Effect Of Biochar Application Mode On Sloping Farmland In Black Soil Region And Its Effect On Soybean Growth And Development

Biochar,as a new product of straw carbonization and return to the field,has become one of the hot spots of many scholars at home and abroad.Biochar is extremely stable and can exist in the soil for a long time.Although there have been many studies on the effect of biochar on water saving and production increase,most of them are based on the short-term application of biochar to study the physical and chemical properties of soil,soil and water The effects of indicators such as the maintenance effect and water-saving and yield-increasing effects are lacking,and there is a lack of accurate guidance and evaluation in exploring the changes of various indicators in the medium-and long-term application of biochar to the indicators,as well as the rational allocation of the amount and duration of carbon application.To this end,this study took field runoff plots on soybean sloping fields as the research object and conducted a 4-year observation.In 2015,C0(0t/hm~2),C25(25 t/hm~2),C50(50 t/hm~2),C75(75 t/hm~2),C100(100 t/hm~2)were set according to the amount of biochar applied In each treatment,the same amount of biochar was applied continuously in 2016,2017,and 2018,and biochar was applied for 4 consecutive years to clarify the changing laws of soil physical and chemical properties,soil and water conservation effects,water saving and yield increase effects after the application of biochar.Establish an improved TOPSIS evaluation model to comprehensively evaluate land productivity,and put forward the best biochar application mode through comprehensive evaluation,provide reasonable suggestions for the optimal biochar application dose and interannual distribution in the black soil area,and provide actual production in the black soil area Theoretical guidance.The results of the inquiry indicate.(1)After applying biochar for 4 consecutive years,the soil bulk density gradually decreased,the porosity gradually increased,and the longer the application period,the more obvious the effect;the field water holding capacity and the carbon application amount showed a linear increasing trend when applying for 1 year,and the field holding capacity of C100 treatment was the largest.In the continuous application of 2 or 3 years,the field water holding capacity increased first and then decreased with the increase of carbon application,and both reached the maximum after C50treatment.When continuous application for 4 years,the field water holding capacity also changed first with the application of carbon application.The increase and decrease change reached the maximum in the C25 treatment;the saturated water content and the withering coefficient showed a gradual increasing trend with the increase of carbon application for 4 consecutive years;the generalized soil structure coefficient(GSSI)with the increase of carbon application for 4consecutive years It showed a trend of increasing first and then decreasing,and the soil three structural distance index(STPSD)showed a trend of decreasing first and then increasing.Both achieved the maximum(small)value(98.31,8.87)in the C50 treatment in the second year.The soil triatomic ratio is closest to the ideal state;the soil available potassium and organic matter content gradually increase with the increase of carbon application for four consecutive years,and the soil alkaline nitrogen and available phosphorus content increase first and then decrease.Phosphorus content increased the most were C75,C50,C50,C25.(2)The annual production flow rate and annual sand production of 4 years decrease first and then increase with the increase of carbon application amount,and the continuous application of 50t/hm~2 of biochar for 2 years to reduce the flow and soil erosion effect is the best According to the analysis of flow and sediment production process,the application of biochar can delay the flow production and sediment production time,and can reduce the flow production and sediment production,but when the carbon application is too high,the flow production and sediment production increase.(3)The application of biochar for 4 consecutive years can increase the amount of rainwater storage within 120 hours after a typical secondary rainfall.The optimal treatments for 4 years are C75,C50,C50,and C25.The application of biochar for 4 consecutive years can increase the soil water storage of the 0～60 cm soil layer in each growth period,but has little effect on the soil moisture content of the 60～100 cm soil layer.C75,C50,C50,C25.The application of biochar for4 consecutive years has little effect on the distribution of soil water content in the 0-100 cm soil layer,but it can increase the soil water content in the 0-60 cm soil layer,but has little effect on the soil water content in the 60-100 cm soil layer.For four consecutive years,the water use efficiency increased first and then decreased with the increase of the amount of carbon applied.The optimal treatments in four years were C75,C50,C50,and C25,respectively.The water use efficiency of C50 treatment in the second year was the largest,27.67%,and the C100 treatment in the fourth year was 5.12%lower than the control treatment.(4)The application of biochar for 4 consecutive years has improved the plant height,diameter,leaf area index and canopy coverage of soybean at each growth stage.The plant height,diameter,leaf area index and canopy coverage of soybean at each growth stage in 4 years have increased The increase in the amount of carbon application showed a trend of increasing first and then decreasing.The relatively better treatments in the same period of each year were C75,C50,C50,and C25,but the plant height and diameter of soybeans at each growth stage of the C100treatment in the fourth year.Both the crude and leaf area were smaller than the control treatment.(5)Application of biochar for 4 consecutive years can increase soybean yield,pod number per plant,grain number per plant and 100-grain weight,and soybean yield,pod number per plant,grain per plant and 100-grain weight for 4 consecutive years all increase with the amount of carbon applied The increase showed a trend of increasing first and then decreasing.In the second year,C50 treatment showed the largest increase in production.For four consecutive years,the water use efficiency increased first and then decreased with the increase of the amount of carbon applied.The relatively superior treatments in four years were C75,C50,C50,and C25,respectively.The water use efficiency of C50 treatment in the second year increased the most.It was 27.67%,and the C100 treatment in the fourth year was 5.12%lower than the control treatment.(6)The improved TOPSIS model can objectively and clearly describe the changing process of land productivity,and propose the best biochar application mode,that is,continuous application of 50 t/hm~2 biochar for 2 years is the best to improve land productivity,followed by the application of 1 The annual biochar of 75 t/hm~2.