Effect Of Irrigation And Nitrogen Fertilizer On Maize Growth And Utilization Of Water And Nitrogen In Hexi Areas

This paper studied how the nitrogen application and irrigation under different growing periods affect the growing, the yield, the irrigation Efficiency and the movement and the soil nitrate migration in the root zone of spring maize through field plot trial in the Hexi District Oasis. Eight irrigation treatments were designed under different growing periods, they are as follow: the maize was irrigated at the whole growth period(CK), no irrigation at seedling stage(I1), no irrigation at jointing stage(I2), no irrigation at heading stage(I3), no irrigation at filling stage(I4), no irrigation at seedling stage and heading stage(I13), no irrigation at seedling stage and filling stage(I14), no irrigation at jointing stage and heading stage(I24)and four nitrogen levels: non-nitrogen(ZN), low nitrogen(LN,60kg N/ha), medium nitrogen (HN,120kg N/ha), high nitrogen(HN,180kg N/ha). The conclusions are as follow:1. Irrigation significantly affects plant height (except Seedling stage) and leaf area, comparing with CK treatment, I2 and I24 treatments is more important to affect the plant height. The influence of leaf area with no irrigation in two growing periods is bigger than in single growing periods and inadequate irrigation will affect the vegetative growth which means that spring maize is very sensitive to water in jointing period,.2. Under the same nitrogen level, no irrigation at seedling stage can slightly affect the yield (the loss of yield is 3.86%) comparing with irrigation in the whole growing period while no irrigation at the heading stage or both the seeding stage and the heading stage have a bigger affect to the yield, 22.59% and 26.41% were loss. the ear weight of spring maize would loss without irrigation at any growing stage, especially at heading stage.3. Improving the level of nutrient supply especially improving the nitrogen supply to crops is the main way to increase production in dry area under the existing water resources condition. In the Hexi oasis irrigation area, the main limiting factor to confine the growth of corn is the nutrients nitrogen, this study shows that nitrogen fertilizer significantly affect its height and leaf area. Plant height, leaf area and yield increase with nitrogen in single growth period without irrigation treatments, and plant height, leaf area decrease in double growth period without irrigation treatments. Too much nitrogen supply is not conducive to the growth of maize with insufficient irrigation.4. In arid areas, a reasonable supply of water and nutrients can improve Plants absorbing both water and nutrients. This experiment shows that the irrigation water using efficiency was higher than CK in all irrigation treatments, and it would be increase with the adding of nitrogen, which means that moderate water stress is conducive to the improvement of water use efficiency. Water use efficiency can cause the loss of yield, the Optimization of water and Nitrogen is the key factor to improve the water use efficiency and yield of spring maize. The Optimization in Wuwei area is giving no water at seeding stage after the winter irrigation, and 180kg N/ha nitrogen (using I1 irrigation treatment under HN stage) can not only get a good yield, but also improve the water use efficiency.5. After sowing 40d, the accumulation of NO3--N in 0~40cm soil layer in Maize root zone comes to a high value, and it increase with the add of nitrogen. At the jointing stage, all treatments show that the accumulation of NO3--N after sowing 70d comes to the lowest stage, which means some of NO3--N in the surface of soil was absorbed by spring maize and the others Migrate deep down to the soil. The residues of NO3--N in soil of no irrigation in single growing stage could be ranked from high to low as follow: MN treatment > HN reatment > LN treatment > ZN treatment,the behavior of no irrigation treatment in two growing periods is HN treatment > MN treatment > ZN treatment >LN treatment。6. The chlorophyll content reached the maximum in the late jointing stage or heading stage, then it begins to decrease. Chlorophyll content increases with nitrogen application, while it reduces without irrigation in the whole growth period, and nitrogen application is more important than irrigation.