Cover Crops: Suitable Green Manure Cover Crops to use for Organic Farming

Cover crops are grown primarily to prevent or reduce soil erosion or to provide nutrients to crops that will be grown in that space.

TWO TYPES:

There are two types of green manures: legumes and non-legumes.

Legumes:

These consist mostly of clovers and vegetables and are valued because they help fix large quantities of nitrogen from the air, making it available to plant roots. Examples of such a green manure would be alfalfa, clovers, beans and peas.

Non-Legumes:

These consist mostly of grasses and grains and are best used for the short-term production of organic matter for the garden.

Impoverished soils can also be improved with the use of cover crops. If you have soils that are harvesting lots of weeds, by planting a grass cover crop the weeds will soon be choked out and the grass will replace the soil minerals that the weeds took out.

When the crop is incorporated in the soil, it will immediately start to break down and should be replanted with a follow-on crop as soon as possible. In warm, humid weather, decomposition can occur in less than six weeks.

Buckwheat: This is a non-legume green manure and one of the best choices for rebuilding poor or acidic soils. It has an enormous and vigorous root system and is a wonderful plant for attracting the bees. Plant seed in spring, and dig into the soil before it sets its seed.

Cowpea: This is a legume that is a good soil builder. It has powerful roots. Inoculate the seed when planting for the first time. Sow seed in spring using 40 kg to an acre or 500 g to each 30 m2.

Fenugreek: A winter legume that does best in fairly rich, loamy soils. Use 20 kg per acre or 250 g per 30 m2.

Millet: Another non-legume, this one does better on poor soil than many other green manure cover crops. Plant thickly using about 17 kg to an acre, or 250 g per 30 m2.

Oats: A non-legume that can be grown on almost any soil provided the climate is cool and moist. Winter oats are only suited to very mild winters. Sow in the spring using 50 kg per acre of 500 g per 30 m2.

Soybeans and Mung beans: These are summer legumes that will thrive on almost any soil type and can withstand long periods of drought. Sow 50 kg per acre or 500 gm per 30 m2.

Wheat: This is another non-legume that prefers a fairly fertile soil with a pH of about 6.4. Sow in the spring using 50 kg per acre of 500 g per 30 m2.

To prepare the soil for a green manure crop begin by first chopping and turning under any existing plants growing in the selected area. Smooth off the area thoroughly until you get a fine tilth and add lime if necessarily. Sow the seed, cover with a thin layer of soil and water well.

These should always be worked into the soil before they have had a chance to seed or flower, because at this stage the plant is at its strongest and contains the maximum of nutrients. If you have a heavy cropping, it is best to chop the growth down before working it into the soil. The finer the crop is chopped, the quicker it will decompose and add the nutrients to your soil that you are after.