Effect of Farm Manure on Dissolution of Underlying Carbonate Rocks and Atmospheric CO₂ Source/Sink

Abstract

To study the effect of farmyard manure application on source/sink of atmospheric CO₂, dolomite and limestone tablets were buried at different depths of soil profile in karst area in Guiyang city, Guizhou province; the dissolution amounts of tablets, soil CO₂, soil pH, and soil water content were monitored. The results show that manure addition decreases the dissolution rate of carbonate rocks, and that dissolution amount of limestone and dolomite is decreased by 10–54% (average 26%) and 25–66% (average 40%), respectively. Using these values, the decrease of CO₂ uptake by dissolution of carbonate rocks can be estimated as up to 26–40% on a Guiyang city scale. Moreover, the results suggest that manure accelerated the generation of soil CO₂; the data show that soil CO₂ concentration in manure profile increases by 23–199% (average 94%) and the CO₂ flux increases by 68% compared with control profile.