秸秆还田量对土壤CO2释放和土壤微生物量的影响

对玉米季、小麦季3种不同秸秆还田量的土壤生物学指标的测定结果表明，在秸秆倍量还田中，随着秸秆量的增加，CO2释放量增加，而且倍量处理的增加量显著大于全量处理；在玉米和小麦季节中，不同量秸秆还田对土壤0～10和10～20cm的土壤微生物量的影响不同，但均能增大土壤微生物量，全量和倍量处理间没有明显差异、在土壤表层及下层，微生物量的最大值均落后于土壤呼吸的最大值，且土壤微生物量达到最大值即其最活跃状态后，下降缓慢，但土壤呼吸减少较快，说明微生物活动存在明显的合成性呼吸与维持性呼吸；综合评价不同秸秆量还田的效应，应采用秸秆全量还田，既能调节土壤物理环境，促进微生物的代谢活动，利于养分的转化，又可以减少环境污染。

Effect of crop-residue incorporation on soil CO2 emission and soil microbial biomass

In a wheat-corn cropping system, the crop residues were crushed and incorporated into soil after harvest. The soil respiration and soil microbial biomass were compared one year later with soil that had doubled amount of residues incorporation or had no incorporated residues. The soil respiration was increased by the residue incorporation and the effect was more apparent when the incorporated residue amount was doubled. The soil microbial biomass was also increased by the residue incorporation. But the effect of the incorporated residue quantity was not significant. Seasonally, the maximum soil respiration appeared earlier than the maximum microbial biomass, but soon turned to decrease. The microbial biomass maintained the high level for a longer period, indicating there was maintenance respiration and biosynthetic respiration as well. The residue incorporation was suggested as a measure to increase the soil fertility, but doubling the amount of residue incorporation seems not necessary.