Effects Of Desulfurization Gypsum And Wind-bound Sand In Improving Soil And Controling CO₂ Emission In Saline Cotton Field

The problem of salinization in Xinjiang is serious,and the ecological environment problem is outstanding.However,due to less annual precipitation and large evaporation in this area,unreasonable agricultural management measures lead to the deterioration of local cultivated land and the aggravation of soil salinization,which in turn leads to a series of environmental problems.This paper mainly discusses the influence of different soil improvement measures on the improvement effect and CO₂ gas emission of saline-alkali cotton fields,including no improvement measures（CK）,desulfurization gypsum 30t/hm²（W1）,desulfurization gypsum 18 t/hm²+aeolian sand 12 t/hm²（W2）,desulfurization gypsum 12 t/hm²+aeolian sand 18 t/hm²（W3）and aeolian sand 30 t/hm².The research results show that:（1）The changing characteristics of soil physical and chemical properties after applying improvement measures in saline-alkali cotton fields in southern Xinjiang were explored At different growth stages of cotton,the soil moisture content of different treatments at the same depth was W2 treatment>W1 treatment>CK>W3 treatment>W4 treatment.The soil temperature of 0-10cm fluctuated greatly under the influence of atmospheric temperature.Compared with CK,the average soil temperature of W1-W4 treatments increased by 0.21,0.44,0.65 and 1.03℃.Compared with CK,the average conductivity of the soil in the depth of 0-20 cm was significantly decreased by 15.17%in W1 treatment,and increased by1.84%～37.90%in W2～W4 treatment.Compared with CK,the average electrical conductivity of W1～W3 treatment with a depth of 20～40 cm decreased by 5.26%～25.97%,and the average electrical conductivity of W4 treatment increased by 10.35%.During the growth period,the soil p H at the same depth in all treatments decreased compared with CK,and the soil p H at0～20 cm and 20～40 cm in W1～W4 treatments decreased by 0.49%～3.10%and 0.6%～3.64%respectively.The average soil SOC content at different depths of each treatment increased with the decrease of desulfurization gypsum application and the increase of aeolian sand application,and the average soil SOC at 0～20 cm was higher than that at 20～40 cm after desulfurization gypsum application and aeolian sand application.（2）The dynamic effects of different improvement measures on soil CO₂ emission in cotton fields were clarified.The application of desulfurization gypsum and wind-deposited sand suppressed CO₂ emissions from cotton fields,and soil CO₂ emissions decreased with the increase of desulfurization gypsum application.The average CO₂ emission fluxes of CK,W1,W2,W3 and W4 treatments during the experiment were 292.28 mg·m^-2·h^-1,253.88mg·m^-2·h^-1,267.75 mg·m^-2·h^-1,284.28 mg·m^-2·h^-1,239.06 mg·m^-2·h^-1,respectively,between treatments at seedling,bud,boll and flocculation stages of cotton.The average and cumulative soil CO₂ emission fluxes were CK>W3 treatment>W2 treatment>W1treatment>W4 treatment among different treatments at the seedling,bud,boll and flossing stages.Soil temperature and water content had an interactive effect on soil CO₂ emission fluxes,and soil temperature and water content were significantly and positively correlated with soil CO₂ emission fluxes under different improvement measures.SOC content was significantly and negatively correlated with cumulative soil CO₂ emissions and total soil respiratory carbon release.（3）The effects of different improvement measures on cotton growth were analyzed.The height of cotton plants under different improvement measures ranged from high to low in CK>W4 treatment>W1 treatment>W3 treatment>W2 treatment;the stem thickness of cotton ranged from large to small in CK>W1 treatment>W3 treatment>W2 treatment>W4 treatment.The application of desulfurization gypsum and wind-cured sand significantly affected cotton yield and cotton carbon emission rate,and the overall cotton yield increased significantly with the increase of desulfurization gypsum application and the decrease of wind-cured sand application.The cotton yield of W4 treatment was significantly reduced by 25.06%compared with CK.The carbon emission rate of cotton in different treatments decreased significantly with the increase of desulfurization gypsum application and the decrease of wind-cured sand application.In conclusion,different improvement measures can improve the physical and chemical properties of soil,among which single application of desulfurization gypsum has a better effect on increasing soil moisture content and reducing soil temperature and conductivity,and single application of aeolian sand has the most prominent effect on reducing soil p H and SOC content at different depths.Different improvement measures can inhibit soil CO₂ emission,but single application of desulfurization gypsum can significantly increase cotton yield.Therefore,based on the improvement effect of the whole growth period,it is concluded that applying desulfurization gypsum 30 t/hm² is a reasonable soil improvement measure,which can better improve the soil in saline-alkaline cotton fields and achieve the effect of water retention,carbon fixation,emission reduction and yield increase.