Effects Of Different Nitrogen Application Rates On Soil Water And Nitrogen Distribution And Spring Maize Growth

Aiming at the low comprehensive nitrogen utilization efficiency of spring maize due to the large amount of fertilizer applied in the agricultural irrigation area of Mu Us sandy land,the effect of different nitrogen application rates on spring maize leaf area,plant height,stem diameter,yield,soil moisture,and nitrate nitrogen was studied.,Ammonium nitrogen transport and distribution,and use the PEST optimized root zone water quality model to simulate the dynamic changes of crop leaf area,plant height,soil moisture and nitrate nitrogen during the growth period of spring maize,and verify it to achieve High-yield,high-efficiency,low-pollution water and fertilizer regulation provides technical support.In this paper,field experiments were carried out in Bulanghe Township,Yulin City,on the southeastern edge of the Mu Us Sandy Land.The results of the study showed that:(1)For the 0～60cm soil layer,the overall change characteristics of the soil moisture content of the same depth under different nitrogen application rates are consistent.The specific manifestation is that the soil moisture content drops sharply from the time of sowing to the jointing stage;from the jointing stage to the late filling stage,the soil moisture begins to fluctuate under the dual influence of irrigation and plant growth;the soil moisture content increases significantly during the wax maturity period.Compared with the treatment without nitrogen N0,the water content of spring corn during the growth period of the treatment with nitrogen has greater changes,indicating that nitrogen has a certain influence and disturbing effect on the water transport in the root zone of spring corn.The key water requirement period of spring maize in this area is the late jointing and the early tasseling period in mid-July.During this period,the irrigation frequency and amount of irrigation can be appropriately increased to promote the growth and development of spring maize.(2)Under different nitrogen application rates,the nitrate nitrogen and ammonium nitrogen in the 0～70cm soil layer in the root zone of spring maize plants are mainly distributed in the 0～30cm soil layer,and the average proportion of nitrate nitrogen is 69.2%.The average proportion of ammonium nitrogen is 52.8%,and the content of nitrate nitrogen is much higher than that of ammonium nitrogen.Compared with ammonium nitrogen,nitrate nitrogen is easier to leaches downwards and accumulates deep in the soil.Increased application of nitrogen has a significant effect on the distribution of nitrate nitrogen in the soil,which is the influence on the distribution of ammonium nitrogen in the soil.Smaller.(3)The leaf area index and stem diameter of spring maize first increased and then decreased with the growth period,showing a single peak curve as a whole;the plant height first increased with the growth period and then remained stable until the end of the growth period.Compared with leaf area,stem diameter and yield,nitrogen application rate had the least effect on maize plant height.Through one-way analysis of variance,it was found that the difference in leaf area of spring maize under different nitrogen rates appeared in the tasseling stage and filling stage,and the difference in plant height and stem thickness of spring maize appeared in the tasseling stage.Comprehensive analysis of the best time to apply nitrogen for spring maize in this area is the tasseling period and filling period of maize.(4)The RZWQM2 model optimized by PEST can better simulate the root zone water dynamics,nitrate nitrogen content,crop leaf area index,plant height and yield during the growth period of spring maize in the study area.Through the simulation of 21 different nitrogen application irrigation treatment scenarios,the results show that the best nitrogen application rate during the growth period of local spring maize is 200kg/ha.