Why the Interest in Soil Sampling Depth?
Many analytical laboratories now recommend shallower soil sampling depths for fields with no-till management than with conventional tillage since nutrients and plant roots are generally more concentrated near the surface. Surface soil properties, such as bulk density, organic matter, pH, extractable nutrients, and plant root distribution change with the adoption of no-till methods. Nevertheless, the impacts on soil test results and fertilizer recommendations are not well understood. Soil pH stratification patterns are less consistent than those reported for nutrients and roots with no-till management. Soil surface acidification can occur, presumably due to near-surface nitrification of ammoniacal N fertilizers and decomposition of crop residues. In contrast, the soil surface can become less acidic than the underlying soil, presumably due to surface liming. Thus, variation in soil profile pH patterns is probably related to liming practices. Recommendations made by soil testing laborator
