Is Gardening Green?

There are some aspects of gardening philosophy that I really wrestle with, and one of them is ecological impact.  There are a lot of good reasons why I believe that people should grow their own food, but I'm not sure that the saving the Earth is one of them.

Growing my own food does allow me to reduce the amount of food transported to me over great distances.  Also, my garden is mostly free of pesticides and totally free of herbicides.  When I do use pesticides I follow the instructions to the letter, and time my applications so as to minimize the threat to beneficials and pollinators.  (Many insecticides are only harmful to these creatures during the time it takes them to dry after being applied, so they should be applied in the early morning on a bright, sunny day.  After that they must be ingested - by an insect actually eating the plant - to kill.) 

However, there are a lot of good reasons to question the environmental benefits of growing your own food:

1. Excess packaging and shipping associated with any product purchased for use in the garden: tools, seeds, fertilizers, soil amendments
2. Environmental damage due to the production of these materials (I'm thinking of things like rock phosphate, chemical fertilizers, peat...)
3. Excess water use above what would be required in large-scale agricultural production
4. Damage to the soil due to improper/unskilled management (here I'm thinking about the fact that most farmers no longer till their land, while most gardeners still do, resulting in loss of topsoil and the disruption of the natural soil food web)
5. Loss of natural environment due to the extra land required for my inefficient (relative to professional agriculture) gardening
6. Extra energy required to store food produced in a seasonal climate for year-round consumption vs. transporting it from more temperate areas

It strikes me that even the most knowledgable and conscientious food-growing projects I've heard of rely on the import of - at minimum - lots of organic material from the surrounding area.  Many of them could not function in the absence of conventional agriculture.  Or they could, but would need to devote considerable land to the sole purpose of producing biomass to add to their food-producing soil.

What do you think?  Is gardening green?  Do the environmental benefits outweigh the drawbacks?

Examining My Subsoil Composition

As a homeowner, I keep a list of small, non-critical home improvement projects I should do when money, creativity, and free time coincide (i.e. never).  Last week while I was daydreaming, two of these projects collided in my mind and an idea was formed. 

The first project was an area of my backyard that just begs for a flower bed.  Grass won't grow there during the summer because of excessive shade, so it is pretty much overrun by weeds and some years is just bare earth.  The trouble is that the soil is not great and is full of tree roots, so I'd prefer to build a raised flower bed.  That means money for soil and for the material that retains the soil, ideally in this case something that can be arranged in an organic, curving shape, like stone or brick.

The second project is the removal of all the dirt deposited in our basement/crawlspace during the flood last spring.  The dirt is still sitting there because, frankly I just don't know what to do with it.  For reasons I won't go into, it can't go back where it came from, can't stay where it is, and can't go anywhere else on the property.  (Okay, it can't go anywhere else because it's really awful subsoil that nothing would grow in, except trees, as you'll see in a moment.)

Oh, if only there were some natural, locally available, dirt-cheap material to build raised beds with...oh, if only there were some useful purpose for yucky clay that turns hard as a rock when dry...oh!  Bricks!  We could make bricks!  It would be fun and educational for R, put all that dirt to good use, and probably make for an interesting conversation piece during cook-outs!

It turns out, you need some pretty particular soil composition to make good bricks.  (I'm not aiming for excellence, but it would be nice if they didn't crumble in the first good rain.)  After reading a lot of crazy stuff on the internet, I've accepted that my bricks "should be" at least half sand, by weight.  How much sand is in my soil?  Let's find out.

I filled a jar about 1/3 with the soil, then filled the rest with water, stirred, fished out some gravel chunks that I thought might break the jar, and then shook really hard for one minute.  This is the classic test of soil composition.  As the soil settles out of the water over the course of several hours, it should separate into easily visible layers according to particle size: sand settles first, then silt, then clay.  Like many things I have read about and then confidently tried, I am thoroughly confused after trying it.

I was not at all surprised to find that there was no visible "sand" layer in my jar.  Here's a picture of the jar a few minutes after I mixed it up.  (I was, conincidentally, making R a peanut butter and jelly sandwich.  This was amusing for me and confusing for him.)

Left: Natural Peanut Butter, Right: Subsoil Suspended in Water

Several hours later, I was beginning to wonder if my soil was entirely composed of one particle size (which I assumed to be clay).

Subsoil, several hours later

By the following day, however, I could see an extremely faint separation between the silt and clay layers, too faint even to show up on camera.  The clay (top) layer represented about 10% of the total height of the soil.  What?  What?  So, my subsoil is mostly silt, with a tiny bit of clay?

Sigh.  I'm going to do some more research about this, because I just don't like being wrong.  But for the time being, I may just try making a dang brick with it anyway.

Establishing New Garden Beds

ETA: Sorry, this was somehow mistakenly published in the Jan 2011 posts!

Establishing a new garden is hard work, and I seem to convince myself to do it in at least one spot every year.  Here's what I've learned so far.


Gardening books often suggest double-digging to establish new garden beds, but I have found this to be a terrible idea around here.  The topsoil here is really only about 6-9 inches deep, with the subsoil consisting of extremely fine clay with large rocks buried in it.  Theoretically, when you double-dig you lift the top foot of soil up, loosen the underlying layer of soil with a large garden fork, and then put the top layer of soil back in place, adding soil amendments and air in the process.  The trouble is, if you try to do that in a location with less than a foot of topsoil, you end up mixing subsoil into your topsoil: in my case large, rock-like clumps of clay.  Also, after the first good rain the soil surface settles down into a cement-like, impermeable layer that just can't be good for plants.  There is a spot in our front flower bed where I double-dug my very first garden, mixing in compost and bagged garden soil; I only grew vegetables in this spot for one year, but four years later the soil in that section is still noticeably poorer (and lower, from me subsequently picking out those clay rocks) than in the rest of the bed. 

I also tried the lasagna garden method with the big backyard garden bed I added in 2010 (see Not Breaking Ground on the New Garden), laying down cardboard and covering it with 6-8 inches of compost I got from the city.  This worked extremely well for keeping the weeds down, but the soil and compost layers were still not well-mixed a year later when I dug a soil sample.  Proponents of the lasagna method claim that worms will slowly incorporate the new materials into the soil beneath.  I did find evidence of lots of worm activity below the cardboard (see Happy Pooping Wormies), but none above during that entire first year.  Maybe I messed it up by using finished compost instead of things like grass clippings and shredded leaves, but I was sufficiently discouraged by the results that I decided to just go back to single-digging.  Also, lasagna gardening is supposed to be less physically demanding than methods that require digging into the soil, but by the time I moved and spread and leveled all that compost I really didn't find this claim to be true, either.

My current preferred method for establishing a new garden bed is to add bagged soil, fertilizer, and vermiculite to the top of the bed, then mix it into the top layer of soil with a shovel, and level it and break up any clumps with a metal rake.  Then, before I plant it, I try to firm it down a bit.  Most books I've ever read say you shouldn't walk on the soil or press on it at all, but I do it anyway because I think it helps prevent that cement I was talking about earlier.  (When the soil is too loose the top layer gets dried out much faster, then the clay particles get stuck together, making the surface very impermeable and difficult to re-wet.  That's my theory, anyway.)  Last spring I also used garden sulfur in my community garden plot beds, which many sources suggest helps break up clay soils, though I can't tell if it did any good or not. I'll probably use it again.

Hmmm, I wonder what I'll think of this method in a couple years?