In case of Zn deficiency in paddy, how much zinc sulphate should be applied in one hectare of soil?

Zinc is one of the essential elements in paddy plants as it involves nitrogen assimilation and protein metabolism. And at the same time availability of zinc is lower in submerged fields like paddy plantations in comparison to normal upland fields. So, it is required to add zinc rich fertilizers to the paddy fields approximately 25 kg per hectare.