Study On The Effect Of Selective Removal Of Corn Straw Components Combined With Biochar To Assist Composting

The development of agriculture and animal husbandry has produced a large amount of organic waste while meeting people’s demand for agricultural and livestock products in China.Cow manure and corn straw are among the major agricultural wastes,and their random piling and burning can cause serious damage to soil and air.How to utilize these organic wastes is a problem that needs to be solved.Composting is a major means to produce organic fertilizer directly from corn straw and cattle manure,which is important for the treatment of agricultural waste.However,due to the lignocellulosic structure,composting using straw usually results in slow composting speed,low quality and poor fertilization efficiency.How to efficiently use corn straw with cow manure to improve compost quality still needs further research.In this study,the feasibility of solid-state fermentation after pretreatment was verified by selecting different alkalis or acids for pretreatment to selectively remove lignin or hemicellulose from the corn straw and adding bacterial agents.Then,the corn straw with different components removed was co-composted with cow manure,and biochar was added to improve the composting effect,and its effects on physicochemical properties and changes in humification and microbial bacterial flora were investigated,and finally,pot tests were conducted to verify the fertilization efficiency of organic fertilizers.The main conclusions were as follows:(1)The pretreatment of corn straw with 2% Na OH and 2% HCl had the best effect,and the degradation rate of corn straw increased by 162.55% and 150.43% after pretreatment,respectively.The effects of 2% Na OH and 2% HCl pretreatment on the surface structure and chemical bonding of corn straw were verified.(2)The best composting effect was achieved in the corn straw treatment group with the addition of biochar and selective lignin removal,with a maximum temperature of 66.6°C,p H at6.46,C/N ratio of 15.25 at the end of composting,seed germination index of 106.6%,total nitrogen,total phosphorus and total potassium contents of 1.94%,1.00% and 1.46%,respectively,the cellulose and hemicellulose degradation rates were 46.47% and 45.20%,and the related enzyme activities(CMCase,Xylanase)were the highest at 350.53 U/g and 167.46U/g,and the FA/HA ratio was 1.52.The correlation analysis showed that TN,HA,GI and p H were negatively correlated with lignocellulose content,and FA and TOC were positively correlated with lignocellulose content.(3)The addition of biochar and selective removal of lignin/hemicellulose from corn straw significantly increased the abundance and diversity of microorganisms in the high-temperature and decaying stages of composting;Firmicutes,Thermobifida and Pseudo Xanthomonas were the dominant phyla in the high-temperature stage.The redundancy analysis showed that p H,TOC,and TOC were the dominant phylum.Redundancy analysis showed that six factors,p H,TOC,TN,GI,FA and HA,were the main environmental factors affecting bacterial community succession.(4)The addition of organic fertilizers alleviated soil acidification and increased the content of fast-acting nutrients such as soil organic carbon,total nitrogen,alkaline nitrogen,fast-acting potassium and fast-acting phosphorus;among them,the treatment group T3 with CB+AC1organic fertilizer improved crop growth,increasing corn plant height to 162.33 cm,straw thickness to 2.63 cm,and total nitrogen,total phosphorus,total potassium and organic carbon content compared to the CK treatment group.The total N,P,K and organic C contents increased by 45.0%,72.0%,60.0% and 50.4%,respectively,compared to the CK treatment group,and promoted crop growth.