Incorporating Lucerne green manure

[compostpopeParticipant]

I was talking to someone about a large plot of lucern in their anthroposophic, dug garden (I’ll fraternise with anyone over the subject of gardening).

They were concerned about how their cultivator will manage to dig it in when the time eventually comes. They are obviously completely nuts and I did clearly point out the error of their ways but was wondering if anybody has experience of digging it in or not (I would have thought a black plastic membrane would do the job as they don’t have enough compost to cover the area – about the size of an allotment). How dificult is it to dig in? How long would would it take to break down under a mulch?

[charlesModerator]

All I know is its deep rooted so may take months to die under mulch, but I cannot be sure and Pete Budd is the man to ask.

[compostpopeParticipant]

Yes he is, and I know he has written informative posts on the subject of green manures but I can’t navigate the new site layout to read them!

As I remember, he digs out the roots – I assume his plot is smaller than the one in question which is too big to do by hand hence the talk of using a cultivator which would probably just chop them up and do little to kill them…..

[charlesModerator]

Check this out, we just refined the Search bar so it finds things! http://www.charlesdowding.co.uk/forums/topic/green-manure/

[compostpopeParticipant]

Thanks, the search bar now works! It found the Great Budd’s reply to my very first query on this site almost three years ago – about the possibilities of using green manures instead of animal poo in a no dig garden! There he states that the roots of lucerne are not pernicious and if I read correctly he chops it down at ground level and puts the tops on the compost heap – no mention of it regrowing.

I tried it on my own allotment but had problems with poor germination, now I’m keen to give it another go.

[Pete BuddParticipant]

Hello everyone; I still utilise lots of green manure, I have just about finished covering all my bare ground with sowings of lucerne, grazing rye, phacelia and field beans. I currently have 2 allotment plots.
Just to recap on lucerne; I try to sow it by the end of August because germination gets tricky later on and small seedlings can get hit by frost/cold /damp conditions. I sow in rows to make it easier to manage and dig it out by chopping into the base of the row from both sides to remove all the top plus about 15cm of root, regrowth is then minimal. It is hard graft and definitely not everybodys cup of tea. I sow 20 to 40 sq mtrs per year and it grows all the next summer to be removed the following spring for a veg crop. The soil on our new allotment site was very poor and some veg types did not produce very well at all. For this reason I have been leaving my lucerne in for an extra year for it to bulk up and make more root. In my opinion the main benefit of lucerne is what the roots get upto below ground level and I will leave you to speculate on that. I hope this information is useful

Pete

[RhysParticipant]

Pete

Do you have any experience of whether any green manure causes subsequent crops to grow better/slower etc?

My very limited use of phacaelia in spring (March – end May) just as a cover crop prior to planting things out in late May (no incorporation of foliage into soil when cut) suggests some things grow a bit slower afterwards, but it may just be bad luck.

I’ve put in a few field beans as a cover this autumn (all germinated well) where salads will grow next spring and am putting some more in now to take out late January before sowing peas for shoots and the like.

Any evidence that this will slow subsequent growth or is it all good?

Cheers

Rhys

[compostpopeParticipant]

Pete

Thanks for the reply. I will pass your tips on to my friends – specifically the extra detail about chopping 15cm below ground level in order to extract enough root to minimise regrowth. It does sound a bit like hard work.

Unfortunately they have broadcast sown their lucerne, and with their larger area I don’t think they will be extracting using your method. I will try and persuade them to use a permeable black plastic mulch and be patient, but fear I will be wasting my breath. They like their cultivator too much!

Still, your input has further inspired me to try using lucern again in my own garden, so thanks once again.

CP

[Pete BuddParticipant]

Rhys

The simple answer is I don t know. There are too many variables; rainfall, temperature, pest cycles, soil type, etc. What can seem like the way to success one year, often results in failure subsequently. I see green manure as one part of the jigsaw, where a healthy, productive, living, growing medium is the objective. As a one off sowing, green manure is unlikely to make a big difference to a following veg crop but by continually rotating it over the seasons and regularly applying the resulting compost to the surface your soil will improve. Finally; try not to let winter rains deplete the topsoil, avoid bare ground, sow an appropriate green manure to stop minerals and nutrients leaching away. Re, phacelia; it covers quickly, provides organic bulk for composting and bees love the flowers. Field beans will add some nitrogen if left to mature and I have recently started using it as a vegetable crop in its own right, drying the beans for use in the kitchen.

Compostpope

A big area of broadcast lucerne sounds daunting! It will easily grow through a 4 in mulch. Rotavating will do a job but pulling out the regrowth along with weed seeds brought to the surface will take some time. Worryingly a lot of people would spray with glyphosphate or its frankenstein child resolva, (at our local garden awards evening, last week, the guest speaker from a nearby garden centre was extolling the virtues of that!). So covering with plastic is probably the only option. I think I would use the permeable woven fabric.

Pete

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