Effects Of Irrigation And Nitrogen Management On Yield And Water And Nitrogen Use Efficiency Of Summer Maize Under Automatic Pipe Channel-Control Irrigation

Huang Huai Hai Plain is one of the main corn producing areas in China.However,the total annual precipitation in this area is less,the water resources are insufficient,and the spatial and temporal distribution is uneven,which seriously affects the agricultural production in this area.At the same time,due to the low education level of agricultural workers and the lack of technological innovation,there are still widespread phenomena such as flood irrigation,blind fertilization,and excessive use of chemical fertilizer not only the waste of water and fertilizer resources is wasted,but also the soil acidification and secondary salinization increase,resulting in the imbalance of soil nutrient proportion,the increase of crop incidence rate and the decline of the quality of agricultural products.In order to achieve high yield of summer maize and improve water and fertilizer use efficiency,the experiment was conducted in the experimental field of Shandong Agricultural University（36°01’11 N,117°0’21 E）in Mazhuang Town,Tai’an City,Shandong Province in 2019 and 2020.The maize variety tested was"Zhengdan 958".A randomized block design was used in the experiment.Under the condition of automatic pipe channel-control irrigation（W₁）,the traditional nitrogen application was 300 kg·hm^-2(N₃₀₀),increased by 10%,330 kg·hm^-2(N₃₃₀),decreased by 20%,240 kg·hm^-2(N₂₄₀),decreased by50%,150 kg·hm^-2(N₁₅₀)and 0 kg·hm^-2（N₀）,at the same time,border irrigation（W₂）was set as the control group,and the nitrogen application rate was 300 kg·hm^-2(N₃₀₀)of traditional nitrogen application.The effects of irrigation mode and nitrogen application rate on Yield and water and nitrogen use efficiency of summer maize were studied.Due to typhoon influence in2020,data analysis is mainly in 2019,and the main results are as follows:（1）In dry years,increasing irrigation and irrigation times can promote the growth of summer maize.Compared with border irrigation,automatic pipe channel-control irrigation can significantly reduce the irrigation quota in the whole growth period of summer maize,reduce the water consumption of farmland,reduce deep leakage and nitrogen leaching,improve water use efficiency and irrigation water use efficiency,and improve the uniformity of water and nitrogen distribution.The quality of irrigation and fertilization was ensured.It was beneficial to the accumulation of nitrogen in grain and plant,increased the number of ears,increased yield by 5.51%,and obtained higher nitrogen harvest index,Nitrogen Agronomic use efficiency and nitrogen use efficiency.（2）The dry matter accumulation of summer maize was seriously affected by water shortage at seedling stage and grain filling stage.With the increase of nitrogen application,the effect of water shortage at seedling stage and grain filling stage on dry matter accumulation gradually weakened.Under the condition of automatic pipe channel-control irrigation,nitrogen application could significantly increase the population dry matter quality of Summer Maize at each growth stage,and promote the dry matter accumulation of maize aboveground.With the increase of nitrogen application,the dry matter accumulation of stems and leaves had no significant difference,or even slightly decreased.Compared with N₀ treatment,the dry matter accumulation of N₁₅₀、N₂₄₀、N₃₀₀ and N₃₃₀ increased by 10.79%、21.06%、21.51%and19.36%respectively.Nitrogen application could significantly increase the number of ears and hundred-grain weight of summer maize.A small amount of nitrogen application had no significant difference in the number of rows per ear and the number of grains per row.Excessive nitrogen application could inhibit the yield components of summer maize.Nitrogen application rate of 240～300 kg·hm^-2 could increase the proportion of dry matter accumulation in vegetative organs and grain yield of summer maize.（3）With the increase of nitrogen application rate under the condition of automatic pipe channel-control irrigation,the plant height,stem diameter and leaf area index of summer maize increased at first and then decreased.Nitrogen application was beneficial to increase the leaf area and photosynthetic efficiency of summer maize,but excessive nitrogen application had a certain inhibitory effect on the growth of summer maize leaves,which was not conducive to the growth of leaves.The maximum values of plant height and leaf area index appeared at 240kg·hm^-2 of nitrogen application.The stem diameter reached the maximum when the nitrogen application rate was 300 kg·hm^-2.Appropriate nitrogen application could increase nitrogen accumulation in stems and leaves of summer maize,and increase nitrogen transport capacity and efficiency in vegetative organs of summer maize,but excessive nitrogen application had no significant effect,even had a decreasing trend.Nitrogen application could improve nitrogen accumulation and translocation in summer maize.Compared with N₀ treatment,N₁₅₀、N₂₄₀、N₃₀₀ and N₃₃₀ treatments increased grain nitrogen accumulation by 22.33%、47.22%、51.78%and 41.04%,and plant nitrogen accumulation by 19.65%、40.6%、44.02%and 36.02%respectively。（4）Under the condition of automatic pipe channel-control irrigation,appropriate nitrogen application can improve water and nitrogen use efficiency,but excessive nitrogen application will reduce water and nitrogen use efficiency.Water use efficiency of N₂₄₀ treatment was significantly higher than that of other treatments.Compared with N₀,water use efficiency of N₁₅₀、N₂₄₀、N₃₀₀ and N₃₃₀ increased by 18.81%、36.67%、33.38%and 27.7%respectively.The nitrogen harvest index of N₁₅₀、N₂₄₀ and N₃₃₀ treatments was significantly higher than that of N₀ treatment,but there was no significant difference between N₂₄₀ and N₃₀₀ treatments,and the maximum value was obtained when the nitrogen application rate was 300 kg·hm^-2.The Nitrogen Agronomic use efficiency of N₂₄₀ treatment was significantly higher than that of other treatments,indicating that appropriate nitrogen application could increase the Nitrogen Agronomic use efficiency of summer maize,but the Nitrogen Agronomic use efficiency would decrease significantly with the increase of nitrogen application.（5）The irrigation amount,water consumption,nitrogen application rate,yield,dry matter accumulation and transport,and water and nitrogen use efficiency of Summer Maize in the whole growth period were comprehensively considered.Under the condition of automatic pipe channel-control irrigation,the suitable amount of nitrogen application was 240～300kg·hm^-2.The period of supplementary irrigation and nitrogen application were sowing,jointing and tasseling,and the field water capacity was the target water content of supplementary irrigation.Irrigation times can be increased in dry years.The ratio of nitrogen application at each stage was 1:1:1,in which the base nitrogen was the bottom application,and the jointing nitrogen and tasseling nitrogen were applied with water.The results of this study will help to reduce the amount of water and nitrogen application in the whole growth period of maize,improve the uniformity of irrigation and nitrogen application,improve the quality of water and nitrogen,and improve the yield and water and nitrogen use efficiency of Summer Maize in Huang Huai Hai region,which is of great significance for efficient irrigation and fertilization and high-yield cultivation of summer maize.