Organic, inorganic and total soil carbon stocks are partially controlled by exposure to environmental conditions, vegetation cover and land use. Geostatistics has helped to understand the distribution of carbon stocks (organic, inorganic and total) in the soils. However, there is little explanation of factors that determine it, specifically arid regions, and their spatial variability. The objectives of this work were to determine the organic and inorganic carbon reserves in agricultural soils of the Comarca Lagunera in Mexico, to establish their distribution and spatial variability using ordinary kriging and to validate the thematic maps whit real data. The correlation spatial of organic, inorganic and total soil carbon stocks of georeferenced samples were examined by an analysis of semivariance; the data were interpolated to obtain thematic maps of prediction of the different carbon stocks. Subsequently, the maps were validated with field data. The organic, inorganic and total soil carbon stocks showed spatial correlation, which was weak for the soil organic carbon storage (82.4%), and moderate for the inorganic and total carbon (26.6 and 35.0%, respectively). The thematic maps of organic and inorganic carbon stores differed, with the inorganic carbon map having an error of 2.01 Mg ha-1 , which was lower than that of organic carbon (4.69 Mg ha-1). The use and management of soils in this area influenced the spatial distribution of carbon stocks, while physiography, parent material and climate intervened in the spatial distribution of inorganic carbon.

The objectives of this study were to identify and rank the covariables of soil-forming factors that affect the distribution and spatial variability of pH in an agricultural area and to obtain a predictive map of soil pH. Samples of topsoil were obtained from different sites and taken to the laboratory, where they were prepared to determine the pH, organic matter, and percentages of particle size. In addition, the values of environmental covariables that affect pH were obtained. A database of the coordinates, laboratory results, and values of the covariables was constructed. Principal component analysis of the covariables was performed, and an analysis of the pH spatial structure was conducted and interpolated to obtain a predictive map of pH. Of the soil physical characteristics, the covariables clay and sand had a greater influence on the spatial behavior of pH with respect to the rest of the covariables of soil-forming factors, while human activity acted as a catalyst of the acidification process. Soil pH exhibited autocorrelation and moderate spatial dependence (66.7%) and was thus spatially predictable. The pH prediction map was accurate (RMSE = 0.158 and MEB = 0.020).

El contenido y comportamiento del carbono orgánico del suelo (COS) en regiones áridas; a través, del tiempo son desconocidos, aun cuando las enmiendas de estiércol bovino en estos suelos han tomado importancia en los sistemas agrícolas extensivos de esas regiones, no existe información que revele los cambios en el estatus del COS. Por tal motivo, los objetivos de esta investigación fueron establecer la distribución del contenido de COS del municipio de Matamoros, Coahuila y determinar los cambios en su concentración, través del tiempo. Muestras de suelo de la capa superficial (0-30 cm) en el año 2015, se colectaron, para estimar el contenido de COS. Estos datos y sus georreferencias se utilizaron para realizar una interpolación con el método geoestadístico Krigin Ordinario y obtener un mapa temático de distribución de COS. Asimismo, datos base de COS del año 2002, adquiridos de un trabajo previo, se emplearon para obtener otro mapa temático del municipio. Los mapas fueron comparados con una tabla de referencias cruzadas y con el índice de concordancia Kappa (ICK). Los resultados mostraron que los mapas no son iguales, como lo confirmo el ICK= 0.1, de tal manera que en trece años el COS se incrementó 65 511.88 Mg. La determinación del contenido de COS y el establecimiento de su distribución espacial, así como su comparación con datos y mapas base de COS existentes, permitieron determinar los cambios en los contenidos de COS a través del tiempo.