YES learning of EVS is important at primary level because at primary level the child adopt the things he has been asked to do and doing those things regularly makes a habit for him and carry on to do that type of things in future and he create an interest also in doing that type of things.
For example the things sleeping at night etc things are taught to the child at prìmary level and he carry on this habit in future are hence if learning of environmental studies S done at primary level then this will gain an interest in child's mind about environment and he could carry on these habits in future.