I have not finished this book and probably will not, for several reasons. As all of Smil's works, this puts a lot of emphasis on the numbers, that is, proportions and orders of magnitudes. It's a twenty year old book though and this severely limits the use of it as the world has continued to move and the data with it. The historical passages and the general bio-agricultural overview was fairly covering and interesting. At one point, Smil makes an assessment on the likely effects global warming might have on agriculture, which I believe would be categorized as almost climate change denialism today, as he point to some study that does not find grounds to worry that agriculture will be negatively affected at all, and that it might in fact flourish under global warming. If I recall, the study tested how plants reacted to small increases in temperatures above the local average (and it was done in a lab setting). Today, we know this is not the case as global warming was never just about slow increases in temperature. Global warming, or climate change as some people insist on calling it for that reason, means more frequent extreme weather: drought, storm, flood etc. And agriculture is already suffering under it.

If you would want to write a book like this today, global warming would have to play a major and towering role in the review. This is why the above passage makes me suspicious of the rest of Smil's work here, and I have great respect for this scholar otherwise.

If I would recommend another book that deals with how to feed the world, while combating global warming at the same time, and does take proportions seriously (being heavily referenced and based on data for all the main macronutrients, yield and carbon sequestration potential of different crops) I would recommend Eric Toensmeier's magnificent tome "The Carbon Farming Solution". It wouldn't be bad with a new edition of Smil's work, but until then, Toensmeier's is the best I know.