P. A. Yeomans

Who was P. A. Yeomans?

Percival Alfred Yeomans looked at a farm the way an engineer looks at a mine: as a body with an inner structure that can be read. What he read in the land was water. From that reading he developed Keyline design, one of the most influential ideas in ecological land use of the 20th century: a way of shaping cultivation, dams and channels so that rain is caught, spread across the slope and allowed to soak in, instead of rushing down the valleys and taking the soil with it.

He worked in the dry, erosion-prone farmland of New South Wales, on land as demanding as much of the Mediterranean. That is why his ideas speak so directly to a dry slope in Sardinia.

His path

Yeomans was born in 1905 in Harden, New South Wales. He first made his way in mining, as a mining engineer and gold assayer, and there gained the sense for the flow of water and for the design of machines that would shape his later work. After his brother-in-law died in a grass fire, he turned to running farmland; in 1943 he bought two properties near North Richmond on the Hawkesbury River, Nevallan and Yobarnie.

On these farms he began, from the mid-1940s, about fifteen years of patient experiments: building farm dams, laying out channels, trying new ways of cultivation and observing what happened to water and soil. In 1954 he published the first results in The Keyline Plan. In later life he devoted much of his time to advising, lecturing and writing. He died in November 1984, aged 79.

The idea

Yeomans started from a simple observation. In every valley there is a point where the flatter valley floor suddenly becomes steeper: the keypoint. The contour line through this point, the keyline, became his guide. Dams placed at the keypoint can store water at a height from which it can later flow by gravity. Cultivation that runs parallel to the keyline, slightly off the true contour, leads water from the wet valleys towards the drier ridges, where it has more time to infiltrate into the soil. In this way the same rain that would cause erosion in one place waters the land in another.

His second great idea was an order for planning. In his Scale of Permanence, the elements of a farm are listed from the most lasting to the most changeable: climate, land shape, water supply, roads and access, trees, buildings, fences and finally soil. Whoever plans in this order fits the changeable things to the permanent ones and does not build the farm against its own landscape. It is striking that soil comes last: for Yeomans it was not a fixed given but something that could be built up quickly with the right care.

The work

To make his ideas workable, Yeomans designed his own equipment. The best known is the Keyline plough, a subsoil cultivator with narrow tines that loosens compacted ground without turning the soil, so that water and air can enter. Family and company accounts also credit him with pioneering on-farm irrigation dams in Australia. Farmers and manufacturers report better infiltration and deeper, more fertile soil after Keyline cultivation; independent long-term measurements of the plough's effect remain rare, so these results are best understood as experience from practice.

He wrote four books: The Keyline Plan (1954), The Challenge of Landscape (1958), Water for Every Farm, which was later revised and republished several times by his son Ken Yeomans, and The City Forest (1971), in which he proposed applying Keyline methods to forests around cities. His family carried his work forward, publishing his books and building ploughs under the Yeomans name.

What became of it

Keyline found its way into permaculture early on: David Holmgren used it extensively in his designs, and the scale of permanence became part of permaculture teaching worldwide. Today it is also a foundation of regenerative farming approaches, and in Germany the Seepage Line System has developed it further. In 2013 Yobarnie was added to the State Heritage Register of New South Wales as one of the two farms where the Keyline system was first developed and demonstrated, a rare honour for a piece of farmland and the ideas grown on it.

What we learn from P. A. Yeomans

From Yeomans we learn the order of things. Climate and the shape of the land are given; water comes next, and only then paths, trees, buildings and soil. At Sa Medada, a steep and summer-dry slope in Sardinia, this order is our guide: first understand where the water runs, then decide where to plant and build.

We also learn from his way of reading the land. Every slope has its keypoints and its lines, and whoever recognises them can guide rain instead of losing it. The heavy plough is not suited to every terrain, especially not to shallow, stony slopes; what we take over is his way of seeing: to keep the rain where it falls and let the land drink.