Working the soil in winter?

Xavier Mathias and Les Cahiers du Potager Bio tell us about

Working the soil in winter?

Traditionally, winter marks the end of garden work, the signal for everyone to rest. However, to be more precise, we should write "the end of almost all work," as there is one whose use has persisted through the centuries, despite the intense physical effort it requires: digging, or its mechanized equivalent, plowing. The rest of the coming season depends on this work, which is the most important way we practice our soil. However, actions as simple and commonly performed as digging or plowing are increasingly being questioned by many agronomists, who advocate gentler techniques. I am not qualified to decide this heated debate, as it calls into question the age-old foundations of agriculture. My aim is to offer you an overview of the different possibilities, with their mutual advantages and disadvantages.

Digging with soil turning

This is the most common practice in our vegetable gardens, and paradoxically the most contested. It is criticized for causing too much disturbance of the soil: digging brings up the lower layer - an anaerobic environment, that is, living with almost no air penetration - instead of the aerobic, highly oxygenated environment. This effect is of course undeniable, it is up to the gardener to be reasonable. This work, whether done manually, but especially mechanically with a cultivator or a neighboring farmer's tractor, must, despite the temptation of the power of motorized equipment, remain reasonable. It is risky and useless to plow deeper than 30cm. The disturbance of the layers, the risk of bringing up clay, of hitting large blocks of stone are too great.

This method, practiced wisely, is not without many advantages. Worked relatively deeply, your soil is loosened, particularly the paths separating the rows, subject to the gardener's passages. Performed in large clods before winter on heavy, clayey soils, it allows time for the frost to do the most delicate work: crumbling.

It also offers the possibility of quickly burying before planting either amendments (manure, compost etc.) or waste from previous harvests. However, if it is not quickly followed by sowing, it will have the disadvantage of leaving your soil bare, therefore more susceptible to winter leaching.

It's also a technique for fields that have remained "dirty." End-of-season fatigue, sometimes fed-upness, lack of time, or simply a rainy autumn, and within a few weeks, the weeds take over and deploy treasures of vitality to re-establish themselves. In these circumstances, surface plowing is an appropriate response to these attempts at resistance.

Digging without turning the soil

This is the leading method in organic farming. Mechanized for large areas (subsoiler, "Michel teeth", "actisol", etc.), it is nevertheless feasible in all gardens with a simple flat or toothed spade. However, I would like to point out that suitable tools exist: the "Grelinette" or the "aérabêche".

I'm not going to dwell on a tool whose merits Sébastien praised in a previous issue of Cahiers. However, it's worthwhile to revisit the many benefits this practice offers.

Just deeply disturbed, the earth undergoes no turning over, and consequently no significant upheaval. The layers are not mixed. The microscopic fauna at the base of soil life suffers almost no disturbance. It can thus continue its merry way of transforming and improving the soil.

The upper horizon, richest in organic matter, is not mixed with the lower horizons, which would lead to a dilution of nutrients. Not to mention the ever-present risk, even at reasonable depths, of bringing to the surface these famous heavy clays, or simply a significant quantity of stones for lands with a nearby stony subsoil.

For health reasons, it's impossible to overlook the fact that this no-turning technique is much less tiring than traditional digging. For an equivalent aeration and loosening effect, the time required is significantly less. The actual effort is much easier to make.

Be careful, however, the aerobêche or the broadfork do not allow you to quickly bury crop residues, green manure or amendments. After this initial decompaction work, a pass with the hoe will be necessary to carry out this burying work, followed by a second pass, with the hoe again or with the rake to refine, crumble the surface.

Methods without plowing or digging.

Increasingly practiced, particularly in large-scale cereal crops, these techniques seem ideal from a pedological point of view. The simple yet revolutionary idea is that a land, in order to be in the best possible condition, must be worked only minimally. Nature itself demonstrates this to us: the best soils are those of forests. Never turned, never compacted by any cultivator. It is kept permanently covered by plant waste: dead leaves, bark, dead wood residues, rotting corpses, etc. It is then subjected to an intense animal and bacterial life of transformation of this enormous mass of matter.

So we should do the same in our garden... An idea that's easier to come up with than to put into practice!

Covering the soil: long live green manures

The first question that arises when we consider abandoning traditional digging is how to loosen the ground, which is inevitably subject to compaction simply by cultivating it? Then, in line with this questioning, we can legitimately ask ourselves how we can prevent the grass from re-invading our carefully maintained plot without this in-depth work? The theoretical answer is simple, and once again it is necessary to refer to the environments we know. A developed forest is not invaded: the space is already occupied.

This is what we should achieve in our gardens.