Green manure crop rotation cultivation method for northern severe coastal saline-alkali soil improvement

The invention provides an improved green manure crop rotation cultivation method for northern severe coastal saline-alkali soil, and relates to the technical field of agricultural planting. The method comprises the following steps: performing rotary tillage on a land in late spring and early summer, mechanically sowing sesbania, sowing carrots after the sesbania returns to the field, sowing triticale after the carrots return to the field, sowing sweet sorghum after the triticale returns to the field in the next year, sowing hairy vetch after the sweet sorghum returns to the field, and sowing corn after the hairy vetch returns to the field in the third year. According to the method, sesbania and hairy vetch are smashed and returned to the field in the full-bloom stage, carrots are smashed and returned to the field in the rhizome expansion stage, triticale is smashed and returned to the field in the later full-bloom stage or the early filling stage, and sweet sorghum is smashed and returned to the field in the