Distribution of Total and 0.1 Normal Hydrochloric Acid‐Extractable Zinc in Hawaiian Soil Profiles

Abstract

AbstractIn most Hawaiian soil profiles, the highest concentrations of 0.1N HCl‐extractable Zn were found in the surface horizons. There was a general decrease in extractable Zn with soil depth. Extractable Zn was found to range from 0.1 to 17.9 ppm.The concentration of total Zn appeared to be less dependent on depth than was acid‐extractable Zn. In some profiles, where the extractable Zn followed the general pattern of decreasing with soil depth, the total Zn content remained the same or even slightly ncreased with depth. Total Zn was found to range from 51 to 288 ppm.There was a highly significant correlation between total and extractable Zn. This correlation was especially evident in the relatively youthful and unweathered soils but not in all oxisols and ultisols. There was no correlation between soil pH and extractable Zn.The occurrence of Zn‐deficient plants was better correlated with acid‐extractable soil Zn values than with total soil Zn values. Most soils on which Zn deficiency is found are oxisols or ultiscls that have undergone intensive weathering or have had their subsoils exposed. In a greenhouse experiment, corn (Zea Mays L. plants grown in an ultisol sampled from an eroded site showed more pronounced Zn‐deficiency symptoms and lower vegetative yields than those grown in an adjacent surface‐intact soil.