Spatial Variability of Soil pH, Electrical Conductivity, Moisture, and Temperature Across Three Land Use Zones in Barclayville, Liberia: An Exploratory Assessment using the ST03 Soil Tester

Background of the study: Liberia has no digital national soil map and, until recently, no functioning public soil laboratory, so farmers and planners in remote counties such as Grand Kru County lack site-level soil information. Objective: The study measures the spatial variability of in-situ soil pH, electrical conductivity (EC), moisture and temperature across three land-use and landscape zones of Barclayville City (administrative, agricultural [lowland and upland] and undisturbed land) and to test whether zone or location explains more of the variation. Methodology: the research measured purposively thirty-six (36) selected GPS-referenced locations (12 administrative zone, 12 agricultural zone [7 lowland, 5 upland], 12 undisturbed land) collected at 15–20 cm soil depth on 30 September–1 October 2026 with a handheld Intelligent Soil Tester (ST03) in Barclayville, Grand Kru County Liberia. A rank based was used to explore group differences and Spearman correlations to assess associations The zones were compared with Kruskal–Wallis and Holm-adjusted Mann–Whitney tests, associations with Spearman correlation, and spatial dependence with Moran's I and empirical semi variance and Spatial analyses were exploratory because the sample was small and purposively clustered. The sampling was conducted on 30 September to 1 October 2026, near the end of the Liberia recognized rainy season; no site- specific rainfall series was available to quantify antecedent rainfall. Results of the study: Soil pH averaged 6.10 ± 0.51 (range 4.5–6.6); 27 of 36 points lay between pH 6.0 and 6.6, and the three readings below 5.5 were all in the administrative zone. Zones did not differ significantly in pH (p = 0.094), the EC (median 36.5 µS/cm; p = 0.466) and moisture (66.0 ± 15.2%; p = 0.165), although upland plots were drier than lowland plots (61% vs 78%; p = 0.018). EC rose with moisture in every zone (ρ = 0.61–0.73). Zone explained only 15.5% of pH variance, 7.7% of log EC variance and 5.2% of moisture variance, and points less than 150 m apart were no more alike than random pairs; two points 21 m apart differed by 2.0 pH units. Soil temperature differed among zones (24.4–37.0 °C; p < 0.001), but undisturbed land was measured in the late afternoon and all other zones in the morning, so this contrast cannot be attributed to land use. Conclusion: The main finding is the scale of variation. Zone explained 5–16% of the variance in pH, EC and moisture, points less than 150 m apart were no more alike than random pairs, and two points 21 m apart differed by 2.0 pH units. In this setting land- use zone is a poor predictor of soil condition, and a single reading describes a spot, not a zone. For agronomy and planning in Barclayville, the ST03 is suited to screening and to deciding where to sample for the laboratory, not to setting lime or fertilizer rates; those decisions need laboratory-validated pH and EC from composite samples taken at plot scale.