Great work field growing! Here’s some of my handy work doing the same. Been at it 10 years, let me know if you have a specific question.
I originally use the soil on our land with compost mixed in and now I have soil that hard to dig and fewer fine roots than I’d like. Use the combo mentioned in this thread and in the podcast. If plants are spaced appropriately I don’t see need to divide with material and if you use grow bags, which I highly recommend, you’ll spot large roots from crossing into the neighbors rootage and you’ll split that large root into many fine roots (as happens when using a root control bag). Pro Tip: the fine folks at High Caliper www.treebag.com will let you order whatever quantities you need despite what the website says.