Effects Of Fertilization On Yield And Soil Nitrate Of Dryland Spring Maize

In this study,the spring maize in Shouyang dryland of Shanxi Province was taken as the research object.The effects of Fertilization on the yield,water and nitrogen utilization efficiency and soil nitrate nitrogen were studied through 10-year long-term fertilization experiments under the condition of natural precipitation.It is of great significance to guide the rational fertilization,improve the water and nitrogen utilization efficiency and reduce the soil nitrate nitrogen residue.The main conclusions are as follows:（1）The yield of corn in Dryland is closely related to the amount of nitrogen applied,but the functional relationship between the two is different due to the years of application,the types of fertilizer,and the type of precipitation.With the increase of the amount of nitrogen applied,there is a significant linear,logarithmic or quadratic parabola correlation.Corn yield of chemical fertilizer and organic fertilizer in different precipitation years was in wet year>normal year>dry year.When the amount of precipitation is less or the amount of nitrogen application is more than 300 kg·hm^-2,the effect of organic fertilizer is higher than that of chemical fertilizer.When the amount of precipitation is more and the amount of nitrogen application is less than 225 kg·hm^-2,the difference between chemical fertilizer and organic fertilizer is smaller,even higher than that of organic fertilizer.The partial productivity of nitrogen fertilizer and organic fertilizer decreased significantly with the increase of nitrogen application,and the partial productivity of nitrogen fertilizer in wet year was higher than that in dry year.According to the characteristics of corn yield change in dry land,the suitable nitrogen application amount of chemical fertilizer is 225 kg·hm^-2 or 300 kg·hm^-2 or 375 kg·hm^-2,and that of organic fertilizer is 300 kg·hm^-22 or375 kg·hm^-2 or 450 kg·hm^-2.The nitrogen application level of organic fertilizer is one higher than that of chemical fertilizer.At the same time,with the extension of fertilization years,the suitable nitrogen application amount may be finally stable at 225 kg·hm^-2.（2）Fertilization can significantly improve WUE and ET of maize.The WUE of maize treated with chemical fertilizer and organic fertilizer was 16.2 kg·hm^-2·mm^-11 and 18.3 kg·hm^-2·mm^-1,respectively,which increased by 55.8%and 68.3%respectively.The water consumption of maize increased by 8.9 mm and 14.2 mm respectively.The effect of different fertilizers on WUE and ET of maize was different.Under the organic fertilizer treatment,both of them increased gradually with the increase of fertilizer amount,while under the chemical fertilizer treatment,WUE and ET increased first and then decreased.WUE and ET were significantly different in different years,which were mainly affected by precipitation and its distribution.Fertilization can reduce soil evaporation in leisure period.But this effect is affected by the amount of fertilization and precipitation in leisure period.The annual water consumption of fertilization treatment was higher than that of no fertilization treatment.Long term over fertilization results in excessive consumption of soil water.With the increase of fertilization,both chemical fertilizer and organic fertilizer,the decrease of soil water storage first increases and then decreases.（3）The accumulation of NO₃^--N in soil profile increased with the increase of nitrogen application,and there was a linear positive correlation between them.The content of NO₃^--N in each layer of soil increased with the increase of nitrogen application,mostly as a power function.NO₃^--N was mainly distributed in 0-40 cm soil layer,decreased with the increase of soil depth,and no obvious leaching occurred with the extension of fertilization years.Under the condition of chemical fertilizer,the distribution of NO₃^--N in different years is decreasing type,rising type,single peak type or S-type with the increase of soil depth;the maximum accumulation of NO₃^--N occurs in different soil layers,the peak value of NO₃^--N accumulation increases with the increase of nitrogen application amount,and the accumulation range is gradually widened.With the extension of fertilization years,the soil depth and leaching depth of NO₃^--N maximum accumulation appear continuously With the extension of fertilization years,0-60cm fluctuated,and the interannual variation was large.The content of nitrate nitrogen in each layer of soil below 60cm increased year by year,and the increase was linear positive correlation.The increase decreased with the increase of soil depth,and further increased with the increase of nitrogen application.When the amount of nitrogen applied by chemical fertilizer and organic fertilizer increased from 150 kg·hm^-2 to 225 kg·hm^-2,the content of soil nitrate increased significantly.From the point of view of reducing nitrate nitrogen residue,the application amount of chemical fertilizer and organic fertilizer should be less than 225 kg·hm^-2.At this time,the amount of nitrate nitrogen residue in the soil profile is less,the annual accumulation increase is smaller,and the environmental pressure and the risk of leaching are lower.In conclusion,for the dry land corn field,the application of organic fertilizer was higher than that of chemical fertilizer.The recommended nitrogen application amount in the experimental area is 150-225kg·hm^-2 for chemical fertilizer and 225 kg·hm^-2 for organic fertilizer.Within the range of nitrogen application,corn yield and nitrogen partial productivity were higher,soil moisture was significantly higher than that of no fertilization,and soil evaporation loss and nitrate nitrogen residue in soil profile were significantly reduced.