Using salt water to grow crops.

No, not really, but these dudes in England came up with a clever system of porous pipes that allow water to leak out, but nothing else so it doesn't matter how dirty the input water is. You can read more here. I didn't know you could block the salt crystals because they're pretty small. I know there are fine filters, but those are expensive.

The article doesn't go into much detail, but there is a link to the company making these pipes. Ah, the company doesn't disclose IP so I guess we'll just have to imagine how it could work. It does because they were able to grow plants even inputting salt water into the pipes. The other good news is that water is only pulled from the pipes if the soil is dry so there is no over-watering.

It'll be interesting to see if this technology can undo the desertification in the Middle East.

[Obligatory Idiocracy joke here...it's got electrolytes. It's what plants crave...]