Since cover crops have different functions, it is important to determine what the crop is expected to do. Is the intent to add organic matter to the soil? To add nitrogen to the cropping system? To stimulate soil biological activity? To protect the soil during the winter months?
Cover crops for weed suppression
Several cover crops are considered “smother” crops because they are used to control or suppress weeds. Crops that give the best results are those that are quick to germinate, provide rapid ground cover and form thick canopies.
Cover crops for mulches
The properties of the cover crop residues are very important as they have a direct influence on the outcome of organic matter decomposition (humification and mineralization) and other plant nutrition dynamics. Young and succulent green manure crops with a low C:N ratio will feed soil micro-organisms, while a mature, fibrous green manure crop such as cereal straw will form stable organic matter but provide little stimulation of soil biological activity.
- Saia Oats
Nitrogen fixing cover crops
Legumes such as lupines, clover, vetches and serradella that can fix atmospheric nitrogen, are also able to supply nitrogen to subsequent crops. When sources of manure or compost are not readily available, legume crops can be inserted into a crop rotation to supply nitrogen to the cash crops.
Nitrogen fixing legume crops must be inoculated with rhizobium bacteria at planting. Legume crops require specific strains of fresh or well preserved inoculants. Inoculation is particularly important if the legume crop was never grown previously on the site.
Low maintenance cover crops
Turf type grasses are popular cover crops used in orchards due to the low maintenance of the plant. These grasses usually forms a uniform surface that provides good ground cover as well as weed suppression. Although the idea is to help with soil erosion, water logging, weeds and good ground cover, the popularity remains the fact that it is a very persistent cover crop with low maintenance.
- Dwarf Fescue
Bio fumigation cover crops
To interrupt pest life cycles, it is important to select cover crops of a different family than that of the future cash crop so that they do not harbour pests that can negatively impact the cash crop. Cover crops may also attract beneficial organisms that prey upon or parasitize pest species.
- White Mustard
Decorative cover crops
The right cover crop can even look decorative among other ornamental plants. The show from crimson clover -- its blossoms clustered tightly on upright stalks like strawberry Popsicles -- is so spectacular that you would hardly suspect that it was improving the soil.
- Crimson Clover
Cover crops for water logged areas
Faba bean tolerates water logging better than other grain legumes such as field peas and lupines. It also tolerates acid soil types better than other grain legumes.
The Faba bean plant is tall (may grow to over 1m under optimum conditions), erect and multi-stemmed from basal branches. It has a well-developed taproot which produces an extensive fibrous root system. Plants can flower profusely and flowering may last for up to 5 weeks, depending on soil moisture and air temperature.