GEOSTATISTICAL ANALYSES OF TRACE-ELEMENTS IN SOILS AND PLANTS

Statistical and geostatistical analyses were conducted to estimate both correlation and spatial distributions of trace elements in soils and plants within a corn field. Statistical analysis of AB-DTPA-extractable trace elements in soils and the total elemental content of plants indicated that Mo in corn leaves was negatively correlated with soil Cu and Fe. Copper aggravates Mo deficiency in plants because Cu interferes with the role of Mo in the enzymatic reduction of NO3. Geostatistical analyses of the soil trace elements, Cu, Zn, Mn, Fe, and Mo, showed that these elements were spatially interdependent. Iron, Mn, and Mo in corn leaves were spatial variables characterized by linear, spherical, and exponential variogram models, respectively. However, Cu and Zn contents in corn leaves were randomly distributed in the field. Using the relationship between soil Cu and plant Mo, and a cokriging technique, plant Mo estimation was significantly improved by incorporating the soil Cu information. Compared with kriging, cokriging reduced the mean error of the estimates by about 5 times, reduced the mean square error and the mean kriging variance up to 48%, and increased the correlation of estimates and measurements from 0.49 to 0.61.