Iron availability in alkaline and calcareous soils is very much limited due to high pH and presence of the excess amount of carbonate and bicarbonate ions. Iron is though adequately present in soils, it is not always sufficiently available to plants due to their faster conversion into unavailable ferric (Fe3+) forms. The present study was taken up to understand the availability of Fe in soils and its relationship with various soil properties. A laboratory experiment was conducted with two calcareous soils and a noncalcareous soil and incubated for 45 days with various levels (0, 5 and10 kg Fe ha-1) and sources of Fe (FeSO4 and Fe EDTA) on calcareous and noncalcareous soils. The results revealed that increasing levels of Fe either as FeSO4 or Fe EDTA increased the availability in soils and higher availability was noted with the application of 10 kg Fe EDTA in all the three soils. A linear increase in the Fe availability was observed with the addition of Fe EDTA at 10 kg ha-1 up to 45 days while with the addition of 50 kg FeSO4 ha-1 higher availability was noticed up to 30 days after incubation. Inclusion of amendments viz., 12.5 t FYM and 0.25 % Acetic acid though further improved the availability in all soils, the effect was much better with FYM than the acetic acid in calcareous soils than in noncalcareous soil. A strong negative correlation was observed between soil pH and calcareousness with DTPA Fe availability.
Key words : FYM, Acetic acid, Fe levels and sources, Calcareous soils, Fe availability