Complementing Keyline's water storage system is a uniquely remarkable soil building method that enables the rapid conversion of depleted subsoils into rich, living topsoil. Keyline soil conditioning consists of two primary components - non-inversion tillage (aka subsoiling) and appropriately timed high-density grazing.
Conventional tillage typically relies on the use of a moldboard plow which inverts soil layers, thereby destroying the complex web of soil life. Non-inversion tillage, on the other hand, refers to the use of a 
tractor implement fitted with a number of rigid shanks that rip through the soil profile, acting to decompact degraded soils and provide channels for water infiltration and absorption. The use of a subsoiling plow in pastures creates optimal conditions for the proliferation of soil life - the workers who attend to the stabilization and enrichment of degraded soils. There are a number of different types of subsoiling plows that exist, the chisel plow being a poor but moderately effective one. The Yeomans Keyline Plow, developed by P.A. and Allan Yeomans is widely regarded as the 'Rolls Royce' of subsoiling implements.
The second component of Keyline soil conditioning is well-timed intensive grazing. Once a particular paddock has been subsoiled, the pasture plants are left to regrow until just prior to the formation of young seed heads (at the point of maximum vegetative growth). At this point, livestock are turned out onto the paddock and allowed to graze plants to the ground. This disturbance has several effects...
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With the loss of their aerial parts (leaves and stems), the root systems of these plants die back, making available massive quantities of organic matter in the soil. This organic matter is the catalyst food source for the soil life that transform the soil's structure, character and fertility.
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Additionally, the livestock's manure deposits return another rich source of fertility to the pasture, providing additional food to soil-borne organisms.
It is through this two-part process, repeated over the course of three years, that Yeomans has observed and reported the development of 12-18 inches of healthy, living topsoil. It should be noted that, to this point, no known controlled studies have been carried out to actually record and quantify the effects of Keyline soil conditioning. That is until now. Mark Krawczyk (EcoSystems Design Inc., and Keyline Vermont) and Ethan Roland (AppleSeed Permaculture) have prepared a USDA grant proposal that if awarded, will measure the results of Keyline soil conditioning over a two year period. Download a copy of the proposal here - KeylineProposal_v10.pdf
