Effect Of Five Types Of Amendments On Improving Soil Fertility And Reducing Greenhouse Gas Emissions In Acidic Soils In Southern Hubei Province

Soil acidification is one of the major issues that harm the safety of agricultural ecosystems.The problem of soil acidification,which is caused by agricultural activities such as excessive nitrogen fertilizer application and continuous cropping,is becoming increasingly serious,resulting in a decrease in soil fertility and crop yield,as well as environmental problems such as agricultural non-point source pollution and increased greenhouse gas emissions.In recent years,the soil acidification in the southern part of Hubei province has severely affected crop yield and quality.Therefore,improving acidic soil with amendments has become a top priority,but there are differences in the response of acidic soils to different types of amendments and their effects on greenhouse gas emissions.Based on this,in this study,acidic farmland soil in the southern part of Hubei province was collected,and 5 amendment materials,including lime,dolomite,oyster shell,biochar,and potassium humate,were selected.2 application rates（low and high）were set,and a pot experiment was conducted to study the differences in the physical and chemical properties of the soil and the growth condition of pepper plants under the influence of the five amendment materials.The greenhouse gas emissions during the pepper growth cycle were measured,and the effects of different types of amendments and application rates on the improvement of acidic soils and the emission characteristics of N₂O and CO₂ were analyzed.The following conclusions were mainly reached:（1）Different types and application rates of amendments（lime,dolomite,oyster shells,biochar,potassium humate）significantly reduced soil acidity,and all increased the exchangeable Ca²⁺,Mg²⁺,Na⁺,K⁺and cation exchange capacity of the soil.Among these,the treatment with a high application rate of lime was found to be the most effective for soil acidity improvement,and its exchangeable salt base ions and cation exchange capacity were at a relatively high level.（2）The fertilization effect of two application rates of biochar and potassium humate was better,both significantly improving soil nutrient content.Compared with the CK treatment,during the experimental period,the organic matter,total nitrogen,total phosphorus,and total potassium content in the soil treated with two application rates of biochar and potassium humate increased by 4.74%-74.08%,9.68%-19.99%,6.40%-15.75%,and 11.43%-46.48%respectively.（3）All five types of amendments applied at different rates significantly increased the biomass,plant height,stem thickness,SPAD value of chlorophyll and content of TN,TP,and TK in pepper plants.Among them,applying a high rate of dolomite significantly increased plant height,stem thickness,and SPAD value of chlorophyll in pepper plants,while applying a high rate of lime and biochar significantly increased the biomass and nutrient content of TN,TP,and TK in pepper plants.（4）The application of different rates of five types of amendments had a significant effect on reducing N₂O emissions,among which the dolomite treatment at a low application rate had the best effect,reducing cumulative N₂O emissions by 82.68%compared to the CK treatment.However,the application of different rates of five types of amendments significantly increased soil CO₂ emissions.Among them,the CO₂ cumulative emission was the highest in the treatment with a high application rate of lime,which increased by 82.62%compared to the CK treatment.（5）To comprehensively evaluate the effects of different types and application rates of amendments on soil improvement,fertilization,and greenhouse gas reduction,relevant indicators were selected through principal component analysis and minimum data set method.Compared with the CK treatment,the results showed that the highest comprehensive evaluation score for improvement was the high application rate of dolomite treatment,followed by the high application rate of oyster shell treatment.In summary,each amendment has its own advantages in soil improvement,fertilization,and greenhouse gas reduction.After a comprehensive evaluation and analysis of the effects of each amendment on soil improvement,fertilization,and greenhouse gas reduction,this study recommends the application of dolomite or oyster shell at a high application rate of 8g·kg^-1 for improving acidic soil in the southern part of Hubei province.It has better effects on improving soil,fertilization,chili growth,and N₂O reduction in acidic soil in southern Hubei province.