Compiled by Teresa Watkins  

November 19, 2022

Today?s Dirty Word of the Day comes from the Royal Horticultural Society in the United Kingdom. Green manures are fast-growing plants sown to cover bare soil. Often used in the vegetable garden, their foliage smothers weeds and their roots prevent soil erosion. When dug into the ground while still green, they return valuable nutrients to the soil and improve soil structure.

Green manures are usually sown in late summer or autumn and mop up any nutrients, preventing them being washed away by winter rain. When dug in the following spring, they release these nutrients back into the soil.

Green manures can also be used to cover bare patches of soil in the spaces between crops, or during intervals between one crop and the next. Fast-growing mustard sown before mid-September can be incorporated in October, for example, or the frosted remains left as mulch.

Summer-grown green manures such as buckwheat and fenugreek form dense foliage that will effectively suppress weeds.

Green manures belonging to the pea and bean family (legumes) have the additional capacity of storing (fixing) nitrogen from the air to their root nodules, but only in summer. Nitrogen is a valuable plant nutrient.

Other benefits of green manures include protection of the soil surface from compaction by rain and shelter for beneficial insects such as ground beetles.

Resources: https://www.rhs.org.uk/soil-composts-mulches/green-manures Graphic: Kate Jewell, CC BY-SA 2.0, https://commons.wikimedia.org/w/index.php?curid=13018109