Grain crops are the backbone of the human diet because they are easy to grow. You till the field. You plant the crop. You wait a bit. You harvest the crop. Maybe do some threshing. And you are done.
Not so with rice. Rice takes work. A lot of work. Paddy rice is painfully water-intensive – so much so that its “fields” essentially are huge shallow clay pots. It also is extremely delicate: it must be planted in stalk rather than seed form. Since every single rice plant in essence is a transplant, it must be planted into mud to prevent transplant shock. Since a tractor will sink in mud, this means it has to be planted by hand. Then the field has to be flooded and dried, and flooded and dried again. Fertilizers must be regularly applied, and considering all the moisture, that also typically is done by hand. Once harvested, rice requires two rounds of threshing, with careful attention to saving live rice stalks for the next planting (again, by hand). The fields then must be cleared, their clay linings repaired and re-re-re-flooded for the next season.
In all, paddy rice is by far the most labor-intensive of the world’s grains. In order to keep prices under control, the work has to be completed by the cheapest of cheap labor. The world’s dominant rice-producing regions do not have a reputation for being rich, egalitarian places.
The large (cheap) labor pool that rice demands has many additional impacts, but one is particularly notable – it requires dense population footprints to generate the rice in the first place. In rice cultures, every square foot of usable land is converted to a clay-lined paddy. In difficult terrains such as China’s Guangxi Province, that means converting the mountains themselves into some of the world’s most capital- and labor-intensive farming practices in a bid to keep the cities fed.
For more on how China’s geography makes for a complicated past – and problematic future – see Chapter 14 of The Accidental Superpower.