| Rice and wheat are two major crops in the world, and rice-wheat rotation is one of the most important cropping systems in China. Presently, in rice and wheat rotation areas, there were still given priority to rotary tillage and fine rake surface tillage measures, which existed lots of problems, e.g. large energy consumption, low efficiency, high cost, complicated operating procedures and time consuming, etc. Therefore, in order to solve the above problems, a multiple factorial experiment of straw returning(rice straw, 4500, 9000kg/ha; wheat straw, 3750, 7500kg/ha), and a comparative field trial of tillage and fertilization patterns were conducted under different tillage patterns with no-till, rotary tillage and plough. Soil physical and chemical properties, crop growth, yield and its components were detected and investigated in the trials, for promoting the technology of conservative tillage extension in rice and wheat rotation area, as well as providing reference and guidance for developing simple and efficient mechanization of farming. The main results of the research were as follows in the 2013-2014:(1) The compactness of the soil surface layer(0-20cm) was reduced to 30 kPa approximately after steeping field for 20 hours, reached about 15 kPa after the procedure of rotary tillage and harrow process. However, when the flail knife cutting the straw in front of claw-gripper of the no-till transplanting machine, the soil compactness was decreased to 21 kPa approximately at the same time which was suitable for rice transplanting.(2) The soil bulk density was affected by farming measures and straw returning significantly. Compared with No-till with organic fertilizer(NTOF) and plough with organic fertilizer(POF) treatments, the soil bulk density of rotary tillage with organic fertilizer(RTOF) was reduced in 0-10 cm soil depth, while increased in 10-20 cm. Meanwhile, compared the treatment of no-till with straw & no-till with straw(NTS&NTS) with no-till with half straw & no-till with half straw(NTHS&NTHS), the soil bulk density of RTOF were reduced by 0.079g/cm3 in 0-10 cm soil depth, and 0.032g/cm3 in 0-20 cm.(3) Farming measures and straw returning affected the nutrient content of topsoil(0-20cm) significantly. In the growing period of wheat filling, the content of available nitrogen(Avail-N), available phosphorus(Avail-P), available potasium(Avail-K), total nitrogen(TN), soil organic carbon(SOC) of no-till with straw(NTS) treatment were increased by 11.59%, 3.43%, 9.47%, 5.92% and 10.19% compared with plough with straw(PS), respectively. The content of Avail-N, Avail-P, SOC of NTS treatment were increased by 7.69%, 22.20% and 3.65%, higher than that of no-till with half straw(NTHS). In rice mature stage, the content of Avail-N, Avail-P, SOC, TN of NTS&NTS treatments were increase by 18.18%, 16.13%, 13.31% and 16.13% compared with NTHS&NTHS, respectively. In rice mature stage, the content of SOC of were increased by 9.87% and 6.85%, TN were increased by 9.30% and 3.80%, Avail-k were increased by 18.31% and 10.15%, Avail-P were increased by 50.67% and 18.96%, and Avail-N were increased by 8.04% and 4.16%, compared the treatments of NTOF and POF with RTOF, respectively.(4) Compared with the treatments of plough with inorganic fertilizer(PIF), POF treatment reduced the soil compactness in 0-26 cm soil depth obviously, but the deeper the soil depth increased, the smaller the value of it reduced; POF treatment also raised the content of Avail-K and TN in 0-10 cm, 10-20 cm soil depth, significantly increased the content of Avail-N, the Avail-P and SOC in the 0-10 cm soil layer; Moreover, POF improved the effective panicles per unit area as well as rice yield.(5) The total yield of rice plus wheat of plough with no-till with straw(PS&NTS) treatment was the highest in all different treatments, followed by NTHS&RTS and NTS&NTS. The increase rate of them were 8.31%、5.45% and 4.38% compared with plough with straw & rotary tillage with straw(PHS&RTS) treatment.Based on the above analysis, we can see that the treatment of NTS&NTS is one of the most suitable farming modes in this area. As the same time, applying PS&NTS one year periodically in terms of the soil surface flatness would have higher extension value of promoting crop yield, fertilizing soil, improving machines efficiency and economic profit. |
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