Landfarming is an ex-situ waste treatment process that is performed in the upper soil zone or in biotreatment cells. Contaminated soils, sediments, or sludges are transported to the landfarming site, incorporated into the soil surface and periodically turned over to aerate the mixture. Land Farming is a bioremediation technology. Contaminated soils are mixed with soil amendments such as soil bulking agents and nutrients, and then they are tilled into the earth. The material is periodically tilled for aeration. Contaminants are degraded, transformed, and immobilized by microbiological processes and by oxidation. Soil conditions are controlled to optimize the rate of contaminant degradation. Moisture content, frequency of aeration, and pH are all conditions that may be controlled. Land Farming differs from composting because it actually incorporates contaminated soil into soil that is uncontaminated. Composting also generally takes place in aboveground piles. A land farm must be managed properly to prevent both on-site and off-site problems with ground water, surface water, air, and food chain contamination. Runoff collection facilities must be constructed and monitored. The possible leaching of contaminants from the contaminated soil into the ground and groundwater is a major concern. Land Farming incorporates contaminated soil into soil that is uncontaminated, creating a larger volume of contaminated material. Therefore, the rate at which contaminants are degraded must be balanced with the potential of creating a larger body of contamination. Land farms must not be used to dilute contaminants. If it cannot be shown that biodegradation occurs for all contaminants of concern, land farming should not be used.