The Responses Of Soil Microbial Properties To Different Tillages

With intending to explore tillage practices that increase soil structure property, reduce its losses and maintain sustainable productivity, effects of different tillage practices on soil microbial properities and phyical and chemical characteristics in soil plough layer were investigated. The experiment was conducted at a located experimental station for seven years in Loess Plateau of central Gansu province where the area represents semiarid.The experiment contain four treatments, namely conventional tillage (T), no-tillage no straw cover (NT), conventional tillage with straw incorporated (TS) and no-tillage with straw cover (NTS). Two sequence rotation systems with spring wheat and pea at the Gansu Agricultural University′s farm in Dingxi .In the article"the spring field"and"the pea field"represented the order of rotation spring wheat and pea had been planted in 2008. The main results obtained were listed as follows:1 Conservation tillage has impoved the content of soil microbial biomass carbon and nitrogen1) In the 0~30 cm soil layer of the spring wheat field the contents of SMBC and SMBN followed the order in the treatments: NTS>TS>NT>T while NTS>TS>NT>T,NTS>TS>NT>T in the pea field.2)With the soil layer being deepened,the content of SMBC and SMBN followed the order: 0～5 cm > 5～10 cm > 10～30 cm.2 The differences in the four treatments of soil basal respiration potential were similar to the laws of SMBC and SMBN. No-tillage with straw cover (NTS) did improve soil basal respiration potential significantly.3 Conservation tillage has significantly impoved soil enzymatic activities1)The enzyme activities of the invertase, phosphatase, urease and catalase were shown as that NTS had the highest enzyme activity than NT and TS, and T was lowest in the depth of 0～5 cm and 5～10 cm.2)The enzyme activities decreased as the increase of the soil depth, especially under NTS.3) Long-term conservation tillage so that soil microbial biomass C, N compared to traditional farming increased in varying degrees, possession increases in the proportion of TN and organic C, and has a good parallel relationship between the level of correlation significant.4 The correlation coefficient among the soil microbial propertiesThe positive correlation amony the SMBC,SMBN,soil basal respiration potential and activities of 4 soil enzymes;soil microbial metabolic quotient has a negative correlation with the other soil microbial properties.