Answer: Roots of the grass do not have to be removed. Only the stems, rhizomes and stolons have reproductive ability. Do not till first - that drives the reproductive pieces into the ground and causes a long term weed problem. Scrape or set the sod cutter to a depth of 1/2 to 2" and throw that material in the compost pile. Mixed with leaves and other materials, the grass will be useful in the composting process. Next mix in all the organic amendments. Here's the detailed description: http://www.dirtdoctor.com/Bed-Preparation-Newsletter-2011_vq3812.htm
Products for pest control, lawn and garden care are available in independent garden retailers that stock organic products and online at the Natural Organic Warehouse (NOW).