If drawdown is being estimated on the basis of direct observation of mineral weathering rather than via estimation of alkalinity run-off, it is important to characterize what fraction of the rock was weathered by non-carbonic acids. Non-carbonic sources of acidity in the soil may include protons associated with mineral and organic surfaces and other sources of acidity from organic acids, nitrogen transformations, or sulfide mineral oxidation. If applied rock is weathered by non-carbonic acid that would have otherwise caused outgassing downstream, it may be appropriate to count this avoided outgassing toward the net carbon drawdown of the enhanced weathering intervention depending on how confidently the counterfactual can be characterized and how quickly the outgassing would have otherwise occurred.