Tuesday, May 26, 2015

Planter Project - Part 1

I decided to make some planters that go along the parapet walls of our green roof, so we have more growing space.

Keiter and I rented a zipcar SUV and went out and bought 125 6-foot Forestry Stewardship Council Certified redwood fence pickets.  We had a little adventure getting them, because the only way they would all fit in the car was if we put the passenger seat all the way forward, the driver's seat as far forward as we could, and if Cindy (who is considerably shorter than I) drove home.  I had to ride home laying on the stacks of lumber in the back.  It's a good thing they were pretty wet.  Had they been dry, my entire front side would have been full of redwood splinters!

Anyway, we survived, got things stacked in the basement, and had the zipcar returned on time.  Here's a shot of the stack after I'd built one or two planters... Yup, I own a perfectly serviceable mitre saw, but I'm using a hand saw.  It's good exercise and practice.

The following Sunday, the experiment began!  My plan was to make planters that were three boards tall, sleeved over the capstones, and functioned as self-irrigating or wicking planters.  I wanted to get one long side and one short end out of each fence picket (using 6 fence pickets per planter).  I started  by working on finding the right dimensions for the planter.  I made a rectangle the same width as the capstones, carried it up to the roof, and took a look.

I like the look of it, but I wanted it to sleeve down father over the capstones.  I'm planning to use a pond liner for the bottoms of these (to make them lighter, and to save wood), and I wanted the bottom edges of the sides of the planter to sit relatively close to the capstones, so the pond liner didn't pooch out the sides once the water got in there.

 I ended up making the planter wide enough to sit on the outsides of the flanges.  I cut the contour of the capstones into the end boards to make the planter sit low enough.  Before pulling them up to the roof, I staple the pond liner to the sides.

Then I fit these corner pieces in - they hang down below the edges of the capstones, and I'll be able to attach brackets to the bottoms of the corner posts that wrap around the underside of the capstones if the planters aren't stable enough on their own.

Here's one after the pond liner is installed and trimmed, and I'm starting to stretch the filter fabric.

This is what it looks like after the filter fabric is stretched, stapled, and cut around the corner pieces.  I've created a water reservoir in the bottom section of the planter.  The dirt will sit on top of the fabric.  How will the water get up into the dirt?  You'll see in a minute.

In the basement, I pre-assemble the wooden rectangles of the planter (you can see the 2nd and 3rd courses in the background in the photo above).  So, once the fabric has been trimmed, I sleeve the wooden rectangles over the corner posts and screw the whole thing together, like so: 

This is how the water is going to get up into the soil:  I set three little net cups in position on the fabric in the bottom of the planter.  The soil is going to wick water from the lower trough up into the upper chamber through those net cups.  You can learn more about this style of planter by doing an internet search for "Self Irrigating Planter" or "Wicking Garden."  

I install the net cups in the fabric by cutting a little "X" through the fabric and pressing the cup in.

Finished.  Don't ask me how I'm going to get water into the bottom reservoirs; I haven't finished deciding about that yet.

By the way, it sure is easy to tell which side of this picture is our roof and which is our neighbor's!  I can tell you from personal experience, black roofs (or is it "rooves"?) are HOT - and not in a good way!

I set the first planter on the wall between my house and my neighbor to the East to see what it looked like.  On this side, I plan to install trellises on the backs of the planters to act as a bit of living screen.  I already like how much of my neighbor's unfinished roof is obscured by the body of the planter box.

A wider perspective:

The next day, I made 3 more.

And then I made 4 more.  I spent both of my days off this week making planters.  4 planters/day is the speed at which my process has settled.

In case it wasn't clear earlier, I make the bottom rectangle (with semi-attached pond liner) and the 2nd and 3rd rectangles in the basement.  Then I hoist them up to the roof on ropes.  Ignore the messy back yard.

So, after another weekend spent making planters (today and yesterday), I've got a grand total of 12.  I really hope they work.

I had originally planned to have the planters in groups, with some empty space in between.  But now that we have so many of them up there, we have really started to like the way they define the space and give us a bit more privacy.  We have decided to make enough planters to fill both walls on both sides.  I've already ordered more pond liner.  I guess I know what I'm doing next weekend too!

So, I have to make more planters, figure out whether I need to level the planters to make the water in the reservoirs submerge all 3 net cups equally (since they follow the slope of the roof), decide whether I want to buy and install float valves in each planter (which is probably going to be too expensive, since I can't go with valves that can be fouled by roots growing into them), or if I just want to plumb tubing into the planters from the drip irrigation system and fill them according to a timer rather than their water levels.

And I've got to buy a ton of potting soil and carry it all up to the roof.

Nevermind thinking about that, though!  Here's Keiter - showing off her chicken wings!

Monday, May 11, 2015

How to Get the Lead Out Of Your Soil... Maybe

Urban Farming Nerd Alert!
Today's topic is phytoremediation!  

Since we live in Brooklyn, and Brooklyn has an industrial past, I read that our soil was likely contaminated with lead.  As I understand it, the lead gets into the soil by settling out of the air (in the form of pollution) and flaking off of buildings (in the form of paint).  

I had our soil tested by Brooklyn College in Autumn 2014.  The middle area of the yard tested at 332 parts per million (ppm).  The flower beds around the edge of the yard tested at 413 ppm.  The front yard tested at 453 ppm.  The green roof soil and the potting soil in all the containers on the roof were lead-free.

Once I got our soil test results, I had to figure out what to do about it.  

Brooklyn College's recommendation is: 
  • for lead levels below 100 ppm, no precautions are necessary (the green roof and all the potted plants are safe).
  • for lead levels between 100 and 400 ppm, follow best‐management practices for garden soils, i.e. don’t grow green leafy vegetables or root crops, children should not play in areas of bare soil. Other suggestions would be to further investigate actual lead distribution in the area and to test the blood lead levels of children. (this applies to the middle section of our back yard)
  • for lead levels above 400 ppm, the soil should not be used for growing food plants, and remedial actions should be taken for residential use. (this applies to our front yard and the garden beds around the edges of the back yard)
So, for the middle area of the back yard - where the lawn has been - the recommendation is "best-management"...  The lead levels are below 400, so it's okay that we've got an apple tree planted in that section, but the soil is still pretty contaminated, and I'd rather it wasn't.

For the surrounding garden beds, the lead level is over 400, which means we're not supposed to be growing any food plants in that area, and the soil should be cleaned up.  Unfortunately, that's where I've got black raspberry vines, may apples (a native species of plant that produces small fruits in July, not May), and ramps.  I have two theories as to why the edge beds tested higher than the central section of the yard.  First, I've been putting a lot of compost in the central section to try to raise its level up to match the brick walkway.  If I understand my research properly, compost can make heavy metals less accessible to plants.  Maybe the compost also makes heavy metals less detectable to soil tests?  Second theory: the back bed runs along the rear side of our neighbor's garage, and the paint has been peeling off that thing for a long time.  I took soil samples from all around the edge beds, including the back, so maybe the soil from the back skewed the results.

Regardless, I don't want to live with lead in our backyard soil.  I want to clean it up.

Back when I lived in Boston (in the 1990's), I worked with a community action group to get an area along the Chelsea Creek cleaned up.  The soil there was throughly contaminated, and we were told that the only way the land could be made safe enough to become a park was to actually scrape the top 12" of the soil off the land, send it to a land fill, cap the remaining earth with plastic, add new topsoil over the plastic, and, voila: Safe park!  By the looks of it, that's exactly what was done to create "The Condor Street Urban Wild":

It's a wonderful triumph that the site was cleaned and made into a public park.  However, before the soil was scraped off, capped and/or replaced, the land had varied contours.  It had trees.  It was interesting.  I like interesting.

Digging our own backyard down 12", throwing all the soil away, buying 12" of clean replacement soil, and carting everything through the house both ways (we don't have an alley or any other way of accessing the backyard) didn't sound like a viable option.  It sounded wasteful in every way, and it would likely remove any character that's there.

But then I remembered I had once heard that sunflower plants pull toxins out of soil.  I did a lot of internet research and found that sunflowers aren't the only plants with the ability to "clean" soil.  In fact, other species of plants draw lead up into their roots, stems, and leaves even better than sunflowers!

According to my research, indian mustard (Brassica juncea) was one of the best plants for bio-accumulating lead and phytoremediating soil of all those I read about.  Here's how it is supposed to work:  

You seed the contaminated soil with indian mustard, grow the plants to maturity, pull them out (roots and all), and dispose of them.  While I could find no record of any land that had been 100% cleaned by this process (perhaps because no one has tried for long enough), The Boston Health Department conducted a study for 2 years in Dorchester, MA in 1997-98.  During those two growing seasons, they managed to reduce the lead in the soil by 63%.

So I thought this year I'd give it a shot!  I tilled the middle part of the back yard with a pitch fork and sowed the whole thing with indian mustard seeds.  I left the side beds un-touched for a control to my experiment.  In the Fall, I'll pull up all the indian mustard plants and retest both the central area and the side beds to see if there has been any change in the lead content.  Of course, I'm hoping we see a noticeable improvement in our lead levels.

Half-way through tilling the back yard with our new tiny pitchfork.
Mustard Greens (about 3 weeks old)
Below is a wide shot of the back yard today.  You might notice that I've taken down the back fence, scraped and painted the back wall of the neighbor's garage, and thereby hopefully stopped the flow of lead into the soil from that source.  

In my next garden post, I'll explain the cube-shaped contraption in the back.  In the meanwhile, baby mustard greens look nice as a lawn!

If you'd like more information on phytoremediation and creating a lead-safe garden, have a look at the Lead-Safe Yard Manual and this paper called Phytoremediation for Lead-Safe Yards.