In the process of anaerobic dry fermentation to produce biogas, maintaining a suitable pH in the environment is more conducive to the degradation of crop straw. When the pH in the fermentation environment is too low, the process of anaerobic digestion by anaerobic bacteria is inhibited. Therefore, it is necessary to quickly adjust the pH. In this work, we studied the control technology of a pH regulation system and then constructed a T-S fuzzy controller. Upon simplifying the T-S fuzzy controller, the system delay time was reduced, and two genetic algorithms with different fitness performance indicators were used to optimize the T-S fuzzy control. The simulation experiment in this study was designed through simulation software, and the results show that the improved control method has a fast regulation ability. Finally, on-site experiments were conducted using the four control methods under the acidification conditions set in the experimental device. The results show that the control method used in this study to improve performance by integrating the error sum of squares has a short control time and small oscillation and overshoot, and it can better regulate the environmental pH to achieve appropriate conditions when acidification occurs during anaerobic dry fermentation.

The soil application of organic materials, such as biochar and organic fertilizers, serves as an important approach to maintaining soil nutrient cycling and enhancing soil quality. Here the effects of biochar and organic fertilizer application were comparatively analyzed relative to soil organic matter, NPK (nitrogen, phosphorus, potassium) content, and soil surface electrochemical properties. The primary factors influencing soil surface electrochemical properties were identified. It was found that application of two organic materials could increase the contents of total nutrients and available nutrients. Among all indicators, nitrate nitrogen showed the most significant increase, with T1 and T2 increasing by 34.2% and 75.7% compared to CK, respectively. The two organic materials enhanced soil surface charge quantity, specific surface area, and surface charge density. SOC and HS contents were identified as the top two influencing factors for changes in soil surface electrochemical properties. The explanation index of SOC reached 70.1% and 39.4% for T1 and T2, while those of HS were 20.3% and 31.2%, respectively. These efforts elucidated the impacts of the return of organic fertilizer and biochar to the field on soil surface electrochemical properties, which could provide data support for enhancing arable land quality and fostering healthy soil development.

Rural organic wastes are spatially dispersed across agricultural production areas and settlements, creating challenges for collection, treatment, nutrient recovery, and return to agricultural land. This study developed a township-scale spatial planning framework integrating waste quantification, centralized and decentralized composting, nutrient recovery, and techno-economic assessment in Beiyang Township, eastern China. Agricultural residues were allocated to five centralized composting reactors, whereas household kitchen waste was treated using decentralized bins. Machine-learning models estimated total carbon (TC) and total nitrogen (TN) retention under three composting-adoption scenarios. The defined study area was estimated to generate approximately 8745 t yr⁻¹ of rural organic waste, 82.8% of which originated from agricultural production. Under the high-adoption scenario, with 70% of agricultural waste and 75% of kitchen waste composted, retained TN was equivalent to approximately 27.9% of annual local crop N fertilizer demand on a total-N basis. Economic performance improved with increasing waste participation. Under the baseline scenario, four centralized reactors and the decentralized system were financially viable, whereas one reactor was non-viable. Under the moderate- and high-adoption scenarios, all configurations achieved positive NPVs and IRRs above the 10% benchmark rate. The framework supports coordination of rural organic-waste treatment, nutrient recycling, and sustainable agricultural land management at the township scale.