concerns with using cardboard/newspaper as a mulch

I live in Alabama and I have used cardboard on a couple of different occasions to kill off grass and add carbon to the soil. I usually just lay out cardboard from boxes with all of the metal and plastic off and then top that with leaves, compost, grass clippings, etc. This has happened on 2 separate occasions when I start this in the early fall and then by early spring I can dig these areas up to mix in the organic matter. The cardboard is still recognizable as cardboard but it is easy to rip to pieces and include into the soil. One year later I haven't found any pieces of cardboard in the soil because it has all broken down. I don't know if this is because I live in Alabama and we have such a long time period for things to break down or if its because I have overly active soil buddies or if it is something else. But, I haven't really had a problem with 1 layer of cardboard breaking down within a year and a half. This doesn't address any issues of toxicity leaching from the cardboard if there are any.

New member here...great forum!

I have nothing to really add to the toxic or not part of it, but as for the cardboard causing problems for years by blocking water and air...I think that may depend on the climate. In my area (New York State) we average 40+ inches of precip annually. I put down cardboard (appliance boxes mostly) with any tape and staples removed about a month ago, and topped with a thick layer of straw. The cardboard is so soggy and soft already, burdock (which had been trimmed to the ground prior to mulching) is pushing up through it. (Yeah I know you can eat burdock roots but the stuff is a PITA and can really take over so I discourage it as much as possible.)

My take on the toxic part is that it's a one-time event and if an underlayer of mulch helps me permanently kill more of my lawn, the over all environmental benefit is a positive, but that's just my opinion.

Interesting thing about the straw topping - the wild turkeys love it. They spend about 3 weeks scratching through it for insects (I see a lot of pale colored spiders in straw), while fertilizing it. I do have to keep replacing the straw as they scatter it outside the boundaries though. They seem finished now, so I will let the area be until next spring. After the snow has flattened the straw, I can dump compost on top and maybe seed with clover and other stuff...still trying to figure that part out. I have a pear tree, some rhubarb and salvia planted so far.

Paul, your timing is impeccable.

bumping this up at this time.

I JUST YESTERDAY, was so fed up with an area of quackgrass that i couldn't dig or pull that was driving me absolutely bananas.

it was around 4 baby wild plum trees and they were being horribly stunted and swamped by  the weeds.

we pulled a bunch of them the day before, but they were breaking off from our drought..the soil is baked so hard..and mulch wasn't doing it.

so

i went through the woodshed and garage and found as many cardboard boxes as i could (they were from tree deliveries so hopefully better quality cardboard???)

and i cut them up and placed them over the smashed down quackgrass and weeds around the 4 wild plums, and piled pulled weeds on top of the cardboard..it is raining today so it is getting waterd down some..but as i said..we have a drought so i'm not sure how much good it is doing..but at least i can see the 4 tiny little wild plum trees sticking above the holes in the cardboard now..rather than 2 1/2 feet tall weeds and no baby trees !! wish me luck

I've used cardboard and paper under mulch for years.  Wouldn't start a new bed without it.  I know a number of people who avoid the glossy stuff and colored inks,  but if you are only using it in the establishment phase, traces of most minerals are either harmless or beneficial.  I mean puting a few sheets of the Sunday comics, that might have a bit of copper in the blue or green inks, under 6" of hay isn't the same as eaiting the stuff.  I don't have any idea how much newsprint it would take for, again just as an example, the copper to build up to toxic levels, but all living things need copper in trace amounts.

If you are paranoid about never bringing anything into your garden that might contain a trace of some harmful substance, don't ever use any rock-derived product.  Limestone has a fair amount of uranium in it.

BTW:  The lye you get from wood is KOH, not NaOH.  It will raise the pH, but is a source of K. That's one of the main reasons wood ash is good for a garden.

In paul stamets book he says that cardboard, North American, Canadian or Eurpopean cardboard is alright and he is a scientist who understands all the ins and outs of that sort of thing so i should think its all right. rose macaskie.

I've been asking people questions about using glossy paper/card, but there seems a pretty infinite set of variables on toxicity.
In my own situation, I use anything vaguely (in its most basic sense) organic that I bring onto my place.
While I'm willing to compost/mulch anything and everything , I'm not confident in 'encouraging' others to do the same without informing them of the potential for various vague  harms,
which is enough to put all but the most danger-loving folks off!

well sometimes i feel that if you weigh the pros and the cons, you'll generally come out with a decision that will best suit your own area. For the quackgrass here..the pro is to smother than mess and hopefully allow the trees to grow while the quackgrass is dying ..and then when the cardboard and mulch is sufficiently degrading i can plant around the now larger trees. This is the plan around the trees i've been mulching around ... eventually to plant around the baby trees, but in the meantime to kill off the quackgrass, if even just temporarily so that the baby trees can survive

For me the brown paper feed sacks are the answer to use.  Have to smother the grass as Brenda says and I have them to dispose of anyway.  The worms love them, and the old wood I use too. 

From an organic certification point of view black and white newsprint is acceptable in compost but not full colour.

Must be about the concentrations of inks I guess, as 4 colour printing puts, well 4 times as much ink on a page.

I use cardboard on my paths, covered with fresh lawn clippings.  It's my main defense against quack grass -- my main nemesis.  And, it does retain and trap moisture, a concern in my ecotype (zone 4, zeric-mesic, northern Rockies).  I get the cardboard from boxes full of produce waste from a local "alternative" commercial store ("organic") for my compost.  So, it probably has all the bad things. 

But, I _really_ like the idea of developing a commercial product that functions the same as the cardboard and is designed specifically for garden use.  I'm always looking for uses for small-diameter trees that I thin in the wildland-urban interface.  And, ironically, our local cardboard mill (owned by a not-so-local multi-national Stone Container) recently shut down.  So... I'd love to see someone start a successful small cardboard-for-gardening mill. 

BTW, how about inoculating these cardboard weed shields with edible fungi?  Soooo many benefits to fungi, ranging from protein to useful enzymes...  I've been experimenting with inoculating piles of wood chips (pines, D.-fir, etc.) but haven't had much luck, for various reasons (off topic).   

I wonder does burning the pulp products("any") break down the toxins further along, then you can apply the ash?

Just to explain my situation, we recycle glass(broken, I save jars fo rcanning certain things and if there is a choice between glass or plastic jars in packaging I will pay more for glass), plastics, metal, magazines(and magazine like paper), food waste is composted/animal food, clothing is passed on or put away to recycle, anything else is saved up and a dump trip is done once a year. We don't have garbage service. We burn the paper(which ends up being MOSTLY computer paper--which will go way down once the kids are out of school/house ha, and cardboard, brown paper bag).  We live way out of town so burning is not an issue, as long as you follow the summer burn ban--and we heat with wood too for that matter.

ANyways, that ash goes on the garden.

I have seen some shredder scissors(do they even work?) that would be cool to shred the comp paper for chicken bedding(as it is I make my own hay). Personally I think the ash is the better form.  I will use cardboard to weedblock an area for awhile, but I pull it up and reuse or burn it. Here with the big rain in winter and the clay soil paper seems to take forever to break down--other natural stuff breaks down fine, but the paper just sits there.

Sorry that ended up rambling--again, my question is, would paper turned to ash be "safer" or toxins be broken down farther along. I don't do the big compost pile thing to cook stuff. I suppose burning the paper is simply kinda flash composting?

even shredded paper and cardboard does tend to take a while to break down when used as a mulch in the garden..it seem to work a little better if it has at least been partially composted with other materials before adding it to the garden.

i have put some into the compost tumbler with other materials and then taken it out and it still hasn't quite broken down ..but it doesn't clump up and stay as nasty as it does when added directly to the garden as mulch..so you might try combining it with some compost first before putting it on the garden.

it is also UGLY..when not covered with some organic mulch..but i guess i don't mind so much as long as i get enough green plants over top of it (right now growing pumpkin vines over where i put the last batch on the garden)..

@wyldthang, have you tried feeding them to a worm box?  I remember hearing that worms like newspaper...but won't swear by it.  If so, perhaps it's true with other papers.  Also, I wonder if any edible mushrooms would eat them.  Nothing in the world better than mushroom compost (except the commercial kind, which is laden with mercury to control aberrant microbial behavior...). 

Rickster wrote:
@wyldthang, have you tried feeding them to a worm box?  I remember hearing that worms like newspaper...but won't swear by it.  If so, perhaps it's true with other papers.  Also, I wonder if any edible mushrooms would eat them.  Nothing in the world better than mushroom compost (except the commercial kind, which is laden with mercury to control aberrant microbial behavior...). 

worms most definitely like paper products.  I've put down cardboard down on dog-trampled spots and later picked them up to find "worm tracks" carved in the bottom.  I've also had the same experience with newspaper.  I've read other people feeding their worm bins shredded paper and having it magically disappear in short order!

Seeing these "tracks" on the bottom give me a double dose of the smiles:  1)I have hungry worms!  2) They're disposing of my copious amounds of cardboard!

well i'm getting more mulch now to cover cardboard with so i might be using a little more of it. I still try to partially compost anyway my shredded stuff before putting it out, makes it softer and less clumpy.

Husband nearly cut his big toe off with a small scythe Saturday cutting mulch though..so hey i'm not sure if it is going to pay (tee hee, hospital bills might trump mulch )..

head injury

use newspaper.  as of 2003 95% of newspapers printed using soy based ink.
http://en.wikipedia.org/wiki/Soy_ink

edit: missed this part though.
" Even though soybean oil is an edible vegetable oil, soy ink is not edible or 100% biodegradable because the pigments and other additives that are mixed with the oil are the same as those used in petroleum-based inks. Degradability studies conducted by Erhan and Bagby concluded that the pigment cartier in 100-percent soy ink degrades almost twice as completely as ink made from soy oil and petroleum resins, and more than four times as completely as standard petroleum inks.[5][6] Soy ink is a helpful component in paper recycling because the soy ink can be removed more easily than regular ink from paper during the de-inking process. Again this refers to 100% soy inks which are not commercially viable."

i understand the concerns, but i will be using cardboard and paper to establish plots as i have access to an endless supply.  i don't think i want to use it forever though just like i don't want to use non-organic straw.  and ideally i will at some point be making all my own mulch.

Paul talks about his concerns with using paper/cardboard in his podcast 027: http://www.richsoil.com/permaculture/category/podcast/

i like banana boxes because the worms love the large corregated  layers

let the worms tell you....  no worms  it's bad,  lots of worms  it's probably Ok.

I'd like to add something that Geoff Lawton mentions during the PDC DVD series:

They used thick layers of cardboard and newspaper to create a gley over very sandy subsoil that would not hold any water.
Once again we have to remember that permaculture originates in Australia, a continent that has people living in small and rather arid areas along the coast, most of which have sandy soil !

The lesson to be learned from these remarks should be that cardboard as a foundation for a garden bed is excellent wherever water holding capacity is of the essence.

People who want to use it as an intermediate layer in a raised bed or under a tree (as in Paul's story) should probably look for something more porous,
as should those who live in a wet climate combined with heavy soil.

Glossy paper has a lot of clay in it.

If you're worried about using cardboard for you garden, then you should be in near panic using recycled paper food containers.

  I use cardboard as weed control as it  holds in moisture around the plants + the worms & bugs love it.

I'm not much on using news paper in my garden. I use to use it as a back stop for shooting. Stacked up and tied it was like a block wall when wet.

Also I don't buy the newspaper, it a waste of reading.

(copied with permission)

TOXIC CARDBOARD: An organic gardening expose

By Andy Firk

Boy oh boy, corrugated fiberboard boxes sure are a common sight to see.  "Over three quarters of all perishable goods are being shipped in some sort of a cardboard box or corrugated fiberboard container." (J)  Now, all cardboards MAY not necessarily contain toxins, but from my research, the vast, vast majority sure do, and holy crap, do they contain some toxins!  The percentage of non-toxic cardboard on the market is very low, and quite a mystery to unravel.  Just where to obtain such pure cardborad may be difficult or nearly impossible to figure out, as I have learned this week.  I have been calling a few of our state's cardboard manufacturing facilities, and I continue to find more chemical processing steps in the manufacturing.  Little information is offered up easily by these companies.  These manufacturers do not openly discuss the proprietary ingredients used in the manufacturing of cardboard materials.  This should be enough information for an organically-inclined person with average intelligence to keep them away from their gardens.  From use of cardboard as an under-mulch layer, to a cover for blocking weeds in pathways, there is a commonly held misconception that cardboard is benign, safe, non-toxic, and biodegradable.  Nothing could be further from the natural truth.  If you are not convinced, please read on.



WHERE DOES THE WOOD PULP MIX FOR CARDBOARD COME FROM?

The pulping process of making paper pulp for cardboard often contains horrible chemicals.  Some of the worst polluters in the country are pulp mills.  One pulp mill, the Buckeye Pulp Mill,  who supplies pulp for corrugated fiberboard among other products, releases enormous levels of DIOXIN into the Gulf Of Mexico, here in Florida.  It is ranked as one of the worst polluters in the entire state, if not the worst in terms of certain chemicals being released.  Numerous articles and studies attest to this "should-be-closed" mill.  The Clean Water Network Of Florida published a concise article a few years back. (G)  "According to the 2005 TRI (Toxics Release Inventory), Buckeye reported releasing 240,630 pounds of known cancer-causing toxics, those recognized by OSHA as being carcinogens, to the air and water." (G)  In total "Buckeye admitted emitting 19,537,806 pounds of toxics to the EPA's 2005 TRI, ranking Buckeye the most polluting pulp or paper mill in Florida."  "Buckeye has been in operation for 53 years, polluting the environment, contaminating the fish, and poisoning the air and water with hundreds of very dangerous toxics." (G)  Pulp for cardboard is one part of this nightmare for Taylor County residents.  But let's move on to the specifics of cardboard, especially "corrugated fiberboard", or "wavy cardboard".



RSC, THE MOST COMMON TYPE OF CARDBOARD BOX

"The most common box style is the Regular Slotted Container (RSC)."  "The manufacturer's joint is most often joined with ADHESIVE." (B)  What, if any chemical toxins are an ingredient in this adhesive?  I wasn't sure until I started digging for information.



FORMALDEHYDE

Some community gardens have ruled out the use of toxic cardboard, siting the FORMALDEHYDE ingredient.  Though this is debated.  (A)  Not much information about FORMALDEHYDE in cardboard is available, so let's move on to what we know IS in cardboard.



MANUFACTURING STEPS

Lets examine the manufacturing steps that it takes to make a "natural-looking" sheet of wavy cardboard (aka Corrugated Fiberboard)



SULFATE PROCESS

"Fast-growing pine trees provide the primary raw material used to make corrugated cardboard."  "At the mill, the harvested tree trunks are subjected to the "Kraft Process", also known as the "SULFATE PROCESS" because of the CHEMICALS used to break down wood chips into fibrous pulp." (I)  SULFATE, SO4, is CONTAMINATING our waters near these mills.



POSSIBLE CHEMICALS IN THE PULPING PROCESS

"The manufacturing process begins with pulping, the separation of wood (hardwood and sapwood) into individual fibers, as accomplished by mechanical methods or CHEMICAL treatment." (wiki / 4)



TOXIC SODIUM HYDROXIDE

"First, tree trunks are stripped of bark and torn into small chips. Next, these chips are placed in a large, high-pressure tank called a BATCH DIGESTOR, where they are cooked in a solution, or liquor, made of SODIUM HYDROXIDE (NaOH) and several other ionic compounds such as SULFATES, SULFIDES, and SULFITES. These STRONGLY ALKALINE CHEMICALS dissolve the lignin, the glue-like substance that holds the individual wood fibers together in a tree trunk."  "When the pressure is released after several hours, the wood chips explode like popcorn into fluffy masses of fiber." (I)



CHEMICALS IN THE CORN STARCH GLUE

It is a total myth among organic gardeners and permaculturists that CORN STARCH GLUE in cardboard is non-toxic.  "CORN STARCH GLUE is used to bond the corrugated medium to the liner sheets. Because so much GLUE is used, rail cars or large tanker trucks deliver it as a dry powder that will be stored in huge silos at the corrugating plant until it is needed. Drawn from the silo, the dry corn starch is mixed with water and OTHER CHEMICALS."  "The medium travels next to a set of rollers called the SINGLE-FACER GLUE STATION. Here, one layer of liner is GLUED to the medium. STARCH GLUE is carefully applied to the corrugated edges of the medium, and the first layer of liner is added. From the single-facer, the medium and liner go to the DOUBLE-BACKER GLUE STATION where the other layer of liner from the bridge is added following the same procedure. Continuing through the corrugator, the cardboard passes over steam-heated plates that cure the GLUE." (I)  So, you're still not sure if corrugated fiberboard is toxic, then just drive past one of these plants, I have.  The stench is unbelievable.



CARCINOGENIC PARAFFIN FROM THE OIL INDUSTRY MAY COAT CARDBOARD BOXES

"Other raw materials are used to finish the corrugated cardboard after production.  WAXES made from PARAFFIN or vegetable oils can be applied to make a water-, or grease-resistant container for food products."  "Other equipment in a corrugating plant includes... machines known as CURTAIN COATERS that apply a WAX coating to fruit, vegetable, and meat containers." (I)



TOXIC INKS?

On some cardboard boxes "BRIGHTLY COLORED INKS are also applied to create bold graphic designs for self-supporting displays featuring product name, information, and company name and logo."  "Today, in the corrugated cardboard industry, designers are creating innovative containers that require FOUR-COLOR PRINTING and complex die-cutting."  "Today, inks based on soybean oil and biodegradable waxes and other coatings are BEGINNING to be used in container manufacturing." (I)  Are these currently used inks toxic?  I would guess, yes.  Ah, what the heck, I'll go all out and say, yes they are.  Prove me wrong!



LINERBOARDS ARE "PAPER-LIKE"

They are the flat sheets that hold the wavy sheet in place. (B)  "Linerboard is made of containerboard", defined by the industry as a "PAPER-LIKE material". (B)  These broad ingredient definitions leave legal room for the addition of proprietary CHEMICAL ingredients.  "Linerboards are test liners (recycled paper) or kraft paperboard (of various grades)." (wiki) 



LINERBOARDS MAY BE MADE FROM "KRAFT-PAPER", WHICH IS OFTEN MADE FROM CHEMICAL PULP

Kraft paperboard is described here (D) and is said to be "paper produced from CHEMICAL PULP processed by the kraft process." (wiki / D)  "The raw material is normally softwood pulp from the kraft process. Kraft paper can be white or brown depending on the pulp if it is BLEACHED or unbleached." (wiki / D)  "The liner may be BLEACHED WHITE, MOTTLED WHITE, COLORED...." (wiki)  And remember, just because a cardboard box looks brown and "natural", is no indication as to its level of BLEACHING in the processing steps.



"RESINS" IN CARDBOARD CAN BE SYNTHETIC / ARTIFICIAL RESINS

"Resin - plant sap, particularly from the pine family. Natural resin tends to be unstable due to its properties. SYNTHETIC RESIN is produced by POLYMERIZATION which then results in the PRODUCTION OF POLYMERS since they are more homogeneous and their properties are more predicable and industrially viable." (J)

ADDITIONAL "LAMINATE LINERS" MAY BE ADDED TO INCREASE STRENGTH OR HEAT AND/OR WATER RESISTANCE

"Heat or water-resistant corrugated fiberboard has an ADDITIONAL LAMINATE LINER applied." (J)



LINERBOARD GLUE (aka ATTACHMENT) MAY CONTAIN TOXINS

The corrugated medium "is joined to a flat linerboard with a STARCH-BASED ADHESIVE." (wiki)  "From the paper mill, rolls of kraft paper are transported to a corrugating, or converting, plant.  At the plant, layers of kraft paper are crimped and GLUED to form corrugated cardboard."  "At the beginning of this process, kraft rolls from the paper mill are loaded into a huge machine called a CORRUGATOR."  "Some rolls of kraft paper are used as the corrugating medium, and others are used as liners, the layers of kraft paper GLUED on each side of the medium. After the CORRUGATOR has heated, GLUED, and pressed the kraft paper to form corrugated cardboard, the continuous sheet of cardboard is cut into wide box blanks that then go to other machines for PRINTING, cutting, and GLUING." (I)  Do we know if any toxic chemicals are an ingredient in this adhesive?  I'm not sure.  Again, I would assume so.



TOXINS IN PRINTING OR COLORING?

"The liner may be... COLORED, or PREPRINTED." (wiki)  I do not have information on these additives.



POSSIBLE TOXINS IN THE SURFACE TREATMENTS AND COATINGS

"Corrugated fiberboard can be specified by" various processes including "SURFACE TREATMENTS and COATINGS." (wiki)



THINK RECYCLED CARDBOARD IS A BETTER CHOICE?  THINK AGAIN

"Swedish researchers have determined that health issues as minor as inflammation and as and as serious as cancer may be linked to cardboard packaging made from recycled newspapers."  "Scientists are linking the health risks to the mineral oils in newspaper ink that survive the recycling process."  Recycled from what, other toxic cardboard products?  "Researchers at the Food Safety Laboratory in Zurich tested 119 products from German supermarkets, with 90 of the packages containing unsafe levels of MINERAL OILS."  "The Food and Drink Federation of the UK has called for an investigation to determine potential long term effects." (H)  "Recycled material GENERALLY CONTAINS traces of INKS, ADHESIVES and OTHER CONTAMINANTS which have to be taken into account when determining the product strength and print-quality characteristics. BLEACHING THE PULP is a process aimed at improving print quality but it requires further processing and prolongs the manufacturing cycle." (J)



IN CONCLUSION

So, go ahead and lay down cardboard in the form of "corrugated fiberboard" in your garden rows, or underneath your mulch.  Just don't call your garden organic, and be fully prepared to sit down to a lovely meal of toxic veggies, veggies that have systemically absorbed proven carcinogens through their roots.  Products that require many processing steps can be assumed to contain chemicals that we are not aware of initially.  Take for example the well-intentioned, concerned folks who have been buying BPA-free Plastics as of late.  Well as it unsurprisingly turns out, "another report earlier this month revealed that BPA-free plastics, thought to be more stable and safer, have been shown to also leach toxins into foods." (H)  Remember the precautionary principle - a product or chemical must be proven safe BEFORE it is assumed safe.



TO RECAP, LET'S JUST LOOK AT THE LIST OF POSSIBLE PROBLEMS

1 - Dioxin

2 - Formaldehyde

3 - Sulfates

4 - Sodium Hydroxide

5 - Sulfides

6 - Sulfites

7 - Corn Starch Glue With Added Chemicals

8 - Paraffin Wax

9 - Toxic Inks

10 - Chemical Pulp

11 - Bleaches

12 - Synthetic / Artificial Polymer Resins

13 - Unknown Laminate Liners

14 - Starch-Based Adhesive Glues

15 - Surface Treatments

16 - Coatings

17 - Toxins From The Recycling Process Including "Mineral Oils" and "Other Contaminants"

18 - The Other Unkowns, including the common use of the generic term "Chemicals" in most of the industry articles that I have read.



STILL DON'T BELIEVE THAT IT IS TOXIC?

If you want to stand up for the commonly held, incorrect belief that corrugated fiberboard is biodegradable and non-toxic, then please prove me wrong.  Contact TAPPI, the Technical Association of the Pulp And Paper Industry (E), or ASTM, the American Society For Testing And Materials (F) , and just try getting some information to the contrary from these tight-lipped corporate whores, I dare you.



REFERENCES

A - http://perrone.blogs.com/horticultural/2008/02/i-recently-had.html

B - http://en.wikipedia.org/wiki/Corrugated_cardboard

C - http://www.thomasnet.com/articles/materials-handling/cardboard-manufacturing

D - http://en.wikipedia.org/wiki/Kraft_paper

E - http://en.wikipedia.org/wiki/TAPPI

F - http://en.wikipedia.org/wiki/ASTM

G - http://www.cleanwaternetwork-fl.org/content/disp_article.php?f=issues/032807_dioxin_joyezell.html

H - http://www.oomphorganic.com/2011/04/cardboard-toxins.html

I - http://www.answers.com/topic/corrugated-cardboard-1 ; (This is a very in depth description of the processing steps that it takes to make corrugated fiberboard.)

J - http://www.largecardboardboxes.net/

Great Article Andy.  I needed to come back and read it again.  We tried bales of old straw and it did nothing to keep out the bigger stuff like roses and sumac or poison ivy.  When we go to town there is a cardboard bin behind sears with the big fridge boxes.  Minimal black print, we removed all tape and staples.  I still don't feel great about it after reading your article, but I'm looking for a better way. 

In small keyway beds, I'm going to try snipping any baby sumac or pulling up if possible, cutting growth down and then lay a big layer of straw.  On top of that start creating a compost pile. I'll try to keep it hot and then when the pile is broken down, maybe the heat will have killed what grew below.  When it's nice compost, I can plant and mulch with straw.  That's the plan, no one seems to have a decent alternative for what grows here.

By the way, our first bed we lay the Sears cardboard (not corrugated, just flat cardboard) and it was completely broken down in 7 months.  We get a good bit of rain though, and I threw a lot of grass clippings from mowing pathways with old straw and that probably heated it up

paul wheaton wrote:

Last spring I visited somebody's garden where an apple tree was doing poorly.  After digging around a little, a layer of newspaper was found about an inch under the soil.  It was about a quarter of an inch thick and had apparently been put down to kill weeds about five years earlier.  It killed the weeds.  And it was making the tree sick.  And it wasn't breaking down.

I wouldn't jump to the conclusion that the paper was making the tree sick because of chemicals.  Since its purpose was to kill weeds by excluding air and/or water, that might have the same effect on the tree roots, by preventing water soakage and forcing it to run around the tree.  Just a thought.


Nor do I share the same level of aversion to toxic gick.  Granted, I won't spray chemicals around.  But anything hydrocarbon is, by definition, composed of hydrogen and carbon, and can be broken down by bacteria, fungi, or best, composting.  Paul Stamets has some interesting stuff about cleaning up Superfund sites with mycelium.  Typha will dispose pretty safely of DDT, 2,4-D and various other nasties. 

As for myself, I have found that used motor oil will compost quite readily, at 2-3 gallons per cubic yard of compost.  It takes longer to break down than the rest of the material, but after a few months, weeds are quite happily growing in the piles.  I of course laugh sardonically when veg-hippies tell me you can't compost bones.  You can compost almost anything... which is what I do with cardboard and paper, btw.  I tried it for mulch once, and critters spread it everywhere, so I just put it through the shredder and into the compost pile.

Sheet mulching seems to me a tactic for killing weeds, provided you're growing stuff in raised beds above the sheet mulch.  I wouldn't use it over tree roots.  Use a fast growing cover crop instead.

paul wheaton wrote:

veggies that have systemically absorbed proven carcinogens through their roots. 

Generally plants absorb only mineral elements through their roots. Some plants (mostly those adapted to difficult environments i.e. not vegetables ) absorb some soluble organic compounds. This statement is a bit of a stretch

amazing info thanks..guess I'll rethink using cardboard under mulch

reading the  OP I was strongly reminded of the dihydrogen monoxide controversy and it scared me about as much.

WHERE DOES THE WOOD PULP MIX FOR CARDBOARD COME FROM?

Dioxin- I'm a bit of a sceptic about dioxin. For one thing accusing an industry of making dioxin is like accusing a teenager of masturbation. Dioxin forms whenever any chlorine containing compound (such as salt) is burned, so we have all been producing dioxin ever since the first stone age person built a fire out of driftwood on a beach. It also forms naturally. Zac Goldsmith makes dioxin when he burns his toast in the morning. If dioxin was as dangerous  as some environmentalists claim we would not be here. It seems to be a convenient stick for Greenpeace to beat corporations they don't like (e.g. the ones that don't give them big donations). It amounts ultimately to a campaign against the use of  fire. Wow! seriously radical ecoprimitivism!

"Environmental" cancer scares have become increasingly common. The reason is that most people don't care about the environment anything like as much as they care about themselves. Cancer is emotive. Everyone in developed countries  knows someone with cancer. You can talk to the public about saving marine mammals, wild salmon, rainforests, wild flowers, etc. and how the decisions they make in the supermarket affect these things until you are blue in the face. Then tell them that product x increases their risk of cancer [sub]by 0.0000000001%[/sub] and  suddenly its headline news. No one seems to ask how these caring green environmentalists discovered this subtle statistical variation (answer: a huge  amount of vivisection and an unholy alliance with the  massive multinational corporate money laundering scam known as cancer research).Most cancers happen because we are living
longer and not dying of other things. Most of the remainder happen due to well understood lifestyle factors (smoking, women not having as many babies as in the past etc.). This leaves a small percentage caused by a variety of unknown causes that may well include pollution. Fascinating! But lets leave this to the pharmaceutical companies (let them spend their own money for a change), spare some lab rats and divert our energy to some real environmental issues. I digress. dioxin is the great granddaddy of cancer scares which are a kind of propaganda which will ultimately only discredit environmentalism.

I also don't see any evidence that dioxin is actually in cardboard boxes at all or in significantly higher quantities than anywhere else

I realise I've probably alienated90% of the people in  this forum. Not a good start


>RSC, THE MOST COMMON TYPE OF CARDBOARD BOX

>"The most common box style is the Regular Slotted Container (RSC)."  "The manufacturer's joint is most >often joined with ADHESIVE." (B)  What, if any chemical toxins are an ingredient in this adhesive?  I wasn't >sure until I started digging for information.

Here in Bulgaria  I find few boxes with adhesive. Those I do find are mostly coloured so I don't use them

FORMALDEHYDE

A possible maybe

SULFATE PROCESS

In big quantities a pollutant.In small quantities plant food.


TOXIC SODIUM HYDROXIDE
Toxic because when concentrated and pure it is a strong alkali. Dilute traces of sodium hydroxide in the environment will react with organic acids to make harmless salt, water, carbon dioxide and oxygen. As I don't get serious skin burns from handling cardboard I  would assume it is not strongly alkaline and therefore  doesn't  contain concentrated sodium hydroxide. A simple pH test could resolve this.

SULFATES, SULFIDES, and SULFITES.
See entry onsulphate above. Card does not seem to be strongly alkaline


CHEMICALS IN THE CORN STARCH GLUE

Another possible maybe. Something unknown in the cornstarch glue. It  smells bad apparently. Bone or fish glue perhaps?

CARCINOGENIC PARAFFIN FROM THE OIL INDUSTRY MAY COAT CARDBOARD BOXES

>"Other raw materials are used to finish the corrugated cardboard after production.  WAXES made from >PARAFFIN or vegetable oils can be applied to make a water-, or grease-resistant container for food >products."  "Other equipment in a corrugating plant includes... machines known as CURTAIN COATERS that >apply a WAX coating to fruit, vegetable, and meat containers." (I)

Sounds like we are talking about waxed cartons etc. rather than plain brown card. I stopped using orange juice cartons as plant pots because nothing seemed to thrive in them, but it may be that they just got soggy and stopped draining properly

TOXIC INKS?

>On some cardboard boxes "BRIGHTLY COLORED INKS are also applied to create bold graphic designs for >self-supporting displays featuring product name, information, and company name and logo."  "Today, in >the corrugated cardboard industry, designers are creating innovative containers that require FOUR-COLOR >PRINTING and complex die-cutting."  "Today, inks based on soybean oil and biodegradable waxes and >other coatings are BEGINNING to be used in container manufacturing." (I)  Are these currently used inks >toxic?  I would guess, yes.  Ah, what the heck, I'll go all out and say, yes they are.  Prove me wrong!

So don't use coloured/glossy cardboard  

LINERBOARDS ARE "PAPER-LIKE"

>They are the flat sheets that hold the wavy sheet in place. (B)  "Linerboard is made of containerboard", >defined by the industry as a "PAPER-LIKE material". (B)  These broad ingredient definitions leave legal >room for the addition of proprietary CHEMICAL ingredients.  "Linerboards are test liners (recycled paper) or >kraft paperboard (of various grades)." (wiki)

Another possible maybe, Cardboard is a "paper like material"

LINERBOARDS MAY BE MADE FROM "KRAFT-PAPER", WHICH IS OFTEN MADE FROM CHEMICAL PULP

>Kraft paperboard is described here (D) and is said to be "paper produced from CHEMICAL PULP >processed by the kraft process." (wiki / D)  "The raw material is normally softwood pulp from the kraft >process. Kraft paper can be white or brown depending on the pulp if it is BLEACHED or unbleached." >(wiki / D)  "The liner may be BLEACHED WHITE, MOTTLED WHITE, COLORED...." (wiki)  And remember, >just because a cardboard box looks brown and "natural", is no indication as to its level of BLEACHING >in the processing steps.

Possibly maybe,possibly may contain traces of bleach, which possibly may turn into dioxin if it possibly somehow maybe catches fire in your garden and possibly maybe slightly increase your risk of cancer if you possibly maybe forget to clean the surface of your vegetables



"RESINS" IN CARDBOARD CAN BE SYNTHETIC / ARTIFICIAL RESINS

>"Resin - plant sap, particularly from the pine family. Natural resin tends to be unstable due to its >properties. SYNTHETIC RESIN is produced by POLYMERIZATION which then results in the PRODUCTION >OF POLYMERS since they are more homogeneous and their properties are more predicable and >industrially viable." (J)

Yes and......? Are polymers inherently dangerous? If so I had better get rid of all my clothes immediately

>ADDITIONAL "LAMINATE LINERS" MAY BE ADDED TO INCREASE STRENGTH OR HEAT AND/OR WATER >RESISTANCE

>LINERBOARD GLUE (aka ATTACHMENT) MAY CONTAIN TOXINS

Possibly maybe. something toxic has been added here or possibly not. No evidence of any kind has been presented here

>TOXINS IN PRINTING OR COLORING?

>"The liner may be... COLORED, or PREPRINTED." (wiki)  I do not have information on these additives.

If it's coloured don't use it. Precautionary principle. Again, no evidence.

POSSIBLE TOXINS IN THE SURFACE TREATMENTS AND COATINGS

Possible maybe

This whole article seems to be stretching the doctrine of the precautionary principle to new extremes.

Maybe my goats are shitting plutonium. Can we prove they are not? The goats are remaining tightlipped on the subject.

Perhaps manufacturers of recycled cardboard (who always regarded themselves as environmentalists until greens fell for the "low chlorine" (i.e. non recycled) paper label) have had one too many phone calls from terrified, paranoid people who rant about fluoride.

The worms and slow worms love my cardboard mulch.An  organic farmer I knew used wet newspaper and bran to catch slugs  which raised eyebrows with the certifiers until she showed them the worms under the paper.



At a protest I was involved in against a waste incinerator(we won!)someone suggested that it would be better to ban the few toxic chemical additives that make most our waste too toxic to burn and then separate and burn cardboard and the like for energy  (paper recycling is not always as green as people think) . A similar  argument could apply to biodegradable waste.A few largely unnecessary chemicals mean lots of biodegradeable waste goes into toxic landfills. At worst we need to  talk to the industry (politely) and ask if anything besides cornstarch is really needed to glue boxes that will be used once.There might even be some environmental funding that could sweeten a dealto phase out toxic glue (if it really is toxic)

To summarise  I still can't see anything to worry about with plain brown cardboard.
Building earthships and raisedbeds with cadmium rich old car tires on the other hand .........
but that's another thread

I remember my parents standard practice was to lay newspaper inbetween the veggie rows.  My dad then spread the grass clippings on top.  It was always moist and at the end of the season the newspaper was almost non-existant.  Want to go fishing?  Just roll the newspaper back and find tons of nightcrawlers - but toward end of summer it would all fall apart.

I thought my mom left the sections whole and it was a small town back then so maybe the newspaper layers weren't as thick as the one you found.  As with everything maybe moderation regarding thickness is important. 

Oh and this garden grew spectacular awesome veggies - glorious veggies.  The only thing I can see I'm doing different than my folks is I'm not using the newspaper grassclippings mix - my veggies have a long way to go.

Thanks Pignut.  You saved me a great deal of typing.  Corn Starch glue stinks because it begins to ferment from being stored in a humid environment.  Sodium Hydroxide?  Oh my.... almost all hard milled soap is made from Sodium Hydroxide.  Food grade Sodium Hydroxide as well as food grade Sulfuric Acid are used as.... you guessed it.... processing and preserving food.  Have you ever eaten a Black Olive?  Do you know how Olives are processed?  They are soaked in Sodium Hydroxide and when compressed air is added to the brine the Olives turn black. 
This article is full of "chemical scare" tactics that seem a bit excessive.  The word Chemicals is used as if it was what we as humans must avoid all of them.  The biggest problems with the paper industry is not the end product but the manufacturing process that dumps unconscionable quantities of pollutants into the environment.  The end product is not as "toxic" as Mr. Firk suggests.  His defiant "Prove me wrong" statement which appears multiple times throughout his article begs for debate but it isn't going to happen here.  I worked in the printing industry for a long enough period to know that soy based inks have been the standard for so long that toxic inks just aren't a problem.  There used to be a problem with excessive amounts of lead used in the really colorful shiny printing but even the lead was removed about 15 years ago.  If you drive by a Biomass Plant that converts cellulose into alcohol for distillation you will not believe the stench.  Fermenting those types of cellulose are difficult and the process produces the most unbelievably vile odor imaginable.  I applaud Pignut for very well presented retorts to the arguments presented by Mr. Firk.  Some paper may be toxic but not much of it.  I would suggest that finding any concentrated toxic chemicals in any of my compost is not possible and I have composted tons of cardboard..... literally tons.  The point is that natural environmental processes produce some chemicals that are toxic when they are concentrated.  Ammonia is a natural by product of decomposition.  Using Mr. Firk's logic all compost is toxic.  Huh?  Let's use some logic here.  Beating on the paper industry for polluting is commendable but it is a huge stretch to suggest that the paper products produced are poisoning the environment when composted.  That is just not a valid conclusion even using his "evidence."  I suppose I have left myself open to the argument of not supplying a bibliography to back up my statements but so be it.  I am just responding to looks like a valid argument, on the surface, against using paper as compost but if you "dig a little deeper" into the pile you will discover that the paper itself is not where the toxic materials are found.  The environmental problems are where the paper is produced.
Peace.

Perhaps we should get some soil tested in a garden started with a cardboard/newspaper mulch. Knowing what goes into making the products doesn't tell you if those things are in the finished product or whether or not they biodegrade when composted or if they add any appreciable toxicity - particularly if it is used only to start a garden. Otherwise, it's just conjecture.

Has anyone actually done a soil or compost test?

BenjaminBurchall wrote:
Perhaps we should get some soil tested in a garden started with a cardboard/newspaper mulch. Knowing what goes into making the products doesn't tell you if those things are in the finished product or whether or not they biodegrade when composted or if they add any appreciable toxicity - particularly if it is used only to start a garden. Otherwise, it's just conjecture.

Has anyone actually done a soil or compost test?

Great idea Benjamin.  I have about a ton of screened finished compost.  It seems to pile up faster than I can use it because I have such a tiny piece of earth to feed.  It is about 25-30% paper from multiple sources but over half of the paper product came from corrugated paper (cardboard).  I should take some to the county extension agent and have it tested. 

Dave,

Do it! Do it! Do it! It only costs $8 a bag for testing here and you get the results within a week. Not expensive or complicated at all. Of course, we'd need to know what else you put in there. So, contamination from other sources could be eliminated.

This is another reason I'm desperately trying to get a garden again. I could try and do some controlled experiments. I moved last year and haven't had one for way too long now. I'm not living in a situation where I could even have a container garden.

BenjaminBurchall wrote:
Perhaps we should get some soil tested in a garden started with a cardboard/newspaper mulch. Knowing what goes into making the products doesn't tell you if those things are in the finished product or whether or not they biodegrade when composted or if they add any appreciable toxicity - particularly if it is used only to start a garden. Otherwise, it's just conjecture.

Has anyone actually done a soil or compost test?

Just to give you heads up, it may require sending to a special soil lab for testing for hazardous chemicals or elements in the soil/compost, so may not be as cheap...

so may not be as cheap...

Hopefully not. My agro-consultancy firm just had samples submitted for a client. It only cost $8 a sample. Hopefully, the testing fees are comparable elsewhere. I think people think it's more expensive to do than it really is. Some municipalities will do soil and water testing for residents for free - even though most people don't know that.

The only other additions to my compost is from my kitchen and yard trimmings.  I do not use anything other than compost in my yard and only eat organic vegetables. There are no other possible sources for toxic chemical contamination. 

IMO Andy Firk is full of that stuff I shovel up from my cow pasture to put in my compost pile. I have been using unwaxed corrugated cardboard, from produce boxes, to lay under my raised beds for years now. As another commenter on this thread has mentioned, the earthworms thrive on it and in it, and they reduce it to worm castings after it has smothered the quackgrass.

I use the waxed corrugated cardboard in the wood stove in place of kindling. I don't need much of it to get a good blaze going. I also use the waxed stuff for fire starter in my barbecue, and on top of my TLUD biochar barrels.

The unwaxed cardboard, cut and rolled up to fit inside two #10 cans, which fit together in the wood stove, makes a great feedstock for biochar also.

Firk's scaremongering is a classic example of making the perfect the enemy of the good. Obviously not all cardboard is created equal. Obviously gardeners and farmers need to use some common sense. I avoid using waxed, painted, or plasticized cardboard in my garden, and stick to the plain brown stuff that produce has been packed in. Air, water, bacteria, fungi, and earthworms take care of the rest. And yes, I call it organic.