Sunday, June 14, 2009

The Plants and Soils have Wisdom

Mother Nature has had billions of years to evolve and adapt and has created the ecosystems we have today. The Soil supports human life and is alive with soil organisms, most of which are microscopic bacteria and fungi.

Healthy soil requires a wealthy diversity of microorganisms. Very little is known about how long-term agricultural land management affects the composition and genetic diversity of bacteria and fungi in soil. We know that forage, natural fertilizer applications, and cattle grazing increases the diversity of soil microorganisms and that conventionally tilled cropland with inorganic fertilizer results in a low diversity of soil microbes.

Conservation agricultural systems with wise use of animal manure is known to improve soil quality by increasing the number and type of soil microorganisms. Soil bacteria play a fundamental role in a vast array of ecological processes.

So if the diversity of soil bacteria in soils is reduced through stress these stresses could lead to a collapse of the soils ecosystems – and therefore to a consequent lack of productivity. It may not be leaching, erosion and runoff that are the primary culprits in worldwide soil fertility declines.

Even if there seem to be abundant “nutrients” to support vegetation, without the nutrient cycling and interaction with plant roots and other soil species (fungi, bacteria, nematodes, algae, yeasts, protozoa, turbellarians, tardigrades and rotifers...) the plants cannot thrive.

There was an interesting experiment done in November 2000 by the FAO.

Researchers in Brazil dug up a 25 x 25 cm block of degraded pasture land and buried it in a nearby forest, and in its place planted a similarly sized block of forest soil. A sort of “soil swap” you could say.

Within a year, the aggregate structure of the pasture sample had been completely restored to levels typical of native forests, while the "orphaned" block of forest soil had become compacted and had lost most of its porosity.

What did they conclude made the difference? Soil organisms. The forest earth was rich in "ecosystem engineers" - earthworms, termites, millipedes and ants. The native macro-faunal communities in the pasture land had been all but lost. What does this teach us?

Soil biodiversity plays an enormous role in sustainable agriculture.

1 comment:

  1. Lloyd,
    Awesome. This totally relates to my questions about the Pailisser triangle. Thanks for that.

    So, it seems the triangle wouldn't support soil organisms, but I have had some thoughts about this. The first is that I recently read the trees create their own rain. By transpiration, they send moisture into the atmosphere and that contributes to rainfall in the region. So, it would seem, you could make more rainfall occur in the triangle by planting trees around the edges and then, as they produced more rain, you could work your way inward, always sequestering bio-char where you plant the trees as you go along.

    The second, though, is that you'd have to be very careful in doing something like that. Geo-engineering often has repercussions we can't easily predict when we start the initial design. There would have to be some very careful and far-seeing research done. Also, if we had to wait for trees to grow and cause changes in soil conditions, the rate of sequestration might be reduced.