The Effect of Surface Soil Thickness on Corn Yields: I. As Determined by a Series of Field Experiments in Farmer‐Operated Fields

Abstract

AbstractA study was conducted to determine the effect of surface soil thickness on yields of corn and to learn whether nitrogen fertilizer would substitute for surface soil thickness in producing yields of corn on the minimal Brunizem soils of southwestern Iowa.During 1957 and 1958, 55 nitrogen fertilizer experiments were distributed over the existing range of surface soil thickness. The corn yield obtained from each of 5 nitrogen fertilizer rates was measured at each site. By means of a multiple regression analysis it was found that application of nitrogen fertilizer at the rate of 100 pounds per acre for corn completely substituted for surface soil in 1957 but failed to do so in 1958. Under the soil and climatic conditions that prevail in the area studied, nitrogen fertilizer can substitute completely for surface soil thickness in some years but not in others. Apparently, climatic factors influence the degree of such substitution.