Why Use Green Manures?
Most gardeners, especially those who are intent on growing a range of vegetables for the kitchen, know only too well the importance of incorporating nutrients into the soil prior to planting. During the growing period, vegetables will take up and use several types of nutrients, especially nitrogen, as do most green leaf type vegetables.
Unless the soil is replenished with nutrients, it will soon become exhausted and infertile. Digging in well-rotted, organic matter in the autumn and winter months will readdress the balance and the soil will be ready for the next batch of vegetable crops come the following spring and summer. However, there is an alternative to digging in organic matter or compost, and that’s green manure.
What are green manures?
Green manures are fast growing plants that are generally sown after a crop has been harvested or before any new vegetable plants are ready to go out into their permanent beds. The idea is to sow the seeds of these specific plants quite generously so that they form a carpet over the ground. To this effect, they are also ideal for supressing weed growth too so this method could be used between rows of vegetables for this very purpose.
There are various types of green leafy plants, which are used especially for this process, and selection may depend on the type of soil you have and the reason for growing green manure. For example, replenishing nitrogen levels in the soil, improving drainage or soil structure or for use as a ground cover in weed control. Think of green manure as a natural soil fertiliser.