Pedo-Transfer Functions for Predicting Total Soil Nitrogen in Different Land Use Types under Some Tropical Environments

Nitrogen pedo-transfer functions were developed for different land use types, soil depths and agro-ecologies across eight states in Nigeria. The results showed that total nitrogen had a good relationship with the soil organic carbon; therefore, the functions developed were based on the relationship between organic carbon and total nitrogen as other soil parameters (pH, and particle size distribution) had little contribution and no significant correlation (p>0.05) with total nitrogen. Correlation and forward stepwise regression and Kendall’s Coefficient Concordance were used to fit and validate the developed model with datasets other than those used for the model formulation. The R2 of the best fitted regression models varied from 0.77 to 0.85. We obtained a generalized fitted model (TN = 0.0736*OC, R2 = 0.83) which is independent of the agroecology and the land use types. Significant fitted models were also obtained for the arable farms (TN = 0.08*OC, R2 = 0.85) and the plantation farms (TN = 0.0698*OC, R2 = 0.83). It was discovered that variations in agro-ecology, land use, and soil depth did not significantly affect the model performance.