Hi Sudeep
It looks like you did a really good job on the old tamiya kit is it??
I also don't have a grassinator so I have tried using a hair dryer to blow the grass up so to speak, then I just tease it up a bit more with a stiff brush. I also turn the diorama on it's side as I blow it do that gravity also helps.
If you want you can see the results do far on WIP dio I am doing that is called my 1st dio & model in 25yrs & see if maybe that is the type of result you may like to start with??
I would maybe carry the ground work all the way up to your boarder as it looks like the ground drops away, unless that is a ditch or something you have model in.
Happy Modeling
Cheers Mike