One of the primary benefits of any cover crop is its contribution to the organic matter in the soil as well as any additional nutrients it might contribute. To take proper advantage of this, the crop must be tilled in or at least cut and left in place to compost - if you remove it, you are removing both the organic matter as well as the nutrients, i.e., the nitrogen fixing root nodules.

Alfalfa is often recommended to be planted to help loosen heavy soils because of its deep root penetration. Be sure to select an annual variety if used as a cover crop.

Attra has an excellent discussion of various cover crops, their contribution to the soil and appropriateness in various areas.

Here is a link that might be useful: Attra - cover crops

Alfalfa fixes nitrogen too like vetch does. But Vetch fixes more nitrogen than Alfalfa.

Which to use depends on many things sometimes something like how long will that crop be in place. For Alfalfa roots to get deep enough into the soil to pull up deep micro nutrieints can take several years. Vetch will grow in soils that Alfalfa may have a hard time or that could cause Alfalfa to take years to well establish.
The important thing is to get organic matter into the soil and not to be overly concerned about pulling up micro nutrients from the soil.

I was allways partial to Buckwheat rather than Alfalfa ....

and I think I went to high school with Harry Vetch......

have a great weekend ........JE

How long would you have to leave Alfalfa in the soil to get it's full benefit?

Several years sounds too much. I would sow in august....I'm zone 6 means this crop would die in the winter by snow cover, cold e.t.c.
So turning it into the soil in spring is worthless as all the nutrients would have been killed by then.

Nutrients don't get "killed". Even nitrogen, which tends to partially gas off with decomposition, will be retained b/c there's not much decomposition going on in winter. Spring is usually when cover crops are tilled in.

You mentioned feeding your goats. Why not compost their manure and then return that into your soil?

Alfalfa is not nearly as aggressive as some other cover crops it takes 2 years to get a good stand and usually needs a nurse crop to keep weeds down

Neither hairy vetch or alfalfa would normally be winter killed in zone 6

You mentioned goats is this an area that you can rotate out of garden and into pasture?

I have not personally tried them until next spring but Field peas look to be promising and cheap cover crop for northern areas the link gives info on them and most other cover crops hopefully help answer most of your question U of MN has some cover crop info also if you goggle that

Here is a link that might be useful: cover crops

OK good info guys, thanks.

The goats make a great manure all pellets and when you have them in their stables they step on it(by moving around) and make it into a beautiful dust that is already broken down for you to add into your soil.

Have any of you used Rhizobia Inoculant,8.7oz for 150 ft. row.
It will help any cover crop or bean/pea preform better.

15 feet?! I don’t think that’s right...