Using Chemistry to Sustain our Soil
As resources become more precious through our need for uncontaminated water, productive soils, and sustainable energy sources, we need to find ways to harvest them without harming the environment. When the environment has been compromised with careless or unintentional practices, we need to determine the most effective ways to restore it.
Soils may be one of our most important resources. In agricultural systems, soils can hold water and nutrients until crops need them. As the costs of fertilizers rise and the environmental price of using excess nutrients damages water supplies, the role of the soil to supply nutrients as they are needed and with minimal input from fertilizers becomes paramount. Soils in the Palouse, for example, have abundant stores of potassium, but this essential macronutrient is tied up in minerals that can dissolve too slowly to meet a crop’s requirement. Dr. James Harsh is working with other scientists in soils, geology, and physics to determine the mechanism of potassium weathering from soil minerals and the role of microorganisms in the process. This knowledge will help us to answer the question “What is a healthy soil?” and design management systems that allow efficient and sustainable use of soil nutrients.
Soils also protect the water supply from harmful contaminants. When plutonium was produced at the Hanford Site during World War II, waste materials including radioactive elements, toxic metals, and organic solvents were released to the soils and sediments. The soil is acting as a filter for many of these contaminants, slowing their transport to groundwater and the Columbia River. Dr. Harsh has been working with Dr. Markus Flury, a soil physicist in Crops & Soils, to determine how the interaction of these chemicals with mineral particles determines their mobility. Working with scientists from national laboratories at Hanford, Los Alamos, and Idaho Falls, they recently determined that radioactive cesium could ride “piggyback” on mobile colloidal particles, but was quickly stripped off and fixed by the soils and sediments. As a result, cesium will not reach groundwater before losing most of its radioactivity.
James B. Harsh, Ph.D.
Professor / Scientist
Crop and Soil Sciences
Washington State University
PO Box 646420
Johnson Hall 245
Pullman, WA 99164-6420
Dr. Harsh came to WSU in 1983 after earning three degrees from the University of California at Berkeley in conservation of natural resources and soil science. He has always been interested in the interface between agriculture and the natural environment and how we can use chemistry to solve problems of contaminant fate and nutrient availability. A crop sharing arrangement with a family farm in Iowa and a home garden keep him in touch with the land on a practical level. Work with other scientists in physics, biology, geology, and engineering, keep him from looking at the world too narrowly. He has collaboratively published 54 referred journal articles and nine book chapters.