The Effect of Surface Soil Thickness on Corn Yields: II. As Determined by an Experiment Using Normal Surface Soil and Artificially‐Exposed Subsoil

Abstract

AbstractIn an experiment involving corn yield responses to rates of nitrogen fertilizer on artificially exposed Marshall subsoil and normal surface soil, results were obtained in 1958 and 1959 which indicated that equal corn yields could be obtained on either surface or subsoil, provided that adequate nitrogen fertilizer was supplied. Maximum corn yields on both subsoil and normal soils were approximately 100 bushels per acre in 1958 and 125 bushels per acre in 1959. Yields on subsoil control plots (0 N) were 45 to 50 bushels per acre lower than from corresponding surface soil plots. A regression analysis of the data indicated that the production of maximum corn yields on subsoil required 35 more pounds of nitrogen per acre in 1958 and 52 more pounds of nitrogen per acre in 1959 than on normal soil. Nitrogen availability in the untreated surface soil exceeded that in the untreated subsoil by the equivalent of about 70 to 75 pounds of fertilizer nitrogen per acre per year.