Study On Distribution Of Water-nitrogen And Optimal Furrow Length Division

It is important to improve irrigation water use efficiency and effective utilization of nitrogen. It can make a contribution to reducing the waste of irrigation water and fertilizer and improving soil and groundwater environment. To research how to improve irrigation water use efficiency and the effective utilization of nitrate-N, determining the optimal division of border length, the test selected guan-zhong area in shaanxi province as experiment location and chose the corn variety of “jing-bei 288” as experimental material. The test conducted a research on changes of water and nitrate-N in the field in different border length treatment(80m, 120 m, 240m) under the fixed irrigation condition of 75% inflow cutoff. Then, the test conducted an analysis about physiological index of corn plant, dry matter accumulation and yield in the whole growth period. Finally, the test gave a description of change regulations of physiological index of corn plant, dry matter accumulation and yield and raised the selection standard of optimal division of border length.The main conclusions are as follows:⑴Change regulations of the crop physiological indicators in the whole growth period.In the whole growth period of summer maize, plant height and stem diameter are increasing gradually with a decreasing rate of increase in the growth progress. While the leaf area index of summer maize shows a single-peak curve, reaching a maximum at the beginning of filling period.⑵Change regulations of dry matter accumulation of summer maize.In the whole growth period of summer maize, the leaf dry matter accumulation of summer maize shows a single-peak curve, reaching a maximum at the beginning of filling period. Stem dry matter accumulation increases gradually in the whole growth period with a decreasing rate of increase. The total dry matter accumulation of corn also increases gradually in the whole growth period, showing an S-curve and a faster growth rate between heading period and filling period.⑶Change regulation of grain yield distribution.Grain yield various along the border as follows: in the treatment of 80 m border length, yield of the middle of border check is relatively high and yield at the ends of border check is low. In the treatment of 120 m border length, yield at three quarters of the border length from the head of border is relatively high. In the treatment of 240 m border length, yield at four-fifths of the border length from the head of border is relatively high.As for different border length, yield per unit area in the 80 m border length condition is less than that in the 120 m border length condition, but more than that in the 240 m border length condition.⑷Optimal division of border length.From the point of irrigation water use efficiency, the experiment conducted an analysis on the change of soil moisture before and after irrigation by researching the situation of irrigation water use in different border length conditions, summarizing change regulation of irrigation water use efficiency along the border that 80 m border length >120m border length >240m border length. So 80 m border length should be selected as the optimal division of border length.From the perspective of effective utilization of nitrate, the experiment conducted an analysis on nitrate accumulation on each soil layer in different depth from 0 to 200 cm and nitrogen leaching along the border by studying the distribution of nitrate-N in the field in different border length conditions, summarizing the change regulation of nitrate-N use efficiency along the border that 80 m border length >120m border length >240m border length. So 80 m border length should be selected as the optimal division of border length.From the view of grain yield, the experiment conducted an analysis on total yield, yield per unit area and distribution of yield along the border by researching grain yield of each field in different border length, summarizing the change regulation of grain yield along the border that 120 m border length >80m border length >240m border length. So 120 m border length should be selected as the optimal division of border length.In conclusion, 80 m border length should be regard as the optimal border length division standard with a slight decrease in grain yield but higher irrigation water use efficiency and higher nitrate-N use efficiency.