Effects Of Biochar Application On Soil Water And Salt Transport And Cotton Growth Under Film Drip Irrigation In The Arid Area Of Xinjiang

Soil salinization is a common threat to cultivated soil and is widely distributed in arid and semi-arid regions of the world.As the largest province in China,xinjiang occupies a large proportion of saline soil in the territory of the country.The salinization of cultivated land makes a large number of land resources unable to be utilized,which leads to the decline of the comprehensive production capacity of xinjiang's agriculture and seriously restricts the development of xinjiang's agricultural production.Therefore,it is urgent to seek effective and practical salinized soil improvement technology.In recent years,with the development of salt-soil improvement technology,more and more new improvement ideas and techniques have come into being.As a new soil improver,biochar is considered as the most safe,effective and economical way of carbon sequestration and emission reduction.This paper is based on cotton grown by drip irrigation under mulch in 2018?2019 and applied different amounts of biochar to 0?30cm soil layer.By measuring soil physical and chemical properties,soil water and salt,soil temperature,cotton growth and yield and other indexes,this paper analyzes the effects of different amount of biochar on soil water and salt transport and cotton growth and define the optimal application range of biochar.The main research results and conclusions are as follows:?1?The effects of biochar on physical and chemical properties of saline soils in xinjiang were clarified.The application of biochar can significantly reduce the soil bulk density,and the larger the amount of biochar,the lower the soil bulk density.The decrease ranged from 1.7%to 18.2%.The total porosity of soil increased with the increase of the amount of biochar,and the increase ranged from 3.6%to 30.5%.Because the p H of biochar is lower than that of xinjiang saline soil,the p H of soil decreased with the increase of biomass carbon.?2?The effect of biochar on soil moisture migration was clarified.The soil moisture content of each soil layer at different locations of B10 and B25 treatment was generally higher than that of other treatments,but the effect of B10 treatment was better.The soil moisture content of B50 and B100 treatment was lower than that of CK treatment in two years'growing season.In 2018,the water storage in the root area of the B10 treatment was significantly higher than other treatments,and the water storage in the root area of the B100treatment plot fluctuated greatly.In 2019,the water storage in the root area of the B10treatment and B25 treatment was similar and significantly higher than that of other treatments.The water storage in the root area of B50 treatment and B100 treatment was similar and generally smaller than that of CK treatments.?3?The influence of biochar on soil salt transport was clarified.Due to the application depth of biochar,the effect of biochar on soil salinity was only in the depth of 0-40 cm soil layer,and there was no significant effect on the depth of 60-100 cm soil layer.B10 treatment and B25 treatment can significantly reduce the soil salinity,and have a good effect on reducing the degree of soil salinization.The B100 treatment and B50 treatment will increase the soil salinity relatively and aggravate the degree of soil salinization.After irrigation,the application of biochar can promote the leaching of soil salts.The results of the 2018experiment showed that the soil salt leaching effect was enhanced with the increase of the amount of biomass carbon.Among the results of the 2019 experiment,the soil salt leaching effect was the best with the treatment of B10 and B25.?4?The effect of biochar on soil temperature was clarified.Biochar can increase the minimum temperature and decrease the maximum temperature of soil in 5cm soil layer,it can also increase the temperature and maintain the temperature of the 5cm soil layer.The change of temperature characteristic value in B10 and B25 treatment was obvious,but the change of temperature characteristic value in B100 and B50 treatment was not obvious.In general,the effect of biochar on soil temperature is not significant.?5?The effects of biochar on cotton growth and yield were clarified.The increase of plant height,stem diameter,number of fruit branches and leaf area index could be promoted by applying biochar.However,too much biochar will produce negative effects.Both B10treatment and B25 treatment can significantly increase the dry matter mass of cotton plants and bolls,while B50 treatment and B100 treatment have the effect of reducing the dry matter mass of cotton plants and bolls,and the reduction effect is more obvious with the increase of the amount of biochar.B10 treatment and B25 treatment can significantly improve cotton harvest density,single boll weight and seed cotton yield.B50 treatment and B100 treatment had no significant change in cotton harvest density and single boll weight compared with CK treatment,but B50 treatment and B100 treatment could reduce seed cotton yield.In addition,the boll number of each cotton plant increased with the increase of biomass carbon.?6?It was preliminarily determined that the optimal application range of biochar was10?25 t?hm^-2,and the application amount should be closer to 10 t?hm^-2,with better effect.