It is at this time of year that soil-covering ‘green manure’ crops planted post-harvest really prove their worth. Their main purpose is to prevent nutrients - especially nitrogen - leaching out of the soil, storing them for subsequent crops to utilise.
Many species can be used for this, but a mix using cereal rye or westerwolds ryegrass and vetch is the best. Rye or westerwolds pick up and store around 90% of the nitrate in the soil. This would otherwise be washed away during winter rains as nitrogen in the form of nitrate is very water soluble.
Vetch, as a legume, fixes nitrogen once the soil starts to warm, so adding yet more fertility. These mixes are tolerant to at least minus 15°C, so can withstand the harshest winter conditions.
In the spring when the green plants are incorporated the nitrogen is released into the soil for use by the next crop while it also adds a huge amount of vital organic matter.
For more information on protecting your soil with green manures, ask for a free copy of our ‘Sort Out Your Soil’ or download it here.
Date Posted: 10th January 2014