Organic Sweet Corn Performance in Clover Systems

By Scout Nelson

Research conducted by South Dakota State University at the SDSU Southeast Research Farm examines how organic sweet corn performs when grown with clover living mulch systems under changing weather conditions.

Sweet corn is a warm season crop that prefers warm soil and well drained conditions. In South Dakota, spring weather is often unpredictable, with sudden cold snaps or heavy rainfall. These conditions can strongly affect crop emergence and early growth, making sweet corn production challenging for organic farmers.

The study took place during 2024 and 2025 growing seasons in a USDA certified organic field. Researchers compare sweet corn grown with three clover living mulch systems to a bare ground control. Living mulch is a cover crop grown alongside the main crop. The clover types include white clover, kura clover, and red clover. The clover plots are planted two years before sweet corn. All treatments are strip-tilled to allow direct seeding. Sweet corn is planted in mid-May and harvested in early August each year.

Weather plays a major role in crop performance. In 2024, heavy rainfall occurs after planting but does not cause major delays. In 2025, a late spring cold period slows sweet corn emergence. During this time, clover grows faster than the crop, creating early competition that affects plant height and yield.

Clover type also influences results. Red clover causes the most challenges and produces the lowest number of marketable ears in both years. After mowing, red clover does not recover well and weeds become dominant. White clover and kura clover perform better in wet conditions, and spread through stolons, and rhizomes, helping suppress weeds later in the season.

Yield results show that bare ground systems produce the highest quality sweet corn in both years. In 2024, the total marketable yield is similar across treatments. In 2025, clover systems produce much lower marketable yields than bare ground.

The study shows that living mulch systems can improve weed control but also increase production risks. Farmers should consider strong planting beds and proper early season fertility before adopting these systems.

Photo Credit: gettyimages-oticki