Topic: Green Manure

[raisedbedted]

Hi All

I had planned to try growing some green manure this year, the plan is that as stuff comes out I would replace with GM possible to overwinter.

I have bought a variety of GM seeds from the organic seed company.

But I read Bob Flowerdews article in KG that GM is good for farmers who have the machinery to plough in but for domestic gardens it is an arduous task to get rid of what in effect are pernicious weeds.

Has anyone got experience of GM and any advice on whether to avoid?

I'm a bit worried now that all I'll be doing is replacing one set of weeds with another!

[derbex]

I use Green Manure, grazing rye, phacellia field beans and buckwheat so far. Can't say that I find it a huge problem, some of them are killed off by frost anyway. The trick is not to let them set seed (unless you want them to), that way you don't really get a problem from things like the beans, phacellia and buckwheat. I believe Grazing Rye can be more of a problem -although in my case it's getting the stuff to grow. I scythed mine down a month or two ago and then covered the plot, I may well recover with newspaper and cuttings or some such and plant through.

Jeremy

[Merlins Mum]

I have just sent for some buckwheat and clover, and planned to dig it in when the time was right!
MM

[Clayhithe]

I use broad beans.

Easy to grow,  not pernicious weeds,  good compost,  roots trap nitrogen,  grow any time of year,  very tasty :D

There was a useful discussion a month or so ago ::)

[philcooper]

They certainly are not pernicious weeds!! They all go away once dug in. The do a great job overwinter of preventing leaching of nutrients, the reverse in fact, they add to the nutrients when dug in!

The only slight snag is that some, I found grazing rye, are harder to dig in than others.

Most are relatively easy to dig in and, as has been said, if you do it before they flower, they rot down quickly. If you leave them to flower then the styems tend to be tough and they take longer to rot.

One point that is not often mentioned is that you shouldn't sow seed for 2 -3 weeks after digging in green manure. There is some "thing" released by all plants as they decompose that prevents the germination of seeds. This does not apply to plants or tubers.

There's a very good description of the characteristics, what they do for the soil, when to sow, dig in and how easy they are to dig in at http://www.kitchengardens.dial.pipex.com/greenmanure.htm

Phil

[Derek]

John

Thank you for your most interesting point. Do you grow broad beans as a stand alone green manure or as an extended general crop?

I can also picturing an Autmn sowing with the digging-in taking place in the following spring... I suppose what I am really trying to say is which is the most effective way to use this plant as a GM

Derek

[Merlins Mum]

One point that is not often mentioned is that you shouldn't sow seed for 2 -3 weeks after digging in green manure. There is some "thing" released by all plants as they decompose that prevents the germination of seeds. This does not apply to plants or tubers.
Phil

Yes I'd heard this. 

One of the reasons I want to grow them is because I heard they keep moisture in the ground, and where my lottie is, it is VERY windy and so dries the soil, making it very dusty on the surface.
Also read they are a good habitat for frogs and toads which I want to encourage so they can eat my slugs for me!  ;D

MM

[philcooper]

Whilst they are growing, green manures, like all plants will take water from the soil. However they will prevent a dust bowl effect by protecting the surface from the wind.

When dug in they will produce humus which will make the soil more water retentive and less likely to produce a dusty surface.

They are certianly good for wildlife as it tends to prodcus a "total cover" as opposed to rows with gaps between. This is, as you say, is good for all amphibians (we have newts). The one I really like is Phacelia which grows very quickly during the summer and so suppresses weeds but has a blue flower that attracts insects and butterflies (assuming you leave it to flower) and is not difficult to dig in even after flowering.

Phil

[derbex]

Don't you find it self-seeds Phil? Mine does -although it's not a big problem. Phacellia is one of my favorites too -I'm trying to save the seeds for next time.

Jeremy

[wardy]

My plotty neighbour used green manures for the first time last year and ploughed them in with her brand new mantis a few weeks ago.  They ploughed up very easily and she was very pleased that she'd done it and was recommending it to me.  My allotment is still nearly all weed covered (still) so my soil is protected but as I proceed to clear it I shall be using green manures rather than expose vast areas of bare soil to the harsh winds we get across my allotment.

As usual Phil, you are a mine of info.  Ta  ;D

[philcooper]

Jeremy,

It does and I try to leave a few of the seedlings to grow on, whatever else happens to be in the bedas single plants are quite "thin" with their ferny foliage

Phil

[redimp]

What are the practicalities of gathering seed from green manures such as red clover.  This could be a good reason to allow them to flower if the seed is easy to gather and all arrives at about the same time or in spurts.

[Merlins Mum]

I have sent for some red clover and I intend to let it flower as it attracts bees  :)

MM

[redimp]

I am planning to do the same on the basis that the only bees that can reach red clover nectar are long tongued bumble bees.  These are the rarer one and bumble bees, unlike honey bees do not discriminate and will take nectar from all the flowers on the plot (e.g. beans) whereas honey bees will stick to the flower that attracted them in the first place.

[Merlins Mum]

Great minds think alike redclanger  ;D ;D
MM

[Clayhithe]

Do you grow broad beans as a stand alone green manure or as an extended general crop?Derek

Derek,

As soon as I harvest anything I fill the gap with broad beans,  spaced about 6 inches.
When I sow something else.  I pull the beans and either compost them or dig them in elsewhere,  at whatever stage.   The young tops are quite tasty!
If they're sown at the end of the season they stay until I need the ground in Spring.
6 inch spacing is good for weed suppression,  but not for harvesting,  although a good many do crop.  I then use the beans for more GM sowing!
The food crop is kept in place in the rotation,  at 12 inch spacing,  always from new seed.   I grow far more than we need and use the spare beans to keep the GM going.

I recognise the potential for disease,  but I've been lucky so far.
The results are that every bit of ground is always covered,  and as much nitrogen as possible is going back into the soil or into the compost heap.

Sorry to be long-winded,  but I'm a nitrogen-cycle anorak ;D

[wardy]

Have you not tried any other green manures by way of comparison.  I want to grow some and wonder what influences choice.  Should choice be based on the soil ph or weather conditions or what?  I'm new to this subject  :)

[Sprout]

I've sown some red clover and phacelia based purely on reading that they weren't too difficult to dig in.

[philcooper]

Wardy,

I choose based on:

1. time of year - that usually rules half of them out for any given piece of ground, 2. how long the plot will be "unoccupied" which again reduces the choice and
3. what will follow the GM, using rotation rules - this applies to legumes and brassicas (most GMs are legumes, brassicas or "other")

I don't think pH comes into it - unless someone knows different!

Phil

[wardy]

Ta Phil for sage advice again  :)  I shall have to get myself a proper diary sorted out so I can plan stuff a bit instead of just winging it all the time.  I need to know where I put what and when and if I don't write it down I'll forget and then any thoughts of plot rotation will be out the window!  I didn't realise that the GM's had to be included in the rotation.  So much techy stuff to take in  :)