I’m not an expert, but will throw out what I’ve done/thought along with the grains of salt that folks should take with it.
Before I put in the trees, I went with winter rye in the fall, lightly disked in as soon as I saw seed heads. This was followed by buckwheat, oats, vetch, that I let go until fall. Repeated the rye, disked in spring, and planted my trees. I went with an in row planting of oats/buckwheat again and regretted it. I seed with a broadcast spreader. Having irrigation, removing/incorporating near the trees is next to impossible. I accepted this issue and have dealt with volunteers for a few seasons. I’m amazed that things can keep reseeding year to year despite my cold environment.
Moving to a new part of the orchard, I started the same way, except for the incorporation of woodchips mentioned above. I’ll be moving trees from the nursery to the orchard this spring. Last year’s summer planting consisted of buckwheat, field peas, sunflowers, and some sort of brassica. The planting was timed for a late august/early sept bloom of buckwheat and late sept/early October bloom of sunflower. It worked out perfectly, made for an awesome sight after the trees lost their leaves, and my bees had a couple of extra months with some nectar and lots of pollen to gather. (7 of 7 colonies are still humming away). The brassica was underwhelming for the bulk of the time, but it was the longest living thing in the field. I want to say it lasted 3 weeks after the frost that did in the sunflowers.
Vetch: I love it, but will plant it sparingly (not with broadcast) as it seems to make HUGE masses of plant matter in year two. Last year, I had to manually rescue many of my young trees that were being overwhelmed by vetch-balls. Fortunately, I had tree cages that kept the plants off of my trees. Without it, liberating the trees would have taken a lot of work. Some of the balls (multiple plants, for sure) were 5-6 feet across and 2-3 feet deep of impenetrable plant matter. They killed all of the plants that lived under them. With trees, playing the long game, I’m happy to chop and drop most everything. The vetch, on the other hand, scares me. If I left a mass on the ground, I fear it would offer great cover for vols, etc. I’m sure to get vetch into the alleyway, and hit it until shredded with a brush hog.
Sunflower note: The bees absolutely love it in the fall. They are gorgeous. It is also my cheapest cover crop seed. I use 50lb bags sold as bird food. $15 each. I broadcast at 150 lbs per acre and get a LOT of plant matter. Before winter hits, I brush hog them. Then the turkeys come…so many turkeys! The biggest thing that worries me about sunflower… the seeds are collected by vermin. With the extra food, I’m sure next season’s vermin will start with a larger population. OF course, maybe with the seeds, they’ll be least tempted by unprotected plants in the orchard (currants, aronia, etc). When I blew out the irrigation system in the end of October, several of the valve boxes were 3-4 inches deep in sunflower seeds. The amount of work it took a vol/mouse to move that many seeds is impressive.
I put in radishes last year just to see what they would look like. Not a lot of green matter, but the radishes themselves were huge. Some 4-5 inches across, 2 feet long. The weird thing… they seemed to have more radish above the ground than below. Maybe this was due to my exceedingly sandy soil? The dog enjoyed chasing and destroying radishes with tops thrown his way. It was great entertainment until I realized that they gave him wicked gas. Live and learn.