| I collected samples from four previously established liming experiments in order to characterize the long-term effects of liming on cation exchange properties and test various proposed models for the relationships between pH, base saturation (BS), and cation exchange capacity (CEC). Limed sites generally had higher pH and BS, more organically bound Al and less bound hydrogen, and fewer E horizons. Limed organic horizons had lower organic matter content than controls, and limed mineral horizons had lower effective CEC, suggesting that podzolization may be disrupted or masked in limed soils. Regression analyses testing models of charge development on organic matter suggest that sites binding non-exchangeable Al should be excluded from the pool of potentially dissociable functional groups. Results for models of exchangeable cation equilibria suggest that exchangeable Al does not behave as a base cation, but rather is part of an equilibrium with organically bound Al that buffers pH change. |
