Delayed Planting Challenges: Cover Crop Considerations

 

High waters and saturated soils across many counties in South Dakota have producers worried about getting their crops planted in a timely manner this spring. In many areas, typical cash crops will not be a possibility. Producers may need to develop alternative plans.

 

 

Leaving fields or large areas in fields fallow is not a good option and can have detrimental effects on the next crop (which follows the fallow period). After a fallow season, corn, sorghum, wheat and other crops can experience phosphorus (P) deficiency due to lack of P uptake. This can stunt growth and create uneven stands. This is referred to “fallow syndrome” and is the result of reduced populations of arbuscular fungi found in soils (vesicular arbuscular mycorrhizae), which help to facilitate P uptake by roots. Lower populations of these fungi result from tillage and a lack of growing plants during the fallow period. In addition to this issue, fallow practices leave soil bare and unprotected with no living root activity. This can lead to erosion, soil crusting, reduced carbon, and a decline in overall soil health.

 

 

One alternative to fallow is to consider planting an annual cover crop mixture. There are numerous cover and forage crops that can be used to help address wet fields. Cover crops can contribute to the overall health of soils reducing erosion, increasing plant diversity, capturing/recycling nutrients, increasing soil biological populations, increasing soil organic matter(carbon), suppressing weed growth, improving moisture management, and providing more forage if needed. Cover crops can improve the overall health of soils, and improve yield and economic potential for the following crops. Cover crop mixes spread risk and provide a diversity of species tailored to particular objectives. Multiple planting methods also make cover crops a flexible option; methods such as drilling, air seeding, aerial seeding, and broadcast seeding are all viable depending on the specific situation.

 

High waters and saturated soils will make planting traditional cash crops challenging this spring. 

 

Prior to planting any cover crop, producers should check the herbicide history of fields. It can be assumed that any herbicide with a rotation interval that impacts a common cash crop will most likely affect a cover crop species from within a similar crop type or plant family. For example, any herbicide applied that has a long rotation interval requirement before peas will most like also have a long rotation interval for lentils and other legumes. This is a general “rule of thumb.” Most herbicide labels do not list rotation restrictions for many cover crop species.

 

There are several tools and resources to help choose the right cover crop mix for a field. The time within the growing season in which seeding occurs will help to determine whether to plant cool season or warm season species, or a mixture of both.

 

If soils allow for planting by early to mid-summer, warm season cover crops should be the primary plant type in the mix. However, if a producer chooses to wait until later summer to plant (after ~August 10), cool season crops should be the primary crop of choice as they thrive better in cooler fall temperatures. Planting a mix of broadleaves and grasses reduced risk and the crop canopy will likely close faster, providing weed control, pest management, soil biological diversity, and more. Each cover crop provides unique benefits to the soil; take careful consideration when choosing a mix. For basic information on species, see Figure 1. To get started creating a mix see the NRCS Cover Crop Excel Worksheet (Additional Resources tab), which provides suggestions and resources to tailor mixes for specific situations and purposes. 

 

Figure 1. USDA-ARS Cover Crop Chart.

 

 

For producers who are signed up for CSP (Conservation Stewardship Program), EQIP (Environment Quality Incentive Program) or other government programs, be sure to check with your local NRCS office to ensure you follow contract requirements before planting a cover or forage crop. In addition, crop insurance, planting dates, and proven yields have to be considered as part of a whole farm risk management strategy. For those who choose prevented planting insurance, pay careful attention to dates and stipulations. While the planting deadlines for insurance of small grains in South Dakota has passed, corn (May 25 or 31) and soybean (June 10) deadlines are still approaching. If producers do not make prevented planting deadlines and choose not to plant intended cash crops, cover crops may be an excellent alternative.

 

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