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Accounting Spatial Variability of Soil Properties and Mapping Fertilizer Types Using Geostatistics in Southern Ethiopia

Laekemariam, Fanuel, Kibret, Kibebew, Mamo, Tekalign, Shiferaw, Hailu
Communications in soil science and plant analysis 2018 v.49 no.1 pp. 124-137
autocorrelation, boron, calcium, cation exchange capacity, copper, fertilizers, geostatistics, iron, kriging, magnesium, manganese, models, nitrogen, nitrogen content, nutrients, organic carbon, pH, phosphorus, potassium, soil heterogeneity, soil sampling, sulfur, zinc, Ethiopia
This study assesses soil spatial variability and maps fertilizer types using geostatistics. A total of 789 soil samples were collected from Wolaita area, Southern Ethiopia. Ordinary kriging was employed. The result considering coefficient of variation exhibited diverse soil variability (10% to 236%). Exponential semivariogram model described spatial structure of organic carbon (OC), total nitrogen (N), phosphorus (P), magnesium (Mg), boron (B), iron (Fe), zinc (Zn), cation exchange capacity (CEC) and potassium(K)/Mg. Semivariogram model was spherical for pH, calcium (Ca), manganese (Mn), and Gaussian for sulfur (S) and K. Spatial dependence was strong (Cu, Fe and Zn), moderate (pH, OC, N, S, Ca, Mg, B, Mn and CEC), and weak (P and K). Autocorrelation was between 276 and 15,118 meters. Overall, 46% of nutrients (N, P, K, S, B, and Cu) obtained from soil were deficient. Thus, for site-specific nutrient interventions, three fertilizer types (NPKSBCu, NPSBCu, and NPKSB) are suggested.