Keyline design

Yeomans described a system of amplified contour ripping to control rainfall runoff and enable fast flood irrigation of undulating land without the need for terracing it.

Contour plowing both above and below the keyline and parallel to it ipso facto is "off-contour", but the developing pattern tends to drift rainwater runoff away from the center of the valley and, incidentally, prevent erosion of its soil.

This ipso facto develops a pattern of off-contour cultivation in which all the rip marks made in the soil slope down towards the center of the ridge.

Cultivation following Keyline pattern also enables controlled flood irrigation of undulating land, which increases the rate of development of deep, fertile soil.

In many nations, including Australia, it is important to optimize infiltration of rainfall, and Keyline cultivation accomplishes this while delaying the concentration of runoff that could damage the land.

The limitations of the traditional system of soil conservation, with its "safe disposal" approach to farm water, was an important motivation to develop Keyline design.