Spatial variability of soil bulk density at coffee-crop plot level. Variabilidad espacial de la densidad aparente del suelo a nivel de lote en café.

Bulk density (Bd) relates to other soil physical and chemical properties, provides information about its use and management, and affects directly plant growth. The spatial variability (vertical and horizontal) of Bd at coffee-crop plot level was studied in two cartographic soil units, an andisol at the experimental station La Catalina known as Chinchina, and an inceptisol located in Marsella municipality known as 200. In each site a plot of 2.5 ha (210 x 120 m) was selected for a systematic grid sampling every 30 m, and measurement of Bd at depths of 0-5, 5-10, 10-20 and 20-30 cm. The data were analyzed using descriptive statistics and geostatistics. The respective semivariograms were determined and later adjusted using mostly spherical models; then the variability maps were generated by interpolation using Kriging. The analyses allowed to find greater horizontal variability than vertical. and sampling distances to find spatial variability of Bd at the depths of 0-5, 5-10, 10-20, and 20-30 cm, were respectively 288, 149, 123 and 113 m in Chinchina, and 93, 113, 112 and 103 m in the 200 soil unit. These maps aim to guide specific management activities at the plot level in order to optimize crop production.