Fertilizer

Mineral fertilizers have played a pivotal role in the success of the agricultural production systems. Continued exponential growth in human population and increasing demand for biofuels point to ever-increasing demand for fertilizers. Despite the apparent success of the current agricultural production systems, overuse of fertilizers has caused severe environmental problems and increasing numbers of health concerns. Overapplication was, and in many places is still, thought to be an insurance policy against yield-limiting nutrient losses. Moreover, increasingly affluent societies have also changed their dietary preference dramatically increasing meat consumption. This demand has resulted in significant changes in animal agriculture with larger concentrations of livestock. The increase in concentration of animals has compounded environmental contamination problems associated with the disposal of the resulting manures. Overall, environmental and human health concerns associated with fertilizer overapplications are the result of two main problems: (1) the disruption of the natural nitrogen and phosphorus nutrient cycles because of the massive infusion of nitrogen and phosphorus fertilizers; and (2) the inadvertent release of heavy metals and radionuclides from mineral fertilizers and pathogens, veterinary pharmaceuticals, and endocrine disrupters from organic fertilizers. This article will discuss these issues and their environmental and health consequences in detail. Finally, a case study will be used to illustrate how agricultural landscapes can be redesigned to reduce these consequences.