ALL ABOUT FERTILE SOIL, WHAT IT IS AND HOW IT’S MADE – Allan Yeomans 1985
Here I try to describe in basic terms what fertile soil really is and why it is possible and practical to massively enhance the fertility levels of farm soil.
Rich top soil is just dead subsoil plus a lot of reasonably stable humus plus a heap of active fungi, a mass of air breathing microbes and lots of earth worms, all with masses of dead plant root material to eat, air to breathe, water to drink and space to live in. If your soil is like that you know you don’t have a problem growing anything.
Some subsoils are more highly mineralized than others. But that’s determined by the near surface geology, and to change that you have to change farms. But fortunately, over geological time scales, endless mixing has been going on so there are very few soils, anywhere in the world, that don’t have all, or almost all, of the minerals and elements required by healthy plants. True, the elements may not be readily “available”. But also fortunately, vigorous active soil life produces their own tiny blobs of powerful acids that crack the inert rock particles and make the trapped elements available to the system. If it wasn’t like that, then life on land just would not exist.
For you, on the farm, on the property, on the ranch there is one thing that you can do much better than nature can. And you can do it in an instant.
You can create the abundant space needed to allow soil life to do its thing, to massively proliferate. One deep pass with a subsoil plow that produces minimum disturbance of soil layers and the perfect microbe and earthworm housing estate is created. The soil fertility creation process can thus be speeded up, in many cases a thousand fold. What took centuries can be done in two or three seasons. And improvements can continue to produce soil to unprecedented fertility, for decades.
For nature to create space, unassisted, it had to wait for a tree to grow to maturity, then wait for it to die and then eventually fall over so finally the tree’s roots could loosen up the deep, hard, subsoil.
Or nature can do the job with grasses. That works, but it can take centuries for grasses to battle their way into dense compacted subsoil and loosen the stuff. It took centuries to create the deep, rich prairies and savannas of the world
Pouring expensive chemicals, year in and year out to just produce saleable crops is invariably more expensive than turning poor soils, dead soils and “worn out” soils, into rich and permanent and hugely productive soils.
The end products of all this soil activity are stable humic and fulvic acid molecules. Really the difference between the two is academic. They are both mainly made of carbon atoms. And technically, that mixture is what “humus” is. The individual molecules are enormous. They contain hundreds of carbon atoms. And very few of these molecules are ever exactly the same.
To grow, plants need soluble chemicals to absorb into their roots. That’s what the tiny blobs of acid produce. Big problem. Sure the plants need them but being soluble; every time it rains they are going to get washed away. All those valuable elements ending up in the ocean.
Knobble surfaces are the answer. Both tiny clay particles and humic acid molecules have surfaces that can loosely trap the stray elements they find floating around. They’re hold the atoms tight enough so they don’t float away; and still loose enough for the plant roots to collect and use them as needed. The elements get “chelated” onto the knobbley surfaces. The large humus molecules are many times better doing this than is clay, and clay is better than almost any other geological material.
So for plant roots these surfaces act like super market shelves, all full of nutritious goodies. That’s the way it’s always worked.
Many strong agricultural fertilizers work by destroying and looting the shelves. It’s obvious why we lament that after a few years the chemicals “don’t seem to work so well anymore”.
You get a soil test done. Soil tests test for what’s “available”. They don’t actually test for what’s really there and what can become “available”, with the help of prodigious soil biological activity.
Then you are advised what chemicals to buy.
And then, much to their vexation, you decide there has to be a better way.
How Do I Find The Keyline?
When the geology of an area has had time to settle down, when all the exposed rock faces have weathered away the final result is gently undulating country.
The topographical form of that gently undulating country, the fundamental “shape” of that country is always exactly the same in every country on every continent on the whole planet.
Big rivers are fed by smaller rivers. The smaller rivers are fed by even smaller rivers and they in turn are fed by hundreds of creeks. Then finally the creeks are fed rain water from the thousands of small primary valleys that feed into them. The primary valleys are the end of the chain, or really the beginning of the chain of rain to the sea. for the floor of a primary valley only receive the water from the sides of that valley and nowhere else. That the start.
Walk up the floor of a primary valley and at first it is fairly flat, just a gentle slope. Then suddenly it gets steeper. And where it suddenly gets steeper is the Keypoint of that valley. And a contour line passing through the Keypoint of a valley, is the Keyline.
When plowing up the hill, parallel to the Keyline, rain falling in the furrowers will tend to drift out towards the adjacent ridge. And the weird thing about the Keyline is that plowing parallel to the Keyline and moving down from the Keyline, we find again that rain falling in the furrowers will tend to drift out towards the adjacent ridge.
A contour that passes through the steep valley floor will continue out to where the adjacent ridge is steeper and a contour passing through the flatter part of the valley floor will continue out to where the adjacent ridge is steeper. It always happens that way. The relative steepness pattern swaps at the Keyline. That was my father’s peculiar and amazingly insightful discovery. (Indecently, it was me who came up with the name “Keyline”. Around 1950 it was.)
Between the river’s outlet into the ocean and the primary valleys way upstream, the shape of the rivers and creeks are like fractals. Where every pattern is an enlarged version, or conversely a reduced version of every other pattern.
But geological movements and reshaping never stops so very often the formation of these inevitable fractal valley patterns are disturbed and the weathering has to start all over again. So classic, well defined Keylines don’t always exist.
But that doesn’t matter for the principal of pegging a contour and plowing parallel up from that line, or paralleldown from that line, can always be used to control the drift of rain water across the land and prevent its concentration.
Viscous, earth gouging erosion, needs big volumes of water moving fast. The flow has first to become concentrated. Keyline pattern deep working does two things. It allows the rain to soak in fast and secondly it prevents what doesn’t soak in from concentrating into tiny fast flowing rivulets.
Keyline means you keep the water and, you stop erosion.
For a more adetailed explanation, find it in my book PRIORITY ONE, and go to Chapter 7, HISTORY OF TWENTIETH CENTURY SOIL CONSERVATION AND KEYLINE . Or just click this link. Chapter 7