Effect Of Different Hydraulic Elements On Distribution Of Water-nitrogen Space Under Border Fertigation

Border irrigation is one of the most important irrigation methods in China,which exists the problems such as waste of water and fertilizer and low utilization efficiency.The study on optimizing the technical parameters of border irrigation can alleviate the shortage of agricultural water in China,that is great significance to improve the efficiency of water and fertilizer utilization.In this study,the summer maize and winter wheat continuous cropping system in the north of Henan Province was used as the research object,the fertigation was carried out for irrigation system,and three different fields and fertilization parameters were designed,the corresponding inflow rate of border width(1.5,2.3,3.2 m)was 6,3.9,2.8 L/(m·s),border length(40,60,80 m)and the timing(with applying fertilizer as the whole course,as the first half border length,as the later half border length).The spatial distribution of water and nitrogen,crop yield and water use efficiency under different parameters of border irrigation were studied by orthogonal design method,and the optimal combination of border irrigation application parameters was explored.Under the premise of both high yield and high yield,the quality of irrigation and fertilization and the utilization efficiency of water and nitrogen are improved,and a theoretical and technical support is provided for the irrigation system and fertigation of the birder irrigation.Winter wheat and summer maize were used as research crops in the experiment.The main results are as follows:(1)After two days of fertigation,soil water and nitrate were concentrated in the root layer of crop.The variation range of soil water and nitrogen was relatively small below the root layer,and the increase of soil water and nitrogen showed a decreasing trend with the increase of soil depth.The spatial distribution of soil water was greatly affected by the inflow rate per unit width,and the distribution of soil water along the border length space was similar in different treatments.The spatial distribution of nitrate nitrogen was affected by the inflow rate per unit width and the timing.The accumulation of the treatment of with applying fertilizer as the first half border length was higher in the upper reaches of the border field,and the accumulation of treatment of with applying fertilizer as the later half border length was in the middle and lower reaches.(2)The coefficient of variation of soil volume moisture and nitrate nitrogen content along the border length direction was greatly affected by the distribution of soil water and nitrogen before irrigation,and the coefficient of variation of some treatments were increased.After two days of fertigation;The effect of different treatments on the spatial distribution variation coefficient of soil volume moisture content along border length was not significant,but on the spatial distribution variation coefficient of nitrate nitrogen was significantly.However,the coefficient of variation along the depth direction decreased significantly,and most of the spatial variation coefficients of different treatments were less than 0.1,showing weak variability as a whole.(3)After two days of fertigation,the difference of water and nitrogen storage efficiency in soil was small,and the distribution of water uniformity along border length was slightly higher than that of nitrogen.The effect of each factor on the quality of the irrigation and fertilization was not significant,but the storage rate of the nitrogen was significantly affected.On the whole,the irrigation and fertilization quality index of fertigation treatment is higher than that of broadcast treatment,fertigation can improve irrigation quality.(4)The plant height,leaf area,SPAD value and dry matter accumulation of winter wheat and summer maize were affected by all the factors,but no significant difference was found among thephysiological indexes of crops under different treatments,the proportion of panicle to total dry matter increased from 22.7% to 50% during flowering stage to mature stage of winter wheat,and there was no significant difference between the ratio of panicle to total dry matter.The percentage of panicle increased from 51.3% to 63.9% during heading stage to mature stage of summer maize,and there was significant difference between different treatments at mature stage.(5)There were significant differences in yield and water use efficiency between winter wheat and summer maize under different treatments.Border width and border length were the main factors affecting crop yield and water use efficiency,the water use efficiency of fertigation was higher than that of broadcast.Border width also significantly affected the 1000-grain weight of winter wheat and100-grain weight of summer maize,The crop yield increases with the increase of border width,while the water use efficiency was higher under smaller border width.In general,fertigation can reduce the coefficient of variation of spatial distribution of soil water and nitrogen and improve the quality of irrigation and fertilization.Under the condition that loam soil and 2‰ border field slope,border width,border length and fertilization timing all affected the various indicators of crops to varying degrees.In order to achieve higher uniformity of water and fertilizer and water use efficiency,all indexes and factors should be taken into a higher level,with the inflow rate of2.9 L/(m·s),border length of 60 m and with applying fertilizer as the first half border length can form higher spatial distribution uniformity of soil water and nitrogen.