Dr William Shotyk, Professor and Bocock Chair in Agriculture and the Environment was the ninth speaker for the Bentley Lecture in Sustainable Agriculture, held on 13 October 2011.
Abstract: Although soil is often referred to by many citizens as “dirt”, it is in fact one of our most precious, renewable natural resources. A complex mixture of mineral material, water, air, and organic matter, and full of living organisms, soil represents the interface between the lithosphere, atmosphere, hydrosphere, and biosphere, and represents the “critical zone” for life on earth. Healthy soil is not only the basis of our civilization because it supplies most of our food, but many materials and increasingly energy, are also derived from soil. Soil is an important water reservoir as well as water filter, and the chemical composition of our freshwaters begin their evolution when rainwater reacts with mineral and organic particles in soils. The organic component of soils represents an important carbon sink, helping to stabilize the global climate system; chemical weathering of minerals in soils is another important sink of atmospheric carbon dioxide. But soils are under pressure worldwide from development, erosion, depletion, contamination, and salinization. With the global population approaching 7 billion, per capita soil reserves continue to decline. Sustainable management of our soil resources, whether on the farm, in the forest, or in our cities, represents an important opportunity in stabilizing climate, preserving our water resources, maintaining biodiversity and preserving the health of the planet.