Forms of Iron in Some Soils of Uttar Pradesh

Forms of iron in the major soil groups of Uttar Pradesh and their relationship with soil reaction, calcareousness, organic matter content and mechanical composition were worked out. The total, available (extracted with N NH₄OAc at pH 4.8) and exchangeable Fe varied from 1.38 to 8.48%, 1.2 to 22.2 ppm and 0.4 to 6.6 ppm, respectively. Soils of Bundelkhand and Vindhyan tracts were found to be richer in total Fe as compared to other soil groups. Total Fe generally increased with depth while reverse was true for available form. Of these soils 16% contained less than 2 ppm available Fe and are rated as deficient. The various soils were arranged for iron availability as follows: alluvial>Tarai>Bundelkhand>hill>Vindhyan. The relative abundance of exchangeable Fe in the surface soil followed the order: hill>alluvial>Vindhyan>Bundelkhand>Tarai. There was no definite trend of its distribution in the soil profiles. None of the iron forms correlated significantly with any one of the soil characteristics such as pH, CaCO₃, organic matter and clay content.