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This week's Book of the Week feature is Water for Any Farm, by Mark Shepard.
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Chapter 6: The Fundamentals of Keyline Design
This book is not intended to be a replacement for all of the available information on the Keyline design system. It is merely intended to be a description of the various farm- and ranch-scale water management systems at our disposal in the United States, including the basics of Keyline design. For those interested in learning more about any of the systems we discuss, that information can be sought out in-depth elsewhere.
Arguably P. A. Yeomans’s most significant discovery with the development of the Keyline design system was the magic of landscape geometry. By knowing the locations of the keypoints and Keylines on a piece of land, you can employ some ridiculously simple techniques to synchronize with the basic geometric shape of the land and radically change how that land interacts with water. It all starts with what Yeomans referred to as Keyline Pattern Cultivation. In his own words,
"The objective of the pattern in Keyline pattern cultivation is to direct the shallow overland flow, which results from rainfall run off, to remain evenly spread and not follow its natural flow path to concentrate in the valley shapes. The same technique also provides the means for evenly spreading the water in the system of “hillside” irrigation named “Keyline Pattern irrigation.” It is the Keyline pattern cultivation that can convert what is commonly called “wild flooding” into fully controlled irrigation."
THE PRIMARY VALLEY CULTIVATION PATTERN
“Keyline pattern cultivation of a primary valley is done parallel to and on the lower side of the Keyline or any other approximately contour guide line in the valley area below the Keyline.”
Simple! Simple, but brilliant. In order to keep things as simple as possible, let’s look at a relatively simple (for the United States) landform on a topographical map. Figure 6.1 is a topographical map with the keypoint in each of two primary valleys marked with an asterisk. Beginning at the keypoint, the Keyline of each primary valley is marked in bold. The Keyline is the reference line from which the valley cultivation pattern is derived. All fieldwork in the valley is done parallel to and downward from the Keyline. The dotted lines in Figure 6.2a represent the path that one’s equipment would take in that primary valley whether it be a plow, a mower, or hay baler. Notice, though, that this pattern only goes as far as where the side walls of the primary valleys become steeper and the mouth of the valley opens outward (the turning outward of your wrists in the breadbowl demonstration). This is the extent of the primary valley cultivation. Be sure to look closely at the contour lines in the valley in relation to the cultivation lines. As cultivation proceeds in parallel below the Keyline, the tractor begins to make lines that start at a higher elevation in the valley center then gradually drop in elevation as they go toward the ridge. When cultivating a valley below and parallel to the Keyline, the tool marks, furrows, and wheel-tracks all cause the valley water to drift toward the ridge instead of following their former path directly downslope to the valley floor. Later on in a grazing system, the pathway of animals moving through the paddocks follows and reinforces this pattern as well.
From now into the future, all activity on the land helps to cause water to drift from the valleys to the ridges. This is the way we divide up any overland water flow in the primary valley and get it to spread out toward the ridge. As it drifts toward the ridge, it is soaking into the ground and distributing water to areas whose shapes have already caused water to migrate to the valleys. Keyline pattern cultivation has just reversed the general trend of water in the landscape. Instead of water flowing downhill off the ridges and moving into the valleys, Keyline patterning brings water from the valleys back out onto the ridges. Well, at least that’s what Yeoman’s says they’re supposed to do.
As one can see in Figure 6.2a, the Keyline cultivation pattern doesn’t really work for the primary valley on the right. The left (western) leg of the uppermost parallel below the Keyline actually pitches toward the center of the primary valley and not toward the ridge like Yeoman’s said it would. I know of hundreds of people attempting to set up the Keyline cultivation pattern on their property who have encountered situations like this, and one of the first things people think to themselves is, “have I done something wrong?” Hmm . . . maybe we have! Maybe what we thought was the keypoint was actually the wrong spot. What if we “adjusted” things by choosing another location as the possible keypoint?
In order to see what such a change might do, in Figure 6.2b we deliberately moved both originally marked keypoints, generated a new Keyline and then drew some parallels below the Keyline to see what this would do (remember . . . whether you’re sketching on a paper map or a computer, changing the location of a line at this stage is quite affordable. Once you start to lay out new field cultivation patterns, install terraces or move fences, things get more expensive).
When we began to make parallel passes with equipment below the new Keyline in each primary valley, surface water will indeed follow the cultivation pattern and move from higher in the primary valley out toward the ridges just like Yeoman’s said. Choosing a slightly different location for the “keypoint” (understanding that this location might be some place other than an actual geographic keypoint) is one of the simplest adjustments that one can do to help adjust a system where the landform does not actually behave according to “Keyline geometry.” Primary Valley cultivation isn’t the be-all and end-all of Keyline pattern cultivation, however. There are also primary ridges to consider.
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About the Author:
Mark Shepard heads Forest Agriculture Enterprises and runs New Forest Farm, an 106-acre commercial-scale perennial agricultural ecosystem that was converted from a row-crop grain farm. Trained in mechanical engineering and ecology, Mark has combined these two passions to develop equipment and processes for the cultivation, harvesting and processing of forest-derived agricultural products for human foods and biofuel production. Mark is a certified permaculture designer and teaches agroforestry and permaculture around the world.
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Titles of Similar Interest:
- Growing Food in a Hotter, Drier Land, by Gary Paul Nabhan
- The Drought-Resilient Farm, by Dale Strickler
- Water in Plain Sight: Hope for a Thirsty World, by Judith Schwartz