Study On Rules And Rugulation Of Soil Water-Heat-Salt Spatiotemporal Transfer Under No Winter And Spring Irrigation Cotton Field In Southern Xinjiang

Drip irrigation under mulched has become important support technology in Xinjiang cotton industry development and has showed good economic and ecological benefits.Traditional irrigation on winter and spring consumed the large amount of fresh water resources and it is difficult to adapt to the cotton industry and the sustainable development of water and soil resources in South Xinjiang.Attempts study on soil water and salt regulation concept with flooding irrigation during cotton fellow period to cotton whole growth period,and explore the countermeasures for the regulation of soil water-heat-salt under the condition of no-winter and spring irrigation.Through the field of long-term(2012-2015)experiment,indoor experiment,quantitative qualitative analysis and numerical simulation,study on the temporal and spatial changes of soil water-heat-salt with drip irrigation condition under no-winter and spring irrigation in southern Xinjiang.The main results include:(1)Soil water-heat-salt distribution and changing characteristics in cotton fields with no spring and winter irrigation methods under drip irrigationSoil water content in 0-30cm increased with irrigation quota under drip irrigation about no winter and spring irrigation,soil water content during seedling stage,budding stage,blossoming and boll-forming stage and boll opening stage were 14.19%,16.37%,15.45%and 13.42%.but soil water content in 40-100cm during different growth period were 12.24%,15.50%,16.01%and 13.41%respectively.Drip irrigation during cotton growth period supplied 40-100cm soil water content under no winter and spring irrigation pattern.No winter and spring irrigation with drip emergence should increased soil temperature,daily average soil temperature in 0-10cm higher 7.17℃ and 1.86℃ than air temperature and spring irrigation fields on before sowing,higher 5.15℃ and 0.44℃ than air temperature and spring irrigation fields on after sowing.0-30cm average soil salt content higher than 40-100 on pre-sowing under condition of no winter and spring irrigation methods.Soil salt content accumulation cotton growth period less than pre-sowing period.Soil salt content increased after consecutive four years under no winter and spring irrigation,0-30cm,40-100cm and 0-100cm soil salinity increase rate for 23.50%,13.82%and 19.41%respectively by an annual.(2)Soil water-heat-salt distribution and changing characteristics on freezing and thawing periodIrrigation and soil surface with corn straw mulching was beneficial to maintain soil water content during winter fallow period;under the same soil surface,soil moisture storage in 0-100 cm under winter irrigation was higher than no winter irrigation,and under the same winter irrigation quota,soil moisture storage in 0-100 cm under corn straw mulching was higher than cotton stubble and bare fields;WICM moisture storage was 29.10%and 10.36%higher than WIB and WICS respectively,and NWICM moisture storage was 14.97%and 2.21%higher than NWIB and NWICS respectively.Mulching of soil surface and irrigation could prevent soil temperature from decreasing during soil temperature falling period and play cooling effect during soil temperature rising period;winter irrigation with corn straw mulching could stabilize soil temperature.0-10cm soil temperature no winter irrigation pattern increased faster than winter irrigation,it’s beneficial to cotton earlier planting.Salt accumulation on soil surface of winter and no-winter irrigation methods,0-30 cm soil salt content was arranged as bare fields>high cotton stubble fields>corn straw mulching fields.Winter irrigation with 200 mm amount could leach soil salt,the leaching effect was corn straw mulching fields>high cotton stubble fields>bare fields,and the leaching rate was 34.86%,15.82%and 7.26%respectively.Under no winter irrigation,soil salt content was accumulated,and soil salt accumulation rate was bare fields(10.11%)>high cotton stubble fields(7.96%)>corn straw mulching fields(3.01%).(3)Appropriate irrigation quota and irrigation management strategy for cotton fields with no winter and spring irrigation for drip irrigation under mulchUnder condition of no winter and spring irrigation with cotton straw during freezing and thawing period in southern Xinjiang were cotton seedling stage irrigation quota 0.25 ET0,irrigation two times,budding stage irrigation quota 0.60 ET0,irrigation 4 times,blossoming and boll-forming stage irrigation quota 0.85ET0,irrigation 7 times,boll opening stage irrigation quota 0.55ET0,irrigation 2 times.Under long-term drip irrigation with no winter and spring irrigation pattern,winter irrigation interval three or four years under soil salt content less than 2g/kg-3g/kg,in the initial salinity(3g/kg-5g/kg)of soil salt content can choose two or three years for a winter irrigation or with the first year for winter irrigation and every other year spring irrigation to realize the control of cotton fields salt content.Provide theoretical support for cotton industry,soil and water resources sustainable development in southern of Xinjiang.(4)Simulating studies on soil water-heat movement in freezing and thawing periodUsing SHAW model simulation analysis about NWIB and NWICM treatment with soil temperature has high precision for simulation of soil water content.