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

A question came to the lab. The base saturation numbers look a little out of whack on the soil test. The 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.

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. Addition of magnesium or calcium in the liming materials will also increase the soil test of these nutrients and effectively increase the relative percentages of both.