Effects Of Straw Returning On Environment And Agronomic Techniques Matching For Mechanization With Rice-Wheat Duble Cropping System

According to the fact that incoordination between rice-wheat production mechanization and agronomic techniques, and great difficulty of rice/wheat straw returning were the main obstacle for realizing agricultural modernization. In the present study, In order to investigate the effects of rice-wheat production mechanization on the regional water environment, field plot experiments were carried out to study the characteristics of surface runoff of nutrients losses during the paddy season and wheat growing season of intensive rice-wheat double-cropping field of Jiangsu province under natural rainfall conditions. The main results were indicated as follows:(1) The total volumes of runoff water reached380.37and145.67m3·667m-2during the paddy season and the wheat growing season, respectively. And, total quantities of the sediment by surface runoff reached340.91and47.74kg·667m-2, respectively. Wheat/rice straw returning could significantly decrease the volume of runoff water during the wheat growing season, and, it could significantly decrease the quantity of sediment by surface runoff during the paddy season and the wheat growing season.(2) Soil nitrogen and phosphorus losses by surface runoff mainly concentrated on the earlier stage of rice/wheat growing period, including nutrients losses in runoff water and the sediment by surface runoff. Under conventional fertilization conditions, the total quantities of TN, TP losses by surface runoff during the whole paddy season reached1.70kg·667m-2and87.17g·667m-2, among which45%of TN and15%of TP losses were attributed to runoff water, respectively. And, the total quantities of TN, TP losses by surface runoff during the wheat growing season reached2.12kg·667m-2and323.31g·667m-2, among which95%of TN and60%of TP losses were attributed to runoff water, respectively.(3) The main agronomic techniques matching for rice-wheat production mechanization were indicated as follows:The optimum planting mode for rice production was mechanized transplanting. Furthermore, the optimum mechanical power for wheat straw returning with rotary tillage and deep ploughing should match with the capacity of50or75horsepower tractors during the paddy season, respectively. And, minimum tillage could significantly increase wheat production by6.7%-9.0%and decrease the production cost by4.5%-8.6%, the optimum mechanical power for rice straw returning with minimum tillage should match with the capacity of12horsepower tractors during the winter wheat growing season. During the paddy season, the highest grain yield reached696.72kg-667m-2when9kg-667m-2of potassium fertilizer (K2O) and15.19kg-667m-2of nitrogen fertilizer were applied, and the optimum yield was achieved under the nitrogen application regime with the ratio of40%-30%-30%for basal, tillering and spike stages.(4) In this study, based on the rice-wheat straw returning, the technology system of agronomic techniques matching with agricultural machinery was designed for agricultural production mechanization of intensive rice-wheat double-cropping field of Jiangsu province. Furemore, the results of comparative experiments between integration technology and conventional technology on the agronomic techniques matching with agricultural machinery in Rugao, Xishan and Changshu counties showed that the whole yields of rice and wheat grain increased by3.8%-22.2%.