In order to investigate the effect of grass return under different conditions on soil microorganism

enzyme activities and available nutrients in peach orchard

taking the cleaning tillage as the control

grass return naturally

grass return by mowing

grass return by mowing combined with organic matter-decomposing agent were set up in this study with a 3-year experiment. The effect of grass return under different conditions on soil microbial biomass

soil enzyme activities

and different forms of nitrogen and potassium content in soils were studied by collecting rhizosphere and non-rhizosphere region soils in the peach orchard. The results showed that grass return under different conditions could all increase the rhizosphere region soil microorganism quantity. Compared with the other treatments

grass return by mowing combined with organic matter-decomposing agent improved the quantity of rhizosphere and non-rhizosphere region soil bacteria and fungi significantly

which increased by 21.2%~48.2% and 11.7%~17.0% respectively. Grass return by mowing combined with organic matter-decomposing agent accelerated the decomposition and microbial reproduction of straw. Compared with the cleaning tillage

grass return by mowing combined with organic matter-decomposing agent increased soil urease

catalase and sucrose activities by 10.2%~45.4%

26.8%~56.9% and 20.5%~30.7% respectively. Grass return had a positive effect on the accumulation of soil nutrients in peach orchard

and the result was especially obvious on the grass return by mowing combined with organic matter-decomposing agent treatment

which could not only increase the contents of soil inorganic nitrogen and organic nitrogen

but also reduce the nitrogen loss. Meanwhile

it significantly increased the contents of soil available potassium and water-soluble potassium

which were 12.6%~15.6% and 11.4%~39.1% higher than those of other treatments

respectively. In conclusion

grass return by mowing combined with organic matter-decomposing agent was the better way to improve soil microbial biomass

soil enzymes activities and nitrogen and potassium nutrients supply

which could provide a scientific basis for the better management of orchard grass.