Grazing cover crops Amanda Radke

For soil health: Consider cover crops with manure applications

Recapture nutrients for improved soil health with a combination of cover crops and manure.

This morning, we woke up to a crisp bite to the air, and it appears like the last of our late summer weather is officially over for the season. I won’t be surprised if the first frost sets in soon, and we’re scrambling to get as much as we can get accomplished while the weather cooperates.

With weaning just a few weeks away, we’re busy cleaning pens and hauling manure to nearby fields and pastures. Meanwhile, our cow-calf pairs are enjoying an abundant harvest in our cover crops fields, which we are thankful for as our county was experiencing drought-like conditions at the time of planting.

Glen Arnold, Ohio State University (OSU) manure nutrient management field specialist, recently discussed the benefits of both cover crops and fall manure applications to recapture nutrients in the soil and provides recommendations for ways to apply manure for best results.

Arnold writes, “To best capture the nutrients in manure, livestock producers should incorporate fall applied manure and also consider using cover crops. Pen pack beef manure will contain approximately 7.9 pounds of nitrogen per ton (mostly in the organic form), while liquid beef manure from a slatted barn can contain 30 pounds of ammonium nitrogen and an additional 25 pounds of organic nitrogen per 1,000 gallons. Most swine finishing manure contains more than 40 pounds of ammonium (NH4) nitrogen per 1,000 gallons and dairy manure, from facilities bedded with sand, can contain more than 15 pounds of ammonium nitrogen per 1,000 gallons.”

In addition to the benefits of fall manure applications, Arnold says that cover crops, which have primarily been used to control and reduce soil erosion, also have the added benefit of recapturing nutrients in livestock manure and keeping those nutrients from escaping into lakes, streams and rivers.

Arnold says, “In one study, OSU Extension researchers found a cover crop decreased the nitrate nitrogen NO3 concentration in manure amended soil compared with the control soil by more than 70% before the field froze in the fall. This would have primarily been nitrogen that soil bacteria converted from the ammonium form to the nitrate form after it was land applied.”

According to Arnold, the best cool-season grass for capturing excess nitrogen is cereal ryegrass.

He writes, “Because rye over-winters, research has shown it can capture and hold 25 to 50 pounds of nitrogen (organic form) per acre. It germinates at temperatures as low as 34 degrees so can be seeded later than oats. However, less nitrogen will be captured the later the rye is seeded. It will grow later in the fall and begin growth earlier in the spring than wheat. The organic nitrogen stored in the plant will eventually be released as ammonium nitrogen when the plant dies.”

Cover crop mixes usually incorporate a variety of plants including radishes, wheat, clover, annual ryegrass, turnips and oats. With the added bonus of extra forages for fall grazing, Arnold stresses that cover crops are an ideal way to recapture manure nutrients and conserve soil.

He writes, “Cover crop seedings do not have to be perfect. The goal is to combine nutrient recovery and protecting the environment.”

Our cover crop harvest was hardly picture-perfect this year. In fact, it was a gamble to plant at all considering how dry we were in July when we seeded our mixture. However, we ended up with a nice crop with several weeks of potential grazing, and the benefits of the cover crops combined with the manure from grazing are numerous.

The opinions of Amanda Radke are not necessarily those of beefmagazine.com or Farm Progress.

TAGS: Livestock
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