Reddit reviews Homegrown Whole Grains: Grow, Harvest, and Cook Wheat, Barley, Oats, Rice, Corn and More

Closed cycles are a nice idea but in practice you are always losing nutrients through leaching, crop export and mineralisation of nitrogen back into the air. Cropping spaces can't support themselves in terms of fertility, and while cover crops can help with a lot soil carbon and to a lesser extent nitrogen the minerals are going to become a limiting factor in time if you are taking a crop off the land. Often things seem to be going fine for years until some key mineral runs short. Traditionally land was in fallow about 4/5 of the time as weedy pasture over a long period does a lot more good for the soil than a cover crop of 2-3 species for one short season. Trees are important for bringing up minerals as well but difficult to incorporate directly with cropping spaces (animals that browse trees then transport manure like goats are ideal for that). The modern biointensive methods like Jeavons rely on heavy imports of fertility as manure/compost/mulch plus irrigation. The older methods that aren't so input intensive are mostly lost today it seems. I'm experimenting with zero/low input systems here and it is doable but requires more skill than just pumping everything up with water and fertiliser.
There are a few books on growing grains on a small scale
https://www.amazon.com.au/Homegrown-Whole-Grains-Harvest-Barley-ebook/dp/B003PGQK50
https://www.amazon.com.au/Small-Scale-Grain-Raising-Processing-Nutritious-ebook/dp/B005OCTJ3S
The trouble with grains is how dependent they are on local seasonal cycles since they need moisture to grow but dry weather to ripen and harvest successfully. Each species has its own specific preferences for soil and climate (with specific strains for low input conditions necessary beyond that, with the genetics of those old landraces mostly lost as well) and then on top of that each species has its own tricks and equipment for sowing, growing, harvesting, processing and storing. There is a reason why most traditional agricultural regions had just one dominant staple crop and maybe one or two minor ones to complement it.
If you live in a warm humid zone like I do then grains are pretty much off the menu since we get rainy weather at pretty much any time of year, so half the time the crop is ruined (if the birds and rats don't get it first, another disadvantage of growing grains on a small scale). Tuber crops are our better bet but outside the warmer zones the species choice is a lot more limited. With increasing climate instability grain growing might become more marginal even for the industrial farmers.
Keep dreaming and planning- I redesigned my place a few dozen times for years before I moved onto it full time and could put things into practice, but the plans are still changing on a regular basis.