LINGLE, Wyo. – Knowledge, networking and conversations about nutrients were in full bloom Tuesday at the sixth-annual Wyoming Forage Field Day at the James C. Hageman Sustainable Agriculture Research and Extension Center in Lingle. Topics ranged from forage production and management, soil fertility and weed control, to irrigation and hay quality via panel discussions, field and equipment demonstrations.

Dr. Joe Brummer, forage specialist at Colorado State University, helped kick off the day with his presentation, “Cover Crops for Forage: Importance, Establishment, Management, and Utilization”.

“A cover crop is a crop grown to provide some type of a living ground cover,” he said. “Planted … with or between or after the main cash crop … the goal is to have a living root in the ground as many days of the year as possible.”

According to Brummer, benefits of cover crops include: improved soil health and fertility, increased yields of subsequent crops, prevention of soil erosion, soil moisture conservation, protection of water quality, runoff reduction, providing a habitat for beneficial insects, and weed suppression and control.

“Many plant species commonly used as cover crops provide high-quality forage,” Brummer said. “They have a dual purpose – the benefits listed previously plus feed for livestock.”

When grazed, about 90 percent of nutrients from forage are redeposited on the soil, he continued. Brummer advised producers use what’s known as the rotational strip-grazing approach to minimize manure concentration.

“The biggest drawback is the potential for soil compaction, especially on some of our heavier clay-type soils,” he said.

Potential cover crop species include cool season annual grasses, such as wheat, barley, oats; warm season grasses – millets, forage sorghum, corn, sudangrass; brassicas – turnips, kale, canola; and legumes – field peas and clovers.

Each cover crop provides specific benefits, Brummer said. Legumes offer nitrogen fixation – a low carbon-to-nitrogen ratio so they decompose rapidly; grasses are easy to grow, cheap, and produce large amounts of dry matter; and brassicas scavenge nutrients, suppress weeds and pests, and decrease soil compaction – especially radishes.

“I’m a big fan of these tillage radishes and oil seed radishes,” Brummer said. “A big benefit of those is to reduce soil compaction … they have a very deep root system … once (the plant) decomposes, it allows moisture into the soil and breaks that soil up.”

On the flip side, many cover crops have potential toxicities. Brummer warned sorghums may contain nitrate and prussic acid; brassicas can cause issues with nitrates and glucosinolates; hairy vetch is generally not recommended for grazing, as it can lead to kidney failure and photosensitization, especially in black-hided animals, like Angus and Holstein cattle. Most legumes also have the potential to cause bloat; and small grains can lead to grass tetany – specifically lush, early growth.

Brummer recommended cover crop mixtures, as compared to monocultures, stating mixtures may reduce seed costs, increase forage yield, moderate forage quality, increase biodiversity (and therefore provide a more balanced diet), and accomplish multiple soil management goals.

“By adding some of the small grains, cheaper-type seed – you can reduce the seed costs,” he said. “If you’re thinking about mixtures, to me, one the biggest reasons to going to a more complex mixture is to accomplish multiple soil management goals … to achieve soil health/soil management-type goals.”

As part of the conclusion of his presentation, Brummer offered the following tips: don’t mix warm and cool season species for spring planting, although a combination of the two may work for mid-summer planted cover crop; mixtures tend to be dominated by a few species, primarily grasses; and many legumes and forbs don’t compete well and are typically the most expensive alternative.