Cover Crops After Small Grains

 

Due to drier weather conditions small grain harvests are well ahead of average in some Regions of South Dakota. According to USDA- NASS report published on July 24th, 72% of winter wheat was harvested in the state, while spring wheat and oat harvest acres were 28% and 36% respectively.

 

 

Interest in using cover crops after small grain is increasing in South Dakota. Cover crops provide diversity into the cropping system, reduce soil erosion, increase soil biological activity, and also help recycle nutrients in the soil. In addition, due to diverse growing habits of major crops and selected cover crop species, it helps to break disease and weed pressure in the field. Also, cover crops can be used as supplemental fall grazing, especially in the year like 2017 where forage shortage is widespread in the state due to prolonged moisture deficit conditions.

 

 

Even though cover crops can be grown as single species or in a mixture of variety of plant species, they are mostly marketed (and grown) as blends. Selecting fall cover crop mix is critical because in a cropping sequence, it should benefit your next cash crop, not hinder with any kind of yield or growth limiting factor. Rule of thumb is- cover crops should possess growth habit that is contrasting to the following cash crop. For example, if a field is going into corn as a next crop, then higher proportion of the cover crop blend should contain cool season broadleaf species because corn is a warm season grass species. Research data from studies conducted at SDSU Southeast Research farm near Beresford have shown yield advantage in corn when grown into cool season broadleaf cover crop mix residue following small grain cash crop.

 

 

Two major categories of broadleaves commonly used as cover crop species are non-legumes (i.e. turnip, radish, canola, rape, etc.) and legumes (i.e. vetch, clovers, pea, lentil, etc.). These cool season species have high tolerance to cool temperatures and rapid fall growth; however, these species are very low in fiber content and may not accumulate abundant residue cover in the spring. In some cases, volunteer small grain growth in the fall can compensate for cool season grass species which can add to some residue next spring. Species like radish and turnip have enhanced tap roots which will aid in breaking compaction in the ground.