Effects Of Several Conservation Tillage Measures

Effects of conventional tillage and no-till on soil, crop growth under three different cover materials in semiarid area of middle Gansu were studied by the field experiments on spring wheat and field pea in 2001 - 2002, Lijiabu town, Dingxi county. The results shows:1. The treatment of no-till with stubble retention (NTS) could decrease the soil temperature of observed layer remarkably, no-till (NT) and conventional tillage with stubble retention (TS) could increase the soil temperature above 15cm, both conventional tillage with plastic mulch (TP) and no-tillage with plastic mulch (NTP) could prevent soil temperature from falling in the evening.2. No-tillage with stubble retention was good for rainfall accumulation and evaporation restrains during the fallow.3. NTS could improve the water use efficiency of both field pea and spring wheat notably.4. At harvesting of spring wheat, the average soil available nitrogen and available potassium of NT, NTS and NTP were higher than T, TS and TP, but the available phosphorus varies in a contrary way.5. Different covers had affected spring wheat emergence notably, T and NT got the most emergence, followed by TS and NTS, while TP and NTP got the poorest emergence.6. At seedling stage, dry matter accumulation (DM) of covered treatments were less than that of the treatments without cover, but as it arrived to the flowering, DM of covered treatments were almost catch up with or surpass that of treatments without cover, and the average DM of covered treatments were higher than that of treatments without cover at harvesting (esp. NTS).7.Both crops of TP and NTP matured earlier than others while NTS prolonged the growth of crops due to its effect of soil temperature decreasing, that made it use light, heat, water and fertilizer etc. better, and gave time to higher DM accumulation.8. For spring wheat, the yield sequencing is: NTS > T > TS > NT > TP > NTP, and for field pea is NTS > T > TP > NTP > TS > NT.9.For different covers, the net benefits of no-till were higher than that of conventional tillage. For both crops, the ratio of input to output sequenced as NTS > NT > T > TS > NTP > TP.