How to replace grass with a cover crop?

We are over run by 2 types of grass. Unfortunately, I don't know their species but they are persistent as heck and super aggressive. We wish to replace them with a more useful cover crop that will aid our agroforestry and kitchen garden developments. Naturally we are looking at mineral accumulators, especially nitrogen fixing plants. We can get hold of large quantities of reasonably cheap vetch. Our concern is whether we can create a situation that favours the vetch and cover crops so that they succeed in place of the grass.

In zone 1 we have been using sheet mulching techniques but in zones 2 and 3 we are open to suggestions as so far we have only come up with 2 non labour intense methods. The first method is to cover an area with tarp and old carpet until there are no signs of grass in the area and then seed with vetch and other suitable cover crops. The second method is pretty much the same but flip the grass over and then cover crop it. In both methods we are trying to arrest the grass and create an environment that favours the cover crop so that they win the race against the grass and shade it out.

Any suggestions on other methods or on how we can improve the chance of the cover crop coming out on top would be really appreciated. Peace and abundance.

Anyone got any suggestions?

I have had good success with both methods you mention. I think using a tarp is a little easier and works well if the grasses aren't to thick and compacted. I find turning the sod works well if the grasses are really thick (and the cover crop tends to pop a little faster with this method). If you have a large area to seed, do a test plot with both methods and see what works best. For a cover crop I have had good success with vetch, peas, and fava beans (two good food crops and they all self seed really well). Good luck!

Are you able to use animals? Chickens and pigs in moving paddocks can clear some grass.

I've had good success beating weeds by planting a couple of crops of buckwheat - till, plant and when it flowers, let the bee's work the flowers for a few days, till in and repeat.

Thanks for the suggestions. I shall be trying both the tarp and the grass inversion methods on test plots and when the chicken tractor gets finished I will probably switch to that method.

Sorghum is inhibits growth from other plants.

I recommend this site for cover crop info http://www.sare.org/Learning-Center/Books/Managing-Cover-Crops-Profitably-3rd-Edition

You can find some very useful charts in there to select the type of cover crop for your goals.

Just how big are we talking about? 1/2 acre or 12?

I am assuming on the small end if you are even considering manual labor. The one thing that works better than an old carpet for us is an old billboard tarp--black side up to help heat the soil and germinate and cook some more of the grass seed. You can overcook it, though, and kill lots of your biology if you aren't careful.

Bigger areas can use some mechanization. Mow it as close as you can, repeat in a week, then sow the buckwheat. Buckwheat is fast and can help knock back the grass. A few rounds of that and then go for the vetch.