Dynamics of Zinc Fractions in a Calcareous Under AICRP-LTFE Soils

Surfaces soil samples (0-15 cm) were collected to study the dynamics of Zn fractions in the selective treatments of the LTFE's conducted on groundnut-wheat sequence at Instructional Farm, Junagadh Agricultural University, Junagadh during the year 1999 (Initial year), 2010-11 (12^th year) after completion of crop cycle. The selected treatments were T₁ - 50 % NPK of recommended doses in groundnut-wheat sequence, T₂ - 100 % N P K of recommended doses in groundnut -wheat sequence, T₃ - 150 % N P K of recommended doses in groundnut -wheat sequence, T₄ - 100 % N P K of recommended doses in groundnut -wheat sequence + ZnSO₄ @ 50 kg/ha once in three year to groundnut only (i.e. '99, 02, 05 etc), T₅ - N P K as per soil test, T₆ - 100 % N P of recommended doses in groundnut -wheat sequence, T₇ - 100 % N of recommended doses in groundnut -wheat sequence, T₈ - 50 % N P K of recommended doses in groundnut -wheat sequence + FYM @ 10 t/ha groundnut and 100 % N P K to wheat, T₉ - FYM @ 25 t/ha to groundnut only, T₁₀ - 50 % N P K of recommended doses in groundnut -wheat sequence + Rhizobium + PSM to groundnut and 100 % N P K to wheat, T₁₁ - 100 % N P K of recommended doses in groundnut -wheat sequence (P as S S P) and T₁₂ - Control. The water soluble Zn was present in negligible quantity. Exchangeable forms of Zn differed significantly at 12^th year. Potassium enhanced the utilization of exchangeable form of Zn. The application of FYM recorded the highest value of DTPA-Zn at 12^th year. Total Zn content differed significantly in T₉ (34.55 ppm), while residual form of Zn was found non significant at 12th year. The Y x T interaction were found significant after 12^th year in DTPA-Zn, reducible-Zn, per cent available and total available-Zn.