive planting of corn or rice for 4 harvests. Changes of soil available S (MCP?S), ester sulfate (C?O?S), carbon?bonded S (C?S) and unidentified organic sulfur (UO?S) were investigated. Results showed that total S uptake by plant and sulfur concentration in plant shoot were gradually decrease from first harvest to forth harvest, which were related to soil MCP extractable S. During cropping soil MCP extractable S decreased gradually and the amount of MCP extractable S decreased was greater when planting corn than planting rice. Ester sulfate (C?O?S), carbon?bonded S (C?S) and unidentified organic sulfur (UO?S) could be mineralized for plant uptake. The total amounts of S uptake by corn or rice of 4 harvests altogether were greater than the amounts of MCP?S decreased, and the additional S came from organic S mineralization. The percentage of total S uptake came from different organic S fractions was C?O?S>C?S>UO?S. Also, the percentage of total S uptake came from organic S was greater with planting rice in waterlogged condition than that with planting corn in aerobic condition.