Putting Cover Crops to Work
Growing vegetables is hard on a place, and it’s important to put something back for all that we take out. One of our responsibilities as growers and gardeners is to be good stewards of the earth that we use. Feeding the soil is an important piece of increasing the health of our fields. One can add compost, but increasing levels of available phosphorus is becoming a problem and leads to pollution of our waterways. A simple way to both give the soil a boost of organic material and address other common soil concerns is through cover cropping.
Choosing a cover crop and when to plant, should really be a function of the intended result. Review the benefits of cover crops below and consider the many and varied applications to your soil.
- Considered by many to be the lifeblood of healthy soil, organic matter nurtures soil life, holds and recycles nutrients and promotes good soil structure.
- Soils high in organic matter allow for proper soil particle aggregation, aeration and water retention.
- In a process called “nitrogen fixation”, leguminous crops harvest nitrogen gas from the air with the help of bacteria living on their roots called rhizobia.
- Legumes efficiently convert this valuable nitrogen source into a usable form which is then stored in the soil for future crops.
REDUCING SOIL COMPACTION
- Cover crops with fibrous root systems help break up and aerate the soil and once decomposed, leave small channels in the soil through which water and nutrients can move freely, decreasing surface compaction.
- When a compaction issue exists well below the soil surface, those species with deep taproots can break through the hardpan, reducing compaction and allowing for greater root penetration.
- The prevention of soil erosion is best achieved using cover crops that quickly establish a fibrous root system and a substantial canopy above ground.
- For winter cover, even those which do not survive in cold weather can provide excellent erosion control given adequate growth in the fall.
- Organic matter can hold up to twenty times its weight in water.
- Soil planted with a cover crop is less likely to suffer from excessive evaporation, the cover crop restricting direct sunlight and trapping even the lightest rain.
- Many species can out-compete weeds for light, water, or nutrients altogether.
- Some cover crops can act as a physical barrier, suppressing weed seed germination and significantly limiting early growth.
- A few species (Rye and Oats) even have allelopathic properties, exuding compounds during growth and decomposition that inhibit germination of other seeds. In this case, it is important to allow adequate time for decomposition prior to planting a new crop.
Spring planting- Annual Organic Ryegrass, Organic Oats, under-sown Organic White Clover, Organic Medium Red Clover
Summer planting- Organic Buckwheat
Fall planting- Annual Organic Ryegrass, Organic Oats, Organic Medium Red Clover
The importance of cover crops in organic growing cannot be overstated. Many times, cover crops are viewed as something to put on open ground while a “cash crop” isn’t happening. There is value to incorporating cover cropping into a farm plan and thinking of it as a part of the cash cropping process.