Brisbane Local Food

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Mel Landers posted this in Soil4Climate:

I read it a few times and loved the argument.

Mulch versus Compost - Why I choose mulch –Experience, Observation and Research

I have answered so many questions about this that I am going to post this response for everyone.

Experience:

When I was a toddler, my mother had a highly productive garden while we lived in the state of Washington where the weather was mostly cloudy with light rains. So the soil stayed moist.

I began gardening at the age of nine in Central Texas where the weather was full sun, hit temperatures and little rain. The soil was always hot dry and hard and my plants suffered.

In my teens, I mulched the soil with stones. This maintained soil moisture much better than my bare soil and plants grew better. I now realize that this also provided habitat for invertebrates and microbes that did not exist in the hot dry soil.

In my twenties, in Colorado, I tried applying compost, which soon disappeared and I was left with the same conditions I knew in Texas, except that one summer it was too cold to harvest ripe tomatoes. Then I read Ruth Stout’s recommendations and decided to do a trial and I began cutting the grass and weeds for mulch material off the flood plain next to my house

Observation:

I grew the same crops in beds covered with as deep a mulch as I could manage, without covering up my plants and I planted them in beds to which I applied compost. The plants protected by the mulch did not suffer from drying despite less irrigation and they were not infected with leaf, stem and fruit rot like the plants which by that time were in bare soil; after the compost disappeared. The plants in the mulch grew larger and produced more that those with compost. Also, I noticed that the beds covered with mulch did not suffer erosion like those with compost.

In my thirties, on my own farm, I did not produce any compost. I had learned my lesson in Colorado. But, some friends of mine who farmed organically produced large quantities of compost and purchased rock dust, bone meal, etc. Their plants thrived, but they needed to apply organic mulches to many of their crops to prevent them from suffering, despite a drip irrigation system.

I developed a seven year rotation in which I began with a deep mulch and planted different crops as the biomass decayed;
1. Beginning with potatoes planted a foot or so above the soil in the midst of deep hay.
2. The second year, I planted sweet potatoes in the rounded pile of hay that was left.
3. Then I made holes in the hay the third year to plant squash.
4. The fourth year, I planted maize, beans and small leaved squash.
5. By the fifth year, the mulch was the consistency of compost, but was two to three inches deep. Into this, I planted peanuts.
6. In the sixth year I planted tomatoes, peppers and basil with a thinner layer of new mulch.
7. The seventh year was dedicated to root vegetables like carrot, onion, beets, turnips, radishes and kohlrabi. I reapplied mulch for this between the rows.
8.
This is how I learned to grow crops in thinner layers of mulch which still
• stop the compactive and erosive force of the rain,
• prevent wind erosion,
• shade the soil to keep it cool and moist,
• feed the earthworms, arachnids, fungi, bacteria and other organisms,
• provide habitat for some of these,
• deliver minerals from deep in the soil,
• reduce weed growth, etc. (although weeds provide more mulch)

Research:

In my mid-fifties, I studied paleo-climatology and discovered the danger posed by various Greenhouse gasses. I knew from previous study that the composting process is oxidative (like fire) and produces greenhouse gas emissions just like burning does. So, I decided to see what contribution composting makes to the greenhouse effect. Although it is not substantial today, production of compost does contribute much to the greenhouse effect; with home composting contributing a lower percent than large scale composting.

If compost were to be used as a replacement fertilizer for petrochemicals, it would become a major source of both methane and Nitrous Oxide which are much more potent than carbon dioxide; not that the carbon dioxide emissions would not also be substantial if thousands of farms switched to that strategy for organic production.

Then I asked the question about the difference between mulch and compost for soil microbes. It turns out that compost does increase the number of fungi in the soil. But, there is much less hyphal generation and elongation in compost treated soils in comparison with soils protected by mulch. Thus the vital mycohrrizal associations are improved in mulched soils. This, soil moisture levels and earthworm biomass are constant regardless of the thickness of the mulch. Also, Carbon availability is the limiting factor for most soil microbes. So, gassing off the carbon in the composting process leads to less microbial growth than with the biomass being used as mulch.

I discovered that worm manure increases soil enzymatic activity in proportion to the number and size of the earthworm population in the soil. Worms need to eat. Mulch provides them with much greater quantities of food than does compost. Their greater numbers also yields better soil structure. In addition, if there is enough food to keep them fed continually, rather than for a short time, they will completely turn the topsoil twice a year in soils that do not freeze. They also transport the carbohydrates from decaying mulch deep into the soil where it becomes labile and/or stable humus. For all of this, worms need organic mulch over the soil.

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This is a good argument and one that I have thought about quite a few times.  Ruth Stout proved what she thought was the best way to garden.  Mulch with hay and straw to a great depth and she could grow almost anything after a couple of years.  Though I do feel that a good compost added to potting mixes gives a plant a good start, it is the mulch that keeps things growing in our hot and cold weather.  We pile the mulch on our ground and on top of our drums each year, we buy it in bulk and it drop the new stuff over the old mulch and see more worms each year.  There must be some truth in the mulch story. Some people use woodchip instead of grasslike mulch, which is OK if you have the time to allow it to decompose slowly. 

Last week we had big lots of mushroom type growths in our backyard, they looked like the oyster type mushrooms and about 30 cm wide.  

I tend to lean to the mulch being the most beneficial to protecting and enriching the soil microbes. 

I wood chipped mulched the school garden a year ago. The chips had broken down a bit when I put them on but, all & all, the chips were a disaster. It has taken a full year to recover.

Now there I use Vetiver and anything else we chop -- but I'm dealing with  folk who don't see the utility of mulching as much as I do.

The only compost I use is commercially generated composted cow manure which I use in re-planting Vetiver as it has superb water holding and nutrient capacity. Very useful.

And so easy to use for a great price. I just mix it with any old soil to make the Vetiver grow.

The other advantage of mulching, I found, is that when you do it generally, layer upon layer, sections of the garden catch up to one another so that the overall soil quality -- and worm activity -- is throughout. I credit my worm army for that achievement -- working assiduously under the mulch blanket, spreading the good largesse.

That and ground covers...even the weedy type.

I think some of the mulch  is eaten things like worms  white ants snails and grubs  and not just decompose .

Needless to say, I am a dedicated mulcher.

All my experience says so.

I've been laying grass clippings on top of the soil as mulch.I've thrown paper and cardboard, twigs and branches at it...chopped weeds.

Layer upon layer.

I bury kitchen scraps as per 'trench mulching' in rotting holes.

'Tis a great adventure.

Of course, I'm now growing some of my own mulch consciously with the multi use Vetiver grass. And boy do I have earthworms!

From zero to uncountable millions in 8 years....

So I think  Mel Landers nails it.

This Summer past my worm army  was at the topsoil level when in so many previous years the darlings  went deep to escape the heat and any dryness.

I try to both mulch and compost.  (Not, I'm not trying to be a smarty pants.)  I admit that I have some quiet discomfort at the idea that I might be creating greenhouse gas as a result. I've also been trying to shred and compost a lot of our paper waste now as well.  

Further fromMEL LANDERS:

It is the soil, mulch interface is where most decomposition takes place and, given a healthy community of earthworms, the part that is decomposing is quickly ingested and carried into the soil. One of the results of this is that there is little loss of energy and little emission of greenhouse gasses from the biomass. The other result is that the soil microbial community is well fed and able to supply all of the important services that are needed by the plants.

Earthworms provide the only appropriate way of incorporating organic matter into the soil and they work for free. There is no turning involved. There is no need to transport heavy loads of compost or to till it into the soil. It is less work for the producer, requires less energy, drastically reduces atmospheric pollution and salvages the vast majority of the energy in the biomass for the soil microbial; community. It also feeds the soil a proper diet of minerals and Carbohydrates.

If you want to rid your crops of anthracnose fruit rot; mulch. If you want to fertilize your crops; mulch. If you want better soil drainage: mulch, etc. Using the biomass to produce compost, contaminates the atmosphere and robs soil microorganisms of the cool moist environment (under mulch) and the Carbohydrates they need.

If you look at what they use herbicide for that is mulching only problem is what they are using is toxic.

I also think it depends on what you are going to mulch.  I refuse to use lawn clippings directly because it mats and then repels water.  I end up buying sugar cane mulch and composting most everything else for that reason.  I did get my little shredder working properly so I've been using shredded palm fronds as mulch too.  (For a bloke with not one palm planted in his yard, I end up with a surprising number of fronds.)

Have been collecting palm fronds and was cutting the green part off  but found just as easy to pull them off .The hard part if small can cut into pieces with secateurs if big power saw is easier .The hard part if keep moist the fibers will separate .If you had a drive way where these could be layed  flat and ran over i think that would speed up there break up especial if had large trucks.

Lawn clippings do not mat and repel water  -- especially if you undulate them. I don't know how these furphies get shared around.

Golly! They break down in a fortnight!

I'm not saying use lawn clippings as an imperative-- but they are a ready resource.

Free too.

Sugar cane mulch is sure to be chemical additive rich.

As for herbicide -- I'm not a fundamentalist  by any means -- more a regenerative person. Anyone who gets their lawn mowed professionally with mower and brush cutter isn't the type to fret over weed control  by using herbicides.

It may happen -- but we're in suburbia and the neighborhood is rich in these nasty toxic sources --like, for instance, your house, your car, your fence, your neighbor's  habits, your almost anything.

'Toxic free' is an absolute  fantasy.

Indeed anything you may grow with 'no sprays' in mind is sure to be so much less toxic  than any food you BUY  simply because you choose to use no herbicides or pesticides (when the horticulture industry is ruled by these production inputs).

Do you know how peat bogs came about?  We once walked an area on Stradbroke Island and walked through a fresh water swamp and it was a peat bog.  I am assuming it would be an accumulation of mulch matter after becoming wet for some time, turning into a bog of peat.  There would not be many peat bogs in Australia, though Tassie would be the place for them.  That appears to be the end result of years of mulch, we are still working on the early years.

That's how coffee rock is formed and how it's possible to have 'perched lakes' on sand -- as in Fraser and the other great sand islands.

There is  a lot of coffee rock seams around where I live. It is a factor in how the aquifers behave.

The peat bogs in the southern Vic/NSW high country -- assuming they can be protected from brumbies -- are quite amazing and are the crucial element is the water flow to the catchments (like the Murray) during the heat of Summer.

In my garden beds I can no longer rest a step ladder as it sinks and falls over when I climb it because the soil and its mulch covering is so spongy. 

Every time I trowel  the soil-- just one scoop -- I get x number of worm gushing out of the dirt. I've seen my 'soil' become soil after going from yellow sand to black humus. There is  a limit to its depth, but that too is changing as I can now begin to grow fruit trees with expectations.

Relative to the climate change issue -- peat is a great sequester of both carbon and methane as we are horrifically learning now that the permafrost is melting.

In part, I gather that mangrove forests are so carbon storing because they create so much muck among their roots and shoots.They are extremely rich ecosystems precisely because this detritus of the sea/plant interface is layered. If you ever try to walk thru the mangroves the mud depth  created will thwart your progress.

Obviously rain forests are the Permaculture template but that's not the only model worth referencing.

The challenge is sponsoring that interaction between the dead and drying plant layer and the soil beneath it. That's surely related to:

  • what interaction the plant roots generate with the soil
  • the sort of micro climate that sits just above the mulch layer dependent as it is on leaf and stem growth, shade and sunshine, precipitation and humidity.

As a matter of interest i came upon this useful article on growing trees with pasture and crops in Kenya:The tree helping Kenyan farmers beat drought and poverty

In India farmers use Pigeon Pea like this and in Indonesia, they grow Agati. I used to grow frangipani (still do at the school garden) but it was too slow to be useful quickly. My experiments with Agati is very instructive so far. This year I'm pushing the Pigeon Pea envelope too.

The point being, that unlike a good mulch regime, 'full sun' isn't always your friend. Managing shade is an important gardening tool.  And mulch  --among its many other attributes -- also 'shades' the soil.

By harnessing shade and mulch I can get better growing seasons.

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