Zn distribution in soils of Odisha and its management in a cereal based cropping system through graded dose of ZnSO4 application

Zinc deficiency is one among many constraints limiting rice yield. Reports of All India Coordinated Research Project on Micro-Secondary Nutrients envisages that the soils of all distrcts of Odisha are deficient in Zn with an overall state mean deficiency of 33% of samples collected(GPS based). To sustain production and productivity of rice Zn application is inevitable. Since there exist a narrow gap between deficiency and sufficiency value of Zn in soil continuous use may lead other soil related nutrient problems or imbalance. Keeping in view the above facts to find out the optimum dose and frequency of Zn application through ZnSO4, a field experiment was conducted by taking 4 graded doses of Zn (2.5, 5.0, 7.5, 10.0 kg/ha) applied through 3 different frequencies (F1-Once, F2-Alternate year (1st, 3rd, 5th year), F3-Every year upto 6 year) with one no Zn control constituting 13 treatments replicated thrice in a randomized block design. In a rice - rice cropping system grown in an Zn deficient Inceptisols of central farm, OUAT, Bhubaneswar. Results of the 6 cropping cycles revealed that, Rice crop responded to Zn application with respect to increasing dose and frequency with a highest mean grain yield of 4.3 t/ha as well as cumulative yield of 21.3 t/ha in the treatment of residual effect of once Zn application @ 7.5 kg/ha with highest B:C ratio of 1.47 per rupee investment followed by every year Zn application @ 2.5 kg/ha (1.45). Also yields were sustainable at 2, 5 kg Zn/ha every year, 7.5 kg alternate year and 10 kg/ha once Zn application condition within 6 year. Hence from the above study it may be concluded that Zn application is required in light texture sandyloam soils @ 2.5 kg every year or 7.5 kg in alternate year that is 1st,3rd,5th year or 10 kg once which can sustain yield upto 6 year in a rice-rice cropping system.