| Aiming at the status of water deficiency,poor soil,low utilization of water and fertilizers,and agricultural film residues in dry sand areas,This article uses corn as a test subject,In the field experiment of drip irrigation covered by 2a biodegradable membranes in Wulanbuhe Sand Area of Inner Mongolia,the influence mechanisms of degradable plastic film cover and water-nitrogen interaction on soil environmental changes in sandy areas were studied,and effects of different water and nitrogen supply on corn yield in arid desert area,water and nitrogen use efficiency were explored.The coupled water and nitrogen model of corn in drip irrigation under degradable plastic film was established.In addition,the combination scheme was optimized and comprehensively evaluated,and the AquaCrop model was used to simulate the characteristics of the growth process and soil and water environment change of the maize,and to optimize the irrigation program in arid sand area.The water and fertilizer management model apply to the degradable film cover in the arid sand area is proposed,which has a great significance for solving the water and soil environment problems in farmland and improving the efficiency of water and fertilizer utilization,The main findings are as follows:(1)Compared with ordinary mulching,there was no significant difference in plant height,stem diameter,leaf area index,and dry matter quality of aerial parts of corn covered by degradable plastic film.Both the amount of irrigation water and the amount of nitrogen under the cover of degradable plastic film had a significant effect on the plant height,stem diameter,leaf area index and dry matter quality of the above-ground parts of the corn.within a certain range,each physiological index of corn increased with the increase of nitrogen application rate,but excessive nitrogen application would affect the growth of corn.Comprehensive analysis of high water(2016:330mm;2017:390mm)medium nitrogen(280kg/hm~2)treatment was the most favorable ratio of water to nitrogen for corn plant growth.(2)Covering of plastic film can effectively increase soil temperature,moisture content and nitrate nitrogen content in the upper layer(0~40cm)of the soil,and has the effect of heat preservation,moisture conservation and fertilizer retention.In the early growth stage of corn,the effect of degradable plastic film on the soil environment was not significantly different from that of ordinary plastic film.With the degradation of degradable plastic film,the difference gradually increased,which was significantly lower than that of common plastic film in the later growth period of corn.Different water and nitrogen treatments also have a significant impact on the soil environment,The increase of irrigation will promote corn uptake of nitrogen of the upper layer in the soil.Similarly,the increase in nitrogen application will also promote the use of water.The irrigation quota affects the soil moisture content from 0 to 40cm.With the increase of irrigation volume cause the increases of the water content,the nitrate content in the lower layer and the degree of leaching,the decrease of soil temperature and the nitrate content in the upper layer;With the increase of nitrogen application rate cause the increases of the nitrate nitrogen content and the accumulation of nitrate nitrogen in each soil layer.(3)Because of the degradation of degradable plastic film in the later growth stage,the water use efficiency(WUE)is lower than that of ordinary plastic film mulching,but there was no significant difference in corn yield and its constituent factors and partial nitrogen fertilizer(PFPN)under adequate water conditions.Both the amount of irrigation and nitrogen applied to the degradable plastic film had a significant effect on the maize yield and its components,WUE and PFPN.There was a clear interaction between irrigation volume and nitrogen application rate.The lower irrigation quota limited the use of nitrogen.The average PFPN and yield of 2a corn from low to medium water treatment increased by36.87%and 37.18%,and from middle to high water Only 5.93%and 6.22%increase;The same low nitrogen application also limited the use of water.From the low nitrogen to medium nitrogen treatment,the WUE and yield of the 2a corn increased by 7.99%and18.81%,respectively,while the increase from mid-nitrogen to high nitrogen WUE was-3.66%.yield only increased by 3.35%,while the maximum yield of 2a appeared in the high-water N treatments,which were 13875.16kg/hm~2 and 13805.02kg/hm~2 respectively.(4)In the drip-irrigated farmland covered by degradable plastic film in the sandy area,the quadratic regression model of binary irrigation was used to meet the irrigation quota,nitrogen application rate and corn yield.This model predicts that corn yield is highly correlated with actual yield(2016 and 2017 R~2=0.978?0.988),By the main factor analysis of water nitrogen production effect factors,the order of their size:irrigation>nitrogen application,the output increased with the increase of water and nitrogen were first increased and then decreased.After the optimization of the model,the optimal combination of water and nitrogen under different target yields was obtained.The yield under the nitrogen ratio of the nitrogen treatment in the high water was within the target range of13,000 to 14000 kg/hm~2,and the WUE and PFPN were higher.,It can be used as a reasonable irrigation program and water and fertilizer management model under the degradable plastic film cover in arid sand area.(5)According to the parameter rate of Aqua Crop model,the curves of yield and biomass under different mulching coverage were obtained,the canopy coverage,soil volume water content,maize yield and water consumption were simulated in the arid sand area,and the water use efficiency was calculated.The simulation results show that the correlation coefficient R~2 is greater than 0.9,NRMSE is less than 15%,and has higher simulation accuracy.The results showed that the AquaCrop model could better simulate the growth process of Maize under the plastic mulch in arid sandy area.The water production function of Maize with different irrigation water content was established by using local parameters.The results showed that the fitting effect was good,the correlation coefficient was R~2=0.89,the simulated yield of maize could reach the maximum value of13628.08kg/hm~2,and the corresponding irrigation amount was 368.90mm,and the irrigation system under the degradable film covered by the arid sand area was further optimized. |
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