When soybean markets take a dive or remain consistently low, growing more corn sounds more appealing. If you’re considering increasing corn acres by way of continuous corn, keep the following management tips in mind.
Yield impact. Without well-thought-out management, yield reductions can often be as high as 20 to 30 bushels per acre compared with a corn soybean rotation. This reduction is commonly referred to as continuous corn yield penalty (CCYP).
Residue management. Yield drag in continuous corn is more pronounced in cooler and wetter soils. Further, there is an increased risk of disease and allelopathy. The common link to each of these factors: corn residue.
Accumulated corn residue can reduce soil temperatures and reduce nitrogen (N) availability, increase soil moisture and promote survival of insects and diseases. Here are a few ways to help minimize residue challenges:
- Consider selecting well-drained, highly productive soils for continuous corn
- Try to make sure that corn residue is evenly distributed across the field.
- Use tillage to help the residue breakdown from a disease and pest standpoint. This also helps to warm up soils faster in the spring.
- Use row cleaners at planting. This facilitates better seed-to-soil contact to improve stand establishment.
Additional inputs will likely be required. Applying N at multiples times throughout the growing season, including at preplant and sidedress, can help increase nitrogen use efficiency. It’s increasingly important to monitor phosphorus (P) and potassium (K) levels on continuous corn acres, too. Plentiful P and K early in the season helps promote stand establishment and minimize problems with stalk strength and stalk rot as corn plants mature.
In addition to nutrient management, farmers can expect an increase in insect and disease pressure on continuous corn acres. Seed and seedling pathogens and soil pests such as wireworms, seed corn maggots and grubs pose the biggest threat early on, particularly when residue from the previous year’s crop is prevalent.
Corn rootworm, if not properly managed, is another challenge in continuous corn. Planting corn with Bt traits effective against corn rootworm larvae is a good strategy, along with use of a soil-applied insecticide in particularly high-pressure scenarios.
Herbicide limitations. Herbicide options are limited on continuous corn acres. Excess residue can reduce the efficacy of soil-applied herbicides and shield small weeds from contact herbicide applications. Lodged plants and eardrop from the previous year’s harvest increases the potential for volunteer corn, making volunteer corn control especially problematic. Since herbicide options are limited, the only effective management approach may be cultivation.
Hybrid selection. Don’t underestimate the importance of selecting the right hybrids. Choosing hybrids with good plant health is critical for continuous corn, and you should aim to not plant the same hybrid on the same acres two years in a row. In a best-case scenario, select a hybrid with no relation to the one previously grown.