Transport Characteristics of Water and Nitrogen Under Bubbled-root Irrigation with Soil Initial Water Content
LIU Xian;FEI Liangjun;WANG Jia;DAI Zhiguang;ZENG Jian;YANG Yang;Institute of Water Resources and Hydro-electric Engineering,Xi'an University of Technology;
To explore the water and nitrogen transport characteristics under water and fertilizer integration of bubbled-root irrigation,through the indoor fertilizer infiltration test,the migration characteristics of wetting front migration,soil moisture,ammonium nitrogen and nitrate nitrogen were studied under different soil initial water content(4.13%,7.21%,11.06%,14.01%).The relationships between the cumulative infiltration amount,the wetting front migration distance and the soil initial water content of bubbled-root irrigation were established.An empirical model was proposed to calculate the cumulative infiltration volume and the wetting front migration distance under different initial water content.Results showed that:The cumulative infiltration,the wetting front migration distance,the moisture in the body,the distribution and transformation of nitrogen were all affected by the initial water content of soil.At the same time,the cumulative infiltration reduced with the increase of initial soil water content,while the wetting front migration distance increased with the increase of initial soil water content.The higher the initial water content of soil was,the larger volume of wetting body was,and the wilder water,ammonium nitrogen and nitrate nitrogen distributed.The closer to the emitter outlet,the contents of ammonium nitrogen and nitrate nitrogen in the soil were higher.The infiltration coefficient Kdecreased with the increase of initial soil water content,while the infiltration indexαshowed an opposite trend.The fitting parameters aand b of horizontal wetting frontboth increased with the increase of initial soil water content.The vertical downward wetting front migration index cincreased with the increase of initial soil water content,while the infiltration index ddecreased with the increase of initial soil water content.With the continuous redistribution of soil moisture distribution,the moisture distribution in the moist body was more uniform,and the uniformity of water distribution evaluated by Christiansen uniformity coefficient Cu,in moist body was 61.99%,74.27% and 83.60%,respectively,at the end of irrigation,redistribution of 1day and 3days.With the redistribution,the content of ammonium in the wetted body gradually decreased,but the distribution region of ammonium nitrogen was almost unchanged.With the redistribution,the distribution of nitrate nitrogen in the wetted area became larger,the average value of it increased,and the maximum value of it had a downward trend.The above research results can lay the foundation for further researches on water and nitrogen use efficient of bubbled-root irrigation technology.
【Fund】： 国家重点研发计划课题项目(2016YFC0400204);; 国家自然科学基金项目(51279157 51479161);; 国家农业公益项目(201203003)
【CateGory Index】： S152.7;S153
【CateGory Index】： S152.7;S153