Pacific Organics & Yeomans Plow
805-440-3367
P.O. Box 301
Creston, CA 93432
pacificorganics@earthlink.net
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Keyline Design Concepts


Overview

"Keyline design was originally developed by P.A. Yeomans in the 1950s to address dwindling water supplies and soil erosion on Australian rangeland. He worked out a system of ‘amplified contour ripping’ that maximizes productive use of rainfall and facilitates the uniform irrigation of land. Keyline is a comprehensive whole farm water management plan that uses natural landscape contours and cultivation techniques to harvest rainwater and build soil fertility. The central idea behind keyline design from a water perspective is to capture water at the highest possible elevation and comb it outward toward the ridges using gravitational forces, reversing the natural concentration of water in valleys. Maximizing the flow of water to the drier ridges using precise plow lines falling slightly off-contour slows the movement of water and spreads it more uniformly, infiltrating it across the broadest possible area.

The Yeomans plow, sometimes called a keyline plow or subsoiler plow, is an effective technology for helping realize the keyline concept: it is a special chisel plow that loosens the sub-soil without inverting the soil. The small ridges created by the plow on the soil surface facilitate the movement of water downwards through the soil profile and direct the movement of water across the land. The plow also facilitates the transport of organic matter deeper into the soil horizon.
Additional Benefits

Soil Enhancement and Carbon Sequestration

Along with improved water management, enhancement of soil fertility is a key goal of keyline. P.A. Yeomans fundamentally believed that “…soil can be improved beyond its best natural or original fertility and the process is simple, rapid and economical.” The Yeomans plow effectively moves organic matter down through the soil horizon. The Marin Carbon Project is one effort in California working to document the potential of the Yeomans plow to sequester carbon in rangeland soils. The plow works by employing sharp blades on the forward face of the tynes to break up compacted soil. Each tyne has a foot on its base that combs lower layers of the soil, cracking open and aerating the soil, and allowing organic matter to travel downwards.


Erosion and Sediment Control

Keyline systems contribute significantly to erosion control by greatly reducing or eliminating the overland flow that transports topsoil. Keyline systems slow the transport of water, spread it out across a larger area, and sink more of it into the soil, minimizing water erosion and controlling salinity. As a result, the output of sediment-laden water to streams is reduced, which also benefits the aquatic environment in California’s streams and rivers. Keyline also builds healthier soils that are less prone to erosion. The cultivation pattern helps to spread water evenly, stabilizing valleys and further preventing erosion.

Flood Control, Stream Enhancement, Groundwater Recharge, and Watershed Health

By capturing and retaining water, keyline systems help control flooding. The net effect of keyline is to flatten hydrograph peaks, reducing flooding during storm events by storing more water in the soil and in storages, and allowing stored water to seep back into waterways over a much longer period of time. The implementation of keyline plans on multiple farms and ranches in a given watershed can significantly benefit the health of the watershed as a whole, as well as local fisheries and other water-dependent industries such as tourism. Keyline can lengthen the run of seasonal creeks, augmenting supply in drier summer months and improving the quality of water that is returned from farms to waterways. Keyline can also contribute to groundwater recharge, improving the health of wells and in particular increasing water security in alluvial valleys."
Dolman, Brock. "California Agricultural Water Stewardship Initiative: Keyline Design." California Agricultural Water Stewardship Initiative: Keyline Design. Occidental Arts and Ecology Center WATER Institute, n.d. Web. 29 Jan. 2014.