Results of Deep Fertilization and Subsoiling on a Claypan Soil1

Synopsis Subsoil shattering alone on Mexico silt loam depressed crop yields. Applications of lime or phosphate to the plow sole before shattering was slightly beneficial, the residual effects for alfalfa lasting several years. Subsoil applications of lime and triple superphosphate in subsoiler clefts or by deep plowing gave significant corn or alfalfa yield increases in some cases. However, if the soil surface was adequately fertilized the increases over surface treatment alone were small and of questionable value.