The Ultimate Guide to Overseeding Cover Crops

As summer comes to an end, it is a good time to plan for overseeding cover crops. Fall-planted cover crops offer numerous benefits, including reducing soil erosion, improving soil health, and enhancing water quality during the non-growing months of the year. 

Overseeding involves planting cover crops into a standing corn or soybean crop before harvest. This can be done through aerial broadcasting or using high-clearance equipment. While various cover crop mixes can be used, cereal rye, winter wheat, and oats are commonly used species for overseeding. 

Benefits and Challenges: 

• Harvest Operations: Overseeding does not interfere with harvest operations, allowing for earlier cover crop planting and better chances of rainfall, which promotes fall biomass growth. 

• Seed Distribution: Aerial seeding may result in variable seed distribution. To address this, use uniform seed lots and heavier cereal grains like cereal rye and winter wheat. 

• Seed-to-Soil Contact: Poor seed-to-soil contact can hinder seed germination and stand establishment. Seeds may also be susceptible to predation by rodents and birds. 

• Seeding Rate: Overseeding typically requires slightly higher rates than drilled seeding. Recommended rates are 45 pounds per acre for cereal rye and 60 pounds per acre for oats. 

• Timing and Moisture: Complete overseeding applications by early September, assuming adequate soil moisture. Rainfall and soil moisture play vital roles in cover crop establishment. Ideally, overseeding should be done just before rainfall for optimal germination. Dry conditions may lead to delays in germination and less-than-ideal establishment. If possible, postpone overseeding until rain chances improve. Species with better overwintering ability, like cereal rye, can be beneficial in dry soil conditions. 

By considering these factors, farmers can make informed decisions when overseeding cover crops, maximizing the benefits and success of their fall planting endeavors.