ABSTRACT
A study was conducted to evaluate the influence of agricultural lime (CaCO3) on the movement and uptake of inorganic nitrogen for a sweet pepper crop (Capsicum annuum) grown on an Oxisol soil (Coto clay) in north-west Puerto Rico. The Coto clay soil, which contains the 1:1 kaolinite mineral, has a low pH (4 to 4.5). The 1:1 type clays are known to possess a net positive charge at low pH, resulting in the adsorption of negatively charged ions such as nitrate. From an environmental standpoint this characteristic of the 1:1 clay is favorable, since nitrate leaching, a major cause of groundwater pollution in many areas, is reduced relative to soils with net negative charge. However, agricultural plants, such as sweet peppers, favor a higher soil pH (approximately 6.5), which can be obtained by the application of agricultural lime. This, however, may have the negative effect of increasing the potential for nitrate leaching, as the net charge on the soil particles becomes negative with increasing pH.
