News on this issue The main ecological threat posed by agriculture undoubtedly lies in the high levels of pesticide use in conventional farming – fungicides to prepare the soil, herbicides to control weeds and insecticides to control pests. Although some of the more persistent or hazardous pesticides have now been banned, new pesticides may also have negative effects that were unknown when they were initially brought into use. A case in point is the herbicide glyphosate, which has been shown to reduce fertility in mammals. In addition, pesticides have deleterious health consequences for those using them. The use of fertilizers also has negative consequences, particularly concerning water pollution as they can contribute to eutrophication of lakes and rivers (eutrophication is the enrichment of a water body by added nutrients, which results in a reduction in the oxygen content of the water and means that some organisms cannot thrive). Rivers can also be adversely affected by the input of ash and sediment, both of which result from farming practices. Organic farming has been booming in recent years, partly due to consumer realisation of the negative effects of pesticide use on the environment but also due to concern over pesticide levels in food. Organic farmers do not use any chemical fertilizers or pesticides on their crops, and do not grow genetically-modified crops either. The latter are a cause for concern for many people, and often incur the use of increased pesticides such as glyphosate. Habitats may be destroyed when creating additional agricultural land. In particular, wetlands may be drained. In Iceland, scientists and farmers have seen the negative effects caused by wetland drainage, and reclamation of grassland is under way. Photo of East Everglades Agriculture Area. Credit U.S. Fish and Wildlife Service, Stolz, Gary M.     Back