Gardening in April – Minimal cultivation to reduce water and carbon loss

Keith Jordan

Once again a subject that keep rearing is head is drought. Nothing new to many parts of the world, but it is now having an impact here in the UK with rivers and reservoirs dryng up, hose pipe bans and farmers choosing not to plant some crops this season (those that require more water). Even on my allotment I am starting to wonder if it is worth sowing some crops as the soil surface in some places is so dry after another spring drought.

Last year some chard sown in March didn’t germinate until June when the rains finally came. However, based on experiences from last year, in February I had embarked on some ‘extreme mulching’ around fruit bushes, rhubarb, soft fruits, young apple trees, etc. Many layers of card board and paper (first used to line a guinea pig hutch) were laid around the plants to trap in the moisture that had come from rain or snow during the winter. Mulching can be used any time of the year but best the day after significant rain has fallen or artificial watering has taken place. Using materials that are pervious or biodegradable are best, so any new rain can penetrate the layer. Straw, bulky compost or anything that slows evaporation from the soil surface can be used. On an exposed site make sure mulching materials are weighed down and the edges are covered to stop slugs and snails finding an entrance to hide under. Avoid old carpets if you can, unless 100% biodegradable, as you can sometimes be digging bits up years later after they have disintegrated and weeds have grown into them!

Even now I find that un-dug soil on my allotment is still moist – cultivation helps to release the moisture. For many years I’ve found that digging soil (especially heavy chalky clay) in the spring is usually counterproductive – any lumps of soil tend to dry into hard lumps that take months to break down. A more Permaculture/ low dig/minimal cultivation regime is a good approach for many soils, not just in times of drought. As well as conserving soil moisture, low-cultivation reduces the loss of organic matter – the essential material that provides soil with a good ‘structure’ – the mixture of air spaces, water and soil particles that plant roots need and all the worms, bacteria, fungi and invertebrates that are essential for a healthy ecosystem. Cultivation exposes the material to oxygen in the air which oxides the carbon, releasing carbon dioxide into the atmospheres (and reduces the amount of organic material left).

The effect of cultivation and drainage on organic matter can be seen to great effect in the Fens of Cambridgeshire where the peaty soils (almost pure organic material) have shrunk dramatically in 150 years. Take a trip to Home Fen National Nature Reserve over Easter. A cast-iron column (thought to have been part of the Crystal Palace), sunk into the fen in 1852 until its top was level with the peat surface, but now some four metres extends above ground level after years of cultivation and drainage of neighbouring farm land.

If your soil is very compacted it’s best to wait until the autumn to dig (and after that use minimal cultivation). In planting or sowing seeds make a small furrow (to the depth listed on the seed packet), water well first then sow the seeds, cover over with horticultural fleece or mesh (reduces evaporation). Install water butts to maximise your water conservation – using drinking-grade tap water seems excessive for watering on soil that is full of bacteria and fungi! After the rains (if we get some), get into some ‘extreme mulching’!

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