[tackem (OP)]

Could we use the invasive nature of Japanese knotweed to turn areas of desert into useful arable land?

[alancalverd]

Brilliant. Then all you need is the topsoil that blew away thousands of years ago, and the rain that hasn't fallen since the trees were felled.
The stuff infests Britain because it's cool, wet and fertile - like Japan.

[charles1948]

Brilliant. Then all you need is the topsoil that blew away thousands of years ago, and the rain that hasn't fallen since the trees were felled.
The stuff infests Britain because it's cool, wet and fertile - like Japan.

Couldn't we find a use for the knotweed - such as feeding livestock on our farms, or making paper and cardboard  from it?

[Bored chemist]

Couldn't we find a use for the knotweed - such as feeding livestock on our farms, or making paper and cardboard  from it?

If it was good for something, it would be a crop rather than a weed.

[charles1948]

Couldn't we find a use for the knotweed - such as feeding livestock on our farms, or making paper and cardboard  from it?

If it was good for something, it would be a crop rather than a weed.

Isn't a "weed" just a "crop" growing in the wrong place?  Anything growing can be put to some use, surely.

[chris]

If it was good for something, it would be a crop rather than a weed.

Brilliant answer!

[tackem (OP)]

A weed could become a crop in the right place and regenerate dead ground.

[charles1948]

A weed could become a crop in the right place and regenerate dead ground.

That's right.  This distinction between "weed" and "crop" is a human-based linguistic artefact. It has no scientific validity.  Its only justification is a practical one - to enable humans to succinctly differentiate between plants which we find useful - ie "crops"  -  and those which we don't find useful  - ie "weeds"

Isn't there a similar situation with fungi. These organisms have been linguistically divided by humans into two categories: "mushrooms" and "toadstools".  Based entirely on whether they're safe for us to eat (mushrooms), or not safe to eat (toadstools).

Although this distinction has a practical value, from a strictly human viewpoint, it is misleading scientifically.
As is our human distinction between "crops" and weeds"?

[Bored chemist]

to enable humans to succinctly differentiate between plants which we find useful - ie "crops"  -  and those which we don't find useful  - ie "weeds"

That's what I said.

If it was good for something, it would be a crop rather than a weed.

[charles1948]

to enable humans to succinctly differentiate between plants which we find useful - ie "crops"  -  and those which we don't find useful  - ie "weeds"

That's what I said.

If it was good for something, it would be a crop rather than a weed.

So is the difference between a "crop" and "weed"  this:

A "crop" is a plant growing in the right place.  A "weed" is a plant growing in the wrong place.

[Petrochemicals]

https://en.m.wikipedia.org/wiki/African_humid_period

You would need to alter the Earth's orbit.  Some deserts of earth are bands across the entire planet due to the jet streams and weather systems.

https://www.bbc.co.uk/bitesize/guides/znxsgk7/revision/1

Other deserts are due to being far from the ocean, in a rain shadow and/or are at the mercy of prevailing winds. They need more water essentially.

[Hayseed]

I have never heard of Japanese Knotweed. The first google result shows it kinda looks like bamboo.  And shows it's edible and how to prepare tea and syrup from it.  Might possibly be used for pig/goat fodder.

Too bad we can't find a use for the kudzu we have.

[Bored chemist]

Too bad we can't find a use for the kudzu we have.

Well, according to Wiki, it's edible...