Effects Of Water-Fertilizer Integrated Subsurface Irrigation With Ceramic Emitters On Growth And Yield Of Wolfberry

As a local special economic crop,wolfberry has become one of the important industries for farmers in the northwest dry zone to get rid of poverty and get rich,but the drought and water shortage restrict its planting area expansion and yield improvement.The effect of new irrigation technology on soil moisture and yield of wolfberry can help optimize irrigation measures for wolfberry,which is important for sustainable development of wolfberry industry.To this end,this paper based on ceramic emitter outflow characteristics,design a water and fertilizer integration subsurface irrigation with ceramic emitters system,study the different emitter design flow and burial depth conditions of soil moisture content spatial and temporal distribution characteristics,as well as different fertilization methods and fertilization amount conditions of water and nitrogen utilization efficiency,and further analysis of its impact on wolfberry growth and yield,determine the Qaidam wolfberry subsurface irrigation with ceramic emitters suitable technical parameters In order to provide a theoretical basis for the scientific and reasonable irrigation of Chinese wolfberry.The following main conclusions were obtained:(1)A water and fertilizer integrated subsurface irrigation with ceramic emitters system was designed.Based on the adaptive irrigation outflow characteristics of the ceramic emitter,a water-fertilizer integrated subsurface irrigation with ceramic emitters system consisting of a continuous irrigation module,a pressurized fertilizer module and an irrigation pipe network was designed,and an operation mode of alternating micro-pressure irrigation(0.2～0.5 m)and pressurized fertilizer application(10 m)was developed.The test results of system reliability showed that the flow rate of ceramic emitter in the process of applying urea and compound fertilizer tended to decrease slightly with the increase of fertilizer application time,and the average relative irrigation flow rate of ceramic emitter with urea and compound fertilizer treatment was 99.1% and 98.5% respectively at 4 h of fertilizer application time;when the flushing of pipe network after fertilizer application was completed could effectively reduce the water and fertilizer residues attached to the emitter.When the fertilizer application is completed to flush the network can effectively reduce the water and fertilizer residue material attached to the emitter,the application of urea and compound fertilizer treatment irrigator average relative flow rate can be restored to more than 99.5%.The use of ceramic emitters for a short period of time to apply fertilizer under pressure will not cause the emitter to clog and the system can operate effectively.(2)The effects of different design flow rates and burial depths of ceramic irrigators on soil moisture and yield of wolfberry were analyzed.In the main root zone of wolfberry,the soil moisture content of subsurface irrigation with ceramic emitters was maintained near70.6～78.9% of the field water holding rate,and the soil moisture environment was relatively stable,while the soil moisture of drip irrigation showed an obvious alternating wet and dry condition,and the soil moisture content fluctuated within 57.2～93.3% of the field water holding rate.The yield and water use efficiency of subsurface irrigation with ceramic emitters varied significantly among treatments,and subsurface irrigation with ceramic emitters had a better water saving and yield increase effect only under the conditions of suitable irrigator design flow rate and burial depth,among which the best performance was achieved with the design flow rate of 0.15 L/h and burial depth of 30 cm,which increased the yield of wolfberry by 18.9% on average and water use efficiency by Compared with drip irrigation,the average yield of wolfberry increased by 12.7% and water use efficiency increased by 23.8%.(3)The effects of different fertilization methods and N application on soil nitrogen distribution and yield of wolfberry were investigated.Under the same N application rate,the subsurface irrigation with ceramic emitters cavity application and subsurface irrigation with ceramic emitters fertilizer integration treatment increased the yield by 20.3% and 10.9%,respectively,compared with the surface drip irrigation treatment;while in the subsurface irrigation with ceramic emitters fertilizer integration for N reduction treatment,the yield of medium and low N treatments were 87.7% and 79.7% of the yield of high N treatment,respectively.Under the different N application rates of subsurface irrigation with ceramic emitters,the nitrate N content of soil decreased significantly with the reduction of N application rate after harvesting,and the nitrate N content of the same soil layer in the low N treatment was more uniformly distributed while the soil layer where the peak was located was20 cm deeper than that in the high N treatment.(4)The technical parameters of microporous ceramic root irrigation applicable to Qaidam wolfberry were determined.Comprehensive consideration of wolfberry planting production,recommended microporous ceramic root irrigation technology in the Qaidam wolfberry planting area use design flow rate of 0.15 L/h,burial depth of 30 cm ceramic irrigator;in the water and fertilizer integration irrigation,use subsurface irrigation with ceramic emitter,hole application fertilizer can harvest the best yield.