Effects Of Fertigation With Drip Irrigation On Soil Nitrogen And Root Spatial Distribution Of Maize

Drip irrigation is one of the most important technologies to improve the efficiency and yield of crops.It can accurately distribute nutrients around the root system of crops.To explore the regulation effect on soil nitrogen fertilization and root spatial distribution of maize among two irrigation methods.The field experiments were carried out during the maize growing seasons in 2019 and 2020 at the Xinxiang Experimental Station of the Chinese Academy of Agricultural Sciences.Five nitrogen fertilizer treatments of N0 kg/hm²,N165 kg/hm²,N210 kg/hm²,N255 kg/hm²and N300 kg/hm²were set,and Zhengdan 958 was used as the test cultivated.The soil and maize root were sampled simultaneously using the root soil sampler basing on the sampling method of“3D monolith”.The soil nitrogen use efficiency and soil moisture content root were analyzed under different management.Confirm the root system and spatial distribution regularity of soil moisture,soil nitrogen utilization and its coordination control effect on maize yield.The results demonstrated that:（1）Under different irrigation methods study of different nitrogen application on maize plants and plant nitrogen accumulation and distribution of dry matter,our results indicated that the influence of dripping irrigation compared with flood irrigation fertilization,fertilizer have been significantly increased the upper corn dry matter accumulation and LAI and dry matter of popcorn before turning traffic and transport rate of dry matter in front of the flower,in N255 level has reached the highest;At the N255level,LAI of dripping fertilization treatment was 0.67,3.49,4.56,4.53 at V6,V12,VT and milkripening stage,respectively,which have been significantly increased by 4.7%,4.6%,5.8%,10.2%compared with that of flooding irrigation treatment.The dry matter accumulation pre-anthesis was 7935.33 kg/hm²and the dry matter accumulation after anthesis was 16053.17 kg/hm²,which was significantly increased by 13.1%and 44.1%compared with the conditions of diffuse fertilization.With the increase of nitrogen application,the nitrogen accumulation in each organ of maize showed a trend of first increasing and then decreasing among dripping irrigation and fertilization,and all indexes of maize were inhibited by too high or too low nitrogen application rate.（2）The effect of different nitrogen application on the coordination of soil moisture content and spatial distribution of soil nitrogen under different irrigation methods was studied.It was found that with the increase of soil layer number,drip irrigation have been significantly increased soil moisture content of0-50cm,and maintained soil moisture content in the root zone for a longer time than the level of flood irrigation.With the increase of maize growth stage,the soil moisture content under dripping irrigation and fertilization increased firstly and then decreased,and reached the minimum at V6 and R6 stages,and reached the maximum at R3 milking stage.With the increase of soil layer number,the content of nitrate nitrogen first decreased and then increased,and the content of ammonium nitrogen first"down-up-down"trend.The concentration of soil N_minwas concentrated in the topsoil layer,which was inversely proportional to soil depth and RLD.（3）The effect of different irrigation methods on spatial distribution and coordination of maize root system was studied.It was found that the root length among dripping irrigation was significantly greater than that among flooding irrigation,which promoted the root growth into the lower soil.The analysis of root length density（RLD）in different soil layers showed that the root distribution of maize under dripping irrigation and flooding irrigation was basically similar among different N treatments.Among dripping irrigation,the RLD distribution of maize with different N levels decreased with the increase of soil depth,and a large number of RLD were concentrated in the 0-20 cm soil layer.Under the condition of drip irrigation,the soil water content of each treatment profile was between 14%and 17.8%,and the contours of water content were uneven,that is,the distribution of soil water content in the profile was not uniform.The distribution area of RLD of each treatment was significantly increased of nitrogen application rate.Under the condition of dripping irrigation and fertilization,the distribution area of RLD expanded and moved down to the 30 cm soil layer,and there was little distribution in the 40 cm soil layer.However,RLD was distributed in less soil layer under diffuse irrigation and fertilization.Under the condition of dripping irrigation and fertilization,the contours of moisture content were uneven,and the soil surface moisture content increased with the increase of nitrogen application rate.However,the change of soil moisture content among flooding irrigation was not obvious,indicating that the water storage capacity of dripping irrigation was stronger than that of flooding irrigation.（4）It was found that the nitrogen use efficiency（NUE）,NRE,NIE and grain nitrogen accumulation under dripping irrigation were significantly higher than those under flood irrigation.Among dripping irrigation,PEP_N,AE_Nand PE_Nwere significantly lower than those under spread irrigation,while REN was significantly higher than that under spread fertilization,and there was no significant difference in NHI.With the increase of nitrogen application,PPE_N,AEN and PE_Ndecreased gradually.Under dripping irrigation and fertilization,the yield variation ranges（except N0）in 2019 and 2020 are5.71-7.57 t/hm²and 9.78-10.79 t/hm²,respectively.Under the condition of diffuse irrigation and fertilization,the range of yield variation in 2020（except N0）is 10.06-12.48 t/hm².The maximum values were 10.79 t/hm²and 7.56 t/hm²at N255 kg/hm²,respectively.The weight of N1,N2,N3 and N4among dripping irrigation were 160.79 g,167.84 g,173.88 g and 174.05g,respectively,which were increased by 9.6%,5.55%,1.6%and 5.2%compared with that under spread irrigation.Therefore,under the condition of no increase in dripping irrigation technology level,the optimal nitrogen application rate at N255 level was the best nitrogen application rate to increase yield.