Effects Of Straw And Biochar On Soil Organic Carbon Mineralization And Soil Enzyme Activity Of Red Soil In South China

The process of soil formation in southern red soil is composed of desilication and aluminum enrichment and bioaccumulation.Due to the influence of natural factors such as acid deposition,runoff erosion and collapsing erosion,the red soil is characterized by acidity,thinness,stickiness and easy erosion.In recent years,due to the excessive exploitation and utilization of red soil and the intensification of human activities,the southern red soil is facing new soil erosion,which causes soil fertility to decline,which aggravates the degree of soil acidification and affects the formation of soil organic matter.Hidden dangers to the yield and safety of agricultural and forestry crops have hindered the economic development of agroforestry and undermined the integrity of ecosystems.The primary task of improving low-fertility soil is to strengthen carbon sequestration capacity.On the one hand,it can consolidate more carbon sources to meet the needs of crops and soil growth;on the other hand,it can reduce greenhouse gas emissions and form a protection for the atmospheric environment.In order to repair the soil environment of red soil and improve soil fertility,domestic scholars have carried out a large number of related researches,and a large number of improvement measures and technical methods have been applied to the actual production of agroforestry.For example,straw and straw biochar are ideal soil amendments because they are rich in nutrients.It has been reported to have good soil improvement and recovery in agricultural production.However,straw and straw biochar are currently used for lower fertility.There are few reports on the improvement of soil red carbon mineralization and the effects on soil enzyme activity in southern red soil improvement.In view of this,this study selects typical soils in the south,uses hydrogen peroxide to reduce its organic carbon content,and simulates low-fertility southern red soils.The indoor constant temperature culture experiment is used to study corn stalk?S?and corn straw biochar?BC?.To study the changes of soil organic carbon mineralization,enzyme activity and soil properties under the influence of straw and its biochar in low-fertility red soil.The purpose of this study is to reveal the effects of straw and its biochar on the carbon sequestration capacity of low-fertility red soil in the south,and provide theoretical support for restoring the productivity and function of forestry soil ecosystem.The main findings are as follows:?1?When straw and its biochar are applied to low-fertility red soil,it is beneficial to soil organic carbon accumulation,increase the organic carbon mineralization rate of low-fertility red soil,and reduce the soil organic carbon accumulation mineralization rate.During the whole culture period,the accumulation of organic carbon and the rate of organic carbon mineralization were as follows:straw+biochar>straw>biochar>control.Compared with the control,the increase of organic carbon content in biochar treatment ranged from 261.90%to 428.57%,and the range of straw addition treatment ranged from304.76 to 495.24%.The more the amount of biochar applied,the more organic carbon content increased.The biochemical rate of biochar treatment was lower,and the cumulative mineralization rate of organic carbon in 5%BC treatment was 28.62%,which was significantly lower than other treatments.It indicated that straw and biochar had significant effects on the formation of organic carbon in low-fertility red soil.Due to the stability of biochar,its carbon sequestration effect on low-fertility soil was better than straw,which played an important role in soil carbon sequestration.?2?Straw and its biochar enhance the soil properties of low-fertility red soil.During the whole culture period,the pH of the soil could be rapidly improved.The pH of the CK control group was 6.8.On the 30th day of culture,the pH of each treatment ranged from7.4 to 7.7.The promotion effect of biochar on soil microbial biomass was significantly higher than that of straw,and the MBC content in 5%BC treatment was increased to54.796 mg·kg-1,and 47.96 mg·kg-1 in 1.5%S treatment.Compared with CK,MBN content in 5%BC treatment increased by 1.9 times,while that in 1.5%S decreased by 87%.With the increase of charcoal,the increase of NO₃^--N content increased,and the straw treatment significantly inhibited NO₃^--N.The effect of straw and its biochar on NH₄⁺-N was not significant,and the NH₄⁺-N content of each treatment was increased.Biochar promoted DOC more than straw and inhibited DON In conclusion,straw and biochar can reduce the acidification degree of soil and increase the main C and N nutrients in the soil,which has a better improvement effect on low-fertility soil.Compared with straw,biochar is more stable in nature,and the nutrients contained in it are not easily decomposed rapidly,which reduces the risk of erosion of the nutrients required by plants,and is conducive to the accumulation of soil nutrients and the improvement of fertility.?3?The effect of straw on soil enzyme activity is higher than that of biochar.In the early stage of culture?0³0 days?,biochar significantly promoted urease activity.Compared with CK,5%BC treatment increased by 182.52%,and the promotion effect was not as significant as straw;biochar significantly promoted sucrase activity,but the enzyme activity was much lower than that of the straw treatment.On the 180th day,the5%BC+1.5%S and 1.5%S treatment sucrase activities were 2.7 and 4 times,respectively,of the 5%BC treatment.Biochar has no significant effect on acid phosphatase,and straw can significantly increase acid phosphatase activity.The effect of biochar on catalase greatly.On day 360,biochar treatment of catalase activity is significantly inhibited.Compared with CK,5%BC treatment enzyme activity was reduced by 33%,while straw treatment significantly increased catalase activity,and 1.5%S treatment enzyme activity increased by 99%?P<0.05?.On the whole,the application of straw to low-fertility soils has a significantly higher effect on soil enzyme activity than biochar.In summary,straw and biochar are suitable for the improvement of low-fertility red soil in the south,and biochar has better improvement effect.On the one hand,both straw and biochar can rapidly increase the organic carbon content of low-fertility soil.Because biochar is more stable,it can reduce the mineralization of organic carbon,reduce the release of CO₂,and play a good role in carbon sequestration.On the other hand,straw and biochar can rapidly increase soil pH,which is conducive to solving the problem of widespread acidification of red soil in southern China.In terms of improving soil nutrition,biochar is stable in nature and has a special structure.It provides C,N and other nutrients for the soil while reducing the risk of erosion of soil C and N.Finally,both straw and biochar can affect soil microbial activity to varying degrees.Straw is easy to decompose,which is convenient for rapidly stimulating soil enzyme activity,and biochar is relatively stable.Straw and biochar are suitable for the improvement of low-fertilization red soil in the south,with remarkable effects and stable effects.This provides new ideas for further restoration of forestry soil ecology and promotion of intensive forestry economic development.At the same time,straw as agricultural waste will It is selected as a raw material for soil amendments,which enhances the effective use of resources and also protects the ecological environment.