Soil pH and Crop Response to Lime Source and Tillage


  • Richard Wolkowski
  • Carrie Laboski
  • University of Wisconsin-Madison
Project Media

Maintaining the proper soil pH through liming agricultural soils is a hallmark of modern crop production. Benefits of liming include the optimization of nutrient availability and utilization, the reduction of available levels of Al and Mn, the enhancement of N2 fixation in legumes, and improvement in the microbial-aided process of organic matter breakdown. The most common liming material by far in Wisconsin is crushed dolomitic limestone or aglime. Deposits of dolomitic limestone are common in the western, southern, and eastern portion of the state. Few, if any, deposits of limestone are found in the central and northern areas. Other lime sources include various by-product materials and calcitic lime, which is not indigenous to the state and therefore must be transported at significant expense. Lime should be applied according to recommendations that are based on a current soil test. The recommended rate is determined by soil pH desired for the most demanding crop in the rotation, the pH buffering potential of the soil, the soil pH, and the neutralizing index of the lime. The neutralizing index reflects both the purity of the lime relative to calcium carbonate and how finely it has been ground. Obviously purer and more finely ground materials, having more surface area, will react faster pound for pound compared to impure or coarser materials.