Green Manure Crops are just as the name suggests, green lush foliage grown as a crop to provide nutrients to the soil. This can also be called a cover crop. The method of growing greens to help improve soil has been used in sustainable agriculture and farming for a very long time. The crops provide valuable nutrients to the soil and also provide many other great benefits to the home garden and broad acre farms.
Green manure crops are usually a combination of a legume and a grass or grain seeds. The legume provides vital minerals, such as nitrogen and the grass provides the bulk green organic matter.
There are many benefits to applying a green manure crop to your gardens. Here are a few –
* They provide cover to the soil when the area is not being used
* The legumes will add nitrogen to the soil by the process of ‘nitrogen fixation’
* The organic matter provides nutrients to poor soils and improves the soil structure
* Increases humus level
* Increases the microbial activity in ‘dead’ soils
* Increases soil’s moisture level and retention
* Adds organic matter to soil
* Assists with soil erosion
* Increases the resistance to pest and disease problems in soil and plants
* Assists with weed control
* Can be used in conjunction with crop rotation to assist with soil improvement and pest and disease resistance
So, as you can see there are many wonderful reasons to apply a green manure crop to your garden.
Here’s how you do this…
Firstly check the pH level of your soil. It’s best to be around 6 to 7 pH. If you have acidic soil (lower pH level) apply some agricultural lime and compost at least 2 weeks before sowing.
Pre-soak the legume seeds overnight.
Rake the soil over to remove large lumps and sprinkle seeds, mixed legume and grass together, over soil area. Ensure that you use the inoculant mixed in with the seeds. (see note below on inoculant). I use a small bucket to mix a small amount of soil, inoculant and seeds together and then spread over soil.
Rake over the seeds to cover with soil and water well. Seeds should be covered to about 2mm deep.
Depending on the types of legumes and grasses sown, the seeds should germinate in approximately 3-5 days. Keep moist, but not too wet during this time.
During dry weather water regularly to ensure good growth during growing period (only if no rain).
When the plants reach about 10-15cm in height and before flowering, usually around 6 - 8 weeks, depending on the season, the foliage is then cut back to ground level and left to lie on the soil surface. You can use hedging shears or other hand cutters to do this. Don’t remove the roots as they provide stability to the soil and extra food for the microbes.
The green chopping can be left as a green mulch or covered with a light sprinkle of blood and bone and then brown mulch, eg sugar cane or straw, to assist the decomposing process of the green cuttings and increase organic matter in the soil.
Suggestions for legumes and grasses.
Before sowing green manure crops you need to consider what season you will be growing them in and what climatic situation you live in.
You can purchase cool and warm season green manure crop seeds which will include the appropriate plant species for the season. Try Green Harvest for your seeds.
Cool Season Crops include – woolly pod vetch, sub clover, oats and fenucreek
Warm Season Crops include - mung bean, cow pea, buckwheat and millet
(This information is from www.greenharvest.com.au where they have fabulous information on seeds available)
Information on legumes
Last month I wrote an article on Pigeon Pea and how to grow it. Here’s an extract from that article on growing legumes…
Being a legume, Pigeon Pea has the ability to obtain and store nitrogen. This happens with the aid of bacteria called ‘Rhizobium’. These bacteria live in nodules on the plants roots and can take nitrogen from the air and convert it for the plants use. This is called ‘Nitrogen Fixation’. To allow for this process and to use Pigeon Pea and other legumes as a nitrogen improver, the seeds of this plant must have an inoculant present when sown. The inoculant contains the bacteria needed for the specific legume.
So you can see why green manure crops are so beneficial to the health of the soil and such an easy process to create rich, friable humus to grow your plants in.
Give it a try, your garden will thank you for it !!
© cath manuel 22 june 2012