Influence Of Cotton Stalk-char On PH And Ammonia Volatilization Of Xinjiang Cultivated Gray Desert Soil And Sandy Soil

Biochar is a kind of macromolecule stable carbon-bearing material which is decomposed from agricultural and forestry wastes or domestic garbage under high temperature and hypoxia conditions.Its composition is complex,its specific surface area is large,and it has strong adsorption performance.At the same time,p H is very high.Applying it to soil can improve soil porosity,water holding capacity,decrease soil bulk density and increase soil EC.Applying biochar to acidic soil,it can also reduce the acidity of soil by reducing the contents of exchangeable aluminum and hydrogen ions.At the same time,biochar contains a large amount of nitrogen,phosphorus,potassium and other nutrient elements,which can improve the nutrient availability and crop absorption by increasing the nutrient content in the soil.And biochar can affect soil microbial diversity to improve soil and increase crop yield and improve crop quality.In environmental improvement,biochar also has the potential to increase soil carbon sequestration and improve water quality and soil quality.In addition,biochar can also be used as a new clean energy source.The application of biochar to calcareous soils in northern Xinjiang of China can also improve soil properties through physical,chemical,biology and other aspects.However,the p H of calcareous soil was high,and the p H of biochar produced by carbonization of northern crops was about 10.In southern soils,biochar can provide soil p H,but the effect of biochar on soil p H is still to be studied in calcareous soil.If the p H of calcareous soil was increased by applying biochar,the mixed application of cotton stalk charcoal and nitrogen fertilizer would affect the volatilization of ammonia in the soil,thus affecting the availability of nitrogen fertilizer.In this study,cotton stalk-char was used as raw material,and two typical calcareous soils-irrigated grey desert soil and aeolian sandy soil,were used as the research objects.Firstly,the preparation of cotton stalk-char was explored from the basic properties of cotton stalk charcoal and the effect of chemical composition on p H.Secondly,the influence mechanism of cotton stalk carbon on soil p H was explored by indoor simulation experiment,and the consistency of simulation results was verified by pot experiment in laboratory.The effect of cotton stalk carbon application on calcareous soil p H was compared with that of field experiment after several years of outdoor application of cotton stalk carbon.Finally,the effect of different amount of cotton stalk carbon on soil ammonia volatilization was determined by closed absorption method.Through a series of experiments,the following conclusions are obtained:(1)Both carbonization temperature and carbonization time can affect the p H of biochar,and the p H of biochar can be increased by a long period of high temperature.And the p H of carbon prepared from cotton stalk under the same carbonization temperature and time is higher than that of the charcoal of grape branch.So the perparation condition of cotton stalk carbon is lower than that of grape branch.And the reason for the high p H of cotton stalk-char and grape branch-char is that it contains alarge amount of carbonate system and alkaline metal material.(2)The application of cotton stalk-char to calcareous soil in Xinjiang can increase the content of carbonate and alkaline metal in soil,they are hydrolyzed to OH~-to improve the soil p H.After short-term culture,calcium and other substances in biochar gradually dissolved in soil water,and then adsorbed with hydrosoluble potassium and sodium gradually,which increased the content of exchangeable potassium and sodium in soil.The exchangeable calcium content decreased,which made the soil p H fluctuate.However,after 120 days of experiment,the soil p H could not be reduced to it without cotton stalk-char treatment.(3)After planting maize on the basis of simulation experiment,the soil p H also increased after adding cotton stalk-char to irrigated grey desert soil and sandy soil.After 90 days of cultivation,soil p H fluctuation is reduced,but not reduced to not add soil.But in the field environment,the soil p H also decreased after applying cotton stalk charcoal,and after at least 3 years,the soil p H of cotton stalk-char application is lower than that of the soil without cotton stalk-char treatment.At the same time,when the carbon content of cotton stalk was higher than 2.0%,the p H of soil was lower than returning straw treatment.(4)The p H of biochar also affects its adsorption performance,and its electrostatic adsorption performance is mainly through the influence of its effective cation exchange capacity and potential cation exchange capacity.This is also one of the factors affecting soil ammonia volatilization by applying biochar.The calcareous soil could increase ammonia volatilization by increasing soil p H,reducing the electrostatic adsorption of ammonia and participating in soil nitrification after applying cotton stalk carbon to calcareous soil.