Preparation And Performance Study Of Cotton Straw Biomass Carbon Slow Release Fertilizer

There are abundant biomass resources of cotton straw in Xinjiang,but the utilization of cotton straw is still relatively backward.At the same time,as a large agricultural province,Xinjiang applied a large amount of fertilizer,fertilizer utilization rate is low.Based on this background,this study designed related experiments to optimize the preparation conditions of cotton straw biomass carbon,explore the biomass carbon and fertilizer mixing granulation and coating fertilizer processing technology,and make correlation analysis on the influence of different factors on the slow-release performance of fertilizer,in order to provide a certain reference for the efficient utilization of cotton straw biomass resources and improve the utilization rate of fertilizer in Xinjiang.Relevant research conclusions are as follows:(1)In the optimization test of the preparation conditions of cotton straw biomass charcoal,the carbonization temperature was the most influential factor on the carbon yield,the relative surface area and iodine adsorption value was the particle size of the raw material,and the carbonization time had little influence on the carbon yield,specific surface area and iodine adsorption value.The carbon yield,specific surface area and iodine adsorption value of cotton straw under 0.15 mm screen were better than the other two levels.In the limited grinding time,the difference of grain size of cotton straw raw material will lead to the difference in composition,the difference of mechanical properties of different parts of cotton straw will lead to the redistribution of cotton bark,wood,cotton core and other components,and more cotton bark structure will be enriched under 0.15 mm sieve.The optimal carbon preparation scheme obtained by optimization test is to select cotton straw raw material under 0.15 mm sieve and carbonize it at 500℃ for 1h.(2)The performance of cassava starch was better than the other two kinds of starch in the two indexes of fertilizer formation rate and maximum fertilizer crushing pressure.When the binder concentration is 10%,better mechanical properties and higher fertilizer formation rate can be obtained.When the ratio of fertilizer to carbon was 2:1,the fertilizer formation effect and mechanical properties of the fertilizer were better.If the binder mass ratio is too low,it is not easy to form fertilizer.When the binder mass ratio exceeds 10%,the contribution to the fertilizer rate and mechanical properties of mixed granulation will be reduced,so it is better to choose 10% binder mass ratio.The optimal scheme of blending fertilizer production is to use cassava starch with binder concentration of 10%,in the condition of fertilizer-carbon ratio of 2:1,binder mass ratio of 10%.(3)In the study of the coating fertilizer process,the use of boric acid and polyvinyl alcohol crosslinking reaction can improve the water repellency and friction resistance of the coating fertilizer.In the range of test conditions,the higher the temperature,the more obvious the gain effect;In the process of coating fertilizer production,too high proportion of biochar has certain side effects on the water repellent ability and wear resistance of the coating.The concentration of polyvinyl alcohol film forming agent has weak influence on the water repellent ability and wear resistance of the film layer.In this test,the 5% concentration of polyvinyl alcohol has the best performance.The optimum scheme of coating fertilizer production was obtained under the conditions of 5% biomass carbon ratio,5% film forming agent concentration and 80℃ crosslinking reaction temperature.(4)In the performance test of slow-release fertilizer,the slow-release performance of biochar slow-release fertilizer prepared by mixing granulation and then coating was significantly improved,which could delay the peak release of fertilizer nutrients.Meanwhile,the fertilizer core made by mixing could also make up for nutrient loss caused by membrane damage.The time of good structure in water was about 3 days.Boric acid crosslinking improved the water repellent ability of polyvinyl alcohol film in wet environment,but could not prolong its life.After boric acid treatment,the chemical crosslinking and stable crystal structure of the fertilizer film have occurred,so its water resistance has been significantly improved,and the slow release performance of the fertilizer could be improved.