Changes Of Chemical Properties And Enzyme Activities During Vermicomposting Of Severa Organic Solid Wastes

With the goal of environmental friendliness,recycling organic solid wastes such as animal manures,municipal sludge,and mushroom residues can not only scientifically and rationally utilize nutrient resources,but also be crucial for sustainable economic development.And using earthworms to treat these organic solid wastes can reduce their environmental pollution,and also produce high-quality bio-organic fertilizers,which are in line with the national“double reduction”policy and are important for the recycling of resources and the sustainable development of agriculture.In this study,organic solid wastes such as cow dung,pig dung,sludge and mushroom residues were treated by the vermicomposting technology to analyze the changes of physicochemical properties during vermicomposting process of different combinations and different proportions of materials,and to investigate the heavy metal contents,enzyme activities and plant hormones before and after vermicomposting,the results showed that:?1?Vermicomposting reduced the pH of the materials and it tended to be neutral.The contents of organic matter were reduced,and the decomposition rates of the organic matter in all treatments were from 25.07%to 36.40%,which improved the stability of the materials.Vermicomposting increased the nutrient contents?TN,TP and TK?and its available nutrient contents?available nitrogen,available phosphorus,and available potassium?,and promoted the accumulation of nutrients in vermicompost,making a good land use value of vermicompost.Adding mushroom residues into cow dung,pig manure,and sludge could promote the further decomposition of organic matter and the accumulation of nutrient content.When the ratio of cow dung,pig manure and sludge to mushroom residues were 6:4,the increase in nutrient elements were the largest.In addition,the cow dung also had a good effect on the sludge,and the changes in the indicators of adding cow dung in the sludge were superior to the pure sludge treatment?SC4?.?2?As vermicomposting time went by,the heavy metal contents of the materials were increased because of the"concentration"effect,but the content of heavy metals in all products?vermicompost?did not exceed"organic fertilizer"?NY525-2012?.Adding mushroom residues into the cow dung,pig manure and sludge reduced the content of heavy metals in vermicompost,and the addition of cow dung in the sludge also could reduce the heavy metal contents,which is of great significance to the vermicompost as a bio-organic fertilizer application.?3?After 60 days of vermicomposting,the catalase activity increased,and the increase rates ranged from 2.24%to 14.97%.The catalase activity increased with the increase of mushroom residues.When the ratio of cow dung,pig manure and sludge to mushroom residues were 5:5,the maximum were achieved.Vermicomposting reduced urease,alkaline phosphatase and sucrase activities in the materials with varying degrees,and the corresponding decrease rates were 16.11%³2.63%,5.73%⁵1.16%and 16.80%⁶8.36%respectively,while addition of mushroom residues had a certain role in promoting the activities of urease,alkaline phosphatase and sucrose.And the activities of alkaline phosphatase,urease and sucrase increased first and then decreased as the proportion of mushroom residues,when the ratio of cow dung,pig manure and sludge to mushroom residues were 6:4,the three enzyme activities were the highest.In addition,adding cow dung had a good effect of sludge on promoting the enzyme activities,and catalase,phosphatase and sucrase activity increased with the increase of mushroom residues.?4?Vermicomposting increased the contents of tZ,GA₃,IAA,and ABA in all treatments,and the corresponding changes were 94.64%²09.09%,54.55%²35.71%,100.01%¹55.06%and 56.25%¹80.00%respectively.The content of each plant hormone in different material combinations was different,and the four plant hormones had the highest content in pure cow manure?CM4?vermicomposting product,and the lower content in vermicompost with pure sludge?SM4?.?5?Vermicomposting can convert organic solid wastes such as cow dung,pig manure,sludge and mushroom residues into relatively stable bio-organic fertilizers,and the addition of mushroom residues increase the decomposition rate of organic matter,which helps to increase the vermicomposting product quality.