Rotating crops is a cornerstone of sustainable agriculture, and understanding what to plant before and after soybeans is crucial for maximizing yield and soil health. Soybeans, as a legume, have a unique role in crop rotation due to their ability to fix nitrogen, benefiting subsequent crops.

What Crops to Rotate With Soybeans?

Effective crop rotation with soybeans involves alternating them with non-legume crops, particularly cereals like corn, wheat, or barley. This practice helps manage pests, diseases, and nutrient levels in the soil. Following soybeans with a grass crop is highly beneficial for nutrient cycling and overall farm productivity.

Why is Crop Rotation Important for Soybeans?

Crop rotation is more than just a farming tradition; it’s a science-backed strategy. It helps break pest and disease cycles that can build up when the same crop is grown repeatedly in the same field. This reduced pest pressure can lead to fewer pesticide applications.

Furthermore, different crops have varying nutrient needs and root structures. Rotating them allows the soil to recover and replenish essential nutrients. For instance, soybeans are nitrogen-fixing legumes. They pull nitrogen from the air and convert it into a form that plants can use, enriching the soil for the next crop.

Benefits of Strategic Soybean Rotation

• Improved Soil Fertility: Legumes like soybeans add nitrogen to the soil.
• Pest and Disease Management: Breaks life cycles of soil-borne pathogens and insects.
• Weed Control: Different crop types can outcompete different weeds.
• Enhanced Soil Structure: Varied root systems improve aeration and water infiltration.
• Reduced Erosion: Cover crops planted in rotation can protect the soil.

Best Crops to Plant Before Soybeans

When planning your rotation, consider what crops will leave the soil in the best condition for soybeans. The goal is to provide a nutrient-rich environment and minimize any lingering issues from the previous crop.

Cereals as a Pre-Soybean Crop

Cereal grains such as corn, wheat, and barley are excellent choices to precede soybeans. These crops are not legumes, so they don’t compete for nitrogen in the same way. In fact, they can help deplete excess nitrogen in the soil, which is beneficial as soybeans will fix their own.

Corn, in particular, is a popular choice. After harvesting corn, the remaining stover (stalks and leaves) can provide organic matter. Wheat is another common option, often planted in the fall before soybeans are sown the following spring. This allows for a two-crop system within a year.

Other Considerations for Pre-Soybean Crops

While cereals are primary, other crops can also fit into a rotation before soybeans. Canola can be a good option, as it is a different plant family and has different pest and disease profiles. Even a year of fallow (leaving the land unplanted) can be used, though this is less common in modern, intensive farming due to lost potential revenue.

Best Crops to Plant After Soybeans

This is where the nitrogen-fixing ability of soybeans truly shines. Planting a crop that requires a good amount of nitrogen after soybeans can take advantage of the residual nitrogen left in the soil.

Corn: The Classic Follow-Up Crop

Corn is arguably the most common and beneficial crop to plant after soybeans. Corn is a heavy feeder, especially of nitrogen. The nitrogen fixed by the soybeans in the previous season is readily available for the corn, potentially reducing the need for synthetic nitrogen fertilizer.

This corn-soybean rotation is a widely adopted practice in many agricultural regions. It creates a simple yet effective two-year cycle that supports soil health and economic viability. The contrasting root structures and nutrient demands of corn and soybeans help maintain a balanced soil ecosystem.

Small Grains and Other Options

Wheat and barley are also excellent choices to follow soybeans. They benefit from the residual nitrogen and have different growth habits than soybeans, further diversifying the rotation. Planting winter wheat after soybeans is a common strategy, with the wheat overwintering and being harvested the following summer.

Other crops like alfalfa or clover can also be planted after soybeans, especially in systems focused on hay or pasture. These forages are also legumes, but their deep root systems can improve soil structure and their nitrogen-fixing capabilities can further enhance soil fertility over a longer period.

Managing Pests and Diseases in Soybean Rotation

One of the most significant advantages of rotating crops with soybeans is managing pests and diseases. Certain pests and diseases are specific to soybean plants. If soybeans are planted year after year in the same field (monoculture), these issues can become severe.

By rotating with a different crop, such as corn or wheat, you break the life cycle of many soybean-specific pests and pathogens. For example, soybean cyst nematode (SCN) is a major pest that can build up in the soil. Planting a non-host crop like corn for a few years can significantly reduce SCN populations.

Common Pests and Diseases Managed by Rotation

• Soybean Cyst Nematode (SCN): Reduced by non-host crops like corn and wheat.
• Fungal Diseases: Such as sudden death syndrome (SDS) and white mold, are less likely to thrive.
• Insect Pests: Such as soybean aphid, have their life cycles disrupted.

Soil Health and Nutrient Management in Rotation

Crop rotation is fundamentally about improving soil health. Soybeans, as mentioned, are nitrogen fixers. This means they can reduce the amount of nitrogen fertilizer needed for the subsequent crop, leading to cost savings and environmental benefits.

Beyond nitrogen, different crops utilize other nutrients like phosphorus and potassium at varying rates. A diverse rotation ensures that these nutrients are not depleted unevenly. The varied root systems also contribute to better soil structure, improving water infiltration and reducing compaction.

The Role of Cover Crops

Incorporating cover crops into your soybean rotation can offer even more benefits. Cover crops are planted primarily to manage soil erosion, improve soil fertility, and increase biodiversity. Planting a cover crop after harvesting soybeans, or before planting soybeans, can further enhance soil health.

Examples of cover crops suitable for rotation with soybeans include rye, vetch, or clover. These crops can provide ground cover during off-seasons, suppress weeds, and add organic matter to the soil when tilled in or left as mulch.

Putting it All Together: A Sample Soybean Rotation

Here’s a simplified example of a common and effective soybean rotation: