Lab Questions – Impact on Hydrogen and Calcium Base Saturations When Lime is Applied

A question came to the lab. The base saturation #’s look a little out of whack-averages are: Ca-55%, H-23%, K-4%, and Mg-18%. Avg pH is 5.5 but is fairly uniform. Will a lime app bring the Ca up and the H down?

Keep in mind that the base/cation saturation will add up to 100% and the base saturation values are calculated from the soil test results (ppm or lbs/ac) of these nutrients. In some cases the hydrogen saturation is not reported so the reported numbers do not add up to 100%, but the hydrogen saturation is part of the calculations even if it is not reported. Adding any one of these nutrients should lead to a higher soil test result. These higher results will lead to a larger contribution to the base/cation saturation calculation for the applied nutrient and thus a higher percentage. Since the base/cation saturation must add up to 100%, when the percentage of one nutrient increases, the others must go down.

In addition, the H% is calculated from the buffer pH (or soil pH if calculated from TEC), as the soil is limed, the soil and buffer pH increases, leading to a lower calculated hydrogen percent. The reduction of the H%, leads to increases in the other cations.