An Equilibrium-Based Model for Predicting Potential Ammonia Volatilization from Soil

AN EQUILIBRIUM-BASED MODEL FOR PREDICTING POTENTIAL AMMONIA VOLATILIZATION FROM SOIL 

As noted above, the potential for NH3 volatilization depends on the soil s potential to buffer pH, B, which is given by (Avnimelech and Laher, 1977) 

Equation B points out that the amount of acid produced during NH3 volatilization (AA) equals the difference between original NH4 ([NH4]0) minus final NH4 ([NH4]f). By rearranging Equation 8.10, 

Upon rearranging Equation C to solve for [NH3]f and inserting Equation F 

When plotted as 1/NH3 versus 1/NH4, Equation H would produce a straight line with slope ([H]0 + B [NH4]0)/(A W/Arb) andy intercept -B [KJKb. The equilibrium-dependent model described above was used by Avnimelech and Laher (1977) to demonstrate how pH and soil pH buffering capacity, B, control NH3 volatilization (Fig. 8A). This can also be evaluated by carrying out a sensitivity analysis on Equation G, which shows that when B approaches zero (extremely high soil pH buffering capacity), or NH4 in the system is very low, such that H° ([NH4]0-[NH4]r), Equation H reduces to 

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