The release of carbon dioxide when lime is applied may be an unrecognized benefit to crop production. Carbon dioxide concentrations were sampled at depths of 5, 10, 20, and 30 cm within the soil of fallow (uncropped) and cropped plots (Pritchard and Brown 1979). In all plots, CO2 concentrations increased with depth. It is impossible to determine the extent that limestone contributed to the CO2 levels; it was greater in the cropped than in the fallow plots, probably due to root respiration.
The amount of limestone needed to correct soil pH is substantial (Table 9-5) and varies according to the crop to be grown, the pH level of the soil, and the soil type and texture.