Research Of Soybean Water Requirement And Schedule With Drip Irrigation

Drip irrigation is an advanced technique. It has the advantages of saving water, enhancing yields, upgrading quality and high utility. Now there is little about soybean water requirement and irrigation scheduling of drip irrigation. So in practice the conventional irrigation mode is often be used. Drip irrigation reduces soil evaporation among plants, improves evapotranspiration, changes the water requirement of crop. So the schedule of drip irrigation could not be substituted by the conventional irrigation model. As stated above, this paper studied the soybean water requirement and schedule of drip irrigation, the field experiment study for soybean was conducted in Tianye Agriculture Institute in Shi he-zi , Xinjiang province. The main results are as follows:(1) Height of soybean increased with increased amount of irrigation water. And with water consumption between 345mm and 445mm, Leaf area index(LAI), crop growth rate(CGR) and pod growth rate(PGR) increased with amount of irrigation water. Drip irrigation is benefit for dry matter accumulation. Net assimilation rate (NAR) showed a curve with two peaks, the first peak showed in bloom-pod setting stage , the second peak showed in pod setting-seed filling stage. After setting-seed filling stage, Net assimilation rate (NAR) decreased with increased amount of irrigation water.(2) Through analyzing and computing, drip irrigation is very obvious in upgrading water use efficiency. By analyzing yield and quality, drip irrigation is very obvious in upgrading yield and quality. And the result is that in order to attain high yield and good quality, the water consumption should be between 395mm and 445mm in the whole stage of soybean under drip irrigation.(3) Under drip irrigation, 0~20cm soil gravimetric water content was affected obviously by irrigation, and soil gravimetric water content increased with increased amount of irrigation water. Before bloom-pod setting stage, it was obvious different between plants and wide seed lines; after setting-seed filling stage, soil gravimetric water content increased in wide seed lines, and distributed evenly in the soybean field.(4) Under drip irrigation, water consumption of different water irrigation treatments increased with increased amount of irrigation water. Water consumption was most in bloom-pod setting stage and pod setting-seed filling stage. The water requirement of soybean in seeding stage was 2.1mm·d-1, in bloom-pod setting stage was 4.9mm·d-1, in pod setting-seed filling stage was 6.1mm·d-1, in seed filling-autumn stage was 3.2mm·d-1, the whole stage was 4mm·d-1. (5) Through analyzing and computing crop coefficient, we found that crop coefficient is 0.47 in seeding stage, 1.02 in bloom-pod setting stage, 1.21 in pod setting-seed filling stage, 0.84 in seed filling-autumn stage, 0.88 during the whole stage. And the modulus of stage water consumption is 13.3%, 38.1%, 27.9%, 20.7%.(6) According to the arrangement of irrigation and water requirement of soybean, the schedule of drip irrigation is: 35mm for every 7 days in seeding stage, 45mm for every 5 days in bloom-pod setting stage and pod setting-seed filling stage, 35mm for every six days in seed filling-autumn stage, and with water consumption between 395mm and 445mm during the whole stage.