Effects Of Exogenous Organic Acids On Potassium Form And Availability In Reclaimed Soil Of Coal Mine

Potassium is one of the elements that are very important for plant growth and is an important indicator of soil fertility.Potassium enhances the resistance of plants to drought,cold,and pests and plays an important role in the soil ecosystem.The relatively low effective potassium content in reclaimed coal mine soils limits the rebuilding and restoration of mine ecosystems.The secretion of natural low molecular weight organic acids by plants during growth can activate potassium in the soil,increase soil nutrients,and promote plant growth.Therefore,to systematically describe the effects of exogenous organic acid addition on the potassium morphology and effectiveness of coal mine reclamation soils,this paper uses a typical fly ash-filled reclamation soil in Huainan,Anhui Province as the research object,and analyses the fugacity characteristics of low molecular weight organic acids by high-performance liquid chromatography,and screens out three dominant low molecular weight organic acids and finds out the optimal adsorption conditions.An indoor simulation culture was carried out under optimal adsorption conditions to study the effect and transformation of different forms of potassium in reclaimed soil and fly ash-compounded soil by the addition of exogenous organic acids,providing a scientific and theoretical basis for improving the potassium fertilizer content of the soil,which is of great significance for solving the problem of potassium nutrient deficiency in China’s agricultural production.The main research results are as follows:（1）The contents of organic matter,available potassium,available nitrogen and available phosphorus in reclaimed soil were significantly different in profile.With the increase of sampling depth,the contents of four nutrient indexes decreased.There were 8kinds of organic acids in reclaimed soil,but the content of organic acids was relatively low.In general,the content of organic acids in reclaimed soil showed a decreasing trend with the deepening of soil thickness,and oxalic acid was the main soil organic acid.According to the correlation between eight organic acids and soil available potassium,tartaric acid（C₄H₆O₆）,oxalic acid（H₂C₂O₄）and citric acid（C₆H₈O₇）were selected for research,and the relationship between these three organic acids and potassium in soil was deeply explored.（2）Using the adsorption capacity of the reclaimed soil for the three organic acids as the evaluation index,the effects of organic acid concentration,soil particle size,and ambient temperature on the adsorption capacity of the organic acids were investigated,and the optimal adsorption conditions were determined by single-factor and orthogonal experiments.The results showed that the optimum conditions for the adsorption of organic acids on reclaimed soils were:tartaric acid concentration of 15 mmol/L,soil particle size of 200 mesh and ambient temperature of 35°C;oxalic acid concentration of15 mmol/L,soil particle size of 200 mesh and ambient temperature of 40°C;citric acid concentration of 15 mmol/L,soil particle size of 200 mesh and ambient temperature of40°C.The maximum adsorption of citric acid was achieved at a concentration of 15mmol/L,a particle size of 100 mesh,and an ambient temperature of 35°C.（3）The addition of three organic acids increased the five forms of potassium in reclaimed soil to varying degrees.Among them,the ability to activate water-soluble potassium and non-specific adsorption potassium presents the following rule:citric acid>tartaric acid>oxalic acid;the law of the ability to activate special adsorbed potassium and available potassium is:tartaric acid>citric acid>oxalic acid;the ability to activate non-exchangeable potassium is:oxalic acid>tartaric acid>citric acid.With the addition of exogenous organic acids,tartaric acid had the best ability to increase the available potassium pool of potassium in reclaimed soil,with a conversion amount of 47.20 mg/kg and a conversion rate of 19.96%.（4）The five potassium forms of soil with different fly ash ratios were improved to varying degrees under the addition of three organic acids.When the proportion of fly ash was 5%,10%,15%and 20%,the effect of organic acid on the content of available potassium in soil was tartaric acid>citric acid>oxalic acid.Tartaric acid had the best ability to increase the effective potassium pool of potassium in the four fly ash ratio soils.Among them,under the action of tartaric acid,the maximum non-exchangeable potassium conversion amount of 5%fly ash soil was 60.10 mg/kg,and the maximum conversion rate was 33.42%.The results showed that compared with the non-exchangeable potassium conversion amount and conversion rate of reclaimed soil,under the same action of tartaric acid,the soil with 5%fly ash was more conducive to the transformation of potassium forms than reclaimed soil,indicating that under the dual factors of tartaric acid and 5%fly ash ratio soil,the transformation of soil potassium forms can be effectively improved.Figure[23]Table[22]Reference[103]...