Long-term soil acidification model (LTSAM) development and application for analyzing soil responses to acidic deposition

A long-term soil acidification model (LTSAM) which can describe calcareous and noncalcareous soil responses to acidic deposition is developed based on the conservation of alkalinity and Ulrich buffer ranges. The model which considers nine major ions of armospheric deposition, has focused on certain soil processes (weathering of carbonates, silicates, and aluminum (Al) oxides or hydroxides, cation exchange, anion retention, and CO2 solubility). After comparing the model design and simulation results with the SMART, the paper describes several numerical experiments on the sensitivity of calcareous drab soil in Beijing and red earth (nearly dystric cambisol) in Wenzhou of Zhejiang Province in Southern China to acidic deposition scenarios. The modelling results indicate that increase or decrease in atmospheric deposition of base cations and not only changes in deposition of sulfate (S) and H+ must be considered in assessment of critical loads both for red earth and calcareous drab soil.