> Turned out they completely ignored that the traditional method produced not just rice but a long list of other stuff too. I'm not sure if this is the source

> Turned out they completely ignored that the traditional method produced not just rice but a long list of other stuff too. I'm not sure if this is the source you had in mind, but Seeing Like a State offers a similar story from Tanzania. Colonists attempted to move local farmers from polycultures to "more efficient" monoculture farming, and the results were absolutely disastrous. Polycultures helped prevent erosion and soil depletion, tall sun plants covered short shade plants, and mixed crop types spread both farm labor and crop production across more of the year. The counterargument, such as it is, is that we've committed so vastly to intensive, fertilized monocultures that we can no longer produce comparable amounts of anything using traditional methods. Which I think is probably true, but as destroy the soil and aquifers of the Midwest it looks like the modern technique isn't particularly workable either.