Tag Archives: leaf composting

Don’t Bag Your Leaves: An Analysis of Nutrient Loss and Soil Depletion for Leaf Removal

This is the time of year when the leaves all drop in their delightfully whimsical fashion.  And yet, it seems that fall is not an enjoyable time for many, especially if those leaves end up on the lawn. I’ve discussed problems with the practice of keeping a lawn before, and today, I’d like to look at our relationship to leaves and typical practices for dealing with leaves.  People spend quite a bit of their own energy and fossil fuel energy removing leaves from their lawns (raking, blowing, mowing, and so on).  These leaves seem to end up in three places for a typical American household in the sprawling urban and suburban areas:

 

  1. In bags on the side of the roads for “compost” (most common in my area by far)
  2. Blown onto the side of the road and left there and/or picked up by the city (more typical in urban settings)
  3. In a burn pile smouldering away (this also happens a lot where I live).

 

Some of the more radical folk, like permies and guerrilla gardeners the like, might end up composting their leaves in our gardens or otherwise keeping the nutrients on our properties; but this is a rather rare approach and one not practiced by the bulk of the American populace. Many of us who are radical gardeners go out seeking the bags of leaves left on the curb to bring additional nutrients to our properties (I do this every year).  However, not all of us have the benefit of composting or keeping our leaves–not raking, mulching, or composting leaves is illegal in some township or city mandates and also in many subdivisions throughout the US. And leaves aren’t often the only things found in the leaf compost bags–usually when I go out to collect, I find a good deal of other matter and live plants.  This year, at about 10% of the houses where I picked up leaves, I also found the remains of someone’s backyard garden (tomatoes) and at another 10% I found other kinds of food from trees just thrown away (walnuts, apples, acorns, pears, etc).

 

And so, today, I’d like to explore this practice a bit and its long-term impacts on soil health…and what we might do instead.

 

Leaves from the side of the road for my garden!

Leaves from the side of the road for my garden!

What’s Written on the Bag: Linguistic Framing of Leaves

When people talk about the leaves that drop from the trees in the fall, they often call it “leaf litter” or “yard waste.”  Looking at the brown paper bags that people buy to store their leaves in for pickup, they say “Lawn refuse” or “Yard Waste” or “Refuse” on the sides. We label the bags and then frame what we put in them as waste or refuse; something to be discarded.  So we are already creating a framework for seeing materials that come from our yards as “waste” rather than seeing the nutrients in the leaves as a valuable thing.

 

What’s in the Leaves: Nutrients Contained in Fallen Leaves

The other issue I’ve been pondering for some time is the nutritional content of the leaves, and how many nutrients leave a typical American lawn in suburbia each year when they are discarded.  I found a reasonable analysis about the nutrient content leaves here; their calculations are based on one ton of leaves (which, granted, is a lot of leaves).  This section presents a look at the nutrient content in leaves and how much is lost when we put them on the curb (or how much is gained by picking up someone else’s leaves).

 

According to the analysis above, 1 ton (2000 lbs) of leaves has the following:

  • 940 lbs of carbon
  • 20 lbs of nitrogen
  • 2 lbs phosphorus
  • 2 lbs potassium
  • 32.8 lbs calcium
  • 4.8 lbs magnesium
  • 2.2 lbs sulfur
  • Plus other nutrients and a great deal of organic matter (organic matter not calculated)

 

Before I get into my analysis of how much we lose by putting leaves on the corner, I have a few caveats.  First, this kind of analysis requires quite a bit of assumptions and estimations; I’ve done my best, but what I have found might be specific to my local area in South-East Michigan.  Second, I’m certain that leaf nutrition varies pretty widely based on the  soil profile of the region, the nutrients present or absent in the soil already, the types of trees, the weather for the year, and so on.  With that said, I do think even a rudimentary analysis, like the one I’m presenting, gives us some starting points.

 

Methods: On my trips out to get leaf bags from the side of the road this year,  I did some counting in my area to estimate the amounts and weights typical bags of leaves had.  I went out for three weeks and brought back 46 bags of leaves; I went out twice each week to different areas within a 3 mile radius of where I lived. I counted how many leaves people left on the curb and when I got back, I weighed them to get their average weight.  In a fourth week it rained, and while I collected bags, I did not weigh them because the water weight would have impacted my findings. I then did some simple math using the numbers above.

 

Amount of leaves per bag and per yard: Most leaf bags I picked up ranged from 8lbs – 22lbs, depending on whether or not they were shredded. Shredded leaf bags typically account for about 20% of the bags I pick up.  Even unshredded bags are often compacted and pretty heavy, especially if the leaves fell relatively flat or were slightly wet when they went in the bag.    The average for the bags was just above 10 lbs.  People in the suburban area where I go leaf hunting put out an average of 4.5 bags of leaves on collection day; some had many more, and most had been putting them out for a period of weeks. My estimate is that most families in my area put out at least 7 bags of leaves in a fall season assuming they have a few trees in their yard dropping leaves; this amounts to about 98 lbs of leaves (I’m going to round this to 100 lbs to make the math simple).

 

So for each 10 lb bag of leaves put on the curb, it has:

  • 4.7 lbs of carbon
  • .1 lbs of nitrogen
  • .01 lbs of phosphorus
  • .01 lbs of potassium
  • .16 lbs of lbs of calcium
  • .02 lbs of magnesium
  • .01 lbs of sulfur
  • And Iron, Zinc, and much, more.

 

That’s a lot of nutrients.  And that’s just the leaves–I don’t have any way of figuring out what whole tomato plants and other plants ripped up from the soil are also contributing, but I suspect these numbers are much higher.  And then, if homeowners are also removing their grass clippings all season long, that’s a whole other calculation to include.

 

There are alternatives!

There are alternatives!

 

What’s Left in the Soil:  Long-Term Removal of Nutrients and Inadequacy of Fertilization

Now one bag of leaves makes an impact, but perhaps a small one.  The problem is that one bag of leaves isn’t what’s being removed–this is about the long-term systematic removal of nutrients from our landscape.  As I was driving through a bunch of Detroit communities last weekend, what really struck me was the age of the houses.  Many of the houses I was looking at literally were 75 years, 100 years, or older.  In my research on dandelions, I discovered that typical lawn practices prevalent today really rose to popularity after World War II, which suggests that people haven’t been bagging up their leaves forever, but likely they have been doing it for some time.  So let’s assume that for the last 50 years, most citizens of Metro Detroit (or any other city or suburban area) have been removing their leaves from their property.  So if we take the numbers above and assume 100 lbs of leaves being removed each year, we end up with nutrient loss something like this:

 

Nutrient Loss over Time

Nutrient Loss for Fall Leaf Removal for 100 Years (all numbers in pounds)

 

These numbers are striking, but what is even more striking is the fact that I haven’t accounted for any other kinds of “yard waste” such as grass clippings (put out on the curb weekly or bi-monthly by many) or other kinds of yard compost that people don’t want.  I might do a case study of this at some point, but for now, we can see the potential for soil nutrient health decline.

 

I’d like to offer one other piece of evidence as well. My house was built in 1945, so my yard likely suffered the same fate for most of the last 70 years as well.  When I got at my homestead a few years ago, prior to putting in the garden, I ran soil tests.   These are exactly where the leaves (and lawn clippings) would have been taken from (and I knew from taking to my neighbors that the people who owned this house did such practices).  I found that the soil where I wanted to put in my garden was pretty much sand.  It had little organic matter and a P.H. of 8.2 (our PH is high in this area, but the lack of organic matter made it higher).  It had only 8 PPM of Phosphorus (considered extremely low), 22 parts per million of potassium (low) and magnesium of only 27 parts per million (extremely low).  To get my soil prepared for growing crops…what did I do? Went around and picked up everyone’s leaves, imported massive amounts of organic matter in the form of manure, compost, and this year, even a pile of seaweed from a local pond.  And now my soil tests are beautiful and my soil is rich and healthy (and much lower in PH thanks to the organic matter all of the leaves helped create).

 

What’s going back into the soil?  Not enough.

In a natural process, assuming no removal of nutrients, it takes 500 years or more to produce one inch of topsoil.  This gives you a sense, I think, of the enormity of the challenges that face us in regenerating landscapes with these destructive lawn practices.  But, you say, aren’t people putting things back into the soil?  Yes, and we’ll take a look at that next.

 

1) Plants can pull certain kinds of nutrients from the air; typically this is nitrogen and oxygen. So certainly, some nitrogen theoretically could be being brought back into the soil, although typical lawn ornamentals and grass don’t do this well.

 

2) Most nutrients are in the soil, and those nutrients are cycled through the dropping and decay of organic matter.  Trees and other plants (like Burdock, Comfrey, Dandelion), penetrate deep into the ground and pulling up nutrients to the surface, which they then deposit as leaves or dead plant matter.  But how many nutrients are down there for the taking?  If nutrients are systematically removed from the same spot over a 25, 50, or 100 year period, I suspect that at some point, the ground underneath will simply run out of those nutrients. I also have a theory (untested) that this is part of why we have so many plant and tree diseases.  We keep removing organic matter and nutrients from our landscapes in this form, through logging, etc, and those aren’t going back into our system.

 

3) People also often add fertilizers; but most commercial fertilizers focus only on the three macronutrients: nitrogen, phosphorus, and potassium.  All of the micronutrients (some of which are critical to plant and human health, such as magnesium or calcium) are not added.  Fertilizers also come in a water soluble form (nitrate) and cause substantial problems for our waterways (I am not going to spend the time today to describe soil ecology, but a good introduction to it is here).

 

4) Mulch is sometimes also added to select areas.  But wood mulches are very high in carbon and little else.

 

5) Some people do buy compost and add it in select areas (say, a garden) but this is in select areas; I don’t see people dumping compost all over their lawns to make up for the loss of nutrients.  More on this in my next post.

 

So even with the inputs, it seems likely that a substantial net loss in nutrients in the soil immediately surrounding most of our homes and communities due to the “composting” practices of leaves and grass clippings.

Concluding Thoughts

What concerns me about this analysis, if its in the ballpark range at all (and I have reason to believe it is) is that each year, the soil surrounding our homes and in our communities gets more and more depleted as we continue to remove nutrients from our soils systematically through fall leaves and grass clippings.  This leaves me with a few serious concerns:

 

1) More and more people are becoming interested in urban gardening, homesteading, and the like, and yet, if they want to dig up their backyard, they are facing soils with literally no nutrients, organic matter, or life in them (as I faced when I started my homestead).  If we all wanted to do this, where would all the nutrients come from?

 

2) We aren’t looking at a few places of depletion, but probably we are facing it with nearly every suburban and urban home in the US.  When we combine this with modern industrial farming practices that kill soil life and strip the soil bare, its a very worrying issue.

 

3) The systematic loss of particular kinds of nutrients is also concerning; in my herbalism course, we have spent a great deal of time talking about magnesium deficiency (which the bulk of Americans are suffering from) and deficiency in other micro-nutrients; interestingly, many of these showed up in the list of what was in fall leaves and being removed.  Even if you were to grow some veggies in your soil that you added some organic matter to, would there be enough magnesium and other essential nutrients for your own body’s needs?

 

4) Perhaps most worrying of all: if history has anything to teach us, the widespread degradation and depletion of soil and other resources leads to a civilization’s collapse.  Combining this with many other ecological challenges suggests the widespread and systematic need for radical change.

 

I’ll elaborate on these concerns and what we might begin to do about this in my next blog post, which will discuss the concept of restoration agriculture and further discuss permaculture design.

A Guide to Composting with Tumblers, Sheet Mulching, Worms, Chickens, and Piles

Composting is a very easy way to integrate natural processes and nutrients into your garden, flower beds, and life.  While various statistics exist, most commonly, I’ve seen statistics that suggest that up to 50% of what we throw away in the USA is food items or items that are biodegradable.  These are items, like vegetables or stems, that come out of the nutrients in the system.  Americans also like  to rake up/bag up and throw away their lawn clippings, “weeds”, etc.  By sending them into a landfill, we lock those nutrients away and don’t allow them to cycle through the system again.  So composting is an important part of shifting to a more sustainable practice and allows us to build great soils in the process.  By composting, I was able to reduce what I threw away/put on the curb by almost 50%–and now I know how much I was wasting.

Over the last three years, I’ve been experimenting with a number of composting methods.  I currently am the composting site for three families (including my own).  As such, I’ve worked to develop a number of different composting strategies.  All of the strategies that I’ll present here work in combination with each other for different kinds of composting at different speeds.

The final product!

The final product!

Sheet Mulching – Direct Composting in Garden Beds

Materials you can compost: Fall leaves, yard waste, leftovers from last year’s garden (corn stalks, tomato plants, etc.).  Grass clippings, provided they come from a pesticide-free yard (get them from the one that still has dandelions)!

How to do it: In a previous post, I detailed how sheet mulching (preparing new garden beds or adding nutrients to existing garden beds).  Sheet mulching is a great approach because it really only requites you to move the material once–you just lay it in place and the beds make themselves over time.  I really like this approach and use it throughout my homestead.

Finished sheet mulched beds--planted with potatoes, kale, and garlic!

Finished sheet mulched beds–planted with potatoes, kale, and garlic!

Compost Tumbling- Keeping the Critters Out and the Nutrients In!

Materials you can compost:  Any food waste (except meats and cheeses), yard waste, garden leftovers.

How to do it:  For compost tumbling, you’ll want to get a compost tumbler.  You can make one relatively cheaply from an old barrel (fill it up and roll it around the yard) or you can purchase a nice one.  I bought one that is insulated, which theoretically allows one to compost in the winter…..or not.  In hindsight, I would have just made one myself out of recycled materials, such as an old 50 gallon pickle barrel.  I find that my compost tumbler takes about 2-3 months to produce a nice compost (and mine has two sides, so you let one compost down while filling the other one).

Leaf pile and compost tumbler!

Leaf pile and compost tumbler!

The Traditional Open Compost Pile

Materials you can compost:  Any food waste (except meats and cheeses), yard waste, garden leftovers.

How to do it: A compost pile is the simplest form of compost.  You just pile stuff up, wait, and if you are feeling really ambitious, turn it over every once in a while.  I started with a compost pile, but my neighbors dog started coming over, eating out of my pile, and then pooping all through my yard.  So I bought a compost tumbler.  You can prevent your neighbor’s dog from engaging in his nefarious behavior by using palates or scrap wood to create a bin that isn’t accessible from the outside.

Traditional open compost pile (about 50% of previous size, composting for 8 months, no turning)

Traditional open compost pile (about 50% of previous size, composting for 8 months, no turning)

Improved "open pile" with wire cage to keep out neighbor's dog.

Improved “open pile” with wire cage to keep out neighbor’s dog.

Worm Composting (Vermicomposting)

Materials you can compost: Food scraps, mainly.

How to do it:  In February, our permaculture group had a skill share on vermicomposting (and this is the link to a video). Since I provided the materials for the worm composter, I was able to get it at the end of the skill share.  I placed it in kitchen and  its been working really well.  The best thing about it was that I was able to find all of the materials in my garage, and the worms were donated to me by my friend, so it literally had no upfront cost.  You *can* go out and buy expensive worm bins, or you can just use the methods that are in the video (which consist of two opaque tubs, drilling some holes, adding some wet shredded newspaper, adding some worms, and adding food scraps).  The best thing about it is that you can compost this way year round, and you get AWESOME worm castings.

Vermicompost bin - yes, you can also add cardboard!

Vermicompost bin – yes, you can also add cardboard!

The Chicken Method: Let the Birds Do the Work!

Materials: Food scraps, old moldy bread, yard scraps, pretty much anything. We’ve given ours moldy cheese, old sauerkraut, leftovers from going out to eat, even the carcasses and bones of chicken, pork, etc.  They eat it all.

How to do it.  This last method is now my preferred method of composting! For this, you need Chickens in an enclosed coop.  I had my chickens free ranging, which means they help keep the bug populations down.  However, they were destroying the mulching around my perennial beds and I also lost the two bantams (smaller breed chickens) to hawks.  So I built them a larger coop, and with the advice of a friend, started “chicken composting.”  Basically the way it works  is this–you put whatever you want the chickens to compost in the coop.  Most of this they eat, and in a matter of hours, produce a nitrogen-rich dung (which needs to sit about 6 months or it will burn plants, its so high in nitrogen!)  What they don’t eat attracts flies and worms, which they do eat.  I also throw a ton of unshredded fall leaves in there, especially ones like oaks that are harder to compost down.  What you end up with is a wonderful tilled up hummus, straight from the chickens, with minimal work.

Chickens in their enclosure (note the enclosure was built with 90% repurposed materials!)

Chickens in their enclosure (note the enclosure was built with 90% repurposed materials!)

Chickens working the compost!

Chickens working the compost!

Fall Leaves and the Druidic Garden: Leaves as Compost and Mulch

With the passing of Samhain, most of the leaves here in Michigan are now off the trees.  As I bike through my neighborhood or visit surrounding communities, I am always amazed to see people bagging up all of those leaves in the brown “compost” bags and leave them by the side of the road or (worse) burning them in the backyard.  Hold on for a minute!

What my illustrious neighbors bagging the leaves up and leaving them for the waste disposal company may not realize is that those same leaves, yard trimmings, and other waste are sold right back to them in the spring time when they want a little compost or rich hummus for their garden.  Unfortunately, this process is damaging on the environment because: A) fossil fuels are used to transport the leaves to and from their destination; high-powered composting facilities often use additional fossil fuels to automatically turn and process leaves; and finally, they have to be packaged back up and sold to the end consumer–sometimes across counties or states.  Another serious benefit is that the nutrients of the leaves–nutrients that would leech back into the soil if the leaves were left on the ground to decompose naturally–continue to be removed each year as the leaves are put on the curb.  This loss of nutrients in the soil eventually causes most to go out and buy petrochemical fertilizers (which contribute to substantial water pollution).

Burning those little leaves is even worse, however!  Leaf burning destroys many valuable nutrients (although some nutrients are retained in the ash, to be fair), substantially contributes to air pollution, and can cause trouble for health of asthmatics and others.  Not to mention the risk of fires spreading out of control.

Alternatives exist to bagging and/or burning leaves!

Leaves are a precious and valuable resource, and can be used in a multitude of ways in your own gardening practice: as a lawn mulch, compost, as a soil enricher, and as a garden mulch.

This year, I’ve used leaves in several ways to enhance my druidic gardening practice.

Directly in the Garden Beds. First, I used leaves as a basic ingredient of my “raised bed sheet mulching” approach (which I haven’t yet written on but plan on writing on soon).  Leaves were added right to the bed in the fall and will compose over the winter, adding much needed nutrients and humus to my sandy soil.

Leaf Composting. I also built myself a simple leaf composter out of some rusty wire fencing I found in the weeds on the side of the property.  I created a sphere with the wire and weighted the bottom down with some rocks.  Next, I layered about 6 inches of leaves with an inch of soil and/or manure and as I layered it, I wet the whole thing down.  If you layer it in this fashion, the leaves are less likely to mat.  If you wet it down, composting will happen much faster!  I have read that you can also use sacks for leaf composting or even build your own large bin.  The key is to make sure that your leaves don’t blow away before they are composted.  Now that I’ve done this work, I will wait and see what happens in the spring–and how far along my leaves have composted.  Leaf composting is super-easy, and you can use the composted leaves as an excellent soil conditioner or garden mulch.

Mulching. One of the most important lessons that I have learned in my short time on this property is that mulch is your friend.  I planted a number of trees and heavily mulched them–and was amazed to find that even after a week or more of dry weather, when I stuck my hand into the mulch, the roots were still damp.  If you want to use leaves as mulch, you can compost them partially (to avoid matting, again) and then spread them thickly on whatever it is you want to mulch.  The leaves will eventually decompose and will release their nutrients into the soil. In this way, you are mimicking the forest’s natural cycle of falling leaves eventually turning into fertile soil (we speed this up a bit with composting).

Do be aware that certain leaves may change the PH level of your soil.  Pine needles and oak leaves are particularly acidic (but this makes them incredibly useful for say, blueberries or paw paw trees!).  I have been using pine needles as a wonderful mulch on my newly planted blueberry bushes.

If you have a lawn mower, you can also mulch your leaves directly onto your lawn.  Apparently they make mowers just for mulching, but I’ve never seen them so I can’t write more on that process.

This is my first year using leaf composting, so I’ll report how things went in the spring!