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Getting ready for cover crops after corn silage

Sjoerd Duiker Published on 15 August 2013

Football isn't the only fall activity with field goals. After silage harvest, cover crops just make a lot of sense. They can:

1. Help reduce erosion by intercepting the impact of raindrops on the bare soil surface, slowing down the velocity of runoff, and improve soil aggregation – which makes soil less erodible

2. Take up nutrients from the soil, protecting these nutrients from leaching losses over the winter and transforming them so they become available to the next crop

3. Improve soil structure because growing roots penetrate dense layers and break up tight soil, fine roots and root-associated fungi improve soil aggregation, and root exudates feed organisms active in the soil structure formation process

4. Increase organic matter by adding roots and above-ground crop residue, which are the foundation for humus formation

5. Suppress weeds, especially winter annuals

6. Supply livestock feed either for over-winter grazing or harvest in fall or spring

Right now is the time to get ready by making sure you have the seed in store and the drill in shape for no-till planting of the cover crops after corn silage.

It is recommended to have a tractor, operator, drill and seed ready at corn-silage harvest to enable the drill to follow the silage harvester; we have learned that timing is everything when it comes to cover crops.

A lag of two weeks can make a huge difference in cover crop growth in our Pennsylvania climate. Since 2010, we have tried and demonstrated many different cover crops after corn silage on Pennsylvania dairy farms.

Here are some of the solos or mixtures we've tried:

Cereal rye
This is really our tried-and-true crop that is virtually fireproof. It can be established in all of Pennsylvania after corn-silage harvest, even into late October, and still successfully survive the winter.

It can produce very good silage in the spring as long as it is harvested at the right time, which can be challenging if the weather doesn't collaborate. If harvested after soft-dough stage, the feed quality declines rapidly.

Seeding rate should be approximately 112 pounds per acre (2 bu per acre). Aroostock proved a very winter hardy and high-biomass variety, while Huron was a variety that produced less biomass but with a wider window for high-quality harvesting in the spring.

Rye and oat mix (84 pounds or 1.5 bu per acre rye and 70 pounds or 2.5 bu per acre oats)
This mix proved to be a high fall and spring biomass producer. In the southern parts of our state, a lower rate of rye might be combined with a higher rate of oats for high-quality and tonnage forage production in the fall.

For high production, it is important to plant this mix immediately after August silage harvest. The rye guarantees living cover in the spring.

Annual ryegrass and crimson clover (10 pounds per acre and 15 pounds per acre, respectively)
This has become a very popular mixture for high-quality forage production in the spring. Because it includes a legume, it does not need high rates of manure application to flourish – the legume supplies N to the ryegrass.

It is very important to select winter-hardy varieties of ryegrass and crimson clover for our environment and to plant as early as you can after silage harvest. If the cover grows taller than 8 inches before December, it is advisable to mow it off (3 to 4 inches tall) to guarantee winter survival.

Triticale and crimson clover (84 and 15 pounds per acre, respectively)
The triticale is a hybrid of wheat and cereal rye. It does not grow as fast as rye in the fall but can produce high tonnage in the spring and a wider harvesting window than cereal rye for high-quality forage. When mixed with crimson clover, it even makes a higher-protein mix.

Mixes with forage radish
There are several possibilities, like radish and vetch and rye (3, 10 and 84 pounds per acre), crimson clover and radish (15 and 3 pounds per acre) or radish and ryegrass (3 and 10 pounds per acre).

In our trials, the September plantings were typically too late to see much radish growth after corn silage, so the earlier it can be established the better.

We noted the radish flourished in high-fertility situations with manure. This cover crop becomes less attractive in the northern parts of the state or where corn silage is harvested late.

Whatever you do, don't plant radish alone or your soil will be completely bare in the spring – the radish plant dies around the year's end and the residue decomposes extremely fast.

These are just some ideas for cover crops after corn silage. Whatever you do, please make sure you don't miss this opportunity to conserve soil and make good use of manure nutrients after corn silage.  FG

Sjoerd Duiker
Associate Professor of Soil Management and Applied Soil Physics
Penn State Extension

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