The first thing I would recommend is putting your location (USDA Zone at least) into your profile. Location is a big driver in recommendations. There are lots of options. For fall, brassicas are big N users. You want to avoid another legume. Unless you are very far north, it is probably too late for a spring plant. Grasses like corn and sorghum are N consumers as well as buckwheat. Cereal grains like WR will also use N.
What happens with perennial clover is that it fixes N into the soil from the air (like any legume). Depending on the type of clover, you can get 5, 7, or even more years out of a field with good establishment and management. Regardless of what you do, a clover field will get weedy after a while. The reason is that grasses love N. Over time they become harder to control.
I'm pretty weed tolerant. My clover fields get very weedy during the summer. I let the weeds grow and you often can't tell from a distance that it is a clover field. Come fall, I mow it right before the season. With our more frequent rain and cool evenings that favor the clover, it typically bounces back and looks like a great clover field again. Eventually, when I have less than 50% clover after bounce back, I will spray with 1 qt/ac gly right before a rain. The gly with kill all the grasses and top-kill the clover, but the perennial clover will bounce back quickly from the root system. You can't do this with a clover plot that is not fully established but it works well with an older plot. It can be done in the spring or fall but you want a good rain in the forecast. This usually gives me a few more years out of the plot.
I typically begin my rotation in the spring. Buckwheat is a good soil building crop that I like in the spring. It is especially good for smaller plots that get a lot of attention from deer. They typically use it but don't abuse it like ice cream crops that can get wiped out. It is a fast grower and will out compete most summer weeds. I typically use brassica that fall along with Winter Rye. I like PTT and GHR as my brassica component. Keep the rates low in a mix. GHR provides earlier season attraction along with the WR and it provides organic tillage.
The best practice for starting a perennial clover plot is to plant it in the fall with a Winter Rye nurse crop and then during the following spring, mow the WR back to 6"-8" (depending on the type of clover) each time the WR hits a foot or so. This slowly release the clover without killing the WR. The WR keep growing and battling weeds until it dies naturally. I find this method gives me the cleanest field to start with. After that first spring, I become very weed tolerant. I may mow once in subsequent springs if I get around to it and I always mow in the fall right before the season begins.
Thanks,
Jack
