Anaerobic fermentation of organic waste, such as livestock manure, in biogas projects is an environmentally friendly and effective treatment method. The resulting biogas, mainly composed of methane, is a combustible gas with energy properties, while the digestate, containing nutrients such as nitrogen (N), phosphorus (P), potassium (K), and other organic matter, can be used for agricultural irrigation. This article analyzes the current situation of resource utilization of livestock manure in various countries and the progress of biogas projects. It introduces the process, composition, and commonly used filtration methods before applying the digestate to farmland. The summary focuses on the improvement of crop quality, enhancement of soil fertility and the risks of pollution, and environmental hazards associated with the utilization of biogas slurry. The limitations and corresponding solutions for the agricultural utilization of livestock digestate are discussed, and recommendations are made for the technology of digestate irrigation and application to farmland.

Due to its rich nutritional composition, biogas slurry can serve as a special liquid fertilizer. However, the application of slurry in agricultural fields currently faces challenges such as reliance on skilled famers’ experience, low precision, and difficulty in accurately controlling the irrigation dosage. To address these issues, an agricultural biogas slurry mixing agricultural machinery and its system has been designed and developed with the aim of enhancing the precision and safety of slurry application. The structure of the device has been designed, filter components have been selected, and improvements have been made to the structure of traditional connectors. Taking into account factors such as soil and humidity, an algorithm based on biogas slurry conductivity for slurry mixing decisions and the feedback control mechanism has been designed. After assembling the prototype, experiments were conducted, and the results showed that after processing by the system, compared to the calculated theoretical optimum, the concentration error of each component in the mixed fertilizer was controlled within 10%, and the conductivity fluctuation range was within 5%. This indicates that the overall ratio accuracy and stability of the biogas slurry mixing system are high. The biogas slurry mixing agricultural machinery and its system provide a novel intelligent equipment solution for the precise application of slurry, effectively enhancing the accuracy and safety of slurry application, reducing the use of chemical fertilizers during agricultural irrigation, and minimizing pollution to the environment and soil.