May 2009
Forage Matters

As Fertilzer Costs Rise, So Does Interest in Cowpeas

Southern peas, black-eyed peas and field peas are all names commonly used for a warm-season annual legume grown in the South for decades. Most Southerners, even many who live in urban areas, enjoy eating the immature seed (peas) produced by this garden vegetable. In fact, if you asked a number of people to make a list of classic Southern foods, many would include it on their list.

This plant can also be used as a forage crop, in which case it is almost always referred to as cowpeas. In the early part of the 20th century, cowpeas was fairly commonly used for forage, but in the past few decades it has been grown relatively little for this purpose, other than being fairly commonly planted in warm-season deer plots. However, interest in cowpeas, as well as other forage legumes, has increased among livestock producers in recent years due to the fact nitrogen fertilizer costs have risen.

Cowpeas exhibits a number of attributes as a forage crop. It is suited to be grown on well-drained soils throughout Alabama and other Southern states, and is relatively easy to grow. The recommended soil pH range is 5.8 to around 7.0, but it is a bit more tolerant of soil acidity than most legumes. It responds to fertilizer, but does not require high levels of nutrients to be productive. However, there are a number of insects and diseases that can attack cowpeas that sometimes can be a major limiting production factor.

In some situations, cowpeas can make a significant contribution to a summer forage program. Dry matter yields are variable; while they are typically in the range of 3,000 to 4,000 pounds per acre, they can be substantially higher. Forage quality of cowpeas is good, with crude protein levels often being 20 percent or more.

Despite its viney growth habit, cowpeas is sometimes planted with corn or sorghum and harvested for hay or silage, but it is more commonly used as a grazing crop. Good interception of sunlight requires a good amount of leaf tissue being present. Thus, good grazing management must be exercised to prevent overgrazing, especially when the plants are young. When animals are rotated off of cowpeas while there is still a good amount of leaf tissue present, there is normally good re-growth. In some areas, a high deer population may result in overgrazing despite good livestock grazing management. Gains of yearling beef animals grazing cowpeas may be near two pounds per day.

There are many varieties of this plant, especially if one includes all of the varieties commonly used in gardens. There are also some varieties developed especially for wildlife purposes. ‘Iron and clay’ is an old variety probably most commonly planted for forage purposes.

 

Cowpea seed is typically planted in Alabama in late April or May at a depth of one to one and a half inches. When drilled, around 50 pounds per acre are typically used. When broadcast and disked into a prepared seedbed, use of at least 80 pounds of seed per acre is advisable. Cowpea seed, which should be inoculated just before planting, is in short supply in some years or locations. Several herbicides are labeled for weed control in cowpeas.

Don Ball is an Extension Forage Crop Agronomist with Auburn University.