Reuse of agricultural waste: classification, approaches, challenges, and improvement strategies

In recent years, the rapid development of modern agriculture in China has resulted in a large amount of Agricultural Waste not being properly utilized while increasing the output of agricultural products. This has seriously constrained the development of China's circular economy in agriculture. Realizing the resource utilization of agricultural waste can help promote the construction of new rural areas in China and effectively alleviate the current energy shortage problem. Therefore, promoting the resource utilization of agricultural waste is of great significance.

1、 Classification of agricultural waste
Agricultural waste refers to the general term for waste generated from agricultural production, agricultural product processing, livestock and poultry breeding, and rural residents' daily life. According to different standards, there are different classification methods, mainly based on source, maturity level, and nutritional richness. （1） Classification of agricultural waste by source mainly includes two types: agricultural waste and livestock waste. Agricultural waste such as corn stalks, wheat stalks, peanut stalks and shells, and defective fruits and vegetables; The waste from animal husbandry mainly includes the feces of livestock and poultry. （2） Agricultural waste can be classified into three categories based on the degree of maturity: highly perishable, easily perishable, and non perishable. Highly perishable types such as chicken manure, sheep manure, pig manure, cow manure, etc; Easy to mature crops such as rice straw and rapeseed straw; Non perishable items such as corn stover. （3） Agricultural waste can be classified into four categories based on nutrient richness: high nutrient, medium nutrient, low nutrient, and low nutrient. Nutrients such as chicken manure and quail manure are relatively high; Nutrients are moderate, such as sheep manure, cow manure, etc; Nutrients such as rice straw and wheat straw are low; Nutrients such as corn stover are low.
2、 Resource utilization of agricultural waste
At present, there are various ways to utilize agricultural waste resources, including fertilizer utilization, energy utilization, base material utilization, material utilization, and feed utilization. （1） There are two methods of fertilizer utilization: direct method and indirect method. The direct method refers to directly burying agricultural waste in fields, using microorganisms in the soil to release nutrients from agricultural waste, and has the advantages of simple utilization and low labor costs. But there may also be problems such as pests and diseases, and continuous cropping obstacles. Indirect method refers to processing waste through one or more treatment methods before returning it to the field for reuse. The indirect method can not only obtain fertilizers for returning farmland, but also obtain energy substances such as hydrogen and biogas. （2） The energy utilization of agricultural waste mainly includes two methods: anaerobic fermentation and direct combustion pyrolysis. Establishing biogas digesters and utilizing microorganisms to produce biogas from agricultural waste is an early and widely used anaerobic fermentation treatment method. However, due to its low utilization rate, the promotion of this method is limited. In terms of fermentation treatment, hydrogen production treatment of agricultural waste has gradually become a research hotspot. China has made significant achievements in direct combustion pyrolysis. Currently, there are over 300 agricultural waste direct combustion pyrolysis power generation projects in operation or under construction, with an annual processing capacity of nearly 1 0 × 108 t. (III) Basic material utilization of agricultural waste. Basic material utilization is mainly used for cultivating and utilizing various fungi and mushrooms. For example, using fermented fallen leaves of trees to cultivate shiitake mushrooms, the average fresh mushroom yield is 3  5-4.  5 kg /m2； The yield of Yuhuang mushroom increased by 1.5 kg/m2. （4） The material utilization of agricultural waste has a huge output, low price, and wide sources, and can be used as raw materials for the production of various industrial products. Such as plant fiberboard, biodegradable tableware, foam cushioning materials, and can also be used to produce cellulose films and insulation materials. For example, using corn stover fiber, waste paper fiber, and gas-phase corrosion inhibitors as raw materials, and adding appropriate amounts of film-forming agents, adhesives, and other substances, corn stover fiber corrosion buffering packaging materials were successfully manufactured by microwave foaming. （5） The feed utilization of agricultural waste resources in China mainly includes green storage feed, ammoniated feed, protein feed, and animal manure feed. Research has shown that adding Aspergillus oryzae and Geotrichum candidum to fresh chicken manure and bran, and adding urea as a nitrogen source for solid-state fermentation, resulted in a 20% increase in crude protein and amino nitrogen content, respectively 70%, 19 74%. Using it as feed can increase the daily weight gain of pigs by 10% 83%.
3、 Problems in the Resource Utilization of Agricultural Waste
（1） The awareness of agricultural waste resource utilization is backward. Due to the incomplete publicity system for the reuse of agricultural waste, the resource utilization of agricultural waste has not been well known by the majority of farmers in China. Moreover, farmers lack awareness of the reuse of agricultural waste, have insufficient understanding of the significance of efficient utilization of agricultural waste, and lack awareness of the collection and utilization of agricultural waste. （2） The processing technology is not perfect, and the resource utilization rate is low. Currently, the utilization rate of biomass fuels that have been formed in China is only 20%. The main utilization method is fertilizer returning to the field, and some rural areas use burning to treat crop straw, causing serious environmental pollution and resource waste. The main method for treating livestock waste is still returning it to the field, but due to the high content of pests and diseases in feces, if not treated harmlessly, it can also cause pollution. （3） The commercialization level of agricultural waste treatment is low, and the economic benefits are poor. Agricultural waste itself has low economic value, and only through high value-added treatment can the economic value of agricultural waste be reflected. At present, the economic benefits achieved by China in the treatment of agricultural waste are not ideal. This makes it difficult for companies and enterprises involved in the treatment of agricultural waste to expand their production, resulting in significant obstacles to the resource utilization of agricultural waste.
4、 Measures for Resource Utilization of Agricultural Waste
（1） Guide and enhance farmers' awareness of the resource utilization of agricultural waste. Farmers are the main body of agricultural production, and their insufficient awareness of the resource utilization of agricultural waste will seriously hinder the process of resource utilization of agricultural waste. Relevant departments can improve the publicity system through new media such as radio and television, or by hanging slogans, banners, etc., or establish demonstration zones for the utilization of agricultural waste and promote them to raise farmers' awareness of agricultural waste and promote their awareness of the resource utilization of agricultural waste. （2） Relevant departments should strengthen their attention to the resource utilization of agricultural waste and improve the legal system by strengthening legislation and introducing relevant laws and regulations. Relevant departments should strengthen the investigation of the utilization of local agricultural waste, formulate regulations and policies that are in line with the local development status, reward achievements in the rational use of agricultural waste, and punish improper disposal methods. （3） Advanced scientific and technological advancements in the utilization of agricultural waste are the supporting means for improving the efficiency of agricultural waste utilization. Relevant departments should actively introduce high-quality talents in related fields, encourage relevant enterprises to independently conduct scientific and technological research and development, and promote the updating and iteration of agricultural waste utilization technology. Or organize technical training courses and invite experts and scholars to enter the fields to provide relevant technical and knowledge training to farmers. Universities and research institutions should continue to conduct technological research on the resource utilization of agricultural waste, further optimize and update treatment technologies, and accelerate the industrial production process of various research results, transforming scientific research into production technologies. （4） To enhance the commercialization of agricultural waste and improve its economic benefits, relevant departments can increase subsidies for the resource utilization of agricultural waste, provide financial subsidies to farmers and related enterprises who actively utilize agricultural waste, and increase the profits of agricultural waste utilization enterprises by reducing their production costs. On the basis of relevant research, it is also possible to actively promote products obtained from agricultural waste treatment according to local development conditions, gradually open up the market for agricultural waste reuse products, and improve the sales profits of agricultural waste utilization enterprises.