Thanks to Lori McCarter for the image
Personally I would think that generally, yes, mulching
around plants is a good idea. There are voices of contradiction in the air
though.
What if you put too much fresh mulch like wood shavings
around the young plants, would it rot the stems? Do pests and disease live in the bark put on
the paths, were chemicals used in the process that would compromise an organic
garden? I really don’t know and I’m sure
we could debate it over many pints in the pub.
The one thing I would agree with is nature, and how mulching
happens naturally in woodlands and wild places.
There’s a balance of decaying matter that helps to both promote new
growth and sometimes deter others. Balance, that’s what it’s all about and how
we can replicate it in or own gardens.
Mulching
Mulch can be used for a lot of things in the garden. Some discourage seed germination and help to
retain moisture. During warm weather the
soil under cover of mulch stays cooler and retains moisture longer than
uncovered ground, which reduces the need for watering.
I like to think that the best much is free mulch, or as near
to free as you can get. So what other benefits does mulching bring?
In winter, heat that rises off the soil is held in place. It's
the same as when we sleep under a blanket in an unheated house. During the
summer, it's like insulation that keeps the heat out.
Add to its other benefits that mulch aids in erosion
control, reduces compaction from rain and foot traffic and releases nutrients.
Some of the biggest criticisms about mulching is that
different materials could either steal the earth of nitrogen/put too much
nitrogen in the soil, not break down quickly enough and can rot plants. it's interesting to see that mulch doesn't ever "steal" nitrogen, it is just busy doing other things for a short peroid.. Nitrogen is actually just locked in the soil as the microbes use it ingest the rotting much which might not have enough. as the microbes rot the mulch it release the nitrogen back into the soil plus the extra it has obtained from breaking down the mulch. this idea is disclaimed by scientists now though but the debate is still open for nitrogen shortages to temporarily slow down seed germination on the fine layer between the soil and mulch. as i said, there are no easy answers and most gardeners will find out for themselves what works.
I think that these issues are overshadowed, not by the mulch
itself, but the materials the mulch is placed on around the plants and on
paths. Non-biodegradable plastic, old
carpets with nylon thread that tangle up in the fork are the biggest issues as
they can get really untidy and make the ground hard to work.
The amount of nutrients available or how quickly they break
down varies a lot with different mulches. Compost is quickest to decompose and
one of the most nutrient-rich, so that really wouldn’t need a membrane other
than a few sheets of newspaper underneath it.
Newspaper
Regardless of the type of mulch, I’d say put down at least 5
to 10 layers of newspaper before spreading. The newspaper lasts longer than you
may think, under wood chips over a weedy lawn it can last up to seven years. Landscape fabric would do the same but you’ll
be picking pieces out of the soil for years. Mulch can be used on paths, but
keep in mind it’s different to gravel and will need replenishing annually.
Application
When applying mulch, how much depends on which type you're
using. Spread finer-textured products such as yard debris compost or mint
compost 2-5cm inches deep. Coarser wood products such as bark dust, wood chips
and arborist waste can be as deep as 8-10 cm. Try to keep any material at a few
cm away from the base of trees, shrubs and woody perennials.
Some Choices
Bark dust. Good
weed control but can tie up nitrogen in the soil so not good for plants that
aren't established.
Wood chips. Easily
available. Lasts a long time. Good weed control but again can tie up nitrogen.
Bark nuggets. Attractive
appearance and easily available. Lasts a long time. Good weed control but again
it’s a nitrogen thing. It can be expensive if bought in bags too.
Garden/municipal
compost. Good source of nutrients. Locally produced.Can promote weed
growth. Doesn't last long so might need to be refreshed each year.
Tree leaves. Free
and easily available. Good source of nutrients. Not easy to spread to a consistent thickness. Must be mowed or
turned to get it to break down in a season.
Sawdust. Good for
vegetable paths. Holds down weeds well. Repels
moisture because it's so fine. Fresh sawdust isn’t really good for bedding
plants.
Coco hulls. Decorative
but could be expensive and a bit dangerous for pets. HUGE carbon footprint
coming from the other side of the world.
Stray/hay. Great
for keeping the strawberries dry, could attract rodents and be a storage space
for weed seeds
Grass clippings. Breaks
down well and gives nutrients back to the soil. Could get a bit crusty stopping
water getting to the soil and if it’s not yours there might be chemical
residues.
Leafmold. Straight
from the woods this is a great mulch but can have weed seeds in it. Getting
permission to dig some up is a bit tricky sometimes.
My Conclusion
All in all I think mulching works and helps to improve the
health and appearance of the garden, although I must confess, I haven’t done
any mulching this year apart from throwing a few comfrey leaves around. I have
a covering of chickweed instead.
NOTE : There's research to disprove the locked up nitrogen. check out the bottom JEH25 pdf for more information . https://www.facebook.com/groups/GardenProfessors/files/ Here's the quoted section:
Nitrogen deficiency. A common misconception about
woody mulches is that they impose a nutrient deficiency upon
plant materials. This is based on the fact that woody mulches
have a high C:N ratio and nitrogen will be ‘tied up’ by microbes
during the decomposition process. Furthermore,
woody materials that are used as amendments incorporated
into soil or potting mixes will create zones of nitrogen deficiency,
which is visualized by spindly, chlorotic growth of
plants in these zones.
Experimental research reveals that neither nitrogen immobilization
nor growth suppression occurs as a result of
using woody materials for mulch (51, 100). To the contrary,
many studies have demonstrated that woody mulch materials
actually increase nutrient levels in soils and/or associated
plant foliage (5, 99, 114, 125). A zone of nitrogen deficiency
exists at the mulch/soil interface (Chalker-Scott, unpublished
data), possibly inhibiting weed seed germination while having
no influence upon established plant roots below the soil
surface. For this reason, it is inadvisable to use high C:N
mulches in annual beds or vegetable gardens where the plants
of interest do not have deep root systems.
Pests. Many organic mulches, especially those
NOTE : There's research to disprove the locked up nitrogen. check out the bottom JEH25 pdf for more information . https://www.facebook.com/groups/GardenProfessors/files/ Here's the quoted section:
Nitrogen deficiency. A common misconception about
woody mulches is that they impose a nutrient deficiency upon
plant materials. This is based on the fact that woody mulches
have a high C:N ratio and nitrogen will be ‘tied up’ by microbes
during the decomposition process. Furthermore,
woody materials that are used as amendments incorporated
into soil or potting mixes will create zones of nitrogen deficiency,
which is visualized by spindly, chlorotic growth of
plants in these zones.
Experimental research reveals that neither nitrogen immobilization
nor growth suppression occurs as a result of
using woody materials for mulch (51, 100). To the contrary,
many studies have demonstrated that woody mulch materials
actually increase nutrient levels in soils and/or associated
plant foliage (5, 99, 114, 125). A zone of nitrogen deficiency
exists at the mulch/soil interface (Chalker-Scott, unpublished
data), possibly inhibiting weed seed germination while having
no influence upon established plant roots below the soil
surface. For this reason, it is inadvisable to use high C:N
mulches in annual beds or vegetable gardens where the plants
of interest do not have deep root systems.
Pests. Many organic mulches, especially those
