Sunflowers in crop rotation boost corn yields by 35% during drought

Including sunflowers in a diversified crop rotation can improve soil health and significantly increase corn yield stability under dry conditions. This is according to a 26-year USDA-ARS study in South Dakota comparing a traditional corn-soybean rotation with a four-year corn-soybean-spring wheat-sunflower rotation under no-till conditions.

In years with adequate rainfall, researchers found no significant difference in corn yields between the two systems. However, when rainfall was limited during the growing season, corn yields in the four-year rotation were about 35% higher on average than in the traditional corn-soybean rotation.

Researchers link the effect partly to improved soil properties following sunflowers. The study found greater microbial activity, better soil aggregation, improved water infiltration and storage, and reduced erosion. Corn grown after sunflowers also had more mycorrhizal fungi associated with its roots, helping plants access water and nutrients.

Adding sunflowers to the rotation did not reduce economic performance. A separate economic analysis found that the four-year rotation was just as profitable as the corn-soybean system. Researchers also noted that sunflowers require lower spending on seed and fertilizer compared with corn.

Additional benefits were recorded when cover crops were incorporated into the sunflower system. Nectar sugar concentration increased by around 28%, adult bee abundance by 74%, and the number of bee species by 33%. At the same time, the mass of sunflower seeds produced increased by around 36%.

Tags: sunseed, crop rotation, weather conditions, corn, drought