| The sandy and windy semi-arid area is one of the typical agricultural types of dryland farming in China.The technology of film mulching.As an important agricultural technical measure,the technology of film mulching has been widely used in this area due to its characteristics of heat preservation and moisture increased.However,with the changing climate,the problems of insufficient water resources and uneven distribution of rainfall between years in this area become more and more serious.As a result,it is difficult to meet the growth and development needs of traditional crops with film mulching during the growth stage.In order to make better use of the water stored during fallow season,the autumn film mulching technology has been widely used.This technology is applied after harvest and soil preparation of coated,which reducing the ineffective loss of soil moisture in fallow season and realizing interseasonal regulation of farmland water resources.However,whether it will affect the sustainable use of water under using this technology for many years or not was no definite conclusion.On the other hand,this technology is affected by mechanical operation,the application time of base fertilizer is autumn,while improving the hydrothermal condition of soil,nitrogen conversion and utilization are bound to be affected.Therefore,this study is mainly aimed at the problem of water sustainable utilization and nitrogen absorption and utilization,selected maize as the indicator crop,three treatments were set: autumn film mulching(AM),spring film mulching(SM)and no mulching(NM),explored the mechanism of water and nitrogen transport and utilization in sandy and windy semi-arid area.The following result were obtained through 4 years of localization experiment:1.Autumn film mulching of dry land could significantly promote the growth of spring corn,increased the leaf area and dry matter accumulation,and increased the grain yield and biomass yield of maize.Four years experimental datas were shown that the yield of autumn film mulching increased on average by 26.3% and 60% compared with the traditional spring film mulching and no mulching,and autumn film mulching always maintain a high and stable harvest index compared with spring mulch.2.The average surface soil temperature of two film mulching treatments were 2.9 ? higher than no mulching,there was no significant difference in surface soil temperature between three treatments after the canopy was completely covered(55 ~ 61 days after sowing).The water stored in the soil layer between 0 to 100 cm in autumn film mulching was 41.9 mm more than that in the other two treatments at sowing time,and there was no significant difference between three treatments at harvesting time.Autumn film mulching treatment could consume 38.7mm more soil moisture in the growth stage of maize,which promoted the sustainable use of water.The autumn film mulching could increase the water use efficiency of maize significantly in the years of uneven rainfall distribution and different periods of drought.3.The treatment of autumn film mulching reduced ammonia volatilization,increased the content of inorganic nitrogen of soil.The correlation analysis showed that there was a significant positive correlation between the increased of cumulative temperature and the decreased of evaporation in the early growth stage of maize and mineralization of soil organic nitrogen,and there was a significant positive correlation between transpiration and nitrogen uptake at the later growth stage of maize.It was verified that the autumn film mulching treatment in maintaining good water temperature conditions,at the same time it increased the accumulation of nitrogen mineralization in soil during maize growing season and promoted the nitrogen uptake of maize.The residual inorganic nitrogen of autumn film mulching in soil layer 0 ~ 100 cm was significantly lower than spring film mulching,but higher than no mulching treatment.4.Two filming mulch treatments significantly reduced nitrogen loss of fertilizer,increased nitrogen residue of fertilizer,the nitrogen utilization efficiency of total fertilizer were improved,and autumn film mulching treatment also improved the utilization of soil nitrogen.In the first year of fertilizer application in autumn,the total amount of nitrogen absorption is mainly reflected in the increase of soil nitrogen absorption,and increased the using of residual fertilizers in the second year.In two growing seasons,the proportion of nitrogen absorbed from maize fertilizer AM was 51.9%,SM was 44.0% and NM was 34.3% respectively.In conclusion,we preliminarily defined using autumn film mulching technology for many years,the water stored in the fallow season can always be used in the growing season of maize under different model year in this area,ensured the sustainability of water use,promoted the stable yield of maize,improved the water use efficiency,and superior condition of moisture and temperature also promoted the mineralization of organic nitrogen,increased nitrogen uptake by maize in soil and nitrogen availability.However,under the premise of traditional nitrogen fertilizer application in this region,autumn film mulching could reduce the loss of nitrogen fertilizer and improve the utilization efficiency of nitrogen fertilizer,resulted in excessive residual nitrogen in the fertilizer at the same time,there was a risk of nitrogen leaching. |
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