Keyline: More Than Water Harvesting
“We are discovering a new Australia! As yet, few Australians have seen it.” - P. A. Yeomans
Percival Alfred Yeomans is a greatly underappreciated figure in Australia’s history. This is the conclusion to which I have come while reading “The Challenge of Landscape” in preparation for a course in regenerative agriculture in West Sussex this week. Yeomans developed a system of landscape development which dramatically and quickly improves even very poor agricultural land by considering and working with landscape pattern. Within permaculture, the keyline system is often misunderstood or treated vaguely as simply a water harvesting technique, amongst other things. Like permaculture, however, keyline is principally about design —- “… from pattern to detail.”
As a mining engineer, Yeomans came to farming with a unique outlook. He poured over maps, particularly contour maps, with the idea that there must be some pattern which would allow him to work cooperatively with nature’s forces. Allan Yeomans, his son, writes in the introduction to “The Challenge of Landscape”:
“He discovered that a contour line, that ran through that point of a valley, where the steepness of the valley floor suddenly increased, had unique properties. Starting from this line, and cultivating parallel to it, both, above the line, and below the line, produced off contour furrows, which selectively drifted water out of the erosion vulnerable valley. He named this contour “The Keyline”. The entire system became “The Keyline System”.”
Water is primary within the Keyline System but only because it is the first thing over which we may exercise some significant influence in what Yeomans calls “The Keyline scale of relative permanence of things agricultural.” What is more succinctly known as “The Keyline Scale of Permanence” includes:
- Climate
- Land shape
- Water supply
- Farm roads
- Trees
- Permanent buildings
- Subdivision fences
- Soil
One of Yeomans’ most important insights in comparison to his agricultural contemporaries was the recognition that soil can be built quickly. With something of a prophetic ring, he announces:
“Soil will improve until Australian soil everywhere is richer and deeper than nature has ever provided.”
Nevertheless, soil is last on the Keyline scale because, though most important, it is the least permanent. Yeomans sees soil improvement and fertility in general as a function of other more permanent factors with which we must first work:
“If the effect of climate on soil is fully understood, I believe we have a basic knowledge that will enable us to increase the fertility and productivity of any natural soil … While there are many ways of worsening the soil climate to reduce fertility of soil, and we have no doubt employed them all, there are, in my opinion, as many ways of improving the soil climate and increasing fertility … The fertility of good soil can be destroyed before a line of fenceposts will rot. A poor soil can be changed into a highly fertile soil in about a tenth of this time.”
This rapid improvement is achieved through adressing the items on the scale over which we have control in turn, beginning with the foundation of water:
“With full water control from Keyline planning, the farm environment improves, the soil improves; the pasture, crops and stock improve in health and their numbers may increase many fold with the growing capacity of the property.”
Keyline, then, while emplyoying amazing techniques for slowing, speading and sinking water into the landscape, is not just a technique. It is a system of planning or design for increasing fertility through harvesting sunlight while facilitating sensible placement of agricultural elements in accordance with their relative permanence. We’ll get into the geometry and detail of keyline in future posts —- for now, here are some links with great information about Keyline design:
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