Modification Of Nitrogen Movement And Transformation Of Summer Maize And Soil Under Different Rainfall Patterns

Summer maize in North China is one of the major food crops, water shortages and thelarge changesof the raninfall in growing period is one of the main factors that limit the cornyield of this area. Different rainfall have a significant impact on the amount of crop drymatter, soil moisture changes, the nitrate uptake of crop, the movement of NO3-N and NH4-N.This study in2013in Shandong Agricultural University, which is on the water pool of thesouth campus corn park, selection of summer corn Zhengdan958as experimental material,the use of anti-canopy pool culture, and the15N isotope tracing technology, research theeffects on soil moisture, nitrogen change and the amount of dry matter of different rainfallchanges. The main results are as follows:(1) under different water modes the summer corn soil moisture and corn physiologicalindicators significant changes. Different levels of soil moisture content and variations ofeach growth period showed50%A>100%A>150%A>200%A(A indicates the date of theactual rainfall), soil water consumption showed50%A<100%A<150%A<200%A and soilwater use efficiency (WUE) showed50%A<100%A<150%A<200%A. Under the50%modethe dry matter production does not appear to significantly reduce than normal rainfall, whileunder the mode at150%and200%production appeared significantly lower. Appropriate inthe case of rainfall below normal levels of water stress at the same time safeguard theproduction, which can effectively improve soil moisture utilization (WUE).Appropriate inthe case of rainfall below normal levels of water stress at the same time safeguard theproduction, which can effectively improve the soil water use efficiency (WUE).(2) Below-normal rainfall, soil moisture content is low inhibition of nitrate uptake ofsummer maize, and reduced the contet of nitrogen uptake of the summer maize, whilepromoting the transporter of nitrogen to the grain, and nitrogen production efficiency is low;with rainfallamount increases gradually improve the nitrogen allocation gradually in thevegetative organs, reduce to grain nitrogen transfer rate, higher nitrogen productionefficiency; increased rainfall when rainfall over more than50%of normal rainfall, withtherainfall increases, the vegetative organs of the nitrogen distribution rate and transfer rateno significant change and no significant change in the efficiency of nitrogen production.(3) A smaller rainfall below normal levels on soil nitrate transport to the deep magnitudesmaller soil nitrate concentration in the0-40cm, NO3-N maximum profile peak, the closer the peak position from the surface; rainfallhigher than normal levels of summer cornmaturity soil nitrate in the soil0-80cm content less100-140cm soil nitrate content increasedsignificantly; excessive rainfall, summer corn maturity NO3-N the largest profile peak, peakposition from the surface, soil nitrate to deep migration amplitude maximum.(4) Ammonium nitrogen in the soil under different water conditions in the0-60cm soil.0-40cm of soil ammonium nitrogen content was significantly higher than other soil, while nosignificant difference in the other treatments. Low amount of irrigation, the the urea nitrogenleaching of the soil profile is relatively weak, applied urea nitrogen remains in the upper soillayer, and later nitrification gradually transforming into ammonium, making the ammoniumnitrogen content. Watering the large amount of urea nitrogen leaching thus converted into thesurface of the ammonium nitrogen is low, the bottom of ammonium nitrogen ion peak. Thewater conditions of80cm on ammonium nitrogen migration were not obvious.The experiments show that the different rainfall migration and summer corn nitrogentransport has a significant impact on soil nitrogen transformation summer maize grain yieldand the amount of irrigation water consumption, water use efficiency than linear relationship.During the summer maize growing precipitation and its distribution of water demand atdifferent growth stages, appropriate to adjust the amount of irrigation in order to improve thetotal absorption of nitrogen in summer maize nitrogen, reduce leaching of nitrogen in the soil,improve nitrogen use rate.