Note the word “farm”, in worm farm. If you start a worm “farm” you will need to take care of it! Much as you need to feed your pet dog, budgie or guinea pig. You can not leave your wormies and run away for weeks at a time (although they might survive 2 weeks at best which is more than can be said of our furry friends).
As we noted in the compost section you should be using tiger worms (Eisenia foetida) and not pasture worms. What you will need to farm worms is shelter + food.
Shelter - Worms don't like wet “feet”. We know this because we see them fleeing water logged lawns in a deluge only to drown on the great lake that is your footpath or get squished on the same. So first off we need a container with drainage. There are lots of constructions on various scales using just about anything. You may also want access to the worm wee (worm “tea”).
Bath system – old bath + frame with mesh (to raise from bath-floor for drainage) + bed + worms + food + blanky + roof. Raise at one end to drain. Run-off can run out plughole into container for collection. Using the bath system you feed starting from end and slowly move along a bit each day.
(Three) tyre system – High-rise worm tower = 3 x tyres stuffed with damp newspaper sitting on board. Board raised at one edge so run off can be collected in container (possibly set in depression or hole in front of worm tower). Don't leave your worm tower in a sunny spot or you will cook your worms and that is not quite the process we are going for. Also they may hibernate when it gets frosty over winter.
Pile-up – Yep. Just as it sounds. A pile of scraps and worms covered over with something like thick under-felt. Almost free range wormies.
Worm-beds – Worms don't need to doss down in a luxury posturepedic but they do like a nice bed and they do like their bedding to be changed at regular intervals. A lovely new bed for worms can be made out of (moistened) shredded paper + some corrugated cardboard + straw + compost. After harvesting, remove the worm poop (vermicast) and put in a new bed for the next batch of worms to live in. By the way what is a group of worms called? A herd?
Worm- roof –First feed your worms then cover with carpet and then a lid. Keep your worms moist, dark and cool. And keep out excess moisture and air.
Din-dins – don't feed your worms too much! 500g worms will eat 500g of scraps. If you add too much more it may putrify. That means get stinky. And usually the stinky comes with slimy and sometimes blacky. Add any excess foodscraps to a bokashi or compost heap. Your worm has a mostly vegetarian inclination and likes a bit of dung on the side.
So they like vegie peelings, fruit skins and cores, coffee grounds and tea bags, green weeds (but not the seed heads) and cow or horse manure . Treats – corn (cob and meal). Unlike small boys worms do like their brussel sprouts but there are some things they find Yucky. Like small boys they don't like raw onions but they will also turn up their noses at meat and fish, cheese, baked beans, rice or pasta, too much white bread, or cooked spuds. cooked potatoes, grass or cat and dog poo.
Visitors - always cover your worm-farm to discourage fruit fly. If you find slaters taking up residence then your environment has become too dry.
Vermicast – dilute to “tea”. Tea spray can help fight fungus on leaves as well as help increase soil vitality.
Wednesday, August 26, 2009
Bokashi
Ahhh! The choices. What should I use? Compost? Worm Farm? Bokashi? But first up, just what is Bokashi?
Someone somewhere over the seas and far away (a person with a big brainy-box) worked out that a certain mixture of super-microbes was good for super fast fermentation processes and the product of this process would in turn be a good thing for soil and that best of all you could use this process indoors – you can start saving the planet right under your very own bench top! Every country has its own special cocktail or group of these special super-microbes.
Using these it will take 3 weeks to ferment (not compost) your food to a point where it can be usefully disposed of in your garden. The process is anaerobic (occurs in the absence of oxygen), cold (produces no heat), makes no methane (smell) and is easily contained. You need two sets of the bokashi buckets (one starting and one maturing)
The mixture (Boakshi “Zing”) you buy is a mixture of dry crop material, sawdust and EM microbes. This “zing” costs about $6-$8 a bag. It is brilliant stuff.
The bokashi system uses a plastic container in two parts. You put the food scraps in the top part or bucket and then add a fine layer of zing. Some people like to collect their food scraps in an icecream container and add them to the bokashi once a day. Add 1T zing to 1 litre or a 5cm layer of food scraps. When the bucket is full leave 7-10 days to make sure the top layer is fermented. When ready dig a trench in soil, gently mix contents of the TOP bucket and cover with soil. After another 7-10 days you can plant in trench. It is great for sandy soils.
Bokashi is a really useful addition to soils around growing trees. Dig in along the drip lines of trees so as not to disturb the roots of the trees. You can also “store” the bokashi under ground for a month and then you can use it as mulch. A word to the wise for composters. Bokashi does NOT look like compost. It looks like pickles!
You can use bokashi in your compost. Dig a hole in your compost, tip in the bokashi and cover over again. But note it is quite acidic. Put in it a corner away from your worms.
The contents of your bottom bucket will be a liquid. It may be a golden colour with white spotty fungus spots on top. It will usually have no smell. You can use this “tea” as fertiliser or soil innoculant. Dilute to a ratio of 1T to 5 litres of water = fertiliser “tea”.
Bokashi can also be used as a poo composting system. It's an especially good idea for smelly cat and dog poo. First dig a hole and line the sides of the hole with an old bucket that has no bottom. Pick up your dog poo as you are inclined to do (before you step in it) and instead of hermetically sealing it in plastic and sending it off to the landfill chuck it in your outdoor composting doggy-doo toilet hole. Layer with zing! Keep it covered with a slab of wood or bucket cover. Then when it's time, remove your bucket, fill in the rest of the hole with dirt and leave.
Someone somewhere over the seas and far away (a person with a big brainy-box) worked out that a certain mixture of super-microbes was good for super fast fermentation processes and the product of this process would in turn be a good thing for soil and that best of all you could use this process indoors – you can start saving the planet right under your very own bench top! Every country has its own special cocktail or group of these special super-microbes.
Using these it will take 3 weeks to ferment (not compost) your food to a point where it can be usefully disposed of in your garden. The process is anaerobic (occurs in the absence of oxygen), cold (produces no heat), makes no methane (smell) and is easily contained. You need two sets of the bokashi buckets (one starting and one maturing)
The mixture (Boakshi “Zing”) you buy is a mixture of dry crop material, sawdust and EM microbes. This “zing” costs about $6-$8 a bag. It is brilliant stuff.
The bokashi system uses a plastic container in two parts. You put the food scraps in the top part or bucket and then add a fine layer of zing. Some people like to collect their food scraps in an icecream container and add them to the bokashi once a day. Add 1T zing to 1 litre or a 5cm layer of food scraps. When the bucket is full leave 7-10 days to make sure the top layer is fermented. When ready dig a trench in soil, gently mix contents of the TOP bucket and cover with soil. After another 7-10 days you can plant in trench. It is great for sandy soils.
Bokashi is a really useful addition to soils around growing trees. Dig in along the drip lines of trees so as not to disturb the roots of the trees. You can also “store” the bokashi under ground for a month and then you can use it as mulch. A word to the wise for composters. Bokashi does NOT look like compost. It looks like pickles!
You can use bokashi in your compost. Dig a hole in your compost, tip in the bokashi and cover over again. But note it is quite acidic. Put in it a corner away from your worms.
The contents of your bottom bucket will be a liquid. It may be a golden colour with white spotty fungus spots on top. It will usually have no smell. You can use this “tea” as fertiliser or soil innoculant. Dilute to a ratio of 1T to 5 litres of water = fertiliser “tea”.
Bokashi can also be used as a poo composting system. It's an especially good idea for smelly cat and dog poo. First dig a hole and line the sides of the hole with an old bucket that has no bottom. Pick up your dog poo as you are inclined to do (before you step in it) and instead of hermetically sealing it in plastic and sending it off to the landfill chuck it in your outdoor composting doggy-doo toilet hole. Layer with zing! Keep it covered with a slab of wood or bucket cover. Then when it's time, remove your bucket, fill in the rest of the hole with dirt and leave.
Inhibited, Retarded and Excitable Microbes.
Inhibitors - pH – You can alter the pH during the composting process but if you are hot heaping it is a good idea to leave things like lime out of your heap as the microbes don't like it. Your compost will work faster in the 7-8 pH range. So it will end up slightly acidic. Then if you need to, add some lime last thing before you dig it into the soil. Tiny white worms in your compost may indicate that you need to add lime or your compost is too moist.
Also take note that some plants in your garden are allopathic. This means they contain chemicals to ward off other (competing) plants. These are not therefore ideal compost fodder and it is a good idea to throw your rhododendron, gum and walnut bits elsewhere in another corner of your garden. Likewise with diseased plants. Leave these out of your compost. Plants (weeds) such as dock, dandelion couch can be left in a bucket of water to rot until harmless (ie won't grow again). Lupins and gorse are okay if they are green and flowering. They are not so flash if they are seeding, unless that is the new look you are going for in your flower garden.
Activators. - An activator is something that will excite your microbes and as they do all the work they should have a little happiness now and then. Comfrey has a big tap root so has drawn up lots of deep nutrients so it is a good activator for your compost heap. Blood (blood and bone) is also used as an activator. Seaweed, including kelp having grown fast is a source of plant frowth hormone and also mucilage which is a useful frost retardant.
Air - Size matters – make sure if you are cutting or shredding that you don't make your materials too fine as then your compost will get too dense and the microbes can't breathe, then your compost heap will become anaerobic (stinky, black and slimey).
Accelerators – You can add something like EM Accelerator (EM=effective micro-organisms) to your heap mixed in with molasses and water. EM is made by Nature Farm. It's a bit like adding yeast to your bread dough.
Worms – Use tiger worms (not pasture worms)
Also take note that some plants in your garden are allopathic. This means they contain chemicals to ward off other (competing) plants. These are not therefore ideal compost fodder and it is a good idea to throw your rhododendron, gum and walnut bits elsewhere in another corner of your garden. Likewise with diseased plants. Leave these out of your compost. Plants (weeds) such as dock, dandelion couch can be left in a bucket of water to rot until harmless (ie won't grow again). Lupins and gorse are okay if they are green and flowering. They are not so flash if they are seeding, unless that is the new look you are going for in your flower garden.
Activators. - An activator is something that will excite your microbes and as they do all the work they should have a little happiness now and then. Comfrey has a big tap root so has drawn up lots of deep nutrients so it is a good activator for your compost heap. Blood (blood and bone) is also used as an activator. Seaweed, including kelp having grown fast is a source of plant frowth hormone and also mucilage which is a useful frost retardant.
Air - Size matters – make sure if you are cutting or shredding that you don't make your materials too fine as then your compost will get too dense and the microbes can't breathe, then your compost heap will become anaerobic (stinky, black and slimey).
Accelerators – You can add something like EM Accelerator (EM=effective micro-organisms) to your heap mixed in with molasses and water. EM is made by Nature Farm. It's a bit like adding yeast to your bread dough.
Worms – Use tiger worms (not pasture worms)
When your Carbon : Nitrogen : Potassium ratio is all to pot (in yer rot)
So how had the Olde Cold Heap been working out for me? Turns out I had some major flaws in my chuck and leave approach to composting. The major ones were leaching and carbon content.
My heaps are not covered and the rain runs right through them. The leachate running off will contain many goodies my garden would benefit from more than my path. Fancy that. The compost I use now, when it is ready, is brilliant for growing leafy vegetables – not so brilliant for fruiting like, tomatoes or beans (great humungous leafs though!). After a couple of years of this I realised I needed help.
First up, apparently, I needed to improve the balance of carbon to nitrogen in my mix.
In general Nitrogen is your green (rich and wet) plant material, food scraps, fresh prunings and hedge clippings, leaves, annual weeds and animal manure. Take note with animal manure such as horse, cow or zoo-poo that the animals have not been recently drenched as this will knock your worms about. Your pony-on-grass-poo is good but use your race-horse poo with caution (that is if you want racing worms). Also make sure you have had your tetanus booster especially if you are using horse poo. Tetanus bacteria can be found in any soil where there have been horses (pooping) any time in the past 100 years. So except for a few acres of conservation estate that you probably wouldn't be composting in anyway, that's pretty much everywhere in New Zealand.
Your carbon, in general, is your dry and brown material: pea straw, hay (from the stack bottom, alphapha lucerne and any dried out (formerly) green plant stuff. You can also include cardboard, chipped wood (thin layer) or saw dust (fine layer), paper (not coloured), office paper (quite acidic so not too much), charcoal (such as bio-char – see terra preta soils). Note ash can be a useful addition to your compost as it is usually high in potassium. (Pot. Ash) But note don't count it in your carbon ratio as the carbon has burnt off! (makes sense when you think about it)
Correct ratios. You will sometimes see the ratio written as ⅔ Carbon to ⅓ Nitrogen or C: N 30:10. What this may translate to in your compost heap is roughly (one hand height) 5-10cm layer of Nitrogen to (three hand heights) 8-15 cm layer of Carbon.
Get it right - Too much nitrogen will turn your heap into a smelly slime pit, which Fungus the Bogeyman might like, but unless you are Mrs Fungus the Bogeyman, you probably will not. Too much carbon (too brown and dry) will attract mice. If your heap dries out and gets too dry also be aware of legionella spores which can be deadly if inhaled.
My heaps are not covered and the rain runs right through them. The leachate running off will contain many goodies my garden would benefit from more than my path. Fancy that. The compost I use now, when it is ready, is brilliant for growing leafy vegetables – not so brilliant for fruiting like, tomatoes or beans (great humungous leafs though!). After a couple of years of this I realised I needed help.
First up, apparently, I needed to improve the balance of carbon to nitrogen in my mix.
In general Nitrogen is your green (rich and wet) plant material, food scraps, fresh prunings and hedge clippings, leaves, annual weeds and animal manure. Take note with animal manure such as horse, cow or zoo-poo that the animals have not been recently drenched as this will knock your worms about. Your pony-on-grass-poo is good but use your race-horse poo with caution (that is if you want racing worms). Also make sure you have had your tetanus booster especially if you are using horse poo. Tetanus bacteria can be found in any soil where there have been horses (pooping) any time in the past 100 years. So except for a few acres of conservation estate that you probably wouldn't be composting in anyway, that's pretty much everywhere in New Zealand.
Your carbon, in general, is your dry and brown material: pea straw, hay (from the stack bottom, alphapha lucerne and any dried out (formerly) green plant stuff. You can also include cardboard, chipped wood (thin layer) or saw dust (fine layer), paper (not coloured), office paper (quite acidic so not too much), charcoal (such as bio-char – see terra preta soils). Note ash can be a useful addition to your compost as it is usually high in potassium. (Pot. Ash) But note don't count it in your carbon ratio as the carbon has burnt off! (makes sense when you think about it)
Correct ratios. You will sometimes see the ratio written as ⅔ Carbon to ⅓ Nitrogen or C: N 30:10. What this may translate to in your compost heap is roughly (one hand height) 5-10cm layer of Nitrogen to (three hand heights) 8-15 cm layer of Carbon.
Get it right - Too much nitrogen will turn your heap into a smelly slime pit, which Fungus the Bogeyman might like, but unless you are Mrs Fungus the Bogeyman, you probably will not. Too much carbon (too brown and dry) will attract mice. If your heap dries out and gets too dry also be aware of legionella spores which can be deadly if inhaled.
Cold heaps and Hot heaps :Types and volume
Cold heaps are built or established over a lonnngggg period and classically contain mainly food scraps and a few grass clippings. They mostly just sit about slowly decaying until you go bandicooting round at the base to see how its all going. Cold heaps can be any size and vary from a pile of scraps growing in the corner of your garden to those contained in structures called compost bins.
Bins can be made from wood (preferably not tanalised) or you can buy plastic fabricated ones in a variety of shapes, sizes and colours from most garden centres.
The idea behind the black plastic bins is that the black will absorb the sun's heat and heat up the composting mixture and therefore speed up the process. They are also handy because you can put them right next to where you want to use them. (Some people also like them because they are tidy.) Some people also use black plastic bags for leaf mulch or as a portable composting system as well. Mostly not the people who like to have a tidy compost bin.
Wooden compost bins. Some people will have one. Many will have more. The three bin system enables one compost to be almost ready/mature, one maturing, and one that is being added to.
Hot heaps are heaps that are built in one go and they do the composting job a whole lot faster. The ideal minimum size in a colder climate is 1.5m3 . You may get away with 1.2m3 in a warmer climate. In a smaller heap you will also need extra insulation such as carpet, sacks or hay to cover and/or wrap your compost heap.
A hot heap requires a little more attention than a cold heap. Unlike the cold heap, for the first week to ten days your hot heap likes you to remember that it is there. It needs turning. The magic formula is heat + mixing. The temperatures we are aiming for in a hot heap are 65-68 °C. If it gets too hot your compost will turn to ash. You may have seen this inside a pile-up of grass clippings that has been sitting around for a week or so.
Turning – After 3-4 days the heap may spike at 68°C (especially at its center). We turn and leave for another 6-7 days. It may reach 65 °C. Then we turn again. The temperature may reach 58°C. Then we leave it to mature til full term which may take 3-5 months depending on ambient outdoor temperature.
When you are turning you can adjust things like dryness by adding more water or nitrogen if need be.
Bins can be made from wood (preferably not tanalised) or you can buy plastic fabricated ones in a variety of shapes, sizes and colours from most garden centres.
The idea behind the black plastic bins is that the black will absorb the sun's heat and heat up the composting mixture and therefore speed up the process. They are also handy because you can put them right next to where you want to use them. (Some people also like them because they are tidy.) Some people also use black plastic bags for leaf mulch or as a portable composting system as well. Mostly not the people who like to have a tidy compost bin.
Wooden compost bins. Some people will have one. Many will have more. The three bin system enables one compost to be almost ready/mature, one maturing, and one that is being added to.
Hot heaps are heaps that are built in one go and they do the composting job a whole lot faster. The ideal minimum size in a colder climate is 1.5m3 . You may get away with 1.2m3 in a warmer climate. In a smaller heap you will also need extra insulation such as carpet, sacks or hay to cover and/or wrap your compost heap.
A hot heap requires a little more attention than a cold heap. Unlike the cold heap, for the first week to ten days your hot heap likes you to remember that it is there. It needs turning. The magic formula is heat + mixing. The temperatures we are aiming for in a hot heap are 65-68 °C. If it gets too hot your compost will turn to ash. You may have seen this inside a pile-up of grass clippings that has been sitting around for a week or so.
Turning – After 3-4 days the heap may spike at 68°C (especially at its center). We turn and leave for another 6-7 days. It may reach 65 °C. Then we turn again. The temperature may reach 58°C. Then we leave it to mature til full term which may take 3-5 months depending on ambient outdoor temperature.
When you are turning you can adjust things like dryness by adding more water or nitrogen if need be.
Tuesday, May 26, 2009
Library Resources
The DCC Library has a great selection of books on composting. Everything from the Compost Standards of NZ (including soil conditioners and mulches) to Trev's recipes for compost success and an interesting book on compost critters. There is also a good video demonstration prepared by the DCC. See also Organic NZ magazine (the rebranded Soil and Health).
Further the old Soil and Health issues are being scanned and uploaded so the complete back catalogue from 1946 will soon be available on line. To access these you need to sign in with the Australian Library that is enabling this project.
Further the old Soil and Health issues are being scanned and uploaded so the complete back catalogue from 1946 will soon be available on line. To access these you need to sign in with the Australian Library that is enabling this project.
Monday, May 25, 2009
Building a hot heap half way up Mt Cargill on a rainy afternoon – a compost workshop
This weekend I got to stand in the bone chilling rain against a back drop of swirling mist and build a hot heap. Granted that sounds like an oxymoron but nine other hardly souls will bear witness to these facts. I was attending a composting workshop run by Michelle Ritchie.
Let me begin by proudly stating that like my father and grandfathers before me that I am a compostor. I use the traditional NZ three-bin system which in my grandfathers case meant having three humongous piles for composting – one you were adding fresh food and garden scraps to, one that was maturing and one that was ready to use. I grew up on a quarter acre paradise, ¾ less than Granddad's vegie kingdom. Dad had less room for having piles sitting around slowly decaying so he was a regular compost turner. This I discovered is one of the secrets to speeding up your compost.
At the workshop Michelle Ritchie gave us clues as to how we might improve the quality of our compost , as well as speed it up from a lackadaisical 12-18 months to 3-5 months for maturation. Just like in Shrek, it is all in the layers. You really do need the right mix of carbon and nitrogen to get the little microbes giving their all in a timely fashion in the making of your compost. Michelle gave us tips on what makes a good mix, some pointers on using accelerators and things to look out for (and sniff for) to see what might be missing. Then we got out in the aforementioned rain and built one. Glorious stuff.
Michelle gave an inspiring introduction to the Bokashi system and also did a session on worm farms. I finally get why you might want to run more than one system for dealing with your green and household food waste.
The land of the Giant Vegetables
This tale of rot and hume begins in a pilgrimage to a small isolated community in Northern Scotland. I'd read about it in a cookbook and was astonished not so much by the recipes but by photos of a group of gardeners and their
. . . . . . . . . . giant vegetables.
The secret to such gardening loadstone success apparently was they talked to the “divas” or nature spirits of the plants. I was intrigued and decided I'd go and check it out.
Sandwiched between a small fishing village and an RAF air base, the walk to Findhorn is a mighty long one if you are hitching. Not to mention the inquisition from the (friendly) air base personal who are your most likely source of a lift along the road. “What are you doing here?” “I'm going to Findhorn – to see the the giant vegetables”. A laugh, a look of paternalistic concern over my apparent mental state and I was saved the long walk. As we drove past their place, I noticed the RAF obviously weren't going to be show stoppers in the gardening shows that year. Beyond the erection of some large metal mesh fences to prop up some struggling grasses at the road side they appeared to have put little effort into supporting local vegetation. I suspected even the straggly grasses were about to get a regulation chop. And as we drove along the road I was surprised at just how much sand there was! Well (obviously the RAF gentleman was correct about my cognitive abilities) what had I expected? Findhorn is located on a sand spit which is miles long.
With another friendly laugh from my driver, I was deposited at the driveway entrance . Here I was at last. I was really going to meet the people who coaxed green life from nothing. I was greeted and welcomed by a youngish American chap (mild surprise – I obviously had some unconscious expectation of a Northern brogue) and asked to sign into a book in the temple (a temple in Scotland? Where was I ?). After travelling more than half way around the world on a whim (no – he hadn't heard of New Zealand, and politely listened to my explanation of the Dunedin connection), I could stand it no longer. “Can you take me to your gardens ?”, I asked politely,” I want to see the giant vegetables.” The young man looked at me, with the same apparent concern as the RAF gentleman, and said, “We don't go in for that 'kind of thing' anymore. Those people have gone to Eigg”. Well I was buggered if I was going to sit around staring at my navel doing transactional psychoanalysis all day. I left and walked back to the mainland.
It's a bloody sight harder to hitch to Eigg and in fact I ended up in Edinburgh in time for the Arts Festival and scored a spot in the Fringe Art Market, so it wasn't a completely wasted journey.
Eventually I did get to learn a few tricks about growing vegetables in sandy (soil) and I only had to travel a short way along the road from where I live to learn them.
To be continued
Sunday, May 17, 2009
raised beds from recycled materials - what are the possible leachates? A collaborative public wellbeing project.
Raised bed vegie gardening - recycled containment materials - what are the cons? and WHY?!
I have been looking at the use of recycled tractor tyres in gardens after someone mentioned that you couldn't use them for raised bed vegie gardening. Given the increased interest in backyard vegie gardening (sometimes with limited space) I thought there was good reason why one should know one way or the other.
To date every gardener I have spoken to has had a different opinion but no-one can tell me 'why' or 'why not'. Where can we find the definitive why/why not?
The information I found on the internet was inconclusive at best, some nineteenth-hand anecdotal and therefore sometimes confused/confusing. I am reeling from a morning of Chinese whispers on the subject.
So I couldn't help but think about bringing a spot of science into the equation and providing a definitive answer. We have several sustainability experts at the Otago Poly and a big pool of brainy boxes at the university who could help with the qualitative data side of things. We could go national and get a tab from John Key to use DSIR or whatever it is called these days. It would be a fabulous collaborative project for Poly, Uni, Council and Community, NZ! I can see the ODT headlines already "Save the vegies - save the world".
The main answers I am looking for are:
-how evil are used/recycled rubber tyres ? - there is agreement about what nasties go into tyre production, off-gassing of new tyres, toxic products of burning tyres, bio-contamination of "shredded" tyres with hugely increased surface area (as used in weed/playground mats) but what measurements are available of degradation products leaching into soil where they are used for home grown vegies?
ie WHAT does leach into the soil and is it absorbed into the food chain?
- so following on can they be used in vegie gardens or only for ornamental?
- can you use them for some vegies and not others? (root/leafy/fruiting)
- small or large - does size make a difference?
- radial or normal (tyres)?
- drainage? does moisture affect the oxidation/degradation of the rubber? does sufficient drainage assist in any way? (for those placing tyres on concrete bases)
- do different fertilizer regimes have any chemical affect on tyre stability?
- if excess zinc is leached into the soil - is it having a disastrous effect on vegetable growth
- assuming there is leaching and absorption would lining the inner cavity with 120 plastic polythene remedy this situation?
- what do the worms think about all this? A popular method for making worm farms is to use a stack of recycled tyres stuffed with newspaper from which the run off is collected and used as fertiliser - presumably this is "bad" also (if the tyres are degrading and bio-toxic leachate is being generated?)
As an aside - tanalised timbers are often used in raised bed construction. These are also manufactured using some very toxic chemicals. Does leaching occur when these materials are used? Given the recent scenario about inadequate drying of timbers and chemicals still being 'active' when used, do these timbers also raise a problem?
What wood is used in the 'pre-fab' compost bins for sale at Mitre 10 and other outlets. If it is tanalised why is it ok to use it for compost but we don't use tanalised sawdust for mulch? Is there a collollary here between potential toxicity due to increased surface area.
- what other recylced containers are people using for soil containment? Do these pose any risks? eg potting mix bags - what kind of plastic are they made of (these usually have phthalates in them too - are they stable in a polythene -type polymer plastic)
Final thought:
Perhaps it has been done already. If you know the answers to these WHAT and WHY questions I would appreciate if you could find the time to send me the references/links.
I have been looking at the use of recycled tractor tyres in gardens after someone mentioned that you couldn't use them for raised bed vegie gardening. Given the increased interest in backyard vegie gardening (sometimes with limited space) I thought there was good reason why one should know one way or the other.
To date every gardener I have spoken to has had a different opinion but no-one can tell me 'why' or 'why not'. Where can we find the definitive why/why not?
The information I found on the internet was inconclusive at best, some nineteenth-hand anecdotal and therefore sometimes confused/confusing. I am reeling from a morning of Chinese whispers on the subject.
So I couldn't help but think about bringing a spot of science into the equation and providing a definitive answer. We have several sustainability experts at the Otago Poly and a big pool of brainy boxes at the university who could help with the qualitative data side of things. We could go national and get a tab from John Key to use DSIR or whatever it is called these days. It would be a fabulous collaborative project for Poly, Uni, Council and Community, NZ! I can see the ODT headlines already "Save the vegies - save the world".
The main answers I am looking for are:
-how evil are used/recycled rubber tyres ? - there is agreement about what nasties go into tyre production, off-gassing of new tyres, toxic products of burning tyres, bio-contamination of "shredded" tyres with hugely increased surface area (as used in weed/playground mats) but what measurements are available of degradation products leaching into soil where they are used for home grown vegies?
ie WHAT does leach into the soil and is it absorbed into the food chain?
- so following on can they be used in vegie gardens or only for ornamental?
- can you use them for some vegies and not others? (root/leafy/fruiting)
- small or large - does size make a difference?
- radial or normal (tyres)?
- drainage? does moisture affect the oxidation/degradation of the rubber? does sufficient drainage assist in any way? (for those placing tyres on concrete bases)
- do different fertilizer regimes have any chemical affect on tyre stability?
- if excess zinc is leached into the soil - is it having a disastrous effect on vegetable growth
- assuming there is leaching and absorption would lining the inner cavity with 120 plastic polythene remedy this situation?
- what do the worms think about all this? A popular method for making worm farms is to use a stack of recycled tyres stuffed with newspaper from which the run off is collected and used as fertiliser - presumably this is "bad" also (if the tyres are degrading and bio-toxic leachate is being generated?)
As an aside - tanalised timbers are often used in raised bed construction. These are also manufactured using some very toxic chemicals. Does leaching occur when these materials are used? Given the recent scenario about inadequate drying of timbers and chemicals still being 'active' when used, do these timbers also raise a problem?
What wood is used in the 'pre-fab' compost bins for sale at Mitre 10 and other outlets. If it is tanalised why is it ok to use it for compost but we don't use tanalised sawdust for mulch? Is there a collollary here between potential toxicity due to increased surface area.
- what other recylced containers are people using for soil containment? Do these pose any risks? eg potting mix bags - what kind of plastic are they made of (these usually have phthalates in them too - are they stable in a polythene -type polymer plastic)
Final thought:
Perhaps it has been done already. If you know the answers to these WHAT and WHY questions I would appreciate if you could find the time to send me the references/links.
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Me myself and I commenting - I have received some comments via email to stay away from using tyres in any part of the garden as they leach cadmium and not to use treated timber as leachates include cadmium, copper and
arsenic.
And another comment that some leachate comes off the tyres into soil, water etc etc but it's so miniscule it is not really worth worrying about.
And again I am asking, show me the numbers, as there are groups of people I know of advocating the use of tyres, and this concerns me if there is a potential for harm and they will need more than "say so" to think otherwise.
- Pam McKinlay
Show me the numbers indeed! I read somewhere about treated timber.. I think it was research linked from the Wikipedia entry, that quantities were so small as to not be a concern. Different soils drew out different amounts, but nothing on a scale near threatening to humans.
That said, I wonder if the quantities are enough to have an impact on micro organisms which are essential to healthy soils?
Hi. I have heard a rumour and it is just that, though I do have a neighbour who could confirm it for me, that Mitre 10 staff have been told to advise customers to use untreated timber for garden boxing. We use untreated timber in our garden and believe it will last a good couple of years. It's cheaper and not a big deal to replace.
It's not just the danger to us and any micro organisms in our environment that we need to think about. We need to think about the fact that the nasty polluting goes on in the process of tanalising timber, someone has to be involved in this process and buying it creates more demand for it. As always, it's bigger than just us and our vege patch.
I too would like to see some research (has any actually been done?) on the topic. :)
Hi Pam,
You have got me thinking now. I have been successfully growing courgettes in tyres over the summer and eating them, the courgettes didn't seem to suffer, however I don't know about the longer term effects on my health or the health of the soil etc. I also have a very healthy worm farm in some old tyres, the worms are thriving and so are all the other micro-organisms involved. I would have thought that if there were toxic leachates from the tyres the worms would suffer and fail to thrive. This is not the case.
worm farms in tyres! excellent idea!
I have been receiving many replies via email and I am going to summarise a couple of new points here as I will lose track of them in my mailboxes (but I completely understand if people are nervous about commenting in the blog, keep those messages coming).
One respondent has raised the issue of the toxicity of decking timber in relation to infant health and safety ref: Plunket Safety Update magazine.
Another is recommending we legislate tyres under product stewardship priority products in a submission on the Waste Minimisation Act 2008.
http://www.mfe.govt.nz/issues/waste/consultation.html
Please add your voice in this submission.
But back to my original question. I now have a stack of reports to read through, none of which are completely relevant, but I shall see what I can extrapolate from them and then see if I can answer my questions which I think are still relevant and write them up in a new post.
As I am studying, working, caring and mothering this will be my g-job. "g" for Gaia hypothesis maybe, just as well it is winter as it won't need to be "g" for gardening! but at least one of my colleagues will be amazed that I have tended lovingly to my blog three times this week.
Hi Helen and Leigh,
I used to have a tyre worm farm but changed to straight out composting (I run a three bin system like my Dad used to) which the worms were happily rehoused in. But I agree the worms seemed to thrive in the tyres (in size and number).
I got the design for the worm farm from Alice McKenzie, "Wastebusters" in Ashburton - they run a great educational recycling outfit at the dump. They have a HUGE worm farm there and can give you fascinating details about what tiger worms will and can't eat.