This week, Dirty Nails has been working among rows of winter Radar onions. They were planted as sets in September on a sloping piece of ground for harvesting from late May. After an initial fortnight or so, when he was constantly checking his crop and firming-in loosened bulbs, for more or less four months they have been left alone. A healthy cover of weeds subsequently developed. Dirty Nails has resisted his natural gardener's urge to purge them from the ground on account of their soil conservation qualities.

Bare earth on an incline is prone to being washed downhill by winter rains. Experience and observation teaches the home producer favourite overland courses which water takes in response to ground being waterlogged (which can often be the case during early February). During "flash flooding" of previous years, great channels have been gouged from the meticulously tended plot and soil carried away, complete with entire broad bean plants, for deposition at the first big obstacle.

Since then, care has been taken to never leave the susceptible area clean of vegetation from September to April and no such problems have been suffered since. With mild spells punctuating cold snaps being a feature of the last few months, weeds have continued to grow. They bind the soil with their roots and act as a protective buffer to rains falling from above. Similar effect can be achieved by sowing with a green manure such as clover or buckwheat.

To prevent his precious onions from being swamped, Dirty Nails has been evicting any deep-rooted impostors such as seedling dock and dandelion while the soil is wet and they are easy to tease out in one piece. He plunges thumb and first-finger in knuckle-deep either side of the tough anchorage, gets a firm grip, and pulls slowly.

Time has been called for baby creeping buttercup and nettles too. The former produces chemicals in the roots which inhibit growth in adjacent plants, including food crops. Although he clears carefully around the onions themselves to reduce immediate competition and afford a bit of breathing space, Dirty Nails chooses to leave lowly mat-forming wild flowers like chickweed and speedwell between the onion rows as insurance against continued heavy and persistent downpours.

Further precautions against erosion include cultivating lines of vegetables horizontal to the gradient and channelling surface water away from sensitive areas by means of shallow drainage ditches.