We are now approaching the time of year to think about planting fall cover crops. Cover crops can serve many purposes, ranging from erosion control to nutrient sequestration. Depending on the type and species of cover crop, benefits range from providing a Nitrogen source, scavenging nutrients to decrease leaching potential, acting as a soil builder, preventing erosion, fighting weeds, acting as a forage, conserving soil moisture, and enhancing wildlife habitats.
Benefits of certain types of cover crops:
- Can be used as a Nitrogen source due to their ability to fix atmospheric nitrogen into the soil
- Many have good or excellent forage value, such as many clover species, alfalfa, and winter pea
- Many are good weed-fighters, such as turnips, oilseed radish, and mustards
- Many have good grazing and forage value, such as canola, turnips, and oilseed radish
- Good erosion fighter due to fibrous root systems
- Many have excellent grazing or forage value
- Good nutrient scavenger due to vast root system
Cover crops can be seeded in ways to fit any operation. They can be broadcast with or without shallow tillage, drilled, aerial-seeded, or frost-seeded. There are considerations for each seeding method, however. The chosen cover crop must have seeds small enough to fall into cracks formed as the frozen ground goes through freeze-thaw cycles to frost-seed. It is often advised for aerial seeding to increase the seeding rate due to the lower chance of achieving seed to soil contact. Cover Crop stands are usually more uniform after drilling or broadcast with incorporation compared with the other methods. Cover crops emerged sooner and in higher densities after drilling compared with broadcasting (Brenan, E. & Leap, J., 2014).
Timing when you plant your cover crop species is an important step, especially as we progress into late fall. Depending on whether the chosen species is winter-hardy or winter-killed can determine when it should be seeded. What type of crops you have grown or plan to grow in your operation type and the goals you want your cover crops to achieve can dictate the planting window.
When planning how much cover crop seed to purchase, it is important to understand the concept of Pure Live Seed. Seeding rate recommendations are reported as pounds of Pure Live Seed per acre, which is calculated as follows:
% Purity * % Germination = Pure Live Seed (PLS) Rate
If you have a 62.5% PLS Rate and need to seed 15 pounds PLS per acre, you will need 24 bulk pounds of seed per acre:
15/0.625 = 24
It is essential to understand that specific programs, such as EQIP or H2Ohio, may have requirements for rates or planting dates that must be met to receive your payment. Check with your local NRCS, Soil and Water Conservation District or FSA Office for information about programs you may be enrolled in.
It is also crucial to know how to terminate the cover crop you choose to plant. Some cover crops are winter-killed, but winter-hardy species may cause problems with the following season’s cash crop if they cannot be controlled or killed. Rogue cover crops can become weeds in your field and compete with your cash crop for nutrients, space, water, and light.