just as air and water are susceptible to pollution,soil is often our depository for human wastes such as sewage,garbage,and milling residues-sometime deliberately,sometimes thoughtlessly. depending on the technology employed,application of these wastes can contribute to the quality of soil or it can render them unfit for food crops. the most costly pollution cleanup site in the united states tend to be site with contaminated soil. many such site are military installations with organic fuels or solvents spilled on the ground,threatening surface or groundwater. other site, such as the hanford nuclear reservation in washington and the lawrence livermore national laboratory in california,have soil contaminated. when the chernobyl reactor exploded in 1986, 70 percent of the fallout landed on the republic of byelorussia;yet,because food shortages are so common to the region,crops and dairy products continue to be produced on the contaminated soil.