Carolina One Sucker in 2013
Recently we sent out soil samples to the UMass Soil and Plant Tissue Testing Laboratory for analysis of nutrients and other metals, such as lead. In addition, I measured dry weight % organic matter at University of Pittsburgh by burning a known mass of dehydrated garden soil at 550 C for four hours, and weighing it again to measure the mass lost (which is equivalent to organic matter %). It’s interesting to see the patterns that are apparent between the garden at my house versus Todd’s house. To characterize Todd’s and my garden, I took a sample from my two main garden plots, and sampled soil from Bed’s ‘A’ and ‘E’ in Todd’s garden. These two site were chosen because Bed A contains a layer of garden soil imported from AgRecycle, whereas Bed E contains soil largely in place prior to gardening. The data is plotted below.
Macronutrients appear to be high at each site.
And micronutrients appear to be at adequate levels.
Overall we have basic soils. Higher soil pH appears to correlate (R^2 = 0.86) with higher available calcium concentrations found in the macronutrient graph.
Organic matter concentrations are much higher at Todd’s. This is probably because people have been adding mulch to the soils at Todd’s garden over the last couple years and Bed A is composed of imported soil with mulch. The garden soil history at my garden is poorly known. The area was definitely a garden sometime in the recent past, and even possibly over the duration of the 103 year lifespan of the house I am living in. This year I pulled out weeds that were definitely growing for over a year prior to me moving in to the house. Overall, after digging around a bit, the back garden at my house appears to have the best soils (darker, less minerogenic, less coal ash), which do appear to correspond to higher organic matter concentrations.
Available lead and aluminum, which are toxic humans and plants, appear to be at low levels.
The volume of a potting container significantly increases the height of tomato seedlings during the first month of growth
Introduction & Background
I thought it might have occurred by chance. Gazing at seemingly motionless tomato plants day after day I started to notice things I didn’t before. I stumbled upon this peculiar pattern by accident after planting tomato seedlings in my basement. It seemed as though the small plastic pots grew tomato seedlings faster than those in smaller seed trays, holding constant the type of potting mix, lighting, and watering. This could have happened to anyone, but it happened to me and I like statistics, plus I had a yardstick handy. To understand how one could even stumble upon such a pattern, or why anyone would grow tomatoes in their basement, first some background.
I had been gardening with my friend and I wanted to grow my own heirloom tomatoes. Naturally, I read several books about growing them. Since I didn’t have a backyard (well I had a 4 x 6 ft cement pad) for a greenhouse, I decided to grow them under eight 40-watt fluorescent plant/aquarium bulbs (48 inch) in my basement. These bulbs are ideal on a small scale, because they emit visible light at wavelengths that are catered to those preferred by plants and do not get very hot. Therefore the relatively low intensities of the bulbs can be made up for by the fact that they can be placed very close to the plants.
Now when one becomes acquainted with heirloom tomatoes, one will most likely want to grow and taste as many different types as possible. I mean have you ever seen, or more importantly tasted, a fresh Southern Night tomato? Or Striped German? The classic Brandywine tomato has got curves that will arouse, and a taste that will keep you coming back. Especially after picking it fresh from the vine. Moreover, today you could potentially grow a wide variety of these unique plants by buying seeds from Seed Savers Exchange on the Internet. Logically, Todd Wilson and I planned to grow as many varieties (this is going on over three years now with eight or nine) as possible.
The first year growing seedlings under lights was a wreck. I planted seeds inside that should have been sowed outdoors. I produced a swamp in my growing tray that propagated fungi (or something which smelled bad), which killed a few seedlings. In another instance, I planted and then watched lettuce grow, bolt, and go to seed without eating it (I didn’t even keep the seed). I still don’t know why. Maybe I thought lettuce just grew then stayed tasty forever. I was very wrong.
The second year I refined my skills and developed a well thought out plan. I would plant one heirloom tomato type and one variety of heirloom pepper. The types planted; the classic Red Brandywine Tomato and the King of the North Red Pepper (both from Seed Savers Exchange). I planted the tomato seed in each container (10.2 x 10.2 x 7.6 cm) and filled it with Vigoro Organic potting mix (0.10:0.05:0.05) I bought from Home Depot.
At the same time Todd Wilson was growing similar heirloom tomato seeds in a basement under fluorescent lights, except he used “seed trays” (or trays with small cylindrical pot holes compacted together) to start his plants. This practice is a mainstay in farming operations in Pennsylvania, in which a large amount of plants have to be grown in a greenhouse during the early spring. Under these circumstances, in may be hard to use a larger container, because of space or potting mix constraints, therefore seed trays are used so that there is a small volume of potting mix (and surface area) per seedling.
During the second year, Todd and I remarked that my tomatoes appeared larger on average than those he grew in seed trays (2.5 x 2.5 x 5 cm) under relatively similar conditions (although differences in heirloom varieties and lighting). A few ideas flew around as to why one set grew faster than the other. Eventually we settled on fertilizer differences (twice I used Miracle Grow while watering the seedlings) or the size of the potting container.
From there I began my search for understanding how to grow tomatoes faster and more efficiently. With more data, I thought, this finding may be used to find the necessary level of potting mix needed for optimal tomato seedling growth, while minimizing excess potting mix use (e.g. volumes greater than X cm3 do not change the average height). Think of the potential – tomatoes a week earlier!
Methods & Results
In April of 2013, I devised a strategy to find out what may have caused the pattern Todd and I observed the year before. I would sow two heirloom tomatoes in a small plastic potting container (i.e. volume = 10.2 x 10.2 x 7.6 cm = 791 cm3) for every one I planted in the seed tray (i.e. volume = 2.5 x 2.5 x 5 cm = 31 cm3). I employed six varieties of heirloom tomato and grew them under the same conditions. In total, I planted 61 tomatoes split 40 in containers and 21 in seed trays. I used Vigoro Organic potting mix and set the plants under an automatic timer that had the light bulbs on for 15 hours a day. I then devised a system so that I could raise or lower the lights to about 2 to 4 inches above the plants to adjust their level as they grow.
I watered the plants as evenly as possible and twice added a tablespoon of Schultz Plant Food plus (20:30:20) (per gallon of water during watering) that I bought at Dollar General probably around 2002. I placed a small fan with a timer on a table across the room, and set the timer to three 15-minute periods of oscillating wind over a 24-hour period. I labeled the containers and trays carefully and took note of the day I sowed the seeds. Also, I usually let tap water sit in an open container overnight, so that it would evaporate off the added chlorine.
After 26 days of growth (April 5 to May 1st) I measured each plant using a yardstick. I placed the yardstick against the base of the plant and measured up to the highest point. All measurements were logged in a notebook.
At a later time, I typed the tomato measurements into a Microsoft Excel spreadsheet, and converted the measurements centimeters. I then broke up the measurements into two groups – containers (volume = 791 cm3) and seed trays (volume = 31 cm3) – which were then broken down further into heirloom variety. These included; Mariglobe, Italian Paste, Mystery Brandywine (seed saved from feral Red Brandywine tomatoes in 2012), Red Brandywine, and Southern Night tomatoes. Average heights were calculated per variety and per potting volume, along with error bars (Figure 1). This demonstrates that within 95% error, the heirloom tomatoes grown in containers with a volume of 791 cm3 were taller than those grown in seed trays with a volume of 31 cm3 (Figure 2).
What if this occurred by chance?
Could this have happened by chance? Definitely. We are certain that we are uncertain about everything. However, can we determine whether or not that chance was so low that it most likely happened because something caused the pattern to emerge? Yes.
For instance, to approximate results from individual experiments we often calculate the average. This has disadvantages and, in most cases, does not reflect upon the reality of the individual data. There is usually a distribution of values, in which some are probably quite different. Therefore, to account for our uncertainty of the true average (if we measured an infinite amount of seedlings) I calculated the 95% confidence error bars. Or rather, the two values that I am 95% certain the true average height falls between (Figure 1). When the 95% error ranges of the two averages do not overlap, can we be sure that the plant height results are really different? Probably. And probably is not good enough.
To me, the height difference could have still occurred by accident. Fortunately the t-test for two sample means exists, and by default assumes that there is no difference between the average plant heights. After conducting the calculations and gathering the results (i.e. t = 4.45, df = 21, P = 0.0004), I can state with over 99% confidence, that the average plant height difference between the two container volumes is significant and has a very low probability of occurring by mere chance (Figure 2).
What caused the average heights to be different?
This is where it gets really interesting. What caused this to happen? I don’t know. I am confident that there is a significantly different tomato seedling height between those grown in potting containers versus seed trays after 26 days in a basement under eight 48-inch fluorescent bulbs that emit light for 15 hours per day. Beyond that is all conjecture.
Currently, I think it is one or some combination of water/nutrient holding capacity of the potting mix, initial root growth dynamics, or how close the seedlings were to the light.
Of the three ideas, I don’t really think it is the water/nutrient issue. I kept the soils moist during most, if not the all, of the 26 days. Plus, I used Schultz’s plant food. This is assuming that there was some limiting nutrient, which is not known to me at this time. Overall, it does not appear to be the problem to me.
The root-growth idea is a more favorable idea of mine at this point. I say that because the sudden growth spurt does not become apparent until about 14 to 20 days of growth. During first week of growth the seedlings are the same height. However, it is during this time that the initial root growth protrudes into the surrounding potting mix. Upon building a proper root infrastructure, the plant can then begin taking up nutrients to grow leaves and a stem. I think that a certain amount or volume of root growth is needed to facilitate an optimal growth rate for the tomato seedling. Restricting the volume of the early root growth is reflected in the poor growth during the first month. On the bright side, though, after the seedling is “potted up” or put into the ground, it would make sense that normal growth rates would probably return.
Alternatively, a new idea is quickly gaining ground as a new favorite. Could this have occurred because the containers were taller (by 1 inch) than the seed tray? This situation is most precisely described by the light intensity equation, which states that light intensity is inversely related to this distance from the source squared (intensity = watts of light/[4 x π x distance2]). So lets say we had an 80-watt source of light directly 4 inches above the potting mix surface in the container (i.e. 391 cm3). Since the seed trays are 1 inch shorter, they would be 5 inches from the light. Using the equation above, the intensity of the 80 watts of light would be reduced by 64%! I conclude from this that the distance from the source of light is especially important during indoor growing, but how much this could account for differences observed in grow rates is not understood (by me, at least). This, again, comes down to a limitation question. Was the growth rate limited by light that was further reduced by the longer distance traveled to the shorter seed tray containers?
On the other hand, in an outdoor greenhouse this should not make much of a difference. This needs further investigation by people who have greenhouses or live in more favorable climates for growing tomatoes outdoors in the early spring. Future research will figure out the influence of light intensity using fluorescent lights at different distances and with a range potting volumes.
This story and experiment has been to show you that using bigger potting container significantly increases the growth rate of tomatoes seedling during their first month of growth. Faster growth rates probably reflect a tomato plant that is more efficiently transforming light, soil, and water into delectable fruits. Gardeners who want to grow tomatoes faster take notice – potting containers are vital!
Eric Morris recently visited BCGG and other gardeners in Pittsburgh. The following is his account of the current state of urban gardening in 2013.
“Here’s an invasive species,” David Pompeani says as he crouches over a garlic bed in the tiny backyard of a 38th Street home in Lawrenceville. “It’s this morning glory that you can’t get to go away. It’ll grow all over your plants.”
Pompeani digs into the ground and plucks the weed from the soil. Although his gardening is now limited to a few beds in a backyard, it wasn’t long ago that Pompeani himself was invading Pittsburgh soil via the act of so-called guerrilla gardening – or gardening on property that didn’t belong to him.
Guerrilla gardening is one form of urban gardening, a practice that has steadily picked up steam over the past several years. Guerrilla gardens, backyard gardens, community gardens and market-based, for-profit gardens continue to pop up all over Pittsburgh, serving the dual-purpose of providing fresh, homegrown produce for local communities and covering the unpleasant blight of neglected properties.
And it’s not just happening in Pittsburgh.
A 2011 report by the American Planning Association discusses the efforts of city governments to recognize the rising popularity of urban agriculture in North America and respond to the needs of the urban agriculture community.
Community gardens can now be found in all 50 states, according to a 2012 survey by the American Community Gardening Association and Rutgers University. Almost 40 percent of the 9,000 gardens listed in the survey were built within the last five years.
And perhaps most telling, part-time gardener Ron Finley became the man of the hour after a stirring 10-minute speech at a TED conference in Long Beach, Calif. in February promoting guerrilla gardening in low income areas. Finley, who has been rejuvenating vacant lots in Los Angeles since 2010, preached the importance of guerrilla gardening for solving inner-city woes. His speech has received nearly 1 million views on TED’s website.
Pompeani and his small group of friends began their gardening adventures in 2010, planting in a vacant lot on 46th Street in Lawrenceville before moving operations to an empty lot on 38th street, not far from the garden he currently operates in his friend’s backyard.
“Red bricks, coal debris, broken glass – those three things are in infinite supply in the soil,” Pompeani said of the small lot before they had cleared the ramshackle plot of land and hauled in the soil. In place of rocks and bricks, the group planted tomatoes and peppers, a raspberry bush, anything they felt like consuming.
Despite obtaining a permit from the city through Mayor Ravenstahl’s Garden Pittsburgh Program and assuming responsibility for the lot for nearly two years, Pompeani was forced from the lot last fall when the city sold the lot that hosted his gardening operation. A house is currently being built in its place.
Since 1950, Pittsburgh has seen its population decrease by more than half, taking a good chunk of its housing along with it. This has created an abundance of vacant lots around the city, sitting unused, revealing blight.
Ed Jacob of the City of Pittsburgh’s Real Estate Division estimates that there are about 4,000 city-owned vacant lots in Pittsburgh, and the city actively attempts to sell all of them, garden permit or not.
“Having a garden permit does not prohibit us from selling a city lot,” said Jacob. “The permit doesn’t create any sort of warranty or guarantee, other than the fact that, yes, this lot is owned by the city and you’re given permission to garden on it.”
Pompeani wasn’t the only one who was sad to see it go. Denise Chirico’s backyard abutted the rear of the garden, which ran the entire length of the lot some 50 feet to the edge of the sidewalk. And it was wonderful, she said.
“It made the lot look so much better. It looked like it was out in the country, that’s how good the garden looked. I think every vacant lot should have that – here in Lawrenceville and everywhere.”
Well, Rev. John Creasy is working on that.
Just a mile and a half away on a hillside in Garfield, on the corner of Wicklow and Cornwall streets, Creasy, associate pastor at the Open Door Church in East Liberty, spends his Thursday nights at the Garfield Community Farm, curating community gardening sessions at the three acre tract of land of about 25 lots that were once vacant.
“It was just completely abandoned land,” said Creasy.
When he began gardening the land in 2008 in collaboration with two other local church organizations, the lots, which once held houses, were owned by the City of Pittsburgh, the Urban Redevelopment Authority and private owners. Creasy and company bought 14 of the lots for $1,000 each and have been granted permission to use the remaining lots through the Green Up Pittsburgh Program, a city-funded program for residents to assume care for vacant lots in city neighborhoods.
The Green Up and Garden Pittsburgh programs are just a few measures that Pittsburgh has taken to give residents a chance to revitalize their neighborhoods while growing their own food at the same time, according to Leah Smith of the Pennsylvania Association for Sustainable Agriculture.
“Pittsburgh has taken steps to really facilitate urban agriculture,”
said Smith. “The city has recently passed new zoning ordinances to help make it legal for people who want to do urban agriculture in the city. They can now sell products directly from urban garden locations.”
And that’s just what the Garfield Community Farm is doing. Now, the garden is home to what Creasy says is “a little bit of everything,” a variety of produce which the group sells to subscribers, farmers’ market patrons and local restaurants.
They also donate amply.
“This neighborhood is really focused on getting food to our lower-income neighbors, so we get food into the hands of the people in our community.”
The Garfield Community Farm isn’t unlike what Mindy Schwartz was doing in Wilkinsburg several years prior.
For Schwartz, what began with a couple tomato seedlings grew into a garden of tens of thousands of them. In 2001, Garden Dreams Urban Farm and Nursery was born on a quarter-acre site of former abandoned properties on Holland Avenue.
“Allegheny County has a program where if you’re a property owner you can buy a side lot for your own use,” said Hannah Reiff, production manager and one of two employees under Schwartz at the for-profit Garden Dreams.
The Allegheny County Vacant Property Recovery Program allows residents to purchase blighted properties for around $4,000 and reuse them as residential side yards, community parcels or affordable housing developments.
Schwartz bought the two lots where the garden sits in addition to the surrounding properties. She owns a total of four buildings on Holland Avenue and Center Street, two of which remain vacant and the other two acting as a tool shed and seedling growing area.
While Garden Dreams specializes in heirloom tomatoes, Reiff says they grow numerous other vegetables including peppers, lettuce, broccoli and rhubarb, all of which they sell to the East End Food Co-op and Whole Foods markets while also offering their produce at wholesale prices to local schools and nonprofits.
So while invasive species try to take over garden beds everywhere, now there are Pompeanis and Creasys and Schwartzes invading vacant lots all over Pittsburgh, crouching to pluck those pesky weeds so they can get back to revitalizing a city and growing the food that fuels.
We have been slow to update our “many readers” with what has been going on in our own garden, so here are some pictures so you don’t have to read anything. You’re welcome.
Well, as they say, a picture is worth a thousand words. You’re probably pretty tired of reading by now. So, until next time let’s garden responsibly.
We are Bridge City Guerrilla Gardens. Let’s bridge the gap between us, our food, and our communities.
As we inch closer to every Pittsburgh gardener’s favorite date, let’s call it “Get Those Tomatoes In Day,” May 15th, it’s not an uncommon occurrence to see little sprouts popping up all over your garden. If you’re on the ball and have some frost resistant seeds in the ground; peas, spinach, or something like carrots, it may be a daunting task to tell the difference between weeds and your desired crop. This can become especially difficult if some weeds get a jump on your sprouts or if you have never grown the selected plants before. To make identification easier, so you can find your swan amongst ducklings, I’ll include some pictures of seedling that are common to direct seed in the garden. Especially one’s popping up right now! Those are the pictures I have. Womp. Womp.
That being said, I have become pretty partial to starting seedlings, when I can, giving the plants a head start on the inevitable weed pressure, allowing me to prep a proper bed, possibly providing a mulch straw cover.
So, here we go:
CARROT (Daucus carota): Delicate carrot seedlings are notoriously bad competitors with weed pressure. It is important to identify these seedlings and eradicate competing weeds.
SWISS CHARD (Beta vulgaris): As can be seen above, swiss chard “seeds” are actually seed pods containing many seeds. It will make for a better crop if you thin the sprouts down to one every foot or so.
BEETS (Beta vulgaris): Notice that the botanical classifications of beets and swiss chard are the same. Swiss chard is actually a beet that over generations and generations had been selected for it’s green rather than the root (interesting right?). , My picture is of golden beets, if you would have your typical red beet, the sprout would have a burgundy tint to it.
PARSNIPS (Pastinaca sativa): These guys are in it for the long run. You put them in early, and you will take them out early in the fall (or later in the winter…or the next spring). These are a commitment crop, so you will want to give them a great start. They come up looking, well, about likr everything else around them. They have two leaves going in either direction. The difference between them and my weeds were their vibrant green color. They will eventually form their true leaves, which looks like a parsley leaf, or like celery when it forms its true leaves
SPINACH (Spinacia oleracea): The initial leaves are long and skinny, but eventually a broader rounder leaf will form…In the shape of spinach. Yum.
PEAS(Pisum sativum): These are great, for a number of reasons. You can get them in early, they fix nitrogen, and they taste great!
Alrighty! Get weeding. Make sure you leave those beautiful swans alone, and get rid of only the ugly ducklings.
This is an extremely abbreviated list, but if you have any requests, I can set up a photo shoot (If the lighting is just right), and try to weed out, well…the weeds.
Until next time, let’s Garden Responsibly Pittsburgh.
We are Bridge City Guerrilla Gardens. Let’s bridge the gap between us, our food, and our communities.
Pittsburgh is a unique place to garden. This is especially true in old industrial neighborhoods, like Lawrenceville, near the confluence of the Allegheny and Monogahela Rivers. Here the modern industrial economy was born and flourished for more than a century and a half. Over this period, enormous quantities of waste were generated, therefore reclaiming sites for gardening in many places may appear daunting – at first. If it’s not the Japanese Knotweed smothering your site, then it’s the seemingly endless stream of red bricks, coal ash, and empty packs of Newport cigarettes. Do not fear, this article will reveal how anyone with fortitude can get a post-industrial urban vegetable garden off the ground.
When considering a garden locality, first determine how much sunlight reaches the site. If you receive 6 hours of sunlight or more each day, then continue further. Are there patches of soil where vegetation will not grow, despite adequate sunlight and water? Can you smell gasoline or oil on the soils? Is there any odd coloration? If the answer is yes, then DO NOT put a garden there. Consult a professional or contact your local EPA office if it looks hazardous. If the potential site gets adequate sunlight and grows healthy weeds, you’re probably good to go. However, I would still recommend soil testing for lead (like UMASS), especially if you plan to eat root vegetables, such as carrots, or are planning on growing a member of the Brassicas (kale, collards, etc).
To start, you will want to break up the sod into 2 ft x 3 ft patches with a shovel, pitchfork, or “Hound Dog” turf destroyer (pictured in yellow). After thoroughly breaking up the sod, rake up the weeds and soils into a small pile near the edge of the patch. This process will reveal more deeply rooted weeds, which will be loosened considerably. By hand, slowly pull deeply rooted weeds until the patch is cleared. Afterwards, scoop up your pile of weeds, soil, and debris from the patch and deposit them in a bucket or container.
At this point the small area cleared is ready for some soil supplementation that is critical in a vegetable garden. Take some rotten compost and distribute it over the patch. In my garden, I used organic garden compost mix sold at Dollar General. When the compost layer is down, take a handful of bone meal and spread it over the surface. This will add calcium, phosphorous, and nitrogen, which could be lacking in the acidic soils commonly found in Pittsburgh.
Take a ½ inch metal screen secured to a wooden frame to sieve the pile weeds and dirt back into prepared 2 x 3 ft patch. Within this coarse material there will be a few weeds, rocks and other undesirables. Quickly break up soil clumps by hand and sort out weeds from rocks into two separate containers – the rocks and trash for the waste pile and the weeds for the compost. Level the sieved material with a metal rake.
Every year add compost and other organic materials to the soils (i.e. eggshells, coffee grounds, manure). Lime or crushed limestone can be applied if the soils are too acidic. Make sure to thoroughly weed the beds a few times a year. Layering with straw or wood chips around the base of your plants will add carbon and potassium to the soils and will reduce evaporation of water from the soils during dry periods.
So, we’re a little over a week into May, inching closer to that Pittsburgh gardener’s holiday: May 15th. For all of you who don’t know what I mean, May 15th is the accepted last day for frost (In the Bridge City). So, get those not-so-frost-tolerant vegetables ready! I wouldn’t hesitate to get your tomatoes planted today! I don’t forecast any frost in the next week…So, go wild.
That being said, here is what we here at Bridge City have been up to in the month of April!
- Watched seeds (Eggplant, Tomatoes, Peppers, herbs) become seedlings
- Installed end posts, and trellising for peas
- Planted Pink Beauty Radishes, Spinach, Perpetual Spinach(Type of Swiss Chard), Danver’s Carrots, and Beets
- Added Inoculate to nitrogen fixing Amish Snap Peas
- Built a cold frame
- Built medium and small compost sieve
- Installed the American Flag
I’m sure I’ve missed a few things, but this is a pretty extensive list of what we have done. We have flipped the compost a number of times (arguably the most important part of the sustainable garden).
David has checked the rain gauge, I would say on average, four times a day. Certainly at least four times today. Just so you know: 2.25 inches of rain is 45 gallons of rain water (for us), and water is necessary for life. Alright, so is sustenance and food is sustenance, and gardening is food; Keep at it. Good things will happen. As always, we’re making moves.
Do the same!
We are Bridge City Guerrilla Gardens. Let’s bridge the gap between us, our food, and our communities.
I think Elton John said it well when he sang, “It’s the Circle of life, and it moves us all.” The idea that natural processes are cyclical is very important (relatively speaking, this “circle of life” has been ignored for a historically short time period i.e. the oil age). In our current peak-oil-blowoff party, I get annoyed when I see someone throwing away a banana peel. Don’t they know that every nutrient they send away, could have been reintegrated into their environments naturally? We shouldn’t need nutrients from fossil-fuel fertilizers. Elton John said it well, but Sir Albert Howard, said it better:
All the phases of the life cycle are closely connected; all are integral to nature’s activity; all are equally important; none can be omitted. We have therefore to study soil fertility in relation to a natural working systems and to adopt methods of investigation in strict relation to such a subject.
We live in an urban environment and we are growing vegetables and plants. With each tomato we harvest, we are removing nutrients that were once in the soil. This creates a net loss of nutrients, and makes it necessary for us to facilitate the return of these nutrients. We have to — maintain the cycle.
So how can this be done?
Just to get an idea what I am talking about, I’ll list some nutrients that should be in our soil and in turn, grow and nurture our plants. The first three that I will list are macro-nutrients and are used in the largest proportions during plant and fruit growth. Since the introduction of synthetic fertilizers, especially in the wake of the Second World War, macro-nutrients have been especially emphasized leaving, in the dust, the equally important micro-nutrients.
- Nitrogen, Phosphorous, Potassium
- Calcium, Sulfur, Magnesium
- Boron, Manganese, Zinc, Copper, Iodine, Cobalt, Tin, and Nickel
This means that we will have to find some other way to introduce nutrients back into the soil. One option, which we have talked about before is composting (decay). The easiest way, but not the most reliable, is the use of some sort of water-soluble fertilizer. These will add nutrients, but will do nothing to rebuild the soil, and will may cause some sort of excess nutrient run-off. I recommend composting , as it rebuilds the soil, improves soil-water holding capacity, and acts as a nutrient storage center. Today I’m going to talk, albeit briefly, about the “magic” world of nature, and one way it has solved the problem of nutrient replenishment. This is just another part of that all important natural working system.
When you have a garden or a farm, it is important not to grow the same crop in the same place year after year. This will cause a nutrient deficiency, flourishment of pests, and can lead to reduced harvests. This brings me to the point of this post: The first law of being a human — Propagate plants with natural abilities that are to your advantage. At Bridge City we are talking about … peas.
Nitrogen-fixating plants take-in inert atmospheric nitrogen and convert it into a bioavailable form that can be used by plants. In the Bridge City garden we are using leguminous plants to fix atmospheric nitrogen (i.e peas, beans, clovers) which are then added to our compost bins. Many vegetables deplete the soil of available nitrogen (especially collards, tomatoes, corn, etc.), so by growing and composting legumes we essentially have an edible self-replicating nitrogen biomass accumulator on hand! At the same time the whole process is solar powered.
There are some other things to keep in mind as well. First, N-fixing plants need certain types of bacteria in the soil to allow nitrogen fixation to occur, or to meet its full potential. In some cases, the levels of naturally occurring N-fixing bacteria may be low, thereby limiting the potential growth and N-fixation of leguminous plants. You can buy these in a powdery form known as a soil inoculant at your friendly neighborhood K-Mart, where they will be known simply as “Pea and Bean Enhancer.” (THE SAME THING) After adding an inoculant to the soil, you should never have to do it again. The bacteria duplicates exponentially, and should be there waiting for the next pea planting.
Second, the nitrogen collected by the plants will congregate along the roots inside little nodules. You can actually pull the plant out and see these little tumor-like growths protruding from the roots. This is one visually stunning example of nature nurturing, and sustaining itself. These roots can be composted or you can leave them in the soil to decompose, adding nitrogen directly to the soil.
It’s not easy to do everything in a way that is constantly giving back to the soil, and in turn to you. It was Sir Albert Howard who said, “The whole problem of health, in soil, plant, animal and man is one great subject.” If you keep that in mind, you can really make a meaningful difference personally, but also, for something more vast. Just remember that, “Eating is an agricultural act.” Your decision to grow your own food, to eat from locally supplied sources can really make a difference in the way that food is produced, the way the land is cared for, and, in turn, what we will be leaving for future generations.
The gravity-fed rain harvesting system is one of the ways Bridge City Guerrilla Gardens was able to quickly diversify its energy base and utilize previously untapped energy sources for work in the garden. By directing and concentrating the kinetic energy in rainfall and storing it’s accumulated hydro-potential energy above the surface of Earth, we were able to provide both a renewable source of water and the energy to power its distribution to all the plants in the garden.
Until recently we had no means to reliably determine the volume of water accumulating in the barrels. This was a problem because it prevented the rain-harvester-operators from effectively judging the rate at which the barrel will refill after watering (side note: our roof is really small). One way to determine whether stored rainwater drawdown is sustainable would be to measure the volumetric balance of water input minus output. Or in other words, using simple techniques to measure the volume of water gained from precipitation and subtract it from a known volume lost during watering. It turns out that 1 mm of rain that falls evenly across a roof that is 1 m2 will produce about 1 liter of water.
How can we apply this concept to determine input to our system?
Our rain-harvester roof has an area of about 3 m2 (or about 30 ft2), therefore 1 mm of rainfall will produce 3 liters of water. Using a simple rain gauge placed next to the rain-harvester, BCGG estimated a total rainfall of 0.1 inch during a rain storm that occurred on April 9. From this we calculated a total water accumulation of 2 gallons (1 gallon = 3.78 liters). To see how, check out the math below;
(1) (Rainfall at BCGG inch)(25.4 mm/1 inch)(3 m2 roof/1 mm rain)(1 liter/1m2 roof)(1 gallon/3.78 liter)= Water in barrel (gallons)
This can be simplified even further to be;
(2) Rainfall at BCGG (inch) x 20 = Water in barrel (gallons)
Just remember, these equations are catered specifically to the area of the roof for the Bridge City harvester. To customize this equation for your own harvesting system just put the area of your roof into the middle term of equation 1. If your country has water containers that are in liters instead of gallons, then you may want to keep your units metric. If so, simply drop the first and last term;
(3) (Rainfall (mm))(your roof m2/1mm rain)(1 liter/1 m2 roof) = Water in barrel (liters)
What does this mean for tomatoes?
Now that we can easily measure how much is going into the rain harvester, how can we figure out how much is going out? It seems logical that during a wet period an operator may want to maintain a positive water balance to ensure high levels of stored water for times when watering becomes necessary. To measure how much water is used during dry periods, all you need is a state-of-the-art plastic 3 gallon watering container/bucket made in China. It’s simple. Just take note of how many times you filled the container that week and subtract it from accumulated rainfall calculated from the rain gauge. A negative value is a draw-down in water supplies, while positive numbers indicate gains in stored water.
(4) Store rainwater balance = [rainwater input (gallons)] – (3 gallons per watering container fill-ups)
Be as precise as you want. The more often you check the rain gauge, the more accurate your estimated water input will be. The more accurate you gauge your losses, the better you will be able to extend water supplies far into dry spells. Along with monitoring physical water losses, it may also be useful to add mulch and straw to increase water storage capacity of the garden soils, in addition to lowering evaporation rates occurring on the surface. Even more, a guerrilla gardener must always be aware of which plant variety is most sensitive to dry conditions in order to formulate suitable rationing strategies during times in which negative rainwater balance must be sustained.