A green crop is quick growing plants sown thickly on vacant ground or within a vegetable rotation and then dug into the top soil. With in the soil it breaks down to humus and releases nutrients.
In the garden the green crop is usually planted in late autumn, grows through the winter and is dug-in or mulched on top of the soil in the spring. After digging-in it is best to have a delay of up to three weeks before planting the next crop. If space or time is at a premium the green crop may be better harvested them composted or left as a mulch to allow immediate planting of the crop to follow.
The green crop has several functions:
- As a protective cover for the soil (stops the winter weather washing and blowing the soil away.
- To gather nutrients for use by crops to follow
- Maintenance of humus levels
- Roots preserve soil structure
- Shelter and a food source for predators.
Some Useful Green Crops''
Legumes:
These are very important for the maintenance of fertility. They add nitrogen to the soil.
Lupins
Lucerene
Broad beans
Vetch
Clover
Winter Cereals:
These can produce a large bulk of growth through the winter but if left in too long quickly become woody. The strong root system improves soil structure. Their main function is to build up carbon materials to add to the soil.
Comfrey
This useful as permanent stands harvested for green manure or composting. Comfrey have roots that penetrate 3m or more into the subsoil. Thus nutrients gathered from the subsoil will replenish the top soil.
Weeds:
Many weeds have strong, deep root systems which improve soil structure and gather nutrients from the subsoil. It is beneficial to let a bed be fallow for a season as every weed brings different minerals to the garden. However, the seeds left in the soil after digging-in are likely to cause problems for the following crop.
