Cover Crops

By definition, the cover crop does exactly as its name implies. This "bonus" crop does more than merely cover and protect the soil after the main crop is harvested. It replenishes, regenerates and revitalizes. It adds organic material, improves soil quality, enhances nitrogen management, provides erosion control, brings up nutrients from deep soil layers, aerates the soil, and suppresses weeds, insects, and nematodes. Maintaining ground covers through fall, winter, and early spring drastically reduces soil loss.

The roots of certain legume cover crops can supply tons of free atmospheric nitrogen per acre to the topsoil after the cover crop plants are tilled, mowed down, or smothered. Rhizobacteria live inside the legume roots creating a unique relationship that actually converts atmospheric nitrogen into organic nitrogen for the legume to use.

All cover crops supply extra organic matter to feed and breed beneficial soil organisms for soil fertility and soil health.

The roots of certain cover crops can go down several feet below the topsoil and into the subsoil to break up hardpan and pull essential nutrients up to the topsoil level at green manuring time. After 24 months of continuous growth, alfalfa roots can extent over 20 feet down, that can turn it extra organic matter down into the subsoil!

Some cover crops can weed out other plants. Buckwheat, oats, and sunflowers are good types of these allelopathic plants.

Some cover crops can attract beneficial insects and repel bad insects like marigolds and crimson clover.

Some legume cover crops, like white clover, can be planted next to your crops during the warm season to be used as a living mulch.

Cover crops provide organic matter to the soil system. They stimulate biosystems, microbial, and macro-organism activity.

Cover crops reduce soil compaction while increasing water percolation and retention. They help soils maintain a high organic matter level.

Winter cover crop is planted in late summer or fall to provide soil cover during winter. Legumes are popular cover crops due to their nitrogen fixation ability. Popular legumes are crimson clover and hairy vetch.

Summer cover crop occupies the land for a portion of the summer growing season. These warm-season cover crops can be used to fill a niche in crop rotations, to improve the conditions of poor soils, or to prepare land for a perennial crop. Legumes such as cowpeas, soybeans may be grown as summer cover crops to add nitrogen along with organic matter. Non-legumes such as buckwheat are grown to provide biomass, smother weeds, and improve soil tilth.

Cover crops are also used as living mulch. A living mulch is a cover crop that is interplanted within garden, vegetable or ornamental, plants. Living mulches suppress weeds, reduce soil erosion, enhance soil fertility, and improve water infiltration. Living mulches in perennial cropping systems are simply the grasses or legumes planted in the alleyways between rows in orchards, vineyards, Christmas trees, berries, windbreaks, and field nursery trees to control erosion and provide traction.

Popular cover crops

Crimson clover - cool season annual legume. More cold hardy than most other clovers. Grows great on all soil types in 1-2 months. Supplies lots of foliage and roots organic matter. Attracts lots of beneficial insects. The favorite legume green manure of the south.

Hairy vetch - cool season annual legume. It is the most cold hardy of the popular legumes. Can grow in temps below -5 degrees F. Great legume weed suppressor. Grows great with a non-legume like rye as a nurse crop.

Rye, winter wheat, and oats - cool season fast growing grass/grain non-legumes. Rye is the most cold hardy of all green manures, and it can grow almost anywhere. Rye can grow in temps below -20 degrees F. Rye and oats are a great non-legume weed suppressors. These crops can grow fast in a few weeks. Supplies lots of organic matter. Rye must be killed at least 4-6 weeks before planting spring crops to not hinder seed germination.

All beans and peas (legumes) - All beans are warm season except fava beans. Most peas are cool season. The most cold hardy peas are winter peas. Most dry beans and peas sold in bags in grocery stores will sprout and grow fine.

Radishes, mustard greens, rape, kale - Great cheap fast growing cool season annual non-legumes for lots of foliage organic matter. A thick crop of mustard, rape, or kale is a great non-legume weed suppressor. a thick crop of radishes are great for repelling many bug pests all year round.

Buckwheat and sunflowers - Great fast growing warm season annual non-legumes that can break up hardpan, kill weeds, and pull up insoluble subsoil phosphorus from minerals up to the topsoil to make available for next crops. Buckwheat can grow fast on any soil type (4-6 weeks to maturity).

Marigolds and other herbs - warm season annual non-legumes. Marigolds when planted thick, it's great for nematode control and other pest controls. Garlic, onions, and hot peppers control many soil pests.

All cover crops should be either tilled in, mowed down almost to the ground, or smothered by organic mulches before they go to seed, to prevent sprouting later in the year and becoming a weed themselves. The no-tilling option is the best way to get optimal soil health, texture, and soil microbial activity. Recent research has proven that excessive tilling, or tilling too deep, can kill off beneficial fungi in the soil and create soil texture problems and some soil fertility issues. If you decide to go with a no-till garden, you can poke holes in the soil around crop roots with your spade fork, to get more oxygen in the soil to further increase organic matter decomposition and increase microbial activity in the soil. Year round cover crop practices can not only improve your soil health and texture, but also decrease extra periodic plant fertilizers and soil amendments.