Biochar-based slow-release nitrogen fertilizer and preparation method thereof

The invention discloses a biochar-based slow-release nitrogen fertilizer. The biochar-based slow-release nitrogen fertilizer comprises the following raw materials in parts by weight: 75-90 parts of biomass, 42-65 parts of ammonium nitrate, 4-8 parts of zeolite powder, 12-17 parts of humic acid, 5-10 parts of attapulgite, 0.5-1.5 parts of microelements and 0.1-0.4 part of compound amino acid, wherein the microelements comprises zinc, boron, manganese, molybdenum, iron and copper. The invention further discloses a preparation method of the nitrogen fertilizer. Ammonium nitrate is molten in the porous structure of biochar, and zeolite powder, humic acid, attapulgite, microelements and compound amino acid are used together to reduce leaching loss and environmental pollution of the biochar-based slow-release nitrogen fertilizer; owing to a biochar carrier, release of ammonium nitrate is slowed down, the nutrition validity is prolonged, nutritional loss is reduced, and the nutrition utilization ratio of the fertili