Most people don’t know what green manure is. And by it name is sounds like a pile of not so nice rotting waste. What is actually is, is a selection of vigorous growing annual plants (that most of us might recognize as weeds) that can be spread over your vegetable patches or idle flower beds for over the long winter months.
The benefits of green manure are clear but the actually effectiveness is still up for some debate. To explain more, lets first describe the process and benefits of green manure.
A pack of green manure seeds would generally include seeds of Rye, Minerva Maple Peas and English Early Common Vetch amongst others. These seeds should be sown over your vegetable garden at the end of the growing season. Before sowing you would quickly cultivate the soil; i.e. harvest the last of your crops (if spuds be sure to remove al tubers), fork over the soil and rake level. Once cultivated just spread the green manure seed mix. (Application rate vary for read package instructions)
Next you leave your green manure to grow and effectively you let nature take its course until the following spring. The following spring you need to dig the young plants into the soil before preparing for a new year of vegetable sowing. The only important thing to watch out for is to be sure that you don’t let the plants produce a flower / go to seed. Otherwise a second generation of plants will grow and these would interfere with your vegetable crop.
The benefits of green manure include:
Providing a soil cover in winter
The alternative would be bare soil that is exposed to the elements and prone to erosion.
Providing a habitat for soil borne insects and micro organizes
With a continuous cover of green manure your soil can remain active and full of life in time for your new crop in spring
Provide ground cover to prevent weed growth
This is probably the main reason for using green manure. The choice of plants used in green manure have two important factors. First; they are fast growing. Secondly, They are annuals. Therefore these plants will quickly colonize your soil preventing unwanted weeds from growing and because they are annuals, once the plants die and don’t’ have a chance to produce a seed they will not return.
They add nutrients to the soil
Hence the name ‘manure’ Green Manure will slowly breakdown in the soil adding nutrients back to the plants at a slow and steady pace over the year. Green manure mixes will also include a legume place such as the Minerva Maple Peas. These plants ‘fix’ or make Nitrogen and release it into the soil which is essential for plant growth and often lacking in soils in spring
They are organic
Hence the name ‘Green’ Green manures are natural and organic meaning there is no reason not to love them.
But the question remains: How effective are they really?