Complete Neutralization of a Portion of Calcareous Soil as a Means of Preventing Iron Chlorosis1

Abstract Soybeans (Glycine max L. Merr., PI 54619‐5‐1) that are susceptible to Fe chlorosis, were grown in a glasshouse with calcareous (10% CaCO3) Hacienda loam soil (fineloamy, mixed, thermic aquic Natrargid) with a portion of the soil neutralized vs. equivalent mixing of sulfuric acid with all the soil. The objective was to determine if complete neutralization of only a small part of the mass of a calcareous soil could effectively prevent Fe chlorosis. Small acidified spots of soil, equivalent to as little as 0.4% of the CaCO3 in the 1,000 g of the soil used in each pot, placed 3 cm deep under seedlings, was sufficient to prevent the Fe chlorosis. These glasshouse results suggest that comparable procedures be tried for field experimentation with row crops which are susceptible to Fe chlorosis.