Percival Alfred (P.A.) Yeomans
This blog post is the third of the series of our in-depth look on the Harvesting of Rainwater Checklist! This is not my first blog post on Keyline Design. With this blog post, I get to go into the Keys of Keyline Design and further into the benefits of the design work made famous by P.A Yeomans. He didn’t start out as a farmer or agriculturist; He was an Engineer. P.A Yeoman was left with ‘Nevallan’ in New South Wales when his brother in law (Jim Barnes) died in a grass fire in 1944. In the late 1940’s and into the 1950’s P.A Yeoman developed Keyline Design in response to the unpredictable weather patterns on his new property. The foundation of the Design is in the understanding and implementing around the Yeomans Scale of Permanence.
Scale Of Permanence
The Scale of Permanence is the prioritization and the relativity of the elements and the level of impact needed to change a specific element. At the top of the scale is Climate and that’s because there’s no level of change we can make on the element of climate. The land shape follows as we go down the list of elements. The next element is water where we can plan the water features such as on-farm irrigation dams and open contoured channels to change the element. The roads we build, follow on the scale after water and before trees. The groups of trees will wind through undulations in the landscape and form tiered arrays above and below the channel lines. The best building sites reveal themselves and subdivision fence lines can be built. Next on the Scale is fencing. Lastly on the scale is the most changeable element; soil!
The Scale of Permanence & Soil
The soil is the most changeable of all of the elements on the scale of permanence. The human interaction can so easily change that most of the time our reaction to the soil is in a negative response. However, Yeoman has been attributed with being the first person to accelerate soil formation through stacking of different methods. Repealing the ideology that soil takes a thousand years to create an inch of fertile topsoil.
Hydrology & Geology as it applies to Keyline Design
Yeoman’s background as a mining engineer and gold assayer, he understood that when you change the shape and design of the earth within geology, you’re also changing the hydrology around it. That’s why it’s so important that you’re researching and planning accordingly when choosing a rainwater harvesting method that changes the geology because the consequences of mistakes within those changes can lead to disasters.
Hydrology and Water Feature Designs
Water is key in any land development! Understanding the Hydrological cycle is important in understanding water design. I do want to mention that I will be posting a blog dedicated to the Hydrological Cycle in itself in the near future.
The Keyline is the contour line within a primary valley that goes through the key point, and the key point is the point in primary valleys where the slope goes from convex to concave, where the steeper slope of the valley becomes flatter.
In the Design, everything follows the flow of water. Water flowing over land will have a predictable path of movement. The contour lines, the flow will be perpendicular to the contour forming shallow S-curves from the ridge to the valley.
Keyline Pattern of Cultivation is a series of lines parallel to the Keyline which are off contour. They are only close to contour when next to the key line.
Yeomans Plow: Keyline Plowing
Keyline plowing is a form of subsoiling. Yeomans Plow is a Subsoiler tool used for tillage and breaking up soil. The Keyline plow should be integrated with liquid organic fertilizers distribution systems and seeding machines for the best results.
Rhamis Kent, one of our main instructors for World Permaculture Association Permaculture Design Course, has an article on TERA (TRACKED EARTH REPAIR APPARATUS) FOR LARGE SCALE EARTH REPAIR that mentions the Yeomans plow. The use of the right type of tractor (that pulls the plow) is important because with the right tractor you are improving the hydrology with the Keyline Plow. The risk of using the wrong plow can compact the soil.
Swales Vs. Keyline
So two weeks ago I did a Blog post on Swales, now we are moving onto a new rainwater harvesting method and your asking which is better? Let’s first start off by saying each development of land is different and unique. There are different types of harvesting methods within Permaculture because of each piece of land has ecological elements you have to work within (not against)! As a farmer, agriculturist, and permaculturist I have personally used swales as well as keyline. However, Keylines are standardized within a pattern and have equal recurring distance apart.
The Standardization of the Keyline is better for larger scale farms. Keyline also makes the placement of the lower scale of Permanence elements easier to design around such as roads. I do want to REPEAT that picking a Design Or method depends on your end goal results, your climate, your topography, your resources, your site, and your soil. That’s why the scale of permanence is so important.
The key to developing any method of rainwater harvesting method is a good understanding of topography. The understanding of each natural and human-made element that’s within or on the surface of your land. How they work and affect each other is extremely detrimental. The tools we have for mapping topography that wouldn’t have been imagined in 1944 makes this task easier. The availability of tools such as Aerial Photography, GIS, and Drones. Rhamis Kent has an article on 3D ORTHOGRAPHIC MAPPING to better understand these technologies. I believe its time that Permaculture embraces these technologies to produce a better understanding. We are at the age of time where technology is going to increase, and we will be able to look and understand whole systems with a better appreciation!
Whole System Thinking
Whole Systems Thinking is a method to understand how elements and systems are related. How they influence one another within a whole. Other parts of the whole system thinking when it comes to Keyline Design is Holistic Management and Carbon Farming Systems. Those systems are for another blog on another day so stay tuned for those.
Put this Key on your keyring of designs and methods of rainwater harvesting and Permaculture practices to unlock stainability, abundance, and landscapes without wildfires and drought.
Stay Tuned. . . Next Monday’s Blog Post will be on the Vallerani System!