The term "mulch" brings to mind organic material spread atop an area to reduce moisture loss and weed growth. However, mulch can be done with nonorganic stuff too: plastic covers for example, or stones. "Lithic mulch" (see link) is a technique for dryland agriculture that does not contribute to soil fertility or deplete it (see discussion in linked "enrich fields with recycled paper" idea). On pondering how lithic mulch might be done in practice, it seems to me a nuisance to remove the top dressing of stones for each new crop and then replace it. If the stones are left in place, one must work around them. Eventually they will make their way into the soil and new must be applied.

This proposal is for the use of aluminum cans as lithic mulch. Empty cans will be strung end to end along a string which in turn is linked laterally to other similar can lines into a net. This net rests on the ground. Crops grow between the cans. The cans have many properties that lend themselves to this use.

1: They are available in quantity, light and extremely durable.

2: Their form lends itself to being strung in a line.

3: They are reflective and become more so with wear.

4: The round top facilitates runoff of moisture.

5: Most important: they can easily be removed in a unit from the field to facilitate harvest or plowing, then replaced.
-- bungston, Aug 25 2010

Lithic Mulch overview http://www.bahs.org.uk/44n2a4.pdf
[bungston, Aug 25 2010]

Enrich fields with recycled paper Enrich_20fields_20with_20recycled_20paper
This discussion (WcW in particular; thank you) helped me understand C:N rations. [bungston, Aug 25 2010]

Volume calculation http://www.wolframa...75%22))*19.936cu+in
[Alx_xlA, Aug 26 2010]

Once the can-net has been removed from a field, though, won't storage be a problem?

If one takes enough 355 ml cans to cover a quarter section, they would take up 22 Olympic-sized swimming pools, or 55200 cubic metres.

[Link]

(The first value is the area of a quarter section, the second is the area of a the cross-section of a can, and the third is the volume of a can)
-- Alx_xlA, Aug 26 2010


The cans will tend to corrode, and add aluminium to the soil and make a mess. This may not be a huge problem, as many soils naturally contain aluminium, but it deserves a mention.
-- spidermother, Aug 26 2010


The nets could be removed with large dirigibles and stored in the air. Alternatively they could be placed atop an adajcent field.

Not sure about corrosion of aluminum. Cans in fields seem pretty durable.
-- bungston, Aug 26 2010


Aluminum oxidizes very quickly, but unlike steel does so smoothly, without flaking off. The oxide thus forms a strong protective layer unless it is abraded off, preventing material loss.
-- MechE, Aug 26 2010


I don't know what the scrap value of aluminium cans is, but the cost of aluminium (new) is something like £0.70 per pound. Suppose aluminium cans (once collected into respectable numbers) are worth half this, or £0.35 per pound.

A single (empty) weighs maybe 20 grams, putting its value in aluminium at something like 2p.

I figure a single can, lying on its side, covers about 6x12cm, meaning that you need about 140 of them to cover a square metre.

Thus, the scrap value of your aluminium mulch will be something like £3 per square metre.

There's no way this is going to be remotely economical.

Therefore, I proffer you this fish.
-- MaxwellBuchanan, Aug 28 2010


Aluminum cans are worth fifty cents the pound down the street from me. In British terms that's about £0.25, I think, so close enow.

A lot of pure-food fanciers think that aluminum causes Alzhiemer's brain rot, so good luck getting them to eat anything mulched with aluminum.

Cans do corrode, by the way. I have pulled flaking cans out of rivers, and crumbling cans out of an abandoned house.

If you want to do something vaguely like this, recycle the cans, roll the metal out into corrugated sheets, pierce the sheets for rain and plants and stakes, then stick a vacuum lifter on your tractor. Sheets would be much easier to handle, stack nicely, and use less aluminum per acre.

I am tempted to bun this idea as a searing condemnation of consumerist culture--the disposable containers for our tooth-rotting, fattening, and mind-numbing beverages would be valuable to agriculture if we could just be arsed to put them in a different bin--but I don't think the things would be valuable to agriculture. [ ]
-- baconbrain, Aug 28 2010


Aluminum can/does corrode, just not quickly. The ones from the river were probably beaten against rocks, breaking the oxide layer. Not sure what happened to the others, but probably something similar.
-- MechE, Aug 30 2010


Maybe this should be done with plastic drink bottles, then. All the same principles apply except cheaper, lighter, less Alzheimery. Where is Django? Putting Cristoesque expanses of plastic on third-world dryland fields seems django to me.
-- bungston, Aug 30 2010



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