Dynamics of Manganese Fractions in the LTFE’s Soils

Surfaces soil samples (0-15 cm) were collected to study the dynamics of Mn fractions in the selective treatments of the LTFE’s conducted on groundnut-wheat-fodder sorghum at Instructional Farm, Junagadh Agricultural U1,iversity, 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 @ 25t/ha at an interval of 3 years, T₃-1/2 RD of NP, T₄-1/2 RD of NP + K, T₅-RD of NP and T₆-RD of NP+K to respective crops. The water soluble Mn was found very trace. Exchangeable form of Mn differs significantly only at 1st year and after 20lh year only. Remarkable decreased in exchangeable form of Mn was noticed in treatments without application of chemical fertilizers after 20th year. The control and FYM application recorded the highest values of DTPA-Mn at 1st and 20th year, and it was recorded highest (7.241 ppm) at 10th year in treatment T₆. Overall increase in reducible form of Mn was found, but it was non significant when pooled over year. Overall mean registered an increase in total Mn content on the long run basis. After 20th year residual Mn decline in T₁ whereas in other treatments. it was declined at 10lh and increased at 20th year. Per cent available of Mn increased up to 10lh year and then it was decreased. There was overall increase in total available form of Mn after a long run.