THE USE OF MULTIPLE-VARIABLE INDICATOR KRIGING TECHNIQUE FOR THE ASSESSMENT OF THE SUITABILITY OF AN ACID SOIL FOR MAIZE

For adequate quantification of soil quality, specific indicators need to be measured spatially. The choice of indicators, however, depends o n the use to which the quality assessment is to be put. The Multiple-V ariable Indicator Kriging (MVIK) method provides a novel means of inte grating these factors into a single index. The quality of virgin farml and for maize (Zea mays L.) farming was evaluated on a 250 m x 250 m p lot. Soil samples were collected from 100-cm-deep auger holes dug on 3 0 m x 30 m grids in the field. Soil pH, cation exchange capacity, exch angeable Al++, organic C, and soil depth to plinthite were used as ind icators for the assessment. The MVIK method was used to integrate thes e factors into a single index. Based on the variogram of the index, ad ditional points were interpolated by kriging and a suitability probabi lity contour map produced. Areas of low probability for meeting the cr iteria required for maize farming are indicated on the map. Soil condi tions responsible for the failure to meet the criteria were identified , and ameliorative measures suggested. The usefulness of this techniqu e for land evaluation for soil management and for environmental purpos es was also discussed.