Positioning Research Of The Effect Of Biochar Amendment On The Soil's Physical Properties In Semiarid Region

On the Loess Plateau,the vegetation is scarce and the soil structure is poor.Severe soil erosion and soil fertility decline seriously affected the crop yield of the region.The incineration of corn,wheat and other crop residues caused a large number of which lead to global warming.The continue increases of frequency and intensity of extreme weather,climate and meteorological disasters caused inestimable damage to China's agricultural production and ecological environment.The potential of biochar amendment effectively improve soil properties and reduce greenhouse gas emissions is expected to provide a new way for the recycling of crop straw waste in China,and effectively improve the soil environment and living environment on the Loess Plateau.In this paper,sawdust and locust tree skin-derived biochar amendment were added to the experimental plots,and with three different proportions of 1%,3%,and 5%.The physical properties of the soil and the effects of soil water retention characteristics in the semi-arid area were studied by using biochar amendment tests.The results showed that the sawdust biochar and locust tree skin-derived biochar amendment could effectively reduced the soil bulk density,and the 5%locust tree skin-derived biochar amendment had the most significant effect on soil bulk density reduction,reached at 7.83%.For the same type of biochar amendment,the higher the ratio of addition,the greater the decrease in soil bulk density;for the same proportion of biochar amendment,different types of biochar amendment had significant differences on soil bulk density.The sawdust biochar and locust tree skin-derived biochar amendment effectively increased soil water holding capacity in the field,and the 5%locust tree skin-derived biochar amendment had the most significant effect on soil water retention in the field,reached at 19.38%.For the same type of biocha amendmentr,the higher the proportion of biochar added,the greater the increase on soil water holding capacity in the field.The sawdust biochar and locust tree skin-derived biochar amendment effectively reduced soil saturated hydraulic conductivity and the 5%locust tree skin-derived biochar amendment had the most significant effect on reducing soil saturated hydraulic conductivity,reached at 32.17%.For the same biochar amendment,the greater the addition ratio,the greater the decrease in saturated hydraulic conductivity of the soil.The vertical distribution of soil water content is affected by the combined effect of precipitation infiltration depth in the soil and atmospheric evaporation.Within the depth of 0-30 cm,with the deepening of the soil depth,the soil moisture content of each treatment increases,reaching a maximum value of 30 cm.Both sawdust biochar and locust tree skin-derived biochar amendment could effectively improve soil water holding capacity in different degrees.The retained soil moisture content and saturated soil moisture content of the two kinds of biochar amendment had a certain degree of increase compared with the control group,indicating that the biocha amendmentr improved the water holding capacity of the soil to some extent.The coefficient of fit of the Philip infiltration model was between 0.992-0.996.The fitting effect was good,indicating that this model is suitable for simulating the soil moisture infiltration process with biochar.The sawdust biochar amendment had a significant effect on the surface temperature change of the soil.By compared the surface soil temperature of sawdust amendment and control group,it was found that 5%sawdust biochar amendment produced a significant peak in the surface temperature change of the soil.Filled the grain and compared the surface soil moisture content of the sawdust biochar amendment with the control group,it was found that the sawdust biochar amendment had a certain degree of impact on the surface soil moisture content,:but the impact is not a positive correlation.