Study On Slow-release Effect Of Cotton Stalk Biochar On Organic Fertilizer

There are huge waste resources such as straw and manure in southern Xinjiang.In order to make reasonable and efficient use of waste resources,a biochar based organic fertilizer is designed to improve the slow-release effect of organic fertilizer.In this paper,the typical waste in Southern Xinjiang: cotton straw,walnut shell,date branches,corn stalks as raw materials to prepare biochar,explore the adsorption characteristics of different kinds of biochar differences.Using cotton stalk biochar as carrier and pig manure as raw material,cotton stalk biochar based organic fertilizer was prepared to explore the slow-release effect of cotton stalk biochar preparation process on organic fertilizer.Cotton stalk carbon was modified with acid and alkali reagent to explore the effect of modified cotton stalk carbon on slow release of organic fertilizer.Through soil column leaching simulation,the slow release effect of cottonstalk carbon based organic fertilizer in soil was verified.The specific research content and main conclusions of this paper are as follows:(1)Within the test range: the adsorption rates of methylene blue for the four kinds of biochar continued to increase with the increase of time.The effect of adsorption temperature on the adsorption rate of biochar was not stable,and corn stalk carbon and cotton stalk carbon could maintain stable adsorption effect between 25 ℃ and 35℃.Cotton stalk carbon and corn stalk carbon can maintain high adsorption effect in alkaline environment of p H5.5 ～ 9.5.The more biochar was added,the better the adsorption effect was.Among them,the adsorption rate of cotton stalk carbon and corn stalk carbon increased rapidly and the adsorption speed was faster.The adsorption process of methylene blue on biochar is mainly chemical adsorption,in which cotton stalk charcoal has good physical and chemical adsorption effect,and methylene blue is a comprehensive adsorption process in various ways.The adsorption of methylene blue on walnut shell carbon and cotton stalk carbon is monolayer molecular adsorption.The adsorption process of methylene blue on jujube and corn stalk charcoal is multi-layer molecular adsorption.Cottonstalk carbon showed good adsorption effect and was suitable for the preparation of biochar based organic fertilizer.(2)In the test range: with the decrease of particle size of cotton stalk carbon,the release amount of NITROGEN,phosphorus and potassium of cotton stalk carbon based organic fertilizer decreased gradually,and 80 mesh cotton stalk carbon had the best slow-release effect on organic fertilizer.With the increase of pyrolysis temperature,the release effect of nitrogen,phosphorus and potassium of cotton-stalk carbon based organic fertilizer decreased first and then increased,and the cotton-stalk carbon at 500℃ had the best slow-release effect on organic fertilizer.With the extension of carbonization time,the release effect of nitrogen,phosphorus and potassium of cottonstalk carbon based organic fertilizer decreased first and then increased,and 2h cottonstalk carbon had the best slow-release effect on organic fertilizer.With the increase of cotton stalk carbon content,the release of nitrogen,phosphorus and potassium of cotton stalk carbon based organic fertilizer decreased gradually,and 40% cotton stalk carbon had the best slow-release effect on organic fertilizer.Cotton stalk carbon content had the greatest influence on the slow-release effect of organic fertilizer,followed by cotton stalk carbon particle size,pyrolysis temperature and carbonization time.The cottonstalk carbon based organic fertilizer prepared with 40% cottonstalk carbon content,particle size of cottonstalk carbon of 80 mesh,pyrolysis temperature of 500℃ and carbonization time of 2h had the best sustained release effect.(3)Cotton stalk carbon modified by nitric acid,phosphoric acid and potassium hydroxide can further increase the slow-release effect of organic fertilizer nitrogen,phosphorus and potassium.The release of nitrogen,phosphorus and potassium of cotton stalk carbon based organic fertilizer prepared by the optimal scheme was significantly reduced when applied to soil.