Optimization Of The Ratio Of Columnar Biochar-based Fertilizer And Its Performance

Biochar-based fertilizers coulld improve soil quality and fertilizer utilization.However,the traditional biocharbased fertilizers have problems,such as low strength and rapid nutrient release.Therefore,it is necessary to develop a new type of biochar-based fertilizers with high strength and stable slow-release properties.In this study,the columnar straw charcoal-based fertilizer was prepared by one-time molding using the mix of rice husk charcoal,binder,water and compound fertilizer as materials.The ratio of biochar to fertilizer was optimized by an orthogonal test,and then the nutrient slow-release performance of cylindrical straw biochar-based fertilizer was also investigated.Finally,the effect of cylindrical straw biochar-based fertilizer on the yield and quality of lettuce were evaluated through the pot experiments.The results showed that:(1)The ratio of biochar to fertilizer was the main factor of the nutrient content of cylindrical straw biocharbased fertilizer.Water had a significant effect on the molding,anti-breaking,and wear resistance of the fertilizer.The optimal ratio of the cylindrical straw biochar-based fertilizer was determined as the biochar to fertilizer ratio of1:4,water content of 5%,and binder content of 10%.Meanwhile,the nitrogen,phosphorus,and potassium content of the fertilizer were 12.13%,10.20%,and 14.02%,respectively.The maximum compressive strength and the bulk density ratio were 20 N and 98.53%,respectively,which met the industry standards for biochar-based fertilizers.(2)The column leaching and ammonia volatilization experiments were carried out to compare the nutrient leaching and ammonia volatilization characteristics between the traditional compound fertilizer and the cylindrical straw biochar-based fertilizer.The results showed that the nitrogen leaching rate of the cylindrical straw biocharbased fertilizer was lower in the early stage,the ammonia accumulation and volatilization was 38.9% lower than compound fertilizer,and the leaching levels of phosphorus and potassium were both lower than compound fertilizer as well.Therefore,the cylindrical straw biochar-based fertilizer not only has better slow-release performance but also has the ability to reduce emissions.The ammonia volatilization characteristics of cylindrical straw biocharbased fertilizer and compound fertilizer both conformed to the S-shaped model.(3)The application of cylindrical straw biochar-based fertilizer could increase the dry weight of lettuce’s aboveground and underground parts,and promote the accumulation of soluble sugar content and vitamin C content in lettuce.In summary,the cylindrical straw biochar-based fertilizer not only could help the slow-release,energy-saving and emission reduction but also could improve the yield and quality of vegetables,indicating a promising application prospect in agricultural production.