Rehabilitating Your Garden

Radio Show Notes for Wednesday, June 22, 2011 – Click to Listen

Listen to internet radio with Intel News Network on Blog Talk Radio

Today we talk about gardening – and getting the toxic muck out of your lawn or field.

Square Food Gardening


Square Foot Gardening is a technique of intensive planting developed by a retired civil engineer, Mel Bartholomew, in the 1970’s. Mel describes the technique in his book, Square Foot Gardening, as “a system of laying out, planting, and maintaining a productive, attractive garden in any amount of space. The garden is based on a grid of 1-foot by 1-foot squares, with single seeds or plants placed in carefully determined spacings.” Mel goes on to say, “The square foot system lets you make the most of your garden space to conserve the amount of water, soil conditioners, and labor needed to produce a maximum amount of food in that space. A square foot garden takes only one-fifth the space and work of a conventional single-row garden to produce the same harvest.”

To find out more about Square Foot Gardening, please visit the Official Web Site of Square Foot Gardening and Mel Bartholomew, originator and author by clicking here:


I currently raise vegetables in four 8’x 8’ plots, one 8’x4′ plot, and one 4’x4′ plot. I use a slightly modified square foot gardening technique. These plots are situated next to each other in a square pattern with a grass strip between each one. The crops I currently raise include Bush Green Beans, Pole Lima Beans, Broccoli, Brussels Sprouts, Cauliflower, Cabbage, Carrots, Celery, Corn, Cucumbers, Lettuce (probably my favorite), Onions, Peas, Potatoes, Banana Peppers, Green Peppers, Hot Peppers, and Tomatoes. I also grow a few herbs like Greek Oregano, Chives, and Fennel, that are situated in small plots around the main vegetable garden.

The idea behind square foot gardening is that you can plant fruits, vegetables and flowers in raised beds, above infertile soil and even out of the reach of pets. Seeds are planted in 1X1 square foot plots, and when harvested a new plant is installed in the square. Raised beds can sit directly on the ground, or include a bottom layer and be placed on patios, decks or porches. Because of a bad back, and a dog with a propensity to dig up our new plants, we decided to build a 4×2 foot table-top design.
Materials Needed to Set Up a Square Foot Garden

Material costs are variable, depending on the size of garden you plan to build. I personally opted for a 4? by 2? configuration because it fit the table we were planning to use. Most people typically start with a 4? by 4? design for their first square foot garden. I’ll share with you what materials I used, but keep in mind the pricing could be higher or lower depending on your local costs of lumber, soil, etc.

(1) Sheet untreated plywood – $0.00 (leftover scrap from a previous home improvement project)

(2) 2x6x8 pieces of untreated lumber – $7.38
Don’t get treated lumber because treatments can seep into the soil and contaminate your planting area.

(8) #8 x 3? Wood Screws (or deck screws) – $2.94
Use these longer screws to connect the corners of the 2×6?s after cutting to the desired length.

(8) #6 x 1? Wood Screws – $0.98
These were used to anchor the nylon line to create a grid system for the 1×1 planting plots. I also used a few to fasten the sheet of plywood to the 2×6?s to create a bottom to my container.

(1) Pack of Twisted Nylon Line – $4.43
I used this and the smaller screws to create a grid system on top of the container, in 1×1 square foot patterns.

(2) 2cu ft. bags of Miracle Grow Garden Soil (for flowers and vegetables) – $13.54
There were more frugal recipes here for soil, such as 1/3 compost, 1/3 peat moss, and 1/3 vermiculite. However, I could not find the ingredients packaged locally and the individual ingredients bought separately at the larger home improvement stores were more expensive the bags of Miracle Grow. If you have some compost to mix, such as soil generated from a Mantis ComposT-Twin composter, it would really help your soil.

Though we had the longest winter/spring EVER (since I’ve lived here), it has been great for my hardy and semi-hardy veggies! Check out my first harvest:

I am swimming in parsley! Even though I don’t need it all, I learned last year that if I don’t cut and harvest it, the plant sends up a big, thick stalk and won’t keep producing as well. So I cut a little off the outsides. I read somewhere that you can keep it like a bouquet right on the counter. It’s working for me so far!

I’ve also got lots of spinach. The key with spinach is to keep harvesting, and it will keep growing and delay going to seed. I tried to find a meaningful way of measuring (ounces? pints?) and decided on Corelle cereal bowls–two full of spinach!

How do I Detoxify a Garden?

Efforts to produce organically grown vegetables may be undermined by toxins in soil.

Organic gardening has become widely accepted as the way to enjoy the freshest and healthiest produce. Unfortunately, many areas are polluted with remnants of lead, arsenic, petroleum and even mercury, which may be found around old buildings or landfills. According to the “USDA National Organic Standards Board’s definition of April 1995, “Organic agriculture practices cannot ensure that products are completely free of residues.” When your garden soil tests positive for toxins, steps may be taken to clean it up.

Difficulty: Moderate

Things You’ll Need

• Shovel

• Clean top soil

• Compost or humus

• Leafy green plants

• Leaves or newspaper

1 Junk cars and old metal should be hauled away responsibly. Remove and properly dispose of old garbage from the garden site. Painted wood, metals, old batteries and tires are continually poisoning the soil. Try to recycle as much of the trash as you can to prevent further contamination of soil in another location.
2 Remove the top 8 inches of soil. Most soil contaminates reside in the top 2 inches, so digging deep will ensure your ability to remove most of them.
3 Dilute the bad soil across your garden by mixing it with clean top soil, compost or humus amendments. This step—as an alternative or addition to Step 1—works to organically break down toxins over time.
4 A field of growing lettuce can absorb soil toxins. Plant leafy vegetables like lettuce or Swiss chard to draw many heavy metals out of the soil. Do not eat these leafy plants. These plants are meant to be pulled up and disposed of along with the toxins they have absorbed. This process is a science called phytoremediation, the use of plants to detoxify the soil or air.
5 Dried leaves make good natural mulch. Mulch your garden with leaves or newspaper to help your soil break down unwanted elements over time.
6 Keep the soil pH at 7.0 and make sure phosphate levels are adequate. Use the pH level as a guide that detoxification is continuing.

Tips & Warnings

• Grow plants in pots or raised beds while waiting for very toxic soil to become clean.

• Keep your plants at least 75 feet away from vehicle exhaust and other street containments. Walls, hedges and fences work well as additional barriers.

• As long as your garden is testing positive for toxins, do not plant or eat root vegetables like carrots or potatoes. Root crops spend their whole life underground in the toxic soil and will be polluted all the way through.

• Wash all other fruits and vegetables with vinegar and water before eating to remove any toxic soil particles.

How to Detoxify Vegetables & Fruits


Washing fruits and vegetables with commercial vegetable cleaners or simply soap and water removes most contaminants, but the Centers for Disease Control and Prevention recommends other measures for more serious problems like urban flooding. Even on high ground, fill dirt in housing developments could be rich in heavy metals or tainted by building materials. Gardeners who follow correct procedures when working in tainted soil still grow usable crops. Making the produce safe for the table requires extra precautions.

Floodwater Contamination

Step 1

Destroy all leafy produce — lettuce and other greens used in salad — by tilling the crop under. Vigorous plants could regrow, but leafy vegetables eaten raw even later in the season could carry disease pathogens.

Step 2

Remove all flowers and immature fruits which were on plants during the flood. Peas, beans, berries and tomatoes should all be pruned clean. Produce from blooms that open after flooding should be safe to eat if cleaned and cooked thoroughly.

Step 3

Discard any produce with bruising, blemishes, cracks or punctures. Any wounds or soft spots could harbor contaminants.

Step 4

Harvest root crops only if the leafy tops remain healthy. Rinse beets, carrots and other roots thoroughly with clean water before bringing the vegetables into the house. Wash your hands and fingernails with soap and water before the final preparation.

Step 5

Soak all salvageable produce in a chlorine solution of 2 tbsp. chlorine bleach per gallon of clean water. Submerge the produce completely for at least 2 minutes and then rinse under clean running water.

Step 6

Scrub vegetables thoroughly with a vegetable cleaning brush and clean water. Soak and rinse leafy greens intended for cooking — such as spinach or collards — to remove all dirt. Repeat until the vegetables are clean.

Step 7

Peel all root vegetables except beets before cooking. Most contaminants remain in the surface layer. Drain and rinse cooked beets before slipping off the skin.
Contaminated Ground

Step 1

Mix rotted compost or peat and other good humus into the soil before planting to dilute arsenic and other pollutants. Adding new soil within raised beds also reduces problems.

Step 2

Clean leafy vegetables by rinsing thoroughly in diluted vinegar. Add 1/2 tsp. vinegar to each quart of clean rinse water. Properly cleaned salad greens are safe to eat when raw.

Step 3

Rinse root vegetables under running water and scrub thoroughly with a vegetable brush to remove dirt. Discard any roots with flaws, cracks or punctures.

Step 4

Wash all fruits and berries thoroughly before eating. Wind-blown dust could contaminate even taller crops and fruit trees.

Step 5

Peel roots and tubers before cooking to reduce — not eliminate — toxins. The Connecticut Department of Public Health recommends growing fruiting crops like squash, beans and tomatoes instead of leafy greens or root crops.

Tips and Warnings

Root crops submerged briefly in clean floodwaters — standing rainwater or runoff from natural areas — should still be safe to eat. Discard any with soft spots or injuries.

Destroy any produce submerged in floodwaters for over two days. Don’t eat melons from gardens contaminated by floodwaters. Even sanitized melons present a health risk, according to the University of Wisconsin Extension. Wear gloves when working with contaminated produce. Disinfect and bandage any cuts or breaks in your skin immediately to prevent septic infections.


University of Wisconsin Extension: Safety of Produce from Flooded Gardens
Connecticut Department of Public Health: Growing and Eating Fruits and Vegetables in the Newhall Neighborhood of Hamden
The State Journal: Horticulture News – My Garden’s Flooded…Now What Do I Do?

Natural Detox for Soil

If you are dealing with soil that has had weed killers and other pesticides, herbicides or chemicals used on it, you may be surprised to find out that the BEST plant to grow on that soil to cleanse it is dandelion.

Other plants that work very well to detoxify contaminated soil are:

• Brake fern
• Willow trees
• Sunflowers
• Poplar trees
• Indian mustard

Of course, I wouldn’t recommend using any parts of these plants as they will have absorbed the pesticides and chemicals!



Kochian’s cost-effective “green” technology uses plants to “vacuum” heavy metals from the soil through their roots. He says, “Certain plant species—known as metal hyperaccumulators—have the ability to extract elements from the soil and concentrate them in the easily harvested plant stems, shoots, and leaves. These plant tissues can be collected, reduced in volume, and stored for later use.”

While acting as vacuum cleaners, the unique plants must be able to tolerate and survive high levels of heavy metals in soils—like zinc, cadmium, and nickel.

Scientists analyze compounds released from sorghum roots. Link to photo information.

Plant physiologist Leon Kochian (right) and Cornell University support scientist Jon Shaff analyze compounds released from sorghum roots.

“Phytoremediation has been hampered historically by our inadequate understanding of transport and tolerance mechanisms,” says Kochian. To address this deficit, Kochian—working with ARS research associate Deborah L. Lethman, Cornell University postdoctora postdoctoral associates Mitch Lasat and Paul B. Larsen, and graduate students Nicole S. Pence and Stephen D. Ebbs—has been studying a unique and promising metal hyperaccumulator. The plant is Thlaspi caerulescens, commonly known as alpine pennycress.

“Thlaspi is a small, weedy member of the broccoli and cabbage family,” Kochian says. “It thrives on soils having high levels of zinc and cadmium.”

His lab has been trying to discover the underlying mechanism that enables T. caerulescens to accumulate excessive amounts of heavy metals.

How Plants Clean Up

“Hyperaccumulators like Thlaspi are a marvelous model system for elucidating the fundamental mechanisms of—and ultimately the genes that control—metal hyperaccumulation,” says Kochian. “These plants possess genes that regulate the amount of metals taken up from the soil by roots and deposited at other locations within the plant.

Get the Lead Out – Sunflowers love Heavy Metal

By Sarick Matzen

Dumbfounded, I watched the toxic sunflowers sail over the fence — seeds, heads, stalks, and all. It was one more comic moment in the struggle to bring phytoremediation, the use of green plants to clean up toxic soil, out of the laboratory and into the hands of backyard and community gardeners. I hopped the fence, collected the plants from the empty lot, and routed them towards their proper new home, Milwaukee’s lined landfill.

Using sunflowers to clean lead out of soil has become popular in activist gardener circles, thanks in part to widely-publicized efforts by Common Ground volunteers in post-Katrina New Orleans. This past fall I visited two current phytoremediation (“fido-ree-mee-diation”) projects, and spoke with one of the founders of the 2006 Common Ground sunflower campaign. These activists are tackling soil toxicity head-on by growing sunflowers in lead-contaminated soil, harvesting them after the plants have sucked up some of the heavy metal, and disposing of them like hazardous waste. With every crop the soil gets cleaner.

Low-tech, low-cost tools for Do-It-Yourself soil remediation are desp

erately needed, and bioremediation might be the key: many plants, mushrooms, and bacteria can be used to take up toxic metals like arsenic and mercury, and break down organic chemicals like pesticides and diesel fuel. Traditional cleanup methods include removing toxic soil and putting it in a landfill or chemically washing it, techniques that are expensive, wasteful, and rarely benefit poor people. Lead in particular is a problem in urban areas where as much as twenty percent of children might face lower IQ’s, attention deficit disorders, and behavioral problems from high exposure. Furthermore, communities organizing to build food security need to restore soils full of leaded house paint, gasoline, and battery remains.

Yarrow to the Rescue

Finally, when I read that yarrow has secretions (from the roots) that elevate disease resistance on the part of plants in proximity to yarrow, I was excited because here we had a very safe plant.  I bought a lot of yarrow seeds.  More recently, I planted the Fat Mama sunflower and learned that sunflowers detoxify the soil . . . so the plot was thickening!  These seeds are the ones preferred by birds and the seed head can grow to two feet in diameter.  I am thinking of all the nice compost the stalks will make!,_Hyperaccumulators

List of Hyperaccumulators

English name H-Hyperaccumulator or A-Accumulator P-Precipitator T-Tolerant Notes Sources Al-Aluminium A- Agrostis castellana Highland Bent Grass As(A), Mn(A), Pb(A), Zn(A) Origin Portugal. [1] Al – Aluminium 1000 Hordeum vulgare Barley xxx 25 records of plants. [2][3] Al – Aluminium xxx Hydrangea spp. Hydrangea (a.k.a. Hortensia) xxx xxx xxx Al – Aluminium Al concentrations in young leaves, mature leaves, old leaves, and roots were found to be 8.0, 9.2, 14.4, and 10.1 mg g1, respectively.[4] Melastoma malabathricum L. Blue Tongue, or Native Lassiandra P competes with aluminium and reduces uptake.[5] xxx Al-Aluminium xxx Solidago hispida (Solidago canadensis L.) Hairy Goldenrod


Growing Mushrooms=Creating Fertile Soils

Saprophytic and parasitic fungi help create the organic components of topsoil, in alliance with myriad numbers of bacteria, insects, and other organisms. An orchestra of primary, secondary, and tertiary saprophytic fungi render wood into biodynamic soil components. These soils benefit plants that in turn use photosynthesis to manufacture their own foods.

Wood Chips Mushroom Mycelium| Fresh hardwood sawdust and wood chips | Sawdust/wood chips colonized with mushroom mycelium | Rich soil from composted Shiitake block refuse

After producing several crops of Shiitake Mushrooms, the material in Photo #2 was placed in a pile and turned every few months. The result is a nutritious garden soil.

Fungi can selectively raise or lower soil pH, increasing the usability of existing soils without the need for additional adjustment prior to use.

Organic Soil = Good Bacteria

So, what happens when farmers spray their fields with pesticides, herbicides and fungicides? They kill the army of microorganisms that support plant life, rendering the soil dead. Plants cannot grow in dead soil without the aid of chemical fertilizers. Chemical fertilizers do not make for healthy plants. Unhealthy plants do not make for healthy people. So our health rests on the health of the bacteria in the soil.

Mushroom Break-Down

After several years, and redundant experiments to prove to naysayers that our data was valid, we have made some astonishing discoveries. (I am continually bemused that humans “discover” what nature has known all along.) The first significant study showed that a strain of Oyster mushrooms could break down heavy oil. A trial project at a vehicle storage center controlled by the Washington State Dept. of Transportation (WSDOT) enlisted the techniques from several, competing bioremediation groups. The soil was blackened with oil and reeked of aromatic hydrocarbons.

We inoculated one berm of soil approximately 8 feet x 30 feet x 3 feet high with mushroom spawn while other technicians employed a variety of methods, ranging from bacteria to chemical agents. After 4 weeks, the tarps were pulled back from each test pile. The first piles employing the other techniques were unremarkable. Then the tarp was pulled from our pile, and gasps of astonishment and laughter welled up from the observers. The hydrocarbon-laden pile was bursting with mushrooms! Oyster mushrooms up to 12 inches in diameter had formed across the pile. Analyses showed that more than 95% of many of the PAH (polycyclic aromatic hydrocarbons) were destroyed, reduced to non-toxic components, and the mushrooms were also free of any petroleum products.

After 8 weeks, the mushrooms had rotted away, and then came another startling revelation. As the mushrooms rotted, flies were attracted. (Sciarid, Phorid and other “fungus gnats” commonly seek out mushrooms, engorged themselves with spores, and spread the spores to other habitats). The flies became a magnet for other insects, which in turn brought in birds. Apparently the birds brought in seeds. Soon ours was an oasis, the only pile teeming with life! We think we have found what is called a “keystone” organism, one that facilitates, cascade of other biological processes that contribute to habitat remediation. Critics, who were in favor of using plants (as in “phytoremediation”) and/or bacteria, reluctantly became de facto advocates of our process since the mushrooms opened the door for this natural sequencing.



Environmental pollution with metals and xenobiotics is a global problem, and the development of phytoremediation technologies for the plant-based clean-up of contaminated soils is therefore of significant interest. Phytoremediation technologies are currently available for only a small subset of pollution problems, such as arsenic. Arsenic removal employs naturally selected hyperaccumulator ferns, which accumulate very high concentrations of arsenic specifically in aboveground tissues. Elegant two-gene transgenic approaches have been designed for the development of mercury or arsenic phytoremediation technologies. In a plant that naturally hyperaccumulates zinc in leaves, approximately ten key metal homeostasis genes are expressed at very high levels. This outlines the extent of change in gene activities needed in the engineering of transgenic plants for soil clean-up. Further analysis and discovery of genes for phytoremediation will benefit from the recent development of segregating populations for a genetic analysis of naturally selected metal hyperaccumulation in plants, and from comprehensive ionomics data – multi-element concentration profiles from a large number of Arabidopsis mutants.

New Orleans Clean-Up

New Orleans — In the midst of the vast devastation of this city’s eastern neighborhoods, populated during the weekdays mostly by men in hard hats standing on rooftops or next to trucks, the hopeful signs are gutted homes with FEMA trailers in front, a “We’re Open” sign on a neighborhood shop or community initiatives such as the Meg Perry Healthy Soil Project.

Limitations and Concerns

The toxicity and bioavailability of biodegradation products is not always known.

Degradation by-products may be mobilized in groundwater or bio-accumulated in animals. Additional research is needed to determine the fate of various compounds in the plant metabolic cycle to ensure that plant droppings and products do not contribute toxic or harmful chemicals into the food chain.

Scientists need to establish whether contaminants that collect in the leaves and wood of trees are released when the leaves fall in the autumn or when firewood or mulch from the trees is used.

Disposal of harvested plants can be a problem if they contain high levels of heavy metals.

The depth of the contaminants limits treatment. The treatment zone is determined by plant root depth. In most cases, it is limited to shallow soils, streams, and groundwater. Pumping the water out of the ground and using it to irrigate plantations of trees may treat contaminated groundwater that is too deep to be reached by plant roots. Where practical, deep tilling, to bring heavy metals that may have moved downward in the soil closer to the roots, may be necessary.

Generally, the use of phytoremediation is limited to sites with lower contaminant concentrations and contamination in shallow soils, streams, and groundwater. However, researchers are finding that the use of trees (rather than smaller plants) allows them to treat deeper contamination because tree roots penetrate more deeply into the ground.

The success of phytoremediation may be seasonal, depending on location. Other climatic factors will also influence its effectiveness.

The success of remediation depends in establishing a selected plant community. Introducing new plant species can have widespread ecological ramifications. It should be studied beforehand and monitored. Additionally, the establishment of the plants may require several seasons of irrigation. It is important to consider extra mobilization of contaminants in the soil and groundwater during this start-up period.

If contaminant concentrations are too high, plants may die.

Some phytoremediation transfers contamination across media, (e.g., from soil to air).

Phytoremediation is not effective for strongly sorbed contaminants such as polychlorinated biphenyls (PCBs).

Phytoremediation requires a large surface area of land for remediation.




by: Nicole Swaggerty
CSU Public Health Graduate Student

People decide to compost for a variety of reasons. An avid gardener composts to produce nutrient-dense organic matter to enrich their garden soil. Others want to reduce the amount of food and yard waste that goes to the landfill. Whatever the reason, it is important to understand how to properly and safely compost to prevent contamination of fruits and vegetables from the garden. It is particularly important with garden produce that grows in direct contact with the soil and is eaten raw, such as carrots, radishes, leafy greens, strawberries, and melons. Selecting the right materials to compost and handling them correctly can safer for you and beneficial for your garden.

Farmers have used animal manure and bedding as soil amendments for centuries. High in nitrogen, manure is perfect for getting a compost pile cooking. Cow, goat, sheep, chicken, rabbit, and horse manure can be used in a compost pile. However, manure from pigs, cats, and dogs should be avoided. Meat eating animals are more likely to harbor bacteria in their intestinal tract that are pathogenic to humans, and pig manure may harbor parasites. The pathogens Salmonella, Listeria and E. coli O157:H7, as well as parasites such as roundworms and tapeworms have been linked to applications of manure to gardens. These bacteria may not be destroyed by the heat in the compost pile and may survive up to a year or longer. Therefore, it is advisable to ensure that animal feed does not contain any animal by-products, a good reason to know your farmer. Also, the compost bin should be inaccessible to pets, especially if using open-air piles.

Getting a compost pile ‘cooking’ is very important. The Environmental Protection Agency (EPA) states that “certain temperatures promote rapid composting and destroy pathogens and weed seeds.” Compost heat is produced as a by-product of the microbial breakdown of organic material. Regulations by the EPA specify that to achieve a significant reduction of pathogens during composting, the compost should be maintained at minimum operating conditions of 40°C (104°F) for five days, with temperatures exceeding 55°C (131°F) for at least four hours of this period. Most species of microorganisms (i.e., the good guys) cannot survive at temperatures above 60-65°C (140 – 149°F), making it important for compost managers to turn or aerate their systems to maintain the temperature in the correct range.

In composting plant materials, caution is advised when adding weeds (due to possible re-sprouting in the garden) and plants infected by an insect attack because insect eggs could survive the heat of the compost pile. Use caution when composting plants that produce compounds toxic to other plants and the soil, such as eucalyptus, bay laurel, walnut, juniper, acacia and cypress. Pine needles are also acidic and can interfere with the decomposition process; therefore, a general rule of thumb is to use no more than 10% pine needles in one’s compost pile.

Before adding plant and fiber materials, keep in mind they may have been treated with chemicals. Grass clippings from the lawn may have been treated with pesticides, which can take several months to break down; paper products, such as newspapers, contain a variety of inks (soy based inks are recommended); coffee filters and paper towels may have been treated with synthetic chemicals and bleach. Those attempting to maintain an organic garden will need to consider these possibilities before tossing items into the pile. Lastly, thoroughly clean and wash any tools, equipment, and gloves that contact manure before using in the garden area.

Approaches to composting vary. A composting connoisseur views composting as a science, whereby recipes are followed, temperatures are taken, and intricate systems are designed to optimize the decomposition process. Others take the more simplified stance that “compost happens” and not much needs to be done to make the process work. However a person approaches composting, it is still important to be cautious of risks associated with potentially harmful pathogens that can survive and thrive in the compost environment. Below is a quick reference guide to compost materials from EPA. Happy composting!

What to Compost

The IN list

Animal manure
Clean paper
Cardboard rolls
Coffee grounds/filters
Fireplace ashes
Fruits and vegetables
Grass/yard clippings
Hair and fur
Hay and straw
Nut shells
Shredded newspaper
Tea bags
Wood chips

The OUT List

Pet wastes and used cat litter
– Might contain parasites, bacteria, and viruses harmful to humans
Diseased or insect-ridden plants
– Diseases or insects might survive and be transferred back to other plants
Yard trimmings treated with chemical pesticides
– Might kill beneficial composting organisms
Dairy products (milk, butter, yogurt)
– Odor problems and attraction of pests
Meat or fish bones and scraps
– Odor problems and attraction of pests
Fats, grease, lard, or oils
– Odor problems and attraction of pests
Black walnut tree leaves or twigs
– May releases substances harmful to plants
Coal or charcoal ash
– May releases substances harmful to plants

Practice Safe Composting

Test Compost for Pesticide Residues — at Home

Florida’s Online Composting Center includes any number of interesting and unusual treats, including a series of simple and straightforward tests for compost maturity and phytotoxicity. While these are labeled and offered as ways to test whether your compost has matured sufficiently, the California site on the fate of pesticides in compost (PDF format) points out that they can also be used to test for toxins including pesticides.

The simplest though unscientific test offered is this: toss some radish seeds in a couple of small pots of compost and see what happens. Since radishes sprout within a few days, you’ll have your results quickly. If most of the radish seeds (about three-fourths) germinate, your compost can be pronounced clean or at least pure enough. If more than a quarter of the radish seeds refuse to produce viable young, then it might be wise to conduct one of the more scientific tests summarized below.

In these tests, you will either germinate seeds or assess seedling health and growth in compost as well as in a control medium, a potting mixture without compost. The difference between the two sets of pots — those with compost and those without — tells you the impact of the compost.

If seeds don’t germinate or seedlings don’t thrive in the compost-treated mixtures but they do thrive in the controls, then there is something wrong with the compost. One possibility is the presence of pesticides at phytotoxic levels (levels high enough to injure plants.)

The Florida site includes lists of necessary equipment (nothing more high-tech than an eyedropper or a paper cup) and detailed instructions, including graphs, for plotting results and equations for assessing and interpreting them.

Avoid Potentially Contaminated Manure

Perhaps the simplest rule to follow is never to use fresh manure, which contains higher levels of almost all contaminants (pesticides, heavy metals, antibiotics) than the aged, mature version. If you do spread fresh manure, do so in the fall and let it sit out the winter before you plant in it.

If you have your own farm animals, feeding them only organic feed free of additives will eliminate pesticides, some heavy metals, and antibiotics. A clean, well kept barn or other facility, free of treated wood, peeling paint, and half-closed odd cans of varnish waiting to pop their lids avoids several other sources of contamination. Avoid supplements and disinfectants that contain metals.

If you are buying manure, purchase only mature, organic manure, or limit your application.

Co-composting manures (see below) has also been shown to reduce heavy-metal content.

Co-compost Suspicious Materials

A recent experiment conducted in Spain found that when poultry manure was composted with either barley wastes or chestnut burrs and leaf litter, zinc levels dropped from about 2134 mg/kg in the control (almost twice the legal limit) to approximately 813 mg/kg and 883 mg/kg, respectively, in the two experimental heaps. Poultry manure in North America often contains so many contaminants that some areas ban it from being used as a soil amendment.

This mixing of compostable materials is known as co-composting. Note that in the case of manures, mixing the straw or litter used as bedding into the composting manure doesn’t always qualify as co-composting as this bedding is often thoroughly contaminated.

Co-composting works in part by physically diluting the contaminated material. But that physical dilution also makes certain biological and chemical reactions more likely. As the concentration of contaminants is reduced, the concentration of microbes that can break them down, or the attachment sites that can bind them, increases commensurately.

When in Doubt, Leave it Out

This means not composting refuse from plants grown in contaminated soil. To do so merely recycles the contaminants back into plants. The ones that you don’t eat (love that copper taste!) go back into the compost and so on. If you’re adding conventional manures high in heavy metals each year, then the concentration in your soil will gradually rise. Keeping contaminated refuse out of the compost pile will mean that at least some of the pool will be reduced.

An Overview

Problem, Risk Factors, Steps to Take

A. Fumigatus

All composts.  Problematic for people with asthma, compromised immune systems, or injured lungs.

Know the risk factors and whether any apply to you; wear gloves and a mask when handling unfinished compost; give your compost extra time to cure; use only fully mature, fully cured compost; pay attention to possible allergic reactions, and see a doctor if you suspect one.’


Manures, uncovered composts, fresh manure, pet feces.

Use only mature manures; cover compost heaps to keep out animals & their feces; use a hot composting system to kill pathogens.


Public and municipal composts; any compost made from material to which pesticides were applied.     Find out if public compost tests for pesticides and pathogens; know your state laws concerning clopyralid; compost at home and don’t use pesticides.

Heavy Metals

Manures from feed-lot operations or from animals fed treated feed; municipal composts; soil from mining, industrial, and waste sites.     Have your soil tested; learn the history of your land; don’t put contaminated soil in your compost; get manures from organic sources; find out how contaminants are removed from public compost.

What can be used in a compost pile?

Any organic yard material that is the result of cutting, shearing, trimming, weeding, raking, mowing or blowing.   Leaves, grass clippings, weeds, and pine straw are a few suggestions that come to mind.  Even branches and sticks from trimming hedges are fair game, as long as they are chopped into smaller pieces so that they will decompose in a reasonable amount of time.

How big should a compost pile be?

The recommended size for a home compost pile is a minimum of 3 to 4 feet wide by 3 to 4 feet tall.  It needs to be at least this size in order to adequately heat up in the middle. Obviously, it can be much bigger if you have a lot of yard waste.

Do you need some kind of structure for the compost pile?

Not unless you have a reason, such as aesthetics.  A structure can help to keep the heat in, thus decomposing the composting materials faster, and the pile does look better when contained in some way, but this is up to each individual, as composting can be successfully done with just a pile in an unobtrusive part of the yard.

How do you know when compost is finished?

Finished compost looks much like rich soil, and is dark and crumbly.  There will usually still be larger pieces in the finished product, but these can be sifted out and recomposted, if desired.  Otherwise they can be left in the mixture to decay naturally in the garden.

Should a compost pile have a top or cover on it?

In most cases, no.  However, if you want to manually control the moisture of the pile, using some sort of cover is acceptable.  If you have placed the pile in a partially shaded, well drained area, unusually wet seasons will not affect it significantly, and in very hot or dry situations, water can be added as needed.

Is it always necessary to turn a compost pile?

Certainly not.  Composting is done in nature with no interference whatsoever.  However, in the home gardening situation, turning the pile at regular intervals distributes the organic matter more evenly, thus promoting more rapid decomposition.  A pile that is never turned can take over a year to produce finished compost, compared to a pile that is turned frequently, which can produce the finished product in a matter of weeks.  It all depends on your particular needs and gardening goals.

Can I add kitchen scraps to the compost pile?

Please do!  Any organic kitchen waste, such as egg shells, vegetable scraps, fruit rinds, or coffee grounds are fair game for the compost heap.  Do avoid meat scraps and bones, or very oily waste, as these attract rodents and insects, and can cause the pile to emit foul odors.

Can I add newspaper to the compost pile?

You certainly can.  Any newsprint other than the glossy ads will compost nicely.  The inks used, including colored inks, are non-toxic and safe for composting.  Indeed, newspaper is a good source of carbon when shredded and mixed with the other compost materials.

Can fireplace ashes be added to the compost pile?

Yes, if used in moderation.  Fireplace ash does have some nutrients that are beneficial in the garden, but overuse of ashes in the compost has the potential to drastically raise the pH of the pile, which can prove detrimental when using the finished product.

Can I use dog, cat, or human waste in the compost pile?

No, no, no.  Pet and human waste have the potential for carrying disease to the garden, especially the vegetable garden, so dispose of these wastes somewhere away from garden areas.

Do compost piles smell bad?

A properly maintained compost pile should have a pleasant, organic, earthy smell.  Under some conditions, however, odors do occur.  Lack of aeration, too much moisture, and high nitrogen content in the pile can all contribute to unpleasant odors.  Add dry, brown, woody material to the pile and mix thoroughly if it is emitting unpleasant odors.

Will weeds and weed seeds survive the composting process?

In a properly maintained compost pile, the temperatures generated should kill most, if not all weeds and weed seeds.  Weeds with large roots, such as nutsedge should be dried out and chopped before being added, however.  This will reduce their chances of surviving the composting process.  Frequent turning of the pile will also help to ensure that weeds and weed seeds are not transferred into the garden in the finished product.

Can you use diseased plant material in the compost pile?

As a general rule, yes.  The high temperatures generated in the composting process will kill most plant diseases.  A well managed compost pile is important in this case, however, and turning the pile frequently to evenly distribute the heat and composting materials is an important step in reducing the risk of transferring diseases into the rest of the garden.

Should fertilizer be added to the compost pile?

With a good mixture of brown and green plant materials in the compost pile, fertilizer should not be necessary.  However, if you have a lot of brown and very little green, a high nitrogen fertilizer can be used sparingly to help the decomposition process.

Are magazines safe for composting?

I’m getting conflicting reports. I don’t believe most people that say it isn’t, because nobody has definitive proof that it is. I found a study online that states it’s actually really good material (after it’s shredded like mad and rotated every day). The only problem with that study is that it was done in 1989 and it used magazines from 1950 up to 1989. Although, I’m sure there was a lot more worse stuff in magazine ink back then. It seems like it wouldn’t be, because the ink “is toxic” or so everyone says. Please back up your answers with scientific studies. Link to the study is below, it’s really interesting to read.

I asked a couple other people for their opinion. Here is one that I just got today:

Hello Trevor, and thank you for your question. The National Organic Program (NOP) rule states that newspapers or other recycled paper may be used as compost feedstocks, so long as it is not glossy or contains colored inks. The NOP rule governs the production or handling agricultural products that are intended to be sold or labelled as “organic”.

Colored inks often included heavy metals, although soy- and other vegetable-based inks are much more widely used now, especially in newspapers. Glossy paper is more often produced with a chemical pulping process, bleached to increase its brightness, and coated with calcium carbonate or clay minerals — and may be treated with other additives — to improve its printing characteristics. Colored inks used in magazines and other things like advertisements you receive in the mail may still use heavy metals. These may be present only in trace amounts in the finished


Leave a Reply

Your email address will not be published. Required fields are marked *