By James Isleib
Does Michigan State University Extension recommend including a nurse or companion crop along with a new alfalfa or mixed, grass-legume seeding? Not necessarily. It depends on the situation and should be considered carefully. Some people don’t like the term nurse crop since the typical cereal grain used for the purpose may act more like a weed, taking up water and nutrients needed by the more important perennial forage crop. On the other hand, when soil erosion is a serious threat, a nurse crop can save the day.
Here are a few pros and cons to including a nurse crop with your new hay seeding.
Pros
- Nurse crops provide erosion control where needed.
- Nurse crops can help with weed suppression.
- Roundup-ready alfalfa provides easier control of nurse crops at early stage of growth.
- Nurse crops can provide extra forage or grain during the establishment year for a perennial forage.
Cons
- Alfalfa or mixed hay harvest usually begins sooner without nurse crops.
- Nurse crops use water, nutrients and sunlight otherwise available to the perennial forage crop.
- Nurse crops generally reduce first-year perennial forage crop yield and may result in thinner stands.
- Excessive nurse crop seeding rates add to seeding cost.
Generally, nurse crops should be used only when needed. Otherwise, clear seeding of alfalfa or mixed hay is likely to be more efficient in the long run. Waiting to harvest grain from a nurse crop can result in significant reduction of stand in the alfalfa or other perennial hay seedings. Consider the comparable value of oat grain from a thin, nurse crop seeding compared to the value of a good stand of multi-year alfalfa or mixed hay forage established without a nurse crop.
Removing the nurse crop early will reduce the competitive effect on the desired forage seeding. Spray the small grain nurse crop with a labeled herbicide when the small grain is 4-6 inches tall. Of course, if the seeding is mixed grass and legume, killing a nurse crop with a grass herbicide will kill the forage grasses, too.
Delaying nurse crop removal until the small grain is ready for forage harvest is another option. However, it results in extra competition with the perennial forage. Small grains should be removed no later than the boot stage. The seeding rate of small grains used as a nurse crop should be light: 0.5 to 1 bushel per acre of oats, barley or triticale are common. Field peas are sometimes included to improve the protein content of the resulting nurse crop forage.
In 2018, a nurse crop trial funded by Project GREEEN through the MSU Extension Agriculture and Agribusiness Institute will be established at the MSU Upper Peninsula Research and Extension Center. Oat, barley and triticale, with and without 4010 field peas, will be seeded with alfalfa at low, medium and high seeding rates. The nurse crops will be harvested as forage. Total forage yield of nurse crop and alfalfa during the establishment year will be compared. An alfalfa seeding plot without nurse crop will be included for comparison. Alfalfa stands will be evaluated and compared from the various treatments in fall 2018 and spring 2019.