ACCUMULATION OF HEAVY METALS UNDER INTENSIVE CROPPING WITH LONG TERM FERTILIZER APPLICATION IN CALCAREOUS VERTIC USTOCREPTS SOILS

Abstract

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 iron (Fe) and zinc (Zn) 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 Fe and Zn Result revealed that the DTPA available Fe was significantly increased with application of FYM and fertilizer at 4th, 8th and 12th years after harvesting of wheat crop. The application of FYM @ 25 t ha-1 significantly improved Zn content at 8th and 12th years over control. While, in case of the DTPA available Fe after 8th and 12th years were recorded highest with the application of 100% NPK of recommended doses in G’nut-Wheat sequence (P as SSP). The Y x T interaction effect of Fe and Zn was observed significant in pooled analysis after 12th years harvesting of wheat crop. The Y x T interaction effect clearly indicated that the continuous cropping (G’nut-Wheat sequence) with and without fertilizer treatments after a span of 12 years, the accumulation of Fe and Zn, were increased 136% and 42%, respectively over initial year of the experimentation. These results clearly showed that the application of FYM with fertilizer increased availability of Fe and Zn in the soil and above the maximum permissible limit.