title: Response of soil inorganic nitrogen to land use and topographic position in the Cofre de Perote volcano (Mexico).
abstract: This study addressed the effects of land use and slope position on soil inorganic nitrogen and was conducted in small watersheds. The study covered three land use types: tropical cloud forest, grassland, and coffee crop. To conduct this research, typical slope small watersheds were chosen in each land use type. Slopes were divided into three positions: shoulder, backslope, and footslope. At the center of each slope position, soil sampling was carried out. Soil inorganic nitrogen was measured monthly during a period of 14 months (July 2005-August 2006) with 11 observations. Significant differences in soil NH(4) (+)-N and NO(3) (-)-N content were detected for both land use and sampling date effects, as well as for interactions. A significant slope position-by-sampling date interaction was found only in coffee crop for NO(3) (-)-N content. In tropical cloud forest and grassland, high soil NH(4) (+)-N and low NO(3) (-)-N content were recorded, while soil NO(3) (-)-N content was high in coffee crop. Low NO(3) (-)-N contents could mean a substantial microbial assimilation of NO(3) (-)-N, constituting an important mechanism for nitrogen retention. Across the entire land use set, the relationship between soil temperature and soil inorganic N concentration was described by an exponential decay function (N = 33 + 2459exp(-0.23T), R (2) = 0.44, P < 0.0001). This study also showed that together, soil temperature and gravimetric soil water content explained more variation in soil inorganic N concentration than gravimetric soil water content alone.
authors.affiliation: Instituto de Ecología, A. C.,Veracruz, Xalapa, Mexico. adolfo.campos@inecol.edu.mx
authors.forename: Adolfo
authors.initials: A
authors.lastname: Campos C
mesh_terms: D003247:Conservation of Natural Resources; D004784:Environmental Monitoring / Q000379:methods*; D008800:Mexico; D009584:Nitrogen / Q000032:analysis*; D012987:Soil / Q000032:analysis*
chemical_list: D012987:Soil; D009584:Nitrogen