A blog is designed to voice your opinion and record information that can be vital to you or otheres around you. So it is essential to recieve comments on your blog to allow you to depict rather the information is being recieved in the manner you want it to be.
The advice that i would give about getting effective blog comments is to make what your writing about relevent to the target audience that you are trying to attract. Make your ideas clear and make sure you state you objective. that way it will be it will be more effective in getting people to react.