Abstract:Composting is one of the effective methods to utilize agricultural wastes, and agricultural waste compost as a soil amendment could improve soil properties and raise crop yields effectively. In this paper, the wheat straw compost at two different stages of maturity (30d and 90d) were incorporated into topsoil in a greenhouse tomato production system to observe the effect on soil physical properties and tomato yields. Compared with conventional cultivation (CK), the application of 30d and 90d compost treatments improved soil physical properties as the bulk density reduced to 0.8263 and 0.9003 g/cm3, and the ratio of aeration porosity to water-holding porosity increased to 1:3.51 and 1:4.78, repsectively. The two compost treatments improved tomato photosynthesis, for Pn, under 30d compost treatment, 90d compost treatment and CK, exhibited 21.18, 18.77, 18.65 CO2 μmol/(m×s) during fruit-setting period and 21.21, 20.93, 18.92 CO2 μmol/(m×s) during harvesting period. Meanwhile the two compost treatments increased tomato yield significantly, the plot yield, under 30d compost treatment, 90d compost treatment and CK, were 82.48, 80.25 and 68.66 kg respectively. And 30d compost treatment showed superior efficiency in improving soil physical properties, raising net photosynthesis and yields compared with 90d compost. These results indicate that complete maturity isn’t the optimal while wheat straw compost was used as soil amendment, and it is necessary to find the proper composting time and maturity extent based on the compost materials and composting period during compost utilizing.