RESUMEN
Background: Phosphorus (P) sorption measurements and lime application are of great importance for the sustainable management of P-adsorptive soils. Aim: Therefore, this study aimed to evaluate soil phosphorus sorption under different land-use types and to assess lime input during phosphorus sorption. Treatments include the land use of enclosures, grazing, cultivated and ensut land. Method: Surface soil samples were collected to study the physicochemical properties of specific soils. Lime was mixed with the soils of cultivated land for 30 days. P sorption was subsequently assessed for all land-use types by equilibrating soil samples in 0.01 M CaCl2 containing 30 mL of KH2PO4 at 0, 10, 20, 30, 40, and 50 mg/L. Result: The results showed that land use type had a significant impact on external P demand (EPR). The Langmuir model proved useful information in explaining P sorption. P fixation ranged from 136 to 731.67 mg.kg-1 according to Langmuir model and EPR values ranged from 45.9 to 398.7 mg P kg-1 soil. Exclusory area soil has high sorption compared to other land-use whereas enset land-uses the lowest sorption. The result of correlation analysis revealed that exchangeable Aluminium and clay had positively correlated on P-sorption maximum and SPR of both models. Conclusion: It was concluded that there was a significant difference among land-use systems of P-sorption and there had an influence of lime on acidic soil to reduce EPR. So black market p-fertilizer utilization is not recommended to study site. Liming also restored the soil chemistry of cultivated land. Nevertheless, field trials were proposed to validate mineralization rates and EPR values in cultivated soils.
RESUMEN
Agricultural productivity is significantly impacted by soil properties, which vary spatially from a small to a larger area. This variation may be caused by a combination of intrinsic and extrinsic factors, including human activities like soil management practices. The aim of the current study was to analyze soil spatial variability, create a Digital Soil Map (DSM), and test map information with crop in Southern Ethiopia. A total of 18 geo-referenced surface soil samples at depth of 20 cm were collected. Selected soil Physico-chemical properties such as soil texture, pH, organic carbon (OC), total nitrogen (TN), available phosphorus (av. P), sulfur (S), exchangeable bases [calcium (Ca), magnesium (Mg), and potassium (K)], soil micronutrients [boron (B), copper (Cu), iron (Fe), manganese (Mn) and zinc (Zn)] and cation exchange capacity (CEC) were analyzed. The results revealed clay texture with a mean pH value of 4.6 (strong acidity). About 50% of essential nutrients [N, P, S, Ca, Mg, B & Fe] were deficient. The geostatistical analysis has shown that the best-fitted models were exponential for (OC, TN, available P, S, Mg, CEC, B, Fe, and Zn), spherical for (pH, Ca, Cu and Mn), and Gaussian for (C:N, K, K:Mg, and PBS). The range of all soil properties varied from 50 m to 84 m which was above the actual distance between soil samples (i.e., 46 m). The result showed that the spatial dependence values for soil properties of [OC, TN, CEC, PBS, ESP, and Cu]; [pH, C: N ratio, available P, S, Ca, Mg, K, Na, K: Mg ratio and Zn] and [B, Fe, M n] were strong (<25%]; weak (>75%) and moderate (25%-75%), respectively. Model performance using indicators such as prediction mean error (PME), root mean square standardized error (RMSSE), mean standard error (MSE), and root-mean-square error (RMSE) also confirmed the acceptable prediction. The DSM demonstrated the limitation of N, P, S, and B nutrients for intervention. The DSM information was tested under field conditions using haricot bean (Phaseolus vulgaris) with lime and organic fertilizers as treatments. The experiment consists of lime rates (0, 3, 6 t/ha), rhizobium inoculation (inoculated and non-inoculated), and fertilizer types (0, 150 kg ha-1 NPSB, 5 t/ha vermi compost, 10t/ha farmyard manure (FYM)) in Randomized Complete Block Design with three replications. The result exhibited interaction effects of lime, inoculation, and fertilizer types significantly influenced (p < 0.05) biomass and grain yield of haricot beans. Rhizobium inoculation x 6t/ha lime x 150 kg ha-1 NPSB recorded the maximum grain yield (3186.1 kg/ha) which was 26.3 fold over the non-treated soil (117 kg ha-1). In conclusion, the DSM classified the area into distinct management zones which were tested with a crop trial. The results of the trial confirm the importance of site-specific nutrients/amendment application for sustainable soil management.
