Temporal variability of chemical properties in a soil with three cultivation systems

This study has been carried out at the Experimental Station "La Poveda" in Arganda del Rey (Madrid), with the following geographical coordinates: lati tude 40 degrees 19' N; longitude 3 degrees 19' W Gr; and altitude 550 m The main objective was to study the temporal variability of chemical propertie s in a soil with three cultivation systems. In order to study variation wit h time of chemical characteristics, samples were taken in February and Sept ember 1993 and February and September 1994. Organic matter content in the p rairie/vetch-oat system had the smallest variation coefficient with respect to barley and vetch-oat/sunflower systems. Along with the time the barley/ barley system presented a lower organic matter content. The crop systems pa sture/vetch-oat and vetch-oat/sunflower presented an organic matter content 42.86 and 40.54% higher than that presented by barley/barley system, respe ctively.