| The farmers in the Hetao irrigation district(HID)often use flood irrigation with large amounts of irrigation due to less precipitation,which causes the nutrients leaching,groundwater pollution and reduces the water and nitrogen resource utilization efficiency.In addition,the low air temperature in early spring in the HID inhibited the emergence and spring maize growth and yield formation.Therefore,it was necessary to explore the appropriate mulching tillage mode of maintaining soil moisture and increasing soil temperature for improving maize growing environment and increasing yield and resources use efficiency.This study had two experimental factors—mulching irrigation method and nitrogen application level—in a random block design.The mulching irrigation methods included border irrigation+no mulching,border irrigation+transparent plastic film mulching,ridge mulched with plastic film-furrow irrigation+transparent plastic film mulching,ridge mulched with plastic film-furrow irrigation+black plastic film mulching.The nitrogen application levels included 0,150 and 300 kg N/hm~2.The object of this study was to analyze the effects of irrigation,nitrogen application and its interaction on soil water,heat,nitrogen content,maize growth and development,maize yield and water,heat and nitrogen resource utilization efficiency.The main conclusions are as follows:1.Different mulching irrigation methods significantly affected on soil water,heat and nitrogen content.At the seedling stage of maize,mulching significantly improved the soil surface water content,but the improved effect was not significant after the jointing stage.Ridge mulched with plastic film-furrow irrigation significantly increased soil water content and increased soil water storage in the root zone.The average increase in mulch compared with non-mulch treatment was 32.94%.Mulching can also increase soil temperature,reduce the rate of soil temperature decline,thereby increasing the average soil temperature values.Moreover,mulching increased the effective accumulated temperature of the soil.Ridge mulched with plastic film-furrow irrigation produced higher soil temperature than border irrigation under the same mulching condition.In addition,the mulching measure increased the nitrate nitrogen and ammonium nitrogen content in the surface soil,and ridge mulched with plastic film-furrow irrigation treatment not only increased the nitrate nitrogen and ammonium nitrogen content in the surface soil,but also significantly increased the nitrate nitrogen storage in the root zone.Compared with mulching furrow irrigation,the treatment of ridge mulched with plastic film-furrow irrigation increased by 39.15%～42.40%.2.Mulching irrigation methods and nitrogen application amounts had significant effects on maize growth.Mulching and ridge mulched with plastic film-furrow irrigation accelerated maize growth,which significantly increased maize plant height,stem thickness,chlorophyll content,leaf area index and aboveground dry matter quality.Meanwhile,nitrogen application also significantly promoted maize growth and development.The mulching measures significantly increased the maize yield.And,the ridge mulched with plastic film-furrow irrigation produced higher yield than border irrigation under the same mulching measures.The yield of spring maize mulched under conventional nitrogen application increased by 2151～3032 kg/hm~2 compared with uncoated treatment.The yield of spring maize under ridge mulched with plastic film-furrow irrigation increased by an average of 6.13%compared with the two years of mulching treatment.However,there was no significant differences for biomass and yield between ridge mulched with plastic film-furrow irrigation+transparent plastic film mulching and ridge mulched with plastic film-furrow irrigation+black plastic film mulching treatments.3.Mulching significantly improved the resource utilization efficiency of maize.And,the ridge mulched with plastic film-furrow irrigation produced higher water use efficiency,temperature use efficiency and nitrogen use efficiency than border irrigation under the same mulching measures.There was positive relationship between nitrogen application amounts and water use efficiency,temperature production efficiency.And the water use efficiency and temperature production efficiency increased with the increase of nitrogen application amounts.There was a negative relationship between nitrogen application amounts and water use efficiency,temperature production efficiency,and nitrogen use efficiency decreased with the increase of nitrogen application amounts.4.During maturity stages,the soil physical and chemical properties,maize growth and physiological indexes,resources use efficiencies were comprehensively evaluate to analyze the response of crop on treatments using TOPSIS method,grey correlation analysis method,coupling coordination analysis method.The results showed that mulching,ridge mulched with plastic film-furrow irrigation and increasing nitrogen application rate can improve the growth status of maize.And ridge mulched with plastic film-furrow irrigation produced greater effects on maize yield than nitrogen application amounts.Results of trials and model evaluations showed that ridge mulched with plastic film-furrow irrigation+transparent plastic film mulching treatment significantly improved soil hydrothermal conditions,promoted maize growth and development,and improved yield and resource utilization efficiency.In view of the existing situation,ridge mulched with plastic film-furrow irrigation+transparent membrane combined with 300 kg N/hm2nitrogen application level can be adopted in Hetao irrigation area to improve the growth of spring maize and improve the utilization rate of hydrothermal nitrogen resources. |
