The profile distribution of total and DTPA‐extractable manganese in selected soils from the major mineral soil areas in Louisiana

Abstract

Abstract The total and DTPA‐extractable Mn contents in the profiles of selected soils from six major mineral soil areas in Louisiana were determined. The concentration of the total Mn in the soil profiles showed great variations both among the horizons and among the soil areas studied. The highest concentration of total Mn found in the young alluvial soils occurred in the B horizons. In contrast, the older soils from the other areas showed accumulation in the Ap horizons, with few exceptions. The variations of the total Mn appeared to vary more with parent material and clay than with the soil reaction or organic matter content. The range in total Mn for all horizons and soils was between 25 and 2,229 ppm. The DTPA‐extractable Mn was concentrated in the plowed Ap horizons of all soils studied, and there was considerable decrease in the extractable Mn as soil depth was increased. There were as much variation in the extractable Mn among the soil profiles in each major soil area, as among the six soil areas. In general, the younger alluvial soils and especially those developed in the Red and Ouachita rivers alluvium, were lower in extractable Mn, than were the older and more weathered soils. The range in the extract‐able Mn for all horizons and soils was from 0.2 to 103.0 ppm.