Intercropping cover crops can serve a variety of purposes. It may meet regulatory requirements, improve agronomic potential, or increase intercropping production value. Sometimes, a few of these objectives can be met at the same time. But how do you choose the most suitable cover crops from all the species that exist?
If your primary goal is to meet conservation or program requirements, it’s important to understand the current USDA or local guidelines related to cover cropping and intercropping—especially those concerning soil health, nutrient management and water quality. The following overview provides general guidance but does not replace local or program-specific rules.
Are you farming in a priority watershed or environmentally sensitive area? In some cases, only farms in these zones are required to plant cover crops under conservation programs. In other regions, voluntary or incentive-based programs may encourage cover cropping, even outside sensitive zones.
Be sure to check for any species-specific restrictions. For example, while legumes like clover and vetch are widely used for nitrogen fixation, some programs may recommend mixing them with grasses or limit their use in no-till or direct seeding systems due to concerns about nitrate leaching or poor establishment.
Always consult your local NRCS office, state extension service or crop insurance agent to ensure compliance with termination dates, planting methods and species selection under USDA guidelines.
In many regions, late corn harvests or short growing windows can make it difficult to establish a cover crop with enough time for meaningful biomass development. If maintaining soil cover is required by a conservation program or recommended for soil health, there are alternative practices available. One widely used method is mulching with corn residue. After harvest, shredded corn stalks can be left on the field surface or lightly incorporated using vertical tillage or shallow discing. This residue acts as a protective mulch, helping to:
While cover crops offer additional benefits like nutrient cycling and biodiversity, mulching with crop residue is a practical and accepted alternative in many North American conservation systems when cover cropping isn’t possible.
It makes good agronomic sense to choose cover crops that fit in well with the crop rotation. The purpose of a crop rotation is to alternate different botanical species and root systems. This is important in order to fight against pests and weeds by cutting off their development cycle. Species commonly chosen as intermediate crops include grasses, crucifers, legumes and hydrophyllaceous plants.
As an example, if the next crop is:
Cover crops should be sown as soon as possible after the previous crop has been harvested. The aim is to give them time to develop and produce as much biomass as possible. Only then will they be able to provide all the agronomic benefits sought (fixing nitrate, increasing organic matter, improving soil structure, and releasing nitrogen when destroyed, etc.).
Seeding after harvest is possible for most cover crops (oats, foxtail millet, ryegrass, rapeseed, radish, legumes, etc.). Some cover crops, such as foxtail millet, niger and buckwheat, must be planted at this time. It is often the case for certain vetches, clovers, and lentils too, and to a lesser extent sunflowers and grass peas. There is still a risk of water and heat stress for these plants depending on soil and climate conditions in the area at the end of summer. It is better to plant white mustard and flax later on, from August to early September. For later planting, oats, annual ryegrass, rye, and forage turnip are more suitable, but there is no guarantee that they will develop properly due to the lower temperatures at the beginning of winter.
The first consideration is whether the cover crop is to be used for consumption or for your herd. If so, when will you need the forage? For early winter grazing, opt for cabbage, forage rape, or even annual ryegrass. For mowing, opt for oats, rye, or triticale + vetch, as well as annual ryegrass. If needed the following spring, it is easier to mow and make silage with mixtures such as oats, triticale, and rye + protein crops, or even red clover. An annual ryegrass + red clover mix works well too, with little manure.
If you don't raise livestock or sell fodder, it's best to think in terms of the benefits for the next crop. If you plan to sow a winter cereal, opt for mustard, phacelia, or buckwheat, etc. If you intend to sow corn, then crucifers, grasses, and phacelia work well. For sunflowers, go with phacelia, buckwheat, oats, or rye. For beet, a good choice is phacelia or buckwheat. These examples are not exhaustive. Local and national organizations can help you choose your cover crops.
Seeding and crop-destruction methods (shredding, tillage, weeding, etc.) before the following crop can also be an important criterion in your choice of species. These complex subjects are covered in other articles.
Planting a cover crop after wheat harvest is a smart way to improve soil health, suppress weeds, and prepare your field for the next cash crop. Choosing the right cover crop and managing it properly c...
