Poor wet soil - fine mulch/the exception to the rule of clearing cut vegetation?
Posted: Fri Oct 13, 2023 8:10 pm
Protection of wet ground?
My question arises from a starting point of specific areas of land with unfertilised, poor, deep, permanently damp solid clay, with a natural vegetation cover of soft and sharp rush, wood club-rush where soil has been disturbed, yorkshire fog, fleabane and similar wet loving flowering plants. Some of these areas are permanently waterlogged i.e. a bog with perhaps 2 inches of almost peaty soil above the water table, and some other adjacent areas have springs running for 3/4 of the year but dry to a damp state in summer.
The Rule
We meadow makers are told that the fundamental rule is to Cut And Clear the vegetation every year to reduce fertility and allow flowering and other plants to compete with the grasses. However, if the land is naturally poor with a species rich seedbank, surely reducing the already low level of fertility is not the major concern?
Add humus for improvement?
Instead of removing vegetation, should I be considering leaving some of it to rot down and add humus to the soil, to aerate it and encourage soil creatures?
Bare wet earth v. mulch
I usually cut and clear by strimmer in the wet areas, and by flail mower collector in the drier areas, from September to mid October, as there is a lot of the late flowering fleabane and devil's bit scabious in some areas. The drier areas cut in September, produce a flush of new grass growth for ponies coming in in late November, but the wet areas cut in October don't produce much new growth until the following spring. If I strip the vegetation every year, am I not exposing more soil to the rains and potential run off, and reducing the food for the soil creatures, reducing the biomass of the topsoil and encouraging anaerobic conditions?
Mulch v. fertility
The RHS advises gardeners that adding new mulch to a flower bed, does not add many extra nutrients, and the value of mulch lies more in the improvement of the soil texture.
If I leave a fine and shallow mushed up mulch of the existing bog vegetation, then surely that would only be recycling the present degree of fertility, not adding to it?
Mulch and water holding capacity
But then - the RHS also says that adding mulch improves the water holding capability of the top soil - so if the top soil is already frequently very wet, what does that mean?
To summarise
When my strimmer mulches up the bog vegetation, would it not be good to leave a shallow layer of fine mulch which will rot down quickly, (far far more quickly than the adjacent areas of untouched rush and flower stems,) instead of raking up as much as possible and aiming to clear everything? I would still remove the long swathes of rush and flower stems which do smother other plants and shade out anything beneath.
I have been advised to cut and clear a third of the bog vegetation every year, so this must leave 2/3 to slowly rot down in a natural smothering way, with flattened stems over winter for the wildlife. My question concerns the 1/3 which is cut in rotation each year.
Also - protection against poaching
Where I have winter springs, I am putting those long swathes of cut vegetation on top of these different waterlogged areas (not the bog), to protect them from light poaching by red deer jumping a fence and Exmoor ponies walking alongside it. (I appreciate it is not ideal to have the ponies in winter, but this is the only time I can have them.) My reasoning is that it is better to protect the structure of the soil with a mat of vegetation, and, there are probably loads of rush seeds in the ground any way.
Finally, for the rest of the fields, which are drier - but naturally low in fertility, with a good mix and expanse of flowering plants threaded through what is mostly yorkshire fog, creeping bent and cocksfoot - would an occasional shallow fine mulch from the existing vegetation, be a good conditioner for the unforgiving clay beneath?
Would this not be applicable to any land - would it not be a good thing to improve the soil by cutting the existing vegetation and then leaving some of it as a fine mulch, say one year in 3, or at different times of the year?
Your thoughts please?
My question arises from a starting point of specific areas of land with unfertilised, poor, deep, permanently damp solid clay, with a natural vegetation cover of soft and sharp rush, wood club-rush where soil has been disturbed, yorkshire fog, fleabane and similar wet loving flowering plants. Some of these areas are permanently waterlogged i.e. a bog with perhaps 2 inches of almost peaty soil above the water table, and some other adjacent areas have springs running for 3/4 of the year but dry to a damp state in summer.
The Rule
We meadow makers are told that the fundamental rule is to Cut And Clear the vegetation every year to reduce fertility and allow flowering and other plants to compete with the grasses. However, if the land is naturally poor with a species rich seedbank, surely reducing the already low level of fertility is not the major concern?
Add humus for improvement?
Instead of removing vegetation, should I be considering leaving some of it to rot down and add humus to the soil, to aerate it and encourage soil creatures?
Bare wet earth v. mulch
I usually cut and clear by strimmer in the wet areas, and by flail mower collector in the drier areas, from September to mid October, as there is a lot of the late flowering fleabane and devil's bit scabious in some areas. The drier areas cut in September, produce a flush of new grass growth for ponies coming in in late November, but the wet areas cut in October don't produce much new growth until the following spring. If I strip the vegetation every year, am I not exposing more soil to the rains and potential run off, and reducing the food for the soil creatures, reducing the biomass of the topsoil and encouraging anaerobic conditions?
Mulch v. fertility
The RHS advises gardeners that adding new mulch to a flower bed, does not add many extra nutrients, and the value of mulch lies more in the improvement of the soil texture.
If I leave a fine and shallow mushed up mulch of the existing bog vegetation, then surely that would only be recycling the present degree of fertility, not adding to it?
Mulch and water holding capacity
But then - the RHS also says that adding mulch improves the water holding capability of the top soil - so if the top soil is already frequently very wet, what does that mean?
To summarise
When my strimmer mulches up the bog vegetation, would it not be good to leave a shallow layer of fine mulch which will rot down quickly, (far far more quickly than the adjacent areas of untouched rush and flower stems,) instead of raking up as much as possible and aiming to clear everything? I would still remove the long swathes of rush and flower stems which do smother other plants and shade out anything beneath.
I have been advised to cut and clear a third of the bog vegetation every year, so this must leave 2/3 to slowly rot down in a natural smothering way, with flattened stems over winter for the wildlife. My question concerns the 1/3 which is cut in rotation each year.
Also - protection against poaching
Where I have winter springs, I am putting those long swathes of cut vegetation on top of these different waterlogged areas (not the bog), to protect them from light poaching by red deer jumping a fence and Exmoor ponies walking alongside it. (I appreciate it is not ideal to have the ponies in winter, but this is the only time I can have them.) My reasoning is that it is better to protect the structure of the soil with a mat of vegetation, and, there are probably loads of rush seeds in the ground any way.
Finally, for the rest of the fields, which are drier - but naturally low in fertility, with a good mix and expanse of flowering plants threaded through what is mostly yorkshire fog, creeping bent and cocksfoot - would an occasional shallow fine mulch from the existing vegetation, be a good conditioner for the unforgiving clay beneath?
Would this not be applicable to any land - would it not be a good thing to improve the soil by cutting the existing vegetation and then leaving some of it as a fine mulch, say one year in 3, or at different times of the year?
Your thoughts please?