The effect of sampling depth and thatch on soil test results of turfgrass areas

Abstract The effects of sampling depth and thatch on soil test results of turfgrass areas were studied. Several turfgrass areas with known fertility and management histories were sampled in 3.8 or 5.0 cm increments to depths of 10 or 15 cm. Sampling depth significantly affected the levels of P, K, Mg, Ca, and pH in one or more of the areas sampled. The direction and magnitude of change was dependent on such factors as previous rates of fertilization, soil texture, and various management practices. Although soil fertility values changed with depth, changes in fertilizer recommendations due to sampling depth were minimal. Sampling depth data also gave an indication of greater nutrient removal in the surface 4 to 5 cm of soil than at lower depths. The inclusion of thatch with the soil sample increased soil test levels of K and CEC, decreased pH, and did not affect P levels.