Using Green Manure in
#WinsfordGardens a #CTWW weekly challenge
As an alternative to chemical fertilisers, green manure can
be used to improve and protect the soil. It is therefore, a staple of organic
gardening and sustainable agriculture. In Winsford Gardens in Penge, we tried
this last year in the two new flower beds we created where our willow arch had stood
before it was vandalised. If I recall correctly, we used Fenugreek (Trigonella foenum-graecum.) Fenugreek is a
legume (Fabaceae family) and other legumes are the most commonly used
green fertilisers because most of them have symbiotic Nitrogen-fixing
bacteria in structures called root nodules, and because Nitrogen is the most
limiting nutrient in the soil. However, a number of late-flowering
non-leguminous plants can also be used. The Fenugreek was allowed to grow for a
period, and then before it reached full maturity and flowered, it was ploughed
back under the soil by hoeing. In a similar process to composting,
heterotrophic bacteria break down the organic material. The Nitrogen becomes
available to other plants, but the weak acids also react with insoluble soil
minerals to release Phosphates. We have just planted up the two beds so we’ll
let you know if it worked.
A couple of years ago we also planted Comfrey in Winsford
Gardens and used the leaves to make a green fertiliser. Comfrey (Symphytum officinale) is a perennial herb (Boraginaceae
family) with black, turnip-like roots and large, hairy broad leaves that bears
small bell-shaped flowers in a variety of colours. It is a fast growing plant
and Nitrogen hungry, and the leaves can be harvested up to five times in a
single year, after which the plant will rapidly regrow. The leaves and stems
are covered in fine hairs that irritate the skin, so they must be cut wearing
gloves. ‘Comfrey Tea’ can be made when the leaves are soaked in rainwater for
four to five weeks, where they quickly break down into a thick black liquid.
Alternatively, they can be used sparingly in the compost heap as a compost
activator. In addition to the Nitrogen, the leaves are an excellent source of
Potassium (up to three times more than animal manure) which the plant takes
from deep in the subsoil, unavailable to other plants. The Comfrey Tea is very
strong and must be diluted before use on beds.
We
use the compost and the leaf mould that we make ourselves in Winsford
Gardens as a biodegradable organic mulch on the flower beds and
vegetable beds. It is then drawn down into the surface layer by
earthworms and improves the soil structure and fertility. We also use
soil improver made by the London Borough of Bromley from local residents
recycled household garden waste. Other options are to use seaweed, well
rotted manure, spent hops or spent mushroom compost.
and
the Baltic states, which supply most of the peat used in the UK.
Another alternative is to use coir, made from coconut shells or tree
bark. Bark isn't as useful as wood chip as it tends to come in strips
and doesn't give good coverage.
