The great soil nourishers

Green Lifestyle magazine

Heard the words 'green manure' floating around every time winter rolls around, but not sure what it is or how to use it in the garden? We explore their use as an essential cornerstone in a sustainable vegie patch.

Green manure clover

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If you spent the sunny months of spring and summer growing vegies in your backyard, you’ll have hopefully come out the tail end of the season with a burgeoning crop of fruits and vegies. Many summer annuals, such as tomatoes, eggplants, capsicums and sweet corn are heavy feeders – meaning they need a lot of the nutrients found sitting in your soil in order to have the energy required to form those delicious and bright fruits. This can leave your soil at the end of the season feeling a little used and abused.

Winter is the perfect time to restore it with a little care. Enter, green manures. Wondering what they are? They’re nothing to do with the stench-inducing manure of the animal kind, but rather, are leafy green annuals that offer nourishment to your soil in a different way. Grown in any vegie beds or other soil plots that need nourishment or are unused – generally over winter when the garden is more dormant – they are then dug back into the soil in early spring, rather than left to flower and seed for eating, to add nutrients and organic matter. They work to bring more earthworms and micro-organisms into your soil, increase the soil’s water, air and root penetration, and increase nitrogen and water retention.

Certain green manure crops can also be used as living mulches, planted in the understory of your winter greens and brassicas to help protect the soil, suppress weeds and retain water. Clever little plants they are, huh! And the good news is, the time to plant is now.

Legumes are common green manures for their unique ability to restore and ‘fix’ nitrogen back into the soil (something your tomatoes, lettuce, cucumbers and squashes, among others, sucked up from the soil greedily over summer and will need again). Great legume crops include cowpea, broad bean, chickpea, mung bean, soy bean, lentil, alfalfa, vetch and clover, among others.

Meanwhile the grass varieties of green manures, which include the likes of barley, ryegrass, wheat and oat,
are stars for fast growth, keeping the soil enriched over winter, suppressing weeds and increasing the soil’s
organic matter.

If you’re covering a vegie bed that is unused or needs some lovin’, there’s no need to choose and stick to one variety – a mixture of grasses or legumes, or even both together, will work a treat with the legumes providing nitrogen and the grasses offering up plenty of biomass.

Pick up some seeds from organic seed providers such as Green Harvest (www.greenharvest.com.au), or do as many thrifty green thumbs have done before and give bird seeds a go, which are usually a mix of grass varieties. Scatter the seeds across freshly cultivated beds and rake in. Then sit back and watch as those charming greens do all the hard work for you over winter!