Waste disposal nutrient pollution

In recent years, improper disposal of various waste materials has posed serious threats to surface and groundwater supplies and developed into a global scale soil and water pollution problem [1], Heavy metals account for much of the contamination found at hazardous waste sites in the United States, and have been detected in the soil and groundwater at approximately 65% of the U.S. Environmental Protection Agency Superfund sites [2], Dramatic increases in land application of agricultural and municipal biosolids have accentuated the problem. In spite of their beneficial contributions as nutrient sources and soil conditioners, these amendments, if not monitored, pose a considerable environmental risk because of their high heavy-metal concentrations [3],... 

Until better solutions to the problems of disposal of animal manures have been developed, it seems to me that it is best to continue, so far as possible, to follow the age-old practice of returning the manures to the land as directly and efficiently as possible. The soil denatures the wastes more effectively than do other methods, such as the lagoon system. This efficiency, together with the conservation of natural resources, and avoidance of pollution of streams and groundwaters, constitute a strong argument for continuation of past practices even if the expense involved is higher than the value of the nutrients that are conserved. 

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