Employing Nightcrawlers (Lumbricus Terristoris)


There will always be those who during economic hard times, and particularly economic meltdowns, prefer to take personal responsibility for food security rather than join angry protesters. Of course access to land will be necessary and in many cases there may not be enough land to feed oneself and perhaps dependents. It is recommended by some that very close spacing is a good way to maximize production, but I am not one of them. Though close spacing economizes space above ground, the roots below are cramped which would tempt the gardener to resort to costly soil additives of many kinds. A better practice would be to increase topsoil depth. In this regard nightcrawlers should be employed as nightcrawlers are Nature’s premier topsoil builders.

Rather than ingesting organic matter that is already in the soil they prefer organic matter at the surface and bring it down deep through vertical tunnels, mixing it with subsoil which provides the grit for shredding the organic matter. Like other earthworms they prefer partially decomposed organic matter that provides them with digesting microorganisms. These tunnels also transport oxygen and water, essential for the survival of both worms’ and plants. Surface mulch, therefore, is needed to keep the worms constantly fed. Even cover crops would need to be mulched, otherwise the earthworms may spend too much time hibernating at the bottom of their tunnels.

Maintaining a certain level of moisture in the partially decomposed litter is important, since earthworms breathe by taking in oxygen dissolved in water through their skin. Not so incidentally perpetual mulch helps stabilize soil temperatures. The organic matter brought deep into the soil, after being mixed with mineral-rich subsoil, is brought to the surface for deposit, keeping the tunnels open. Nightcrawler deposits (castings) contain about 70% humus. Rain washes some of these deposits, or castings, back into the tunnels. Where nightcrawlers exist it’s imperative that tilling is avoided since tilling closes off the vertical tunnels and few nightcrawlers will be found.

Where I live, and in the tropics in general, only shallow-feeding and dwelling earthworms exist. Therefore deep soil is found only on bottom land, where soil has accumulated via erosion from upper lands. Obviously, therefore, bottom land should be preserved for market gardening and never built upon. The challenge I have taken on in my tropical paradise is in finding ways to deepen topsoil, though bereft of the advantage of deep-dwelling nightcrawlers.

Subsoil penetrating roots of cover crops is the primary way of converting subsoil into topsoil. Where there is a hardpan layer deep chiseling may be necessary  initially. Deep roots, upon decomposing, provide humus. The deeper range of such soils will contain less oxygen than the upper layers, therefore less microbial activity, and a more stable type of humus. This humus receives and holds nutrients that may be leached from above. As an end product of decomposition the most stable humus is derived from organic matter containing fibrous materials like lignans, waxes and silica. No humus remains stable, however, under conditions of excess oxygen caused by repeated mechanical tilling.

It is useful to note that tropical soils do not contain as fertile a type of clay as is found in temperate zones (hold fewer nutrients on their surfaces).  Humus can compensate for this weakness as it has a much higher capacity to hold nutrients on its surfaces than even the most fertile type of clay. Deeper topsoil invites deeper roots, which sequester carbon and nitrogen, meaning less CO2 and NO2 in the atmosphere and also results in more drought-resistant plants. All-in-all deep topsoil helps purify the air, puts food in more mouths and, for market growers, more money in their pockets. When the true value of earthworms of all types becomes widely acknowledged surely we will establish a National Earthworm Week?

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One response to this post.

  1. I live in a tropical nation and you mention that the bottom land should never be built upon. Is there no way around this at all? Even if, God forbid, I have to use a tiller?

    Reply

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