Soil pH Change and Crop Responses with Long-Term Liming Applications in Tilled and Untilled Systems

An 8-year field study measured soil pH changes annually at various depth increments. Limestone was applied to tilled and untilled field strips annually for 8 years at either a 2.0 Mg/ha rate (100% calcium carbonate efficiency) and once every 4 years at the 8.0 Mg/ha rate (100% calcium carbonate efficiency), or as a water-treatment-plant limestone by-product in two replicated field trials. Liming materials increased soil pH in the 0- to 5-cm and 5- to 10-cm depths with time in untilled soils. Incorporated liming materials increased soil pH faster at the 5- to 10-cm depth and increased soil pH at the 10- to 15-cm depth. Mean maize and soybean grain yields increased for all liming materials, and maize ear leaf P and soybean shoot P and Ca increased after liming at the last year of the study. Consistent surface applications of liming materials without incorporation can mitigate acidification and improve crop yields in highly buffered soils.