I would check with BWI - Jackson and see if they would take POs from the city. http://www.bwicompanies.com/ContactUs.aspx#Jackson1
They would have more information about sports turf than the Co-op, and they deliver. Using Agriculture products, such as Dimetric DF 75, on sports fields will get you in trouble. Especially if you put that information on a site like this. You can also buy as little or as much as you need through BWI.