Accumulation of Copper and Manganese Under Intensive Cropping With Long Term Fertilizer Application in Calcareous Vertic Ustocrepts Soils

A long term fertilizer experiment (LTFE) was started in the year 1999 at Instructional Farm, College of Agriculture, Junagadh Agricultural University at Junagadh to know the effect of continuous application of fertilizers (0, 50, 100 and 150% recommended dose of N, P, K with and without Rhizobium and PSM) and manure (FYM @ 10 and 25 t/ha) on accumulation of copper (Cu) and manganese (Mn) under groundnut wheat sequence. After harvesting of wheat crop, the soil samples were drawn at the interval of 1st, 4th, 8th and 12th years and analysed for Cu and Mn. Result revealed that the DTPA available Cu was significantly increased with application of FYM and fertilizer at 4^th, 8^th and 12^th years after harvesting of wheat crop. The pooled analysis indicated that highest DTPA available Cu was recorded with application of FYM @ 25 t ha⁻¹to groundnut over control. Similar trend was also observed in the case of DTPA available Mn. The Year x Treatment interaction effect of Cu was observed significant in pooled analysis after 12^th years harvesting of wheat crop. The Y x T interaction effect clearly indicated that the continuous cropping (Groundnut-Wheat sequence) with and without fertilizer treatments after a span of 12 years, the accumulation of Mn was increased 23% over initial year of the experimentation. While, the Cu was decreased from its initial value of 1.387 ppm to 1.030 ppm.