>>2430090Yes, they really do. But it depends on your scale I think. The plants that grow fix certain nutrients from the air and soil (hence why so many plant legumes as a cover) and then when you till them in they decay, are eaten by worms and bugs, absorbed by fungi and it all becomes nutrients available in the form the plants can make use of.
In a small scale garden the trade off becomes whether it's worth it to give up growing time for a cover crop versus amending the soil in another way. So we have a decent sized yard but still want to use every bit as much as we can. I just pulled out a bunch of garlic and potatoes so there are bare spots. On a larger scale this might be where I throw in some beans to mostly till in later, but here I'd rather use the space to grow another round of zucchini and cucumbers.
We achieve the same outcome by growing other plants like comfrey, burdock, nettle etc that thrive in rough conditions in other parts of the yard where good veggies don't do well. That way you get good green mulch but still keep your beds producing. Same effect with a different take. As a result we get all kinds of crazy stuff popping up. Last year was lots of slime molds, this year is a boatload of penis mushrooms. It's good fun. As I say though what's most efficient is going to depend on the scale you're working at.
