Effect of different farming methods on soil microbial biomass and soil fertility

The ability of agrosystems to increase soil organic matter by sequestering atmospheric CO2 and restoring organic matter pools is of importance for crop production. An experiment was conducted over 2006 to 2008 cropping years to investigate the dynamics of soil microbial biomass and soil fertility in wheat (Triticum aestivum L.) fields. The results showed that residue retention had dual effects on soil temperature. A positive relationship between soil temperature and soil respiration rate was consistently observed over these years. Residue retention increased soil microbial biomass at 0～10 and 10～20 cm depths with three planting methods. Soil microorganism enhanced the transformation of straw organic carbon to soil organic matter. Based on these data,we conclude that soil microbial biomass may be as a biological indicator to reflect soil productivity.