Effects Of Conservational Tillage Practices On Water And Nitregon Use Of Spring Maize In Loess Highland

Corn has become China first staple varieties.Loess highland is the important area of spring maize production in China.However,uneven rainfall and nitrogen deficiency have severely restricted the production of local spring maize.Although fertilization can increase the yield of spring maize,excessive fertilization will increase the nitrogen residue in the soil and cause environmental pollution and waste of resources.Conservation tillage can improve soil moisture status and optimize soil nutrient.It has received extensive attention.However,conservation tillage varies with climate,soil fertility and other factors.A two-year experiment was conducted in Chang wu Ecological Research Station during 2016-2017 spring maize growing seasons.The field experiment was in a split-plot design,and four tillage methods,such as conventional tillage(CT),film mulching(FM),ridge tillage(RT)and ridge tillage with film mulch on the ridge(RTF)were the main plot and nitrogen levels(N225,N rate 225 kg N ha-1 and N0,no N application)were assigned to the subplot.There are 8 trials and 3 times.The effects of conservation tillage and nitrogen fertilizer on grain yield and yield elements,plant morphology,water use,nitrogen uptake and translocation,and soil available nitrogen content of spring maize on Loess Plateau were analyzed.The results of the study are as follows:(1)Tillage practices and nitrogen treatments significantly affected spring maize yield and yield components.Compared with CT,FM and RTF treatment could increase yield significantly.The FM and RTF treatment grain number per spike increased significantly by 62 and 61;100-grain weight increased significantly by 4 and 2.5 g,respectively;Compared to the CT treatment,the average yields in the FM and RTF treatments increased by 45.4%and 37.6%(P<0.05),respectively.Nitrogen application(N225)increased grain yield significantly.The average grain yield of N225treatment was 8933 kg/hm~2,which was significantly higher than that of 6475 kg/hm~2 without nitrogen(N0),The average grain yield of N225 could significantly increase 2458 kg/hm~2 than N0treatment.(2)Tillage methods and fertilization treatments significantly affected the growth and development of spring maize.Compared with CT,the FM and RTF treatment plant height was significantly increased by 5.7 cm and 4.57 cm.The FM and RTF treatment significantly increased dry matter accumulation,which was a significant increase of 5053 kg/hm~2 and 4613 kg/hm~2 compared with CT.Nitrogen application(N225)significantly increased the dry matter accumulation of spring maize compared to no nitrogen application(N0).The dry matter accumulation amount of nitrogen application treatment was 18259 kg/hm~2,which was significantly increased by 4712 kg/hm~2 than that of N0(13547 kg/hm~2).(3)Tillage methods and fertilization treatments significantly affected the aboveground nitrogen accumulation,water and nitrogen use efficiency.The amount of nitrogen uptake of FM?RTF and RT was significantly higher than CT by 45.5 kg/hm~2,33.9 kg/hm~2 and 25.5 kg/hm~2,respectively.the water use efficiency of the FM and RTF was significantly increased by 8.05 kg/(hm2·mm)and6.68 kg/(hm2·mm)than that of CT.The nitrogen use efficiency of FM and RTF significantly increased by 11.5%and 16.1%respectively compared with CT.(4)Compared with no nitrogen(N0)Nitrogen can significantly increase nitrogen accumulation.The average nitrogen application(N225)treatment was 158.6 kg/hm~2,which was significantly more73.5 kg/hm~2 than N0(85.1 kg/hm~2).Nitrogen application(N225)could increase the WUE of spring maize,The nitrogen application(The average value of N225)water use efficiency was 25.04kg/(hm2·mm),which was significantly increased by 6.04 kg/(hm2·mm)compared to N0(19.00kg/(hm2·mm)).(5)Different tillage methods have different soil dynamics in the plough layer during spring maize growth period.The RTF and FM treatments were more conducive to soil moisture and temperature stability.Compared with CT treatment,the RTF and FM treatments significantly increase soil water content and temperature.In general,under the local climatic conditions,the FM and RTF treatments can increase spring maize yield,water and nitrogen use efficiency in the loess highland area.Therefore,the FM and RTF treatments could adapt to spring maize practice in the Loess Plateau.