Abstract:
: Rice-Rice cropping system is one of the major cropping systems of Odisha occupying an area of 3.31 lakh ha with a productivity of 2.5 t/ha which is much below the
national average (Odisha Statistics). Zinc deficiency is a common under rice cultivation. The soils of Odisha are deficient in Zn up to the extent of 28 %. Nutrient transformations
under submerged condition are different from that of other aerobic systems. Zn utilization efficiency is 5-10 %.Losses of yield of 20% or more as a result of hidden zinc deficiency
can have an economic impact on the farmer. To find out the optimum dose and frequency of Zn application a field experiment was conducted by taking 4 graded doses of Zn
applied through 3 frequencies of once in six year ,alternate year up to 6 year ,every year upto six year to the first crop of a rice - rice cropping system grown in an Inceptisols of
central farm, OUAT, Bhubaneswar, Odisha. After every 2 year of Zn application Zn fractionation study was conducted to find out the possible fate of Zn application on various Zn
pools and on yield of rice - rice cropping system. Results after 5 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 every year Zn application @ 5 kg/ha with highest gross return of 1.33 per rupee
investment . Among the pools affected by Zn application was organic and amorphous oxide bound forms .Residual fraction constituted the highest percent of total Zn among all
fractions .Hence for rice growing lowland soils of Odisha application of Zn @ 2.5 kg/ha every year to the first crop of a rice-rice cropping system can produce a sustainable yield
