Water contamination by nitrate and pesticide in a small watershed under tobacco cultivation

摘要

Tobacco is usually seen as a "dirty crop" due to its risk to human health, both for producers and for smokers. Nevertheless, in many countries the crop has important social and economical impacts. Watershed is the unit where conservation strategies should be planned to favour soil and water conservation and amelioration. Thus, herein we present results on nitrate and pesticide contamination of surface and shallow well waters, in a small watershed under tobacco production. In the watershed with shallow soil and steep slopes, high potential for water resources contamination cropped to tobacco and rapid decline in soil productive capacity and in water quality were observed. The following elements lead to soil and water degradation: improper agricultural practices, utilization of high doses of fertilizers and pesticides, absence of riparian forest, and intense soil use. A shift in agricultural practices is needed in the short term, by including soil, water and wildlife conservation strategies, whereasa change in cash crop, in the long term, is necessary to replace tobacco cultivation.