I'm always interested in someone elses ideas or experiences.  Especially when it concerns gardening and Irises!  I just ran across this web-site entirely by accident, but I'm glad I did.  I found it enjoyable to read about homemade fertilizers etc, mostly because I don't care for chemicals.  I hope you enjoy it too!
http://www.gardenguides.com/91193-homemade-fertilizer-bearded-iris.html