Comment by o11c

Wikipedia has some examples in [1], though it's prose, annoyingly. The earliest dates it has are 6000 BC for Mesopotamia, 4500 BC in India.

But what I find more interesting is rice in China, for which irrigating is radically different both in form and in economic impact. Rice scales largely by manpower rather than land as most crops do. The oldest date Wikipedia gives is 4330 BC (seems too precise) in [2], though I expect paddies are less likely to be preserved in the first place than other kinds of irrigation.

[1]: https://en.wikipedia.org/wiki/Irrigation#Ancient_history

[2]: https://en.wikipedia.org/wiki/Paddy_field