I made up a similar amendment by following Steve Soloman's recipe. Buying this product is more practical for my uses.
Where my garden lives gets about 65 inches of rain within 9 months followed by 3 months of heat and not much rain. My water sources are strained during the hot growing season, as I live upland and off grid. I use this product to feed the soil organisms to keep the soul of the soil available to garden roots during plant stresses of August/Sept..
Spring and summer Red Sails are YUGE and sweet. The roots of brasicas fill the rootspace in a deep, fine mat-like structure, which I pull up by their 2-3" stalks, and chop the roots back into next years compost.
This product is nice to handle bare handed and comes sturdily packaged.
Would recommend, if you have good soil to start with. Could be an important part of a long term soil building program for poorly structured soils.