Fernando Álvarez Mejía

Physical variables that explain alluvial soil variability and their spatial behavior

The objective of this work was to use the principal component and semivariance analyses to select physical variables that could explain the variability of an alluvial soil, in order to establish the spatial behavior of the chosen variables so that the location of experimental plots could be technically defined to study the abrasiveness effect on the wearing away of farm equipment. Field tests were performed in 2008, on a 6,000 m2 flat lot with medium to heavy soil texture (Vertic Haplustepts). An intensive sampling was done in a grid of 10x14 m. The variables which had the most weight on the first three principal components were the contents of silt, fine and intermediate sand, intermediate gravel, soil moisture at field capacity, and the hygroscopic coefficient. Except for the half sand and the field capacity, the other properties showed a high spatial dependence, and their distribution showed that in the experimental plot there are three sectors of differential accumulation of silt and fine sand. The combination of principal component analysis and geostatistics allowed for defining the soil properties involved in the wear of tools, their spatial pattern and the most appropriate way of distributing plots to study soil abrasiveness.

Impactos y plan de manejo ambiental de la labranza convencional

En el presente articulo se senalaron los impactos principales de la labranza convencional; una metodologia para su evaluacion, y finalmente se sugiere un plan de manejo ambiental. Con el estudio del impacto ambiental (EIA), se identifican y predicen el impacto de proyectos y/o propuestas de mecanizacion agricola y en particular de la labranza del suelo. Con la eleccion de adecuados indicadores se hace posible que el desarrollo sostenible sea cuantificado y que tenga continuidad en el tiempo. Abstract In the present paper the main impacts of the conventional tillage were indicated, a methodology for their evaluation, and finally a plan of environmental management is suggested. With the study of the environmental impact (EIA), the impact of projects and/or proposals of agricultural mechanization are identified and predicted and specifically of tillage soil. With the selection of appropriate indicators is possible to quantify the sustainable development and that has continuity in the time.