“…Therefore, the electrostatic adsorption by the surface positive charges of soil minerals plays an essential role in retarding NO 3 -leaching (Ji, 1997;Dynia & Camargo, 1999;Alcântara & Camargo, 2010;Harmand et al, 2010). However, along with the amount of soil positive surface charges, other factors such as aquifer depth, local rainfall, rate and frequency of N fertilization, N uptake efficiency of crops, irrigation management and soil properties (e.g., porosity, texture and mineralogy) must be taken into consideration to assess the risk of groundwater contamination by NO 3 - (Resende, 2002).…”