Allotment Gardening Advice Help Chat
Growing => Grow Your Own => Topic started by: chris mutter on August 24, 2020, 15:04
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Well they have given their all and now their time is up, so do I pull them out and dig them in, Compost them, or even burn them. I have salvaged a few Hundred Beans ready for next years crop. If I get them out I can re dig the ground. Been told to leave them in the ground to rot down. Thank You.
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I’d just pull them out and compost them as they’ll break down quicker in a compost heap. It used to be thought there was some nitrogen left stored in the roots, but this has been debunked as the plant uses this to produce the crop and is left exhausted. Some use beans as a green manure, but these are normally dug in before they get old and woody.
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I pulled mine up yesterday and put them in the compost bin :)
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following on from advice pulled and composted them all, Thank You.
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I’d just pull them out and compost them as they’ll break down quicker in a compost heap. It used to be thought there was some nitrogen left stored in the roots, but this has been debunked as the plant uses this to produce the crop and is left exhausted. Some use beans as a green manure, but these are normally dug in before they get old and woody.
I didn't know leaving them to leach out the nitrogen had been debunked! I guess I'll go and pull mine out and chuck them in the compost instead then. :)
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I think broad beans do leave a fair amount of nitrogen in the soil after they are grown which can be used by a subsequent crop but once they go brown/black, they are neither producing more nitrogen nor taking any up. So how soon you clear them is simply a matter of convenience.
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Vagabond: I didn't know leaving them to leach out the nitrogen had been debunked!
They only fix nitrogen on their roots for the benefit of themselves: it goes into pod production. Once the plant has podded, there's no nitrogen left on the roots, so you may just as well add them to the compost pile.
https://aces.nmsu.edu/pubs/_a/A129/
When the grain from a legume crop is harvested, little nitrogen is returned for the following crop. Most of the nitrogen fixed during the season is removed from the field as grain. The stalks, leaves, and roots of grain legumes, such as soybeans and beans, contain about the same concentration of nitrogen as found in non-legume crop residue.
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Some old-timers used to cut the halm down to a few inches, give them a feed, and try and get them to grow again.
I tried it once, and got a few extra beans, but space is probably better used for another crop. The above method probably predates freezers too!
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The statement, little of the nitrogen produced by the crop is available to subsequent crops does not result in the conclusion that the beans only produce nitrogen for themselves. The correct conclusion is that the legumes not only produce sufficient nitrogen for pod production but also produce excess, leaving some for subsequent crops, although that is little compared the nitrogen they use. They make a net contribution of nitrogen to the soil beyond their own needs. Other non-legume crops around them deplete nitrogen from the soil, so the relative benefit is therefore much greater.
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The statement, little of the nitrogen produced by the crop is available to subsequent crops does not result in the conclusion that the beans only produce nitrogen for themselves. The correct conclusion is that the legumes not only produce sufficient nitrogen for pod production but also produce excess, leaving some for subsequent crops, although that is little compared the nitrogen they use. They make a net contribution of nitrogen to the soil beyond their own needs. Other non-legume crops around them deplete nitrogen from the soil, so the relative benefit is therefore much greater.
But the question was about leaving them in the ground to rot down and release nitrogen, so the advice to pull them up and compost them still stands. A full compost heap is going to be way more use than dead bean plants in the ground :)
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Are you OK to compost them if they have chocolate spot?
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Yes. Chocolate spot on the beans does not stop you composting both pods and stalks.
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Yes. Chocolate spot on the beans does not stop you composting both pods and stalks.
RHS advice is not to compost plants infected with chocolate spot:
Non-chemical control
Maximise air flow around the plants by wider spacing and avoid damp, humid sites
Destroy infected plant material at the end of the season
Eliminate common vetch from the vicinity
Avoid using seed from infected plants
https://www.rhs.org.uk/advice/profile?pid=89
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Chocolate spot is a fungal disease, a form of botrytis specific to broad beans. If parts of the plant are composted and the fungal disease is not destroyed by the composting process, the chance of the resulting compost being used anywhere near broad beans which do not require nitrogen because they are legumes and make sufficient nitrogen for their own growth and store excess in the plants themselves is so minimal as to be excluded for all practical purposes. The assumption that RHS advice is reliable and practical is extremely dangerous. Following RHS advice would mean that every dandelion and every item of couch grass you dig up should be excluded from the compost heap because they are perennial weeds. I find this entirely bizarre advice of zero practicality and can personally testify from decades of experience that they both compost extremely well with no adverse effects.
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Chocolate spot is a fungal disease, a form of botrytis specific to broad beans. If parts of the plant are composted and the fungal disease is not destroyed by the composting process, the chance of the resulting compost being used anywhere near broad beans which do not require nitrogen because they are legumes and make sufficient nitrogen for their own growth and store excess in the plants themselves is so minimal as to be excluded for all practical purposes. The assumption that RHS advice is reliable and practical is extremely dangerous. Following RHS advice would mean that every dandelion and every item of couch grass you dig up should be excluded from the compost heap because they are perennial weeds. I find this entirely bizarre advice of zero practicality and can personally testify from decades of experience that they both compost extremely well with no adverse effects.
Well that's ok then guys, lets rip up all the wisdom and accrued advice of an institution such as the RHS, with decades of research and investigation, because somebody with 60 odd posts on a forum says it's wrong in his view!
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Hot composting may kill the overwintering spores, but there is no guarantee of that, and who wants to have to try to remember where they can and can't risk using their precious compost?
The RHS advice explains the best compost making practice, and is eminently practical because it no doubt recognises that few of us either try or manage to achieve hot composting at all, in which case, apart from allowing pathogens to survive, many perennial weed roots can also live long enough to potentially fight another day.
This year was the third year running I've grown either Wizard field beans or broad beans in more or less the same area, and although they cropped OK, they finished up a blackened, wilting mess thanks to chocolate spot - they went straight in the household waste bin and I'll be growing them somewhere else next year as the spores can overwinter in the soil as well as in the plant material itself.