deep rooting green manure / mulching plants

Hello folks! I am planning to set a new vineyard in a few years. The land ( 1/3 acre) is covered by a wild grass now. My plan is to break and turn the grass sod with a plow and harrow it. I would like to sow some green manure mix there then. I am looking for some deep-rooting plants that also produce enough of biomass. The plan is to chop and drop the green parts and use it as a mulch. Deep roots would decompose during the winter and would act as a soil improving matter which helps the water to soak deep and also the roots of grapevines to penetrate the soil well. I was thinking a hemp, sunflower, some annual clovers and Phacelia would work well. Do you have some other candidates? Thanks for every answer!!

Alfalfa/lucern Is my recommendation It can remain as a permanent part of your isles and cover between vines. It penetrates my solid clay field. The biomass it produces is abundant and easy to harvest or just mow and leave it. If it is allowed to set seed it can be mowed with a scythe and moved to a bare area which will seed it there and develop new land. I have been doing this to my field starting where it was planted by the horses years ago and it gets established without any cultivation. I do the same with vetch but it is not as persistent.

Thanks for your answer Hans. Alfalfa is a great perenial green manure plant and I have it in my older vineyard too, together with a common sainfoin (Onobrychis viciifolia).. I do appologize, I did not mention a important thing in my first post.. I asked for some ANNUAL plant(s) with dense root system and producing enough green biomass above the ground for a soil preparation BEFORE planting the vineyard. My plan is to plough the area first and sow this plant mix there in the first year. I would cut the greens at the end of the season with letting it lay on the ground ("chop and drop"). I would cover it with some additional biomass (straw / hay / wood chips etc.) then. The roots of these annuals would decay during the autumn/winter and would create a nice dense web of microscopic cannals in the soil to help the grapevine root and the water to soak. The mulch on the ground would stay there for the whole next year to save soil humidity and as a anti-weed cover. In the second year would the planting of grapevines take place.. The permanent cover crop (alfalfa or any other) would be established in the third year..

I think the ones you mentioned sound great (though I've never grown hemp before).

I've had good results in a similar situation using a mix of different annuals that have varying heights & root depths. This seems to help bring a balance to the layers of soil; instead of just improving one layer. Plus the variation in growth habits takes up different spaces where more opportunistic & undesirable weeds may try to squeeze in.
I frequently buy the forage mixes that are designed for deer hunting when they get marked on clearance. I've also gotten the boxes of mixed flower seeds that are sold as "butterfly garden," or something like that. Then I mix it all in a bucket, along with any leftover flower/herb/veggie/ect. seeds from the previous year, and go out an broadcast it.
The different growth speeds, germination rates, and plant types gives me the option of going in & cutting the larger stuff down, as needed; or waiting until it's all mature and chopping it all down at once.

I would think something like that would be manageable for ⅓ acre, but if you'd prefer to just stick with one or two types, then the annual clovers, sunflowers, hemp may be best.

Kc Simmons wrote:I think the ones you mentioned sound great (though I've never grown hemp before).

I've had good results in a similar situation using a mix of different annuals that have varying heights & root depths. This seems to help bring a balance to the layers of soil; instead of just improving one layer. Plus the variation in growth habits takes up different spaces where more opportunistic & undesirable weeds may try to squeeze in.
I frequently buy the forage mixes that are designed for deer hunting when they get marked on clearance. I've also gotten the boxes of mixed flower seeds that are sold as "butterfly garden," or something like that. Then I mix it all in a bucket, along with any leftover flower/herb/veggie/ect. seeds from the previous year, and go out an broadcast it.
The different growth speeds, germination rates, and plant types gives me the option of going in & cutting the larger stuff down, as needed; or waiting until it's all mature and chopping it all down at once.

I would think something like that would be manageable for ⅓ acre, but if you'd prefer to just stick with one or two types, then the annual clovers, sunflowers, hemp may be best.

Thanks for sharing your experience!
That is exactly what I want. A mix of lower flowering plants (clovers, vetches, marigold, buckwheat, Phacelia etc.) for insect and soil microbiota and some larger "biomass producers", like hemp, corn, sunflower, mustards..

As KC stated, deer food plot mixes are great. Read the labels between what brands are available.  The seed selection and % can explain price difference between brands.

The grass is normally rye, wheat, or oats, or a combination of them. Then there is usually clover and peas for nitogen fixation. Brassicas and turnips to till down into the soil. Its a great combination.

I generally do the winter(fall) mix but i noticed they had a spring mix also. The past season i used this on land that was torn up from earthworks. I think it was sorghum,  millet, and cow peas. The sorghum and millet took off. I never saw any cowpeas.

Right now, my Tractor Supply has a lot of the deer forage mixes on clearance. I found a couple of small (1-2 lb) bags of daikon seeds for about $2/each, and several of the larger bags of mixed seeds were $6-$10, when they're usually $20-$30.
For flowers, check out the dollar stores for the boxes of mixed flowers that are made to be broadcasted. They're typically $1-$2 each.
I was recently cleaning out the barn, and I found a bucket-full of flower, veggie, and herb seed packets from 2017. I don't know if many/any are still viable, but I am going to just pour them all in the bucket, along with some old alfalfa seed (that I know is still viable), and toss a few handfuls in my garden paths for biomass, and around the chicken/guinea coops to hopefully provide some forage material.

Oilseed radish is a good cover crop, oilseed radish is a unique cover crop that farmers are planting to improve their soil quality for economic crop production. It has the ability to recycle soil nutrients, suppress weeds and pathogens, break up compaction, reduce soil erosion, and produce large amounts of biomass. Freezing temperatures of 20° to 25° will kill oilseed radish which allows for successful no-till spring planting of subsequent crops. As a fast growing, cool season cover crop, oilseed radish is best utilized when planted after small grain (e.g. wheat) or corn silage harvest. Excess nutrients in manure amended soil are rapidly absorbed by this cover crop, thus preventing leaching or runoff of nutrients into water systems, they also get nutrients from depths deeper than most plants so even in low fertile soil they add more nutrients back to the soil when used as a cover crop. The radish root goes to a depth of 12-18 inches deep. Once the crop dies back you can cut just the tops off (mow, bush-hog) and allow them to compost in place or disk them under. I personally would cut the tops as the radish root then rots in the soil leaving 1-1.5 in. diameter holes filled with decomposed radishes in them that would aerate the soil. They need 6-10 lbs of seed per acre so for 1/3 I'd plant 2-3 lbs of seed. The only downside is the smell. Acres of rotting radishes is NOT the best smell in the world but if your 1/3 of an acre is not right next to where you do much outdoor activities it should be fine. (But this is coming from a guy who spreads 8 tons of chicken manure to the acre even in my front yard LOL) Though I've never grown oilseed radishes, I have looked them up as this was one of the cover crops I was looking at using. But because I grow mainly market veggies and because of the chicken manure I use the main thin I needed was (N) nitrogen so I use a clover that stays green all winter here (zone 8b) so it is large and tons of biomass in the first part of spring here in Mississippi. The clover I use is called "Fixation" which is a berseem clover (annual). I also use a low growing perennial clover as a green mulch that also adds nitrogen to the soil. Its a white dutch clover.

PS, on the old seed, most seeds are good for 2-3 years if kept cool to almost freezing, some even are good for 10+ years depending on type of seed. I was told for every 10 degrees over 60 degrees the seed life drops by a year on average so if they were all in the heat they may not even work, but if in a cool area I'd think most if not all would still be fine.