Winter Cover Crop Planting Considerations
DR. TRENTON ROBERTS
FAYETTEVILLE, ARK.
This season’s weather has been very cooperative for summer cash crop harvest, but unfortunately there were also many fields that were not planted and remained fallow for most of the summer. With harvest in full swing it is time to start considering winter cover crop establishment. Now is the prime window for cover crop establishment in Arkansas. Listed below are the recommended cover crop seeding rates and planting practices for cover crops in Arkansas. This list now includes cover crop species that are not recommended for planting in Arkansas as they pose the potential to become weed management issues or they have not shown a consistent ability to establish and survive in Arkansas’ winter climate. All cover crops that are recommended for planting in Arkansas can be established currently, but as we move later in the fall the planting window for the successful establishment of mustards such as radish and turnips will begin to close rapidly. As we progress further into fall, cover crop planting considerations should be focused on winter cereals and winter legumes. For most locations in Arkansas (except south of Pine Bluff – which the cutoff is Oct. 15th) October 1st is generally the cutoff for establishment of mustards. Understanding the growth habits of various cover crops will help producers better understand why fall planting dates are so important for cover crop success. For cool-season mustards such as radish and turnip, the majority of their biomass production occurs in the fall between emergence and when they either go dormant or winterkill. This is especially true for the below-ground taproot growth. If and when these cover crops break dormancy in the spring, the majority of the biomass that is put on is related to flowering and seed production (a small portion of total plant biomass). Canola, a cool-season mustard, is not recommended as a cover crop in Arkansas and is one example of a mustard cover crop that can put on a significant amount of spring biomass after breaking dormancy. Additionally, the more fall growth/ the larger the taproot on cool-season mustards the more likely they are to winterkill. Winter cereals and winter legumes have a much different growth habit. The majority of the biomass associated with winter cereals and legumes occurs when they break dormancy in the spring; therefore, fall planting dates are not nearly as critical. Winter cereals and legumes can be planted much later in the fall as they tend to be more winter hardy and the bulk of their biomass (crucial component of cover crop success/benefits) occurs in the spring. Planting considerations for winter cereals and legumes should be based on soil and environmental conditions. For most areas within the state of Arkansas winter cereals and legumes can be established until Nov. 1st (North of I-40) or Nov. 15th (South of I-40). Although we are currently dry, there is no way to really predict how much longer this weather pattern will hold and if you are interested in establishing a cover crop now is the time to do it. Some soil conditions may be dry, but we have seen that cover crops can be planted into very dry soil and will actually remain unharmed and establish when adequate rainfall has been received. If you are interested in planting cover crops and have the time and seed I recommend that you get the seed in the ground now while its dry and you have the opportunity. I would not wait for a rain shower and then plant. Try and get the seed in the ground first, then wait on the rain. As with any crop, the time and effort put into planning and establishment of cover crops will pay dividends in the benefits realized for the successive cash crop. Please let us know if there are any ways that we can be of assistance. ∆
DR. TRENTON ROBERTS: Associate Professor, Crop, Soil & Environmental Sciences, University of Arkansas