Effects Of Tillage And Cultivation On Wheat-Rice Productivity In A Wheat-Rice Double Cropping System

No-tillage and straw returning is a recently-developed farming practice in China, which produces profound effects on soil environment and the growth of rice and wheat. In order to provide technological and theoretical support for light-duty, high yield, high quality and efficient production in wheat-rice cropping system, and to provide scientific guidance for carrying out no-tillage, reasonable rotation tillage more efficiently, different tillage and cultivation methods were adopted to study its impact on soil environment, nutrition supply of soil and absorption of plants, the growth regulation, yield and grain quality of rice and wheat. The effect of no-tillage and straw returning on soil environment and wheat-rice productivity were studied through different tillage and cultivation located treatments. The main results were as follows.1. Although the topsoil bulk and penetration resistance of no-tillage treatments increased, but no apparent adverse effects of them were observed on wheat and rice growth. In the first month after wheat sowing, the soil respiration rates descended as the falling of soil temperature, especially in the no-tillage treatments. Through five years straw returning, soil organic matter, total N, hydrolysable N, available P and K in CTS(convention tillage and straw returning),NTS (no-tillage and straw mulching),and NTH(no-tillage and high subble remaining) increased 14.3%-23.0%,12.6%-25.3%,13.8%-31.3%,12.1%-19.9%,15.1%-23.7%, respectively, compared with CT(convention tillage)after rice harvest, while the effect in CTB(convention tillage and straw burning) was not apparent in CTS. Soil organic matter, total N, available P and K in RNT (rotation tillage, no-tillage in wheat and convention in rice) and RCT (rotation tillage, convention tillage in wheat and no-tillage in rice) were higher than those in CT, which improved soil fertility as straw returning in rice or in wheat, but the effect was not apparent in both rice and wheat straw returning.2 .Because of no seedling and the interference of wheat stubble in NTS and RCT, the height and tiller quantity of rice were lower. Rice grew rapidly in the later stage in treatments with straw returning, which increased the danger of rice lodging. As for dry matter accumulation, it was decreased in NTS and NTH, and was decreased in the treatments with straw returning in the early stage. But the difference of dry matter accumulation between all the treatments was not apparent in the ripening stage. With rice growth, the content of N, P and K in rice plants decreased gradually, except the content of K in RCT, CTS1, CTS2 and RNT treatment in late tillering stage. As for the accumulated content of N, the treatments with no-tillage were lower than CT, but were higher on content of P and K. Straw returning was not beneficial to the accumulated content of N, P and K in early stage,but the accumulated content of N,P and K was higher in the ripening stage,which those in CTB was lower than those in CTS. Rice yield was higher in treatments with straw returning, but was lower in continuous no-tillage treatments. Though rice appearance quality had tendency to become worse under adverse climate in filling stage in NTS and RCT, the difference of rice milling and appearance quality was not apparent between all the treatments. In NTS, RCT and CTS1, the peak viscosity and breakdown decreased. It showed that no tillage and full straw returning deteriorated rice cooking quality.3. In the early stage, soil water was improved because of straw returning, which promoted the growth of wheat, but the plant of wheat was tenuous. In the later stage, the height of plant was not related with straw returning, which was lower in the ripening stage in no tillage treatments. That improved the ability of lodging resistance. The area of wheat upper-three-leaf was higher in no-tillage and straw returning treatments, which created a base for a higher yield. As for the dry matter accumulation, the no-tillage treatment was higher before the jointing stage, and the treatments with straw returning were higher in the whole stage.The content of N, P and K in wheat plants was highest in tiller stage,with wheat growing, the content of N, P and K decreased gradually. No tillage was adverse, and straw returning was beneficial to the absorption of N, P and K in the later stage. The consecutive no-tillage has slightly effect on the accumulation of N in plants, but it was not apparant in treatments with straw returning. The absorption of P and K was decreased in no-tillage treatments in the later stage. Wheat yield was increased in treatments with conventional tillage plus reasonable straw returning. While NTS and CTS increased the protein and wet gluten content, this was beneficial to the processing quality of strong (or middle) gluten wheat. The peak viscosity decreased in no-tillage and straw returning treatments, which was not beneficial to the noodle quality of middle gluten wheat.