Dynamics of Iron Fractions in the LTFE’s Soils

The dynamics of Fe fractions in the selective treatments were studied by collecting the surface soil samples (0-15 cm) from the LTFE’s conducted on groundnut-wheat-fodder sorghum at instructional farm, Junagadh Agril. University, Junagadh during the year 1979-80 (1st year), 1989-90 (10th year) and 1999-2000 (20th year) after completion of crop cycle. The selected treatments were T₁-Control, T₂-FYM @ 25 t/ha at an interval of 3 years, T₃-½ RD of NP, T₄-1/2 RD of NP+K, T₅-RD of NP and T₆-RD of NP+K to respective crops. On a long run, after 20th year the values of water soluble-Fe were recorded highest in T₂ (0.722 ppm) and T₁ (0.504 ppm) and the lowest in T₅ (0.082 ppm) and T₃ (0.130 ppm). The significantly highest exchangeable-Fe was recorded in T₅ (2.084 ppm), at 10th year. The DTPA available and reducible Fe was found significantly higher under T₁ and T₂, while application of fertilizer registered mostly a decline in long term at 20th year. The total and residual-Fe content did not showed any significant differences either through treatment or through years. The percentage availability and available total-Fe were not affected significantly in pooled years, but Y x T interaction was found significant and in the initial years T₅ and T₆, while in the 20th years T₁ and T₂ recorded the highest values.