Determining suitable vegetables for planting after spring wheat harvest in the Ningxia Yellow River Irrigation Area

Multiple cropping is important for improving land use and ensuring regional food security. Climate change in the Ningxia Yellow River Irrigation Area in recent years favors a multiple-cropping system. Thus, a hierarchical analysis (AHP) with three secondary indicators and twelve three-level indicators was used to determine the vegetable crops that could be planted after spring wheat harvest based on the climate. By doing so, a double-cropping system could be implemented in the Ningxia Yellow River Irrigation Area. In the irrigation area over the past ten years, the annual accumulated temperature ≥ 10 ℃ was 3407.9 ℃, the annual precipitation was 206.4 mm, and the annual evaporation was 1619.3 mm. These climatic conditions are sufficient for leaf and root vegetables cropping after spring wheat harvest. Compared with the theoretical production potential, the actual yield had room for improvement; the conditions were insufficient for fruit vegetable crops after spring wheat harvest. Among 17 vegetable species (varieties) planted after spring wheat, four had higher use efficiency (turnip, mantanghong, baby cabbage, and cucumber), four improved soil fertility (carrot, turnip, celery, and tomato), and four had higher economic benefits baby cabbage, turnip, mantanghong, and pepper (Jiaolong 7). AHP evaluation showed that eight vegetables were suitable for planting after spring wheat harvest based on their comprehensive benefits: baby cabbage, turnip (white turnip), turnip (mantanghong), pepper (Jiaolong 7), pepper (Yangdashuai), endive, celery, and squash (33.0%); they had 143.0%, 121.5%, 77.7%, 46.3%, 43.0%, 35.5%, 33.1% and 33.0% higher comprehensive benefits than kohlrabi. These eight vegetables can be widely cultivated across the area.