Effect of soil disturbance on pedotransfer function development for field capacity

The increasing use of simulation models for design and analysis of land use management options has meant an increased need for detailed soil data. When such data are not available, pedotransfer functions (PTFs) can be used to estimate soil properties such as cation exchange capacity (CEC) and field capacity (FC) from other more readily available data. However, if PTFs for FC have been developed from disturbed samples, there is a doubt as to the accuracy of the prediction for in-situ soils. To determine the effect of soil disturbance on the estimate of FC and the development of PTFs, we determined FC on both disturbed and in-situ samples for soils from four contrasting agro-ecological environments in Mexico. Results suggest that PTFs for FC developed from in-situ samples can be used in simulation modeling, as 89% of the variation across the four contrasting soils was explained; soil organic matter (SOM) being the dominant factor in the function. However, caution is required in using PTFs for FC developed from disturbed soil samples as they overestimated in-situ FC for all soils except for the coarser textured soil. Other PTFs for FC from the literature were evaluated in terms of their qualitative and quantitative estimates of in-situ FC.