Sustainable Management of Biogas Slurry Discharge in Biogas Engineering: As a Chemical Fertilizer Substitute for Garlic Cultivation

Abstract

To address the persistent challenge of managing livestock and poultry manure resulting from agricultural intensification and mechanization, the application of biogas engineering has steadily expanded. Biogas slurry, a valuable byproduct abundant in nitrogen and other nutrients, emerges as an attractive alternative to chemical fertilizers. This study investigated the effects of substituting chemical fertilizers with biogas slurry at varying application rates on garlic growth and soil properties. The results indicate that with increasing application of biogas slurry, the promotion of garlic growth and soil nutrients exhibited an initial increase followed by a decrease. Notably, application of biogas slurry with nitrogen content equivalent to chemical fertilizers (G-1 group) gave the most pronounced promotion effect. In the G-1 group, garlic yield and soil organic matter content reached 1.06 kg/m³ and 40.6 g/kg, respectively, representing increases of 11.6% and 17.6%, respectively, compared to the chemical fertilizer group. Furthermore, after the application of biogas slurry, concentrations of both garlic and soil heavy metals remained within standard limits. Biogas slurry can be recommended as an effective substitute for chemical fertilizers, fostering garlic growth, boosting yields, enhancing soil organic matter content, and promoting biological carbon sequestration.