September 25, 2014 - Issue 5

Aerial Seeding Cover Crops

Earlier planting is one of the main way growers can increase the benefits from growing cover crops.

Planting earlier gives the cover crop more days - with more heat units - before temperatures begin to cool, allowing for more growth of both above- and below-ground portions of the cover crop plants.

Waiting to seed cover crops until after full-season cash crops like corn and soybeans are harvested usually results in only a short time period for the cover crop to grow before temperatures begin to cool in the fall. Farmers who are serious about getting the most benefit from their cover crop may find it necessary to seed the cover crop into a standing cash crop before it's harvested.

There are a variety of methods for seeding cover crops into standing crops. Aerial seeding is one of the more common methods used, particularly when there are a large number of acres to be seeded. Like many other crop management practices, there are a number of details that can make or break the success of aerial seeding in establishing a cover crop.

PROS OF AERIAL SEEDING

Earlier cover crop seeding can make a huge difference in the ability of a cover crop to get adequate growth for the desired impact. For many areas, this time difference can be the difference between success and failure.

Establishment of cover crops without potential damage to standing crops is a benefit. Crops like corn may not stand straight at the end of the season, meaning that high clearance equipment can knock down standing crop, making harvest more difficult and reducing the amount of grain harvested.

No lost time away from normal harvest efforts, as aerial application is typically a contracted service. Many farmers, especially those who are just beginning to explore cover crops, this makes it a more attractive seeding option.

Large numbers of acres can be covered in a short time with aerial seeding. This is an advantage when there are large acres to be seeded in a tight time window, such as trying to seed on a field in front of a predicted rain, or in the early leaf drop period for soybeans.

CONS OF AERIAL SEEDING

Costs can be higher than other options due to the cost of the aerial application equipment.

Seeds will remain on the surface, which is usually not as effective for germination as when seed is placed in the soil - especially when soil at the surface is dry.

It may cost more to seed larger-seeded cover crops, since the volume of seed that must be handled and applied is greater. Smaller seeded cover crops, like grasses, are more prone to drift.

Areas around windmills, windbreaks or residential housing may not be suitable for seeding by fixed wing applicators.

Seed can be caught in some standing crops, like corn, and not make it to the soil surface.

Seed costs are generally higher with aerial seeding, too, since recommended seeding rates are typically higher in order make up for seed lost due to drift and being caught in the canopy of the growing crop.

SOME KEYS TO SUCCESS

Remember that cover crops plants need light and moisture to grow. When seeding into a standing crop, consider the seeding time in relation to the light availability. Seeds must be exposed to sunlight shortly after germinating. Aerially seeding into green canopy with no light penetration to the soil surface can dramatically decrease the odds of success.

Corn leaves should brown at the ear and below when seeding into crops like corn. The amount of canopy (soil shading) can vary depending on hybrids, row spacing and overall growth of the plants.

Seeding should not be done before the leaves begin to turn yellow for crops like soybeans. The idea is to get the cover crop seeds on the ground before soybean leaves drop off the plant, so the dead leaves will not interfere with the cover crop seed getting onto the soil surface, so seed germinates and then receives light after the leaves drop. If seeded into dense crop canopy with no light reaching the soil, the seed may germinate and die.

Soil moisture and rain forecasts are important factors affecting the success of aerial seeding. Seeding onto soils that are very dry with no rain in the forecast will dramatically decrease success, since seeds will not germinate until they can take up moisture.

The number of aerial applicators with experience seeding cover crops is limited in many parts of the U.S. This number is increasing, however. As with most things, working with an experienced service provider may help prevent some mistakes and increase the chances of success.