An open, dry, winter, followed by a dry, warm spring has left the top soil in many areas of South Dakota much dryer than normal. Livestock producers may find themselves looking for supplemental feed this summer as a result of poor grass growth. In situations of moisture deficits most producers are not going to consider planting a cover crop.
However there are some situations where cover crops may have a fit. Cover crops planted now may provide livestock producers with some needed extra grazing and forage during the summer.
Cover Crops: Effects on Ground Moisture
Cover crops can be an important part of keeping moisture in the soil because they keep soil covered and reduce evaporation losses. Dr. Kris Nichols, a soil microbiologist who formerly worked with the USDA in Mandan, ND, states that “a green and growing cover feeds a whole web of soil microorganisms-much more than crop residue.
Most soil organisms are carbon-limited, making them dependent on plant material either directly or indirectly to obtain carbon. Soil that is rich with living organisms has a soil structure more conducive to water retention.
Organisms help form soil aggregates, which allow for better water absorption because there is more pore space between the soil particles for water as well as gas exchange.”
Planting & Selection
Enough moisture in the top soil to enable seed germination will be an important consideration this year. Many producers plant cover crops later in the summer, after small grain harvest. Moisture is often limiting at that time of the year. Cover crops are often seeded in anticipation of moisture. Most cover crops consist of a variety of species. Some of the species have small seeds and will not emerge well if they are seeded too deep. However, these same species only require a minimum amount of moisture to germinate.
Cover crops planted in May and June should include some warm season grasses like sorghum, sudangrass and millet as these will produce more during the warm part of the summer. If a legume component is needed, consider cowpeas and/or forage soybeans. To extend the life of the cover crop into the fall, producers can add oats, triticale, wheat and a cool season legume species such as peas or lentils.
This year it will be important for cover crops to include a healthy component of grass species. Grasses can provide high carbon residue to the fields which will help protect the soil from erosion.
Other crop species may also be included in the mix such as sunflowers, flax and brassica species. The USDA has an interactive cover crop chart that lists numerous species commonly used for cover crops and their characteristics.