Generally, planting crops in monoculture is not recommended. There are many benefits to crop rotation including improved nutrient cycling, soil tilth, weed control, disease suppression and increased yield potential. This is true for any crop including wheat.
However, sometimes weather patterns create situations where a farmer may want to plant wheat after wheat. Such is the case when weather delays soybean planting and harvesting.
About two-thirds of the wheat planted in Michigan follows soybeans. In 2019, soybean planting was delayed or prevented on many farms across the state. Many farmers who did get soybeans planted, planted late, thereby delaying harvest and missing the optimum wheat planting time in the fall. This is a case where planting wheat on wheat ground that was harvested in July is considered.
Planting wheat after wheat can be successful, but there are some factors that need some consideration before planting the second wheat crop.
Many farmers plant wheat no-till, which provides many benefits. However, wheat residue on the surface is a harbor for several wheat diseases including fusarium and Septoria. In a normal crop rotation, there is less risk of these diseases as the residue has degraded.
No-till farmers may want to consider some level of tillage to incorporate/bury wheat residue to prior to planting wheat. This will help reduce potential disease inoculum.
2. Variety selection
Select varieties with disease resistance. Utilize the Michigan State University Wheat Performance Trials as well as ratings from seed companies, agronomists and any other place you can find disease ratings. While fungicides can help protect from diseases, planting resistant varieties in combination with fungicides provides the best control, especially when planting wheat after wheat.
3. Certified seed
Purchase certified seed from a reputable seed dealer. While hiring a contractor to clean and treat seed on your farm may save you money in the short run, purchasing seed that has been run over a gravity table will provide the best uniformity in germination and emergence.
Seedling diseases such as Pythium, rhizoctonia and fusarium can reduce stands significantly. Planting healthy, disease-free seed that has been treated with a fungicide will be more important when planting wheat after wheat.
Earlier in this article, planting disease-resistant varieties was discussed. There are no completely resistant varieties to any of the diseases that affect wheat. Fungicides are necessary to protect yield potential. Fusarium head blight (head scab) is the most economically damaging disease in wheat.
Dockage or even rejected loads for high vomitoxin levels are very discouraging to farmers. When planting wheat after wheat, plan to apply at least one fungicide application at Feekes 9 (flag leaf fully emerged) or Feekes 10.5.1 (anthesis).
5. Cover crops
Planting wheat after wheat provides a great opportunity to plant a cover crop ahead of planting as well as after harvest. Cover crops provide many benefits to the cropping system including nutrient cycling, protection from soil erosion and building soil quality. There are many options for cover crops.
6. Weed control
There are several weed species that invade wheat that need to be considered, including common windgrass and roughstalk bluegrass. Scout your fields to ensure you know what weed pressures you have. When planting wheat after wheat, pay particular attention to controlling these weeds.
7. Straw removal
Wheat straw is becoming more and more important for bedding and a fiber source for dairy farms in Michigan. Wheat straw removes 13 pounds of nitrogen, 3.3 pounds of phosphorus and 23 pounds of potassium per ton of straw.
Make sure your fertility program takes this into account when making fertilizer recommendations for succeeding crops. Straw also supplies organic matter back to the soil. If removing straw, apply manure or use cover crops if possible to continue building soil organic matter.