Tesis presentada para optar al Grado de Magíster en Manejo de Suelos y Aguas / On a global scale, natural biogeochemical cycles are being overwhelmed. Fertilizer and atmospheric deposition dominate total anthropogenic nitrogen (N) inputs to the temperate regions as a whole, with fertilizer accounting for roughly two-thirds of the total (Howarth et al., 1996). On agricultural land, crop and livestock production systems are the largest cause of the global N alteration (Bouwman et al., 2011), with most of the N applied in annual production systems being lost (Robertson and Vitousek, 2009). Moreover, N availability to plants is difficult to predict, since organic matter turnover processes and losses influence the availability (Sørensen, 2001).