The research problem addressed in this study is: How accurate is the Inverse Distance Weighted (IDW) interpolation method in estimating soil organic carbon (C-organic) and soluble iron (Fe) in Bumi Makmur District, Tanah Laut Regency, South Kalimantan Province? The objective of this study was to evaluate the accuracy of IDW interpolation for soil organic carbon and soluble iron in Bumi Makmur District, Tanah Laut Regency, South Kalimantan Province.

The results of this study are expected to contribute additional information and knowledge that can serve as a reference for the application of interpolation methods. This research employed a descriptive-exploratory approach, conducted through direct field surveys followed by soil sampling for laboratory analysis. Soil samples were collected at a depth of 40–60 cm from a total of 40 sampling points across three soil types: 21 Fluvaquept, 11 Sulfaquept, and 8 Sulfaquent. The soil properties analyzed were soil organic carbon (C-organic) and soluble iron (Fe). The resulting data were interpolated using the Inverse Distance Weighted (IDW) method with a cell size of 30 m and a power parameter of 2 (p = 2). Four different numbers of neighboring sample points (N = 5, 10, 15, and 20) were evaluated to determine their effects on interpolation accuracy.