Mohawesh O., Fukumura K., Ishida T. and Yoshino K. (2005).

Abstract

Site-specific crop management requires consideration of the spatial variability within the field. Spatial distributions of soil and canopy properties at the field may affect yield potential, hydrologic response, and solute transport. Thus, describing within-field variability is a fundamental first step toward determining the size of management zones. This study is being conducted at an arable flat cassava plantation area in northeast part of Thailand. Soil is generally Rhodic Kandiustox, and its texture is clay. Dry bulk density, volumetric soil water content, Leaf area index (LAI), and plant height were measured at mesh points on site. Dry bulk density and volumetric water content were measured at depth 0-6 cm. Statistical and additional geostatistical analyses were applied on the measured properties. The correlation coefficient between LAI and plant height was significant. Spherical model best fitted all the experimental semivariograms. The range values of the measured properties were about 30 m. All the measured properties exhibited strong spatial continuity. Among the measured properties LAI exhibited the strongest spatial correlation; plant height exhibited the weakest spatial correlation. The cross-validation showed the goodness of the fitted semivariogram models. The semivariogram model of the dry bulk density was used to estimate the distribution of soil hydraulic parameters in the field. Distribution of soil hydraulic properties across the field can be combined to give useful input for numerical models to simulate water movement and distribution.

J. Japan Soc. Hydrol. and Water Resour., 18 (5), 501-509.

Keywords: dry bulk density, soil hydraulic properties, canopy structure, spatial variability.