The project appears to have created substantial economic benefits. The authors of the study write:
The cost-benefit ratio is in some ways over- and in other ways under-estimated. The benefits are over-estimated in the sense that it does not appear it takes into consideration the fact that greater grain production will dampen prices (it is also unclear how the benefits and costs are discounted or not over time). The benefits are under-estimated because they do not include any of the environmental improvements.
It is useful to contrast these findings with the rather large research on the value of agricultural R&D and extension investments in the U.S. Jin and Huffman calculated the rate of return on spending on agricultural extension in the U.S. at 100%. More broadly, Julian Alston gave the fellow's address at this this year's AAEA meetings on precisely this topic, and his remarks were recently published in the American Journal of Agricultural Economics. He writes:
Given the lower level of development in China, it is certainly possible to imagine that the rate of return on investments in agricultural research and extension being higher than is the case in the U.S. But, can the benefit cost ration really be 10 times higher in China than the U.S. (226:1 vs. 20:1)? One interesting thing about Chinese study in Nature is that, if I read correctly, it didn't entail development of any new genetics, pesticides, etc; rather it seemed to largely entail the application of previously developed "science" and practices to the particular geographies in question, and as such, the costs might have been much lower than in situations where new technologies are being created.
In a sense, the shows an enormously high value to "better information." This contrasts with perspectives such as this one by David Pannell, who argues that better technologies are much more impactful than "better information." One way to reconcile this seeming paradox is that that the "information" conveyed to the Chinese farmers was to use better technologies and practices that were already known to exist. Here in the developed world, the knowledge/technologies are likely already more widely dispersed.
I'll end with this quote from Alston's paper, who articulated the value of increased productivity in a createive way: