that concept of fallow soil

Of course, I've come across the idea of letting soil lie fallow every certain number of years--mostly it feels like something people did long ago, not so much today.

But I'm wondering if there is value in doing that. But what does it look like? Is it bare soil (perhaps weed chop & dropping?), or are you meant to let it get totally weed covered and stay that way for the fallow year? Would a cover of some kind of mulch over bare soil still be considered fallow? What exactly is it that is meant to happen when we let soil lie fallow?

We've been having so much heat and drought here this spring/summer that I wasn't able to plant some of my rows. So they're empty. Some are mulched with last year's leaves (and covered with sticks to hold the leaves). Then I ran out of leaves, so some are covered with coarse wood mulch. And there is also some bare sandy soil. Are these fallow, and will that provide a benefit when they next get planted?

I grew up in Kansas where farmers were encouraged to fallow 1/7th of their land every year --- after 7 years, everything had been fallow at least once.  I knew many who did so, but some still tilled the weeds under, which in my opinion, defeats the purpose.

I think there's something to be said for cover-cropping a field with a multi-species seed cocktail and then not touching it for 12 months.  In fact, if you sewed your cover crop in the fall of this year, and then left the field fallow for 18 months before sewing it in Spring a year and six months later, you'd get all the nitrogen fixation by the cover crop, and undisturbed microbes and fungi for all those months.

I am of the opinion that soil erodes if there is not something growing. Winds will blow it away.  Rain washes it away.

Most of my homesite (Zone 1) is fallow.  It was like that when we bought the property and I have no idea why weeds don't want to live there. It is an acre so I just randomly throw out seeds to see what happens.  

It can't be chemical as we are too far from any crops growing.  And the only animals are deer, turkey, raccoons, etc.

I feel living mulch, such as clovers would be better than nothing.

I try to leave some good sized areas "fallow" and wild in the food forest. The wild plants seem to attract tons of beneficial insects to the area that help keep the overall area more healthy and balanced.