Make sure your blog posts have a very clear direction and topic. One of the best ways to encourage commenting is to end your post with a direct question to your readers, to get them to think about your post and want to interact!
Sometimes it could be the subject of the posts...I've recently changed the format of my blog and it's sort of in the "working stages" so I don't have nearly as many commenters as I used to. But my suggestion is to leave readers with a question to answer. Also, make sure that the overall subject of your post is relatable to the readers of your blog.
Not just good original content but also enticing content makes readers like me to leave a comment. Commenting on blogs depends on the what motivates them to comment - based on experienced, they do comment on certain viral issues :)
by the way, did you guys put a survey poll in your blog, so you can know who are your readers?is this work? I also wonder if we can know who view our blog for example what is their name instead of where or which country they are from..in my blog, I did use revolver maps..I can see my readers from which country but dont know who are them...
I think that's technically impossible for now. Unless they voluntarily state their name for example in feedjit. As far as I know, web applications can only get the visitor's ip address. Unless the application have a somewhat 'hacking' algorithm to search for the visitor's cookies and get display names from facebook, google mail, etc. Please correct me if I'm wrong.