Clover and nitrogen fixation

[Dave2002]

Clover is reportedly good for nitrogen fixation. Does this mean that nitrogen is transferred in some form to the soil, or rather that it is captured in the plant, which can thten be dug in to enrich the soil?

Is clover userful if used in an apprpriate wa?

[Old Grumpy]

Does this help?

https://germinal.com/knowledge-hub/n...%20the%20plant.

[oddoneout]

It's interesting this one. The received wisdom is that legumes(and some other plants) can fix nitrogen in nodules on their roots, by the process described in the link OG gives and that that nitrogen in the nodules becomes available to other plants when the legume itself dies or is cut down, hence the advice to leave the roots in the soil. However, on a training course some years ago in connection with mentoring scheme I was involved in we were told that in fact that that doesn't happen. The tutor's summary was "plants aren't altruistic - they fix nitrogen for their own purposes not for the benefit of others". However, I assume that such nitrogen fixing results in greater overall nitrogen content in the plant matter than would be the case with other plants grown on the same soil, especially if that soil is not very good so the growth rate/nutrient content of the plant would be greater than would otherwise be the case.
There is an argument for not digging in the plant matter, as such disturbance to the soil disrupts the soil ecology, but cutting it and leaving on the surface for the soil organisms to deal with, as would happen "in nature".

[Serial_Apologist]

The tutor's summary was "plants aren't altruistic - they fix nitrogen for their own purposes not for the benefit of others".

If I'm not mistaken that assertion has recently been questioned in relation to fungal connections linking tree roots which send "signals" between trees over sometimes quite large areas. This is not to say the "altruism" is intentional, any more than that betweej different species of insects in which one species sacrifices its young to say a community of ants. There is no "ego" involved!

[gradus]

I've read that pea and bean roots fix Nitrogen that benefits the plants that follow them but I've never really noticed any particular growth spurts compared with the same crops in beds that haven't followed legumes, so for me it ain't neccessarily so.
If plants are showing signs of needing more Nitrogen use a fertilizer, a good idea in a year with so much rain washing nutrients through, particulary on our light soil.

[oddoneout]

If I'm not mistaken that assertion has recently been questioned in relation to fungal connections linking tree roots which send "signals" between trees over sometimes quite large areas. This is not to say the "altruism" is intentional, any more than that betweej different species of insects in which one species sacrifices its young to say a community of ants. There is no "ego" involved!

Yes things have moved on quite a lot recently with regards to relationships between plants(and other organisms ) in the soil. However the view that the nodules somehow act like those little pellets of slow release fertiliser, doesn't take into account that once the plant dies the activity that produces the nitrogen also ceases, since the plant can no longer use it or maintain the mechanism in the nodule, and I think that was in part what the tutor meant.

[oddoneout]

I've read that pea and bean roots fix Nitrogen that benefits the plants that follow them but I've never really noticed any particular growth spurts compared with the same crops in beds that haven't followed legumes, so for me it ain't neccessarily so.
If plants are showing signs of needing more Nitrogen use a fertilizer, a good idea in a year with so much rain washing nutrients through, particulary on our light soil.

The way to do that is to try and keep as much of the nutrients in the soil as possible, which means upping the organic matter and as far as possible not disturbing the soil ecology. I sympathise with the problems of a light soil - I had an allotment for more than 30 years which had very sandy soil, which made it inclined to be hungry and thirsty. However just adding fertiliser to boost plant growth creates its own problems - for the soil itself and how it functions(which can create nutrient imbalances) and also in respect of adding to the load of nutrients ending up in watercourses.

[Dave2002]

Really quite an interesting subject this - and I didn't expect it. My interest started when I noticed clover in our lawn, as well as moss. I read - perhaps incorrectly - that clover would help with nitrogen, and indeed I used that as an argument for keeping it when my neighbour made comments about clover creeping into his lawn from our garden. My response was usually "but it's good for nitrogen fixation". I also read that the presence of clover was perhaps an indication that there is a low nitrogen content/availability in the soil.

It does seem that clover [or any similar plant] is able to extract nitrogen directly from the atmosphere, and in that sense it is deinitely a good thing - particularly if it is used as a crop - maybe for animal feed. The first article posted by OG does indeed suggest that clover is beneficial for large scale farming, and reduces or avoids the need for artificial fertiliser, and this results in a significant lowering of greenhouse gas emissions.

I'm not too worried about having an immaculate lawn, and indeed some strips have now been deliberately left to grow fairly wild. The presence of two very large oak trees at the periphery, plus the general climate and rainfall - or lack of it - mean that most water which would keep the lawn green gets taken by the trees. Over the years grass as some gardeners would like it tends to lose out to clover and moss - and indeed other weeds such as buttercups, daisies and dandelions, as well as dock. I have given up trying to remove the moss - and killing it off simply results in large brown dead patches. I do not want to water the lawn - as that is wasteful, and I believe bad for the environment, unless there is some other benefit, such as creating a localised patch of micro climate allowing other plants to grow. That's not going to happen here, with - I estimate - 40+ metre high oaks at the boundary.

I definitely don't want to start using artificial fertilisers on a large scale simply to keep the front patch looking green. This is not Wimbledon - though that gets pretty brown once the players start wearing the grass down, nor a golf course.

[Old Grumpy]

Really quite an interesting subject this - and I didn't expect it. My interest started when I noticed clover in our lawn, as well as moss. I read - perhaps incorrectly - that clover would help with nitrogen, and indeed I used that as an argument for keeping it when my neighbour made comments about clover creeping into his lawn from our garden. My response was usually "but it's good for nitrogen fixation". I also read that the presence of clover was perhaps an indication that there is a low nitrogen content/availability in the soil.

It does seem that clover [or any similar plant] is able to extract nitrogen directly from the atmosphere, and in that sense it is deinitely a good thing - particularly if it is used as a crop - maybe for animal feed. The first article posted by OG does indeed suggest that clover is beneficial for large scale farming, and reduces or avoids the need for artificial fertiliser, and this results in a significant lowering of greenhouse gas emissions.

I'm not too worried about having an immaculate lawn, and indeed some strips have now been deliberately left to grow fairly wild. The presence of two very large oak trees at the periphery, plus the general climate and rainfall - or lack of it - mean that most water which would keep the lawn green gets taken by the trees. Over the years grass as some gardeners would like it tends to lose out to clover and moss - and indeed other weeds such as buttercups, daisies and dandelions, as well as dock. I have given up trying to remove the moss - and killing it off simply results in large brown dead patches. I do not want to water the lawn - as that is wasteful, and I believe bad for the environment, unless there is some other benefit, such as creating a localised patch of micro climate allowing other plants to grow. That's not going to happen here, with - I estimate - 40+ metre high oaks at the boundary.

I definitely don't want to start using artificial fertilisers on a large scale simply to keep the front patch looking green. This is not Wimbledon - though that gets pretty brown once the players start wearing the grass down, nor a golf course.

Spot on, Dave2002, and to be applauded. To me a clover-rich lawn is a thing of beauty and stays a lovely shade of green even when grass is turning yellow/brown.

Watering a lawn with a sprinkler is a phenomenal waste of water and should be outlawed.

[Roger Webb]

.................... I have given up trying to remove the moss .

I too - in Japan in summer months students are employed to pull out separate blades of grass lest they ruin the magical moss gardens. This is now the model for my north facing Welsh border Wye Valley lawns.

[gurnemanz]

Spot on, Dave2002, and to be applauded. To me a clover-rich lawn is a thing of beauty and stays a lovely shade of green even when grass is turning yellow/brown.

Watering a lawn with a sprinkler is a phenomenal waste of water and should be outlawed.

A few years ago I had lots of clover. Fine by me but it did cross my mind that it might be taking over. Without any intervention from me it has now mysteriously disappeared completely.

Fully agree on lawn watering. I believe the roots will survive most droughts.

[oddoneout]

A few years ago I had lots of clover. Fine by me but it did cross my mind that it might be taking over. Without any intervention from me it has now mysteriously disappeared completely.

Fully agree on lawn watering. I believe the roots will survive most droughts.

Lawns are generally able to survive periods of drought(although the ryegrass commonly used doesn't always fare so well), but the combination of drought and high temperatures increasingly seen may be more of a problem. There is work going on to look at alternative species that might cope better, for both recreational grass and pasture needs.
Some useful info here re: clover https://www.rhs.org.uk/weeds/clover-in-lawns
I have quite a lot of white clover in much of my grass area, and when it flowers it is pretty and the bees love it, although care is needed if barefoot. I have the mower blades set quite high as otherwise the little mower can't cope with the moss, but that does means that many of the flowers escape beheading and the plants quickly throw up new ones as well.

[Retune]

Clover is reportedly good for nitrogen fixation. Does this mean that nitrogen is transferred in some form to the soil, or rather that it is captured in the plant, which can then be dug in to enrich the soil?

Nitrogen fixation isn't done directly by the clover itself. Rather, bacteria with the ability to convert atmospheric nitrogen to ammonia take up residence in specialised nodules in the clover's roots. This is a true symbiotic relationship. The plant gets the ammonia, which can be converted to more complex nitrogen compounds like the amino acids that are the building blocks of proteins. In return, the bacteria get an energy source in the form of sugars that the plant has made by fixing carbon from atmospheric carbon dioxide during photosynthesis.

When the clover eventually decomposes, its nitrogen compounds pass into the soil where they can be metabolised by other kinds of bacteria that live there - e.g., ammonium compounds can be turned into nitrates that can then be taken up by species of plants that don't have their own nitrogen-fixing bacteria. In other words, clover and the various types of bacteria involved have provided the soil with organically-generated fertiliser, using nitrogen that originally comes from the air.

[gradus]

The way to do that is to try and keep as much of the nutrients in the soil as possible, which means upping the organic matter and as far as possible not disturbing the soil ecology. I sympathise with the problems of a light soil - I had an allotment for more than 30 years which had very sandy soil, which made it inclined to be hungry and thirsty. However just adding fertiliser to boost plant growth creates its own problems - for the soil itself and how it functions(which can create nutrient imbalances) and also in respect of adding to the load of nutrients ending up in watercourses.

Much of my gardening seems to involve compromising the ideal solution!
Obtaining a sufficient supply of compost/manure is relatively costly eg a tonne bag of green manure is just over £80 delivered and I make nowhere near enough compost on my allotment to meet my needs, at home we can manage to get enough. We used to be able to get an 8 ton load of pig manure - much the best on light soils - for the same price but the farmer has left farming and I prefer to avoid horse muck from the stables as it is invariably packed with weed seeds and being in Suffolk there are relatively few local sources of cow manure but it too has the weed seed problem.
So I'm left with no practical option but to use fertilizer - Growmore usually - sparingly as it has rocketed in price in the last few years as the farming community is only too aware.

[oddoneout]

Much of my gardening seems to involve compromising the ideal solution!
Obtaining a sufficient supply of compost/manure is relatively costly eg a tonne bag of green manure is just over £80 delivered and I make nowhere near enough compost on my allotment to meet my needs, at home we can manage to get enough. We used to be able to get an 8 ton load of pig manure - much the best on light soils - for the same price but the farmer has left farming and I prefer to avoid horse muck from the stables as it is invariably packed with weed seeds and being in Suffolk there are relatively few local sources of cow manure but it too has the weed seed problem.
So I'm left with no practical option but to use fertilizer - Growmore usually - sparingly as it has rocketed in price in the last few years as the farming community is only too aware.

I know the feeling. I couldn't make enough compost for the whole allotment so I had to use it where it was needed on a case by case basis. When I was breeding and showing guinea pigs and when I kept chickens that helped, and for a few years I was also able to get horse muck( from pooh picking and stable mucking out) if I collected it. The weed seeds didn't bother me - there were so many flying around anyway, and they just made extra material for the compost heaps. I wouldn't use it now because of the aminopyralid issue.
Do you use/have you tried green manures? It isn't necessary to dig them in; some will die overwinter and otherwise annuals can be cut down and left to rot in situ or put on the compost heap.
Other things that came my way, but not on a regular basis , more a case of saying yes to an offer when I happened to be in the right place/talking to the right people were grab bags of leaf mould (from the High School across the road which had run out of space to deal with the autumn bounty and was happy to deliver), spoiled straw(some bales that got soaked when a tarpaulin flew away, ditto delivered), and shreddings from tree prunings when a neighbour had work done in her garden, which I had to bag at the time and then transport. Some of those things went on the ground direct to let the critturs/soil life deal with and some went to augment the compost heap. The leaves that hadn't broken down were left in the builders' bags for a couple of seasons to do so.