An Experimental Study On Utilization And Regulation Of Water And Fertilizer Of Crops

It is one of the important subjects in the development of modern agriculture that how to make full use of natural precipitation, give full play in limited irrigation conditions, improve crop yields as well as water-fertilizer use efficiency synchronously, and reduce continuation of nitrogen and phosphorus fertilizer. Taking summer maize and winter wheat as experimental crop and by using combination research method of field experiments and earth column simulation, this paper has researched the influence of different adjustment measures of water, nitrogen as well as phosphorus on summer maize and winter wheat, nutrient uptake, transfer regularity, water-fertilizer use efficiency, and physiological characteristics of maize roots.The contents and major conclusion of this paper are as follows:1,Under the condition of no irrigation, nitrogen and phosphorus fertilizer can improve the leaf area index as well as cumulant expansion of dry matter above ground parts of summer maize, and the growth trend is gradually significant following the growth stage, moreover, the situation reached the summit at 240 kg.hm-2 and 120 kg.hm-2 of nitrogen and phosphorus fertilizer respectively. When nitrogen and phosphorus cumulant expansion is single peak type, nitrogen and phosphorus regulation do not modify the dynamic change law of stem and leaf, but they can increase the nitrogen and phosphorus cumulant expansion of different organs of maize plant, and the effects are better if nitrogen and phosphorus fertilizer are used cooperatively. The absorption regulation of nitrogen and phosphorus is similar in summer maize plant, i.e., jointing stage and filling stage are two peak periods, and nitrogen cumulant expansion shows increase tendency following the increase of nitrogen application rate. Under the regulation measure of nitrogen and phosphorus, the appearance time of maximal rate of phosphorus cumulant expansion of summer maize is later than nitrogen, moreover, the nitrogen and phosphorus cumulant expansion are highest when they are at the level of 240 kg.hm-2 and 120 kg.hm-2, reaching 1.66 g·d-1·m-2 and 0.29 g·d-1·m-2 respectively.2,Following the changing of depth, the variation tendency on soil profile water and nitrate nitrogen of summer maize is basically identical, i.e., the water and the content of nitrate nitrogen are high and show decreasing tendency in 0 to 50 cm soil layer, also the water and the content of nitrate nitrogen are low and little fluctuation in 50 to 110 cm soil layer, moreover, they all reach to minimum in filling stage. Following the increase of nitrogen application rate, the content of nitrate nitrogen in soil of mature period is a steep rise, and following the increase of phosphorus application rate, the content of nitrate nitrogen in soil first increased and then decreased. Nitrogen treatments is lower than no nitrogen treatments of soil moisture content in 0 to 50 cm, but the situation of soil moisture content in 50 to 110 cm is opposite. Nitrogen and phosphorus fertilizer can improve the water use efficiency of summer maize, and the effects are best when the nitrogen and phosphorus amount is 240 and 120 kg.hm-2 respectively.3,Nitrogen and phosphorus fertilizer can improve the yield in summer maize, and increase amplitude first increased and then decreased following the nitrogen application rate. When the phosphorus application rate increases to 120 kg.hm-2, the yield shows decrease tendency. Moreover, the yield of summer maize reaches the highest when the application rate of nitrogen and phosphorus is 259.40 kg.hm-2 and 116.92 kg.hm-2 respectively, and the influence on yield of nitrogen fertilizer is greater than phosphorus fertilizer. With nitrogen and phosphorus fertilizer cooperating application, nitrogen uptake and N harvest index of maize plant can be improved, reaching the highest level when the application rate of nitrogen fertilizer and phosphorus fertilizer reaches 240 kg.hm-2and 120 kg.hm-2 respectively, moreover, soil nitrogen loss can be reduced, also grain quality can be increased. The utilization rate of nitrogen fertilizer and phosphorus fertilizer all decreases following the increase of nitrogen application rate.4,Water, N fertilizer, and the new soil conditioner that mainly material was straws (PJG) can improve accumulation of dry matter of winter wheat, PJG was mixed with 288 kg.hm-2 N fertilizer, it was increased 37.8 %, but it hasn't change the accumulation regularity. Jointing stage and filling stage is 2 accumulation peak period, accounts for 16.7 %~25.5 % and 49.8 %~58.7 % separately. Applied with the straw modifier can improve the photosynthesis rate and water use efficiency of blades. N, P content of winter wheat stem and blades decreases with the pro-long of growth period. K content is high in mature winter wheat. Straw modifier and N fertilizer can significantly increase the N,P content and N, P cumulates in stem and blades. It has litter influence on K content in stem and blades. The beginning time of maximum accumulation rate of N and P is earlier than that of CK. Under the condition of no-irrigation, the beginning time of maximum accumulation rate of N advances with the increasing of nitrogen rate and it is opposite to irrigation. the beginning time of maximum accumulation rate of N is earlier than that of P. Under the condition of irrigation, the maximum accumulation rate of N and P is highest which applied by straw modifier and 288 kg.hm-2, 160 kg.hm-2nitrogenous fertilizers. N and P transportation amount of leaves is lower than that of stem, and N transportation amount is higher than that of P.5,The combined application of high N fertilizes and straw modifier can increase the yield of winter wheat remarkable. The yield is increased to 10.77 % after irrigation. Water, N and straw modifier can improve the water and Nitrate N of winter wheat during green stage and mature stage. Soil moisture of 0~100 cm changes strenuous during green stage, on the contrary, it's in mature stage. After combined application of Straw modifier and N fertilize, water storage of 0~200 cm increases greatly. Accumulation of Nitrate N increases greatly under the condition of large nitrogen rate. Nitrogen rate has great influence on 0~30 cm soil layer and Nitrate N of 0~30 cm soil layer decreases after irrigation. Nitrogen use efficiency of winter wheat and nitrogen productivity decreases with the increasing of N application. Single application of straw modifier or N fertilizer has little influence on water use efficiency of winter wheat. But combined application of high N fertilizes and straw modifier can increases water use efficiency of winter wheat significantly. Combined application of 288 kg.hm-2 N fertilizes and straw modifier Straw has the best effect on water use efficiency of winter wheat.6,Water has more significant influence on dry weight, activity and surface area of root than that of N and P fertilizer in soil column simulating of summer maize. The dry weight of root decreases with increasing of soil depth, especially the 0~10 cm of soil depth. Density of 0~20 cm root length is large. Fist increase and then decrease with the increasing of soil depth. Dry weight and root length density decreases with the increasing of N application rate and increases with the increasing of P application rate. The root-shoot ratio of maize has a decreasing tendency. N and P fertilizer can improve the root activity of maize and the maize activity is sensitive to N fertilizer in the condition of better water.7,According to the correlation analysis between grain yield and root, root dry weight, root length density, combined root area and root activity have a very significant correlation with grain yield and dry matter quantity above ground. Ratio of root weight only has a correlation with that of above ground. Combined root area has a very significant correlation with root activity. Root activity and the nitrogen absorption of root have an important role on maize growth and grain formation and there was a significant correlation.8,combining with the influence of different regulation measure on grain formation and utilizing efficiency of water, considering with the regulation of nitrate-nitrogen accumulation and decreasing the nitrogen loss, the paper suggests that the range of N application is 120~240 kg.hm-2, P application is 120 kg.hm-2. Under the condition of limit irrigation, straw modifier and application of 160 kg.hm-2 N fertilizers can provide a better growth environment effectively for winter wheat.