Originally Posted – July 22, 2011 @ 7:00 PM
One of my favorite aspects of urban farming is breaking ground! It’s like archeology, you never know what could be just a few inches from the surface. If a house is still standing then you could be digging in soil that has not been disturbed in 100+ years as is the case with my neighborhood. I often wish I had a metal detector so I could unearth coins, jewelery and thousands of beer cans. If a house had been demolished then you can often expect to find the foundation and possibly the entire first floor burried a few inches below the surface. Here in Wilkinsburg the demo crews start by removing anything that tests positive for asbestos. If the building is tall or dropping it would be dangerous a crew will remove the third or fourth floor by hand. Otherwise they bring in an excavator with a 3 fingered hand and rip the top floor off and dumpster it. The next step (and this part absolutely kills me) they basically crush the entire first floor of the building into the basement. Then they bring in 6 inches of the stickiest lifeless yellow clay. They claim to spread grass seed but I am pretty sure they just spread hay and let it self seed.
This method of demolition is the only form done in Wilkinsburg and needs to change. But all of the lots have experienced this so instead of throwing in the hat I am going to try to focus on how to work around this. Notice how I did not say “easily work around this” I didn’t say it because there is nothing easy about this. I would be willing to bet that I have had the honor of digging more than a thousand bricks out of the ground over the past year. I often hit a brick one out of every four times I sink a shovel in the ground. Not the treasure I am always hoping to find but they make incredible borders and when you have as many as I do they become a focal point and conversation piece in the garden.
There is really no easy way to get them out of the ground unless you have access to a backhoe. But for those of us who don’t have access to heavy equipment, manually removing them is the only option. My method of getting them out is to expose an edge and use a prybar or spudbar and pop them out of the ground. This is absolutely back breaking work and there are other options but with a budget of nothing this is often the only option.
If you plan on growing root crops, berry bushes or fruit trees you will need to double dig. This means digging the first layer completely out and set it aside then I like to amend and flip the the soil below that as deep as I can without having to remove anymore dirt. This is a good time to add compost or manure to the soil that you removed. Most likely the soil you are removing is solid clay that needs to be cut with organinc material. I personally like to get rid of 50% of the clay and replace it with compost and manure. Eventually your beds will settle below the existing surface and this provides an opportunity to spread a thick layer of whatever rotted organic material you can get your hands on. I like this topcoat to reach 6 inches above existing grade. If weeds are a problem or grass keeps growing through before you spread the topcoat spread newspaper out atleast 12 pages deep. This will kill the weeds and has the extra bonus of being biodegradeable. I don’t really like fertilizing so I try to build my soil up with as many organic nutrients as possible any time a bed is fallow. Durring march I was bringing in yard after yard of manure from agro-cycle and covering every square inch of garden space with a six inch layer. I don’t really bother trying to flip the entire bed but when I plant I will dig the hole with a garden spade and really work my organic medley of animal excrement and biodegradeable human refuse deep into the ground. I don’t like to break my garden soil down into dust I like it lumpy. I turn it over and chop it up with my spade. If you are planning to use bricks as borders I like to put the newspaper on the ground then use the border bricks to help hold the newspaper down. If you do not plan on covering the newspaper with something immediately wait until you are ready to fill the bed unless you want to clean up a giant mess.
One of the questions I seem to get asked alot is if am I worried about contaminents in the soil. Given the fact that I am in a hundred year old neighborhood in what used to be the steel mill capital of the world. I honestly really don’t care about contaminents. My grandparents had a vegetable garden and ate vegetables grown in Pittsburgh soil for years and I would assume if your family is from the burgh they did the same thing.. Tests have shown that the amount of lead absorbed by most vegetables is insignificant unless the soil has tested extremely high for lead. The real danger comes from direct ingestion of the contaminated soil such as unwashed rootcrops and leafy greens. I really don’t worry about this too much, I mean this is Pittsburgh after all… At one time the city and surrounding area would turn black on a daily basis. Lead, mercury, arsenic, chromium, copper, nickel and cadmium are just a few of the metal contaminants found in the soil in and around Pittsburgh. Uranium, cesium, thorium and radium are some of the scarier elements found here as a direct result of the steel industry. Soil tests are readily available and can give you an idea of the types of contaminants that may need remediation in your garden.
Soil remediation can be as easy as digging out your garden beds as deep as you can and replacing the contaminated soil with organic material and topsoil. This is a common method of urban certified organic farms because there is no room for error. Another option is phytoremediation which is defined as soil remediation using plants. This method takes multiple years and requires safe disposal of the contaminated plants to be effective. Phytoremediation also has the benefit of being an aesthetically pleasing option.
-Sunflowers are effective for arsenic and lead. Sunflowers were used after the chernobyl nuclear accident to clean up caesium-137 and strontium-90 with good results.
-Willow trees are effective on cadmium
-Indian mustard(mustard greens), ragweed, hemp dogbane and poplar trees are all effective in lead remediation. Indian mustard is also effective in remediating copper.
-Barley and sugar beets are effective for sodium chloride (table salt)
These plants require several years to work and depending on what you are remediating require responsible disposal of the plant material including the root system. Once the soil has been remediated of heavy metals than you can begin thinking about cover crops. Cover crops are legumes that pull nutrients up from deep in the ground and stores them in its biomass. When these plants are tilled into the soil the organic nutrients are then broken down and redistributed in the top layer of soil. One of the newer plants designed to do this is the “tillage radish” which is a giant, sometimes 6 foot daicon radish that will break through even the most difficult hardpan. The radish is grown over winter and the root system brings nutrients to the surface from deep down in the soil. When the plant dies in spring it is left to rot in the ground leaving behind nutrients and a gaping hole that fascilitates easy tilling of the soil. Clover is probably the most practical cover crop to grow in Pittsburgh. Clover adds and conserves nitrogen focusing it in the top six inches of soil. Clover also helps to create sort of a living mulch that suppresses weeds and grass. Clover does have a few downsides which include becoming invasive and often times is a favorite food of gophers. Some other cover crops that deserve mention are ryegrass, alfalfa, cowpeas, mustard, oats, radishes and turnips. All of these plants are legumes which are plants that fix nitrogen in the soil over the life of the plant. My favorite legumes are beans and peas because they are not only extremely tasty but they are also easy to grow and mature in a relatively short amount of time. After they are done growing and I have exhausted the harvest I will cut the plant off at the ground leaving the root system. The rest of the plant is composted and I flip the soil to break up the root system.
Another option that deserves mention is the no dig option. I do use this method sometimes but I have to admit it is not my favorite. The idea is to kill the grass with cardboard or newspaper then cutting a hole in your paper and planting in the hole. The paper is then covered with grass clippings or compost or whatever you have on hand. The newspaper and mulch help conserve moisture and over the course of the year the newspaper will de-compose. Then the next year you repeat the process and after a few year you will have black well rotted organic topsoil.
I believe the focus should be on enriching your soil during the off season and practicing proper crop rotation. When you have a compost pile you are basically growing soil. Not enough people think of their soil when they are talking about garden output. When you amend clay with your compost you are sowing the seed of life and you are effectively harvesting topsoil. The indians used to use a method known as “the three sisters” method or technique. The sisters are corn, beans and winter squash or pumkin. The corn is planted first and allowed to grow a little, then the beans and squash are planted. The corn serves as a pole for the beans to grow up and since corn uses so much nitrogen it benefits from the nitrogen fixing properties of the beans. The squash leaves serve as a living mulch shading out the grass and weeds and helping to retain moisture. If a spiny squash is chosen it has the added benefit of being a pest deterent.
According to Iroquois legend, corn, beans, and squash are three inseparable sisters who only grow and thrive together. This tradition of interplanting corn, beans and squash in the same mounds, is a sophisticated, sustainable system that provided long-term soil fertility and a healthy diet to generations. The Iroquois believe corn, beans and squash are precious gifts from the Great Spirit, each watched over by one of the three sisters spirits. They also compliment each other nutritionally corn provides carbohydrates and beans provide protien while squash yields both vitamins from the fruit and oil from the seeds.
With a little bit of planning in the early stages and before each growing season fertilizer requirements can be virtually eliminated. If sustainable practices are employed in your garden it will provide years of bumper crops and smiling faces. I will dive into this subject in great detail soon because I believe it is a very important aspect of organic gardening.
Until next time…