I was referring to the practice of not maximizing the productive capacity of the fields. In fact, Professor Rood also referred to that in his third point, regarding optimization versus maximization. It's entirely possible that this is occurring. There's an industrial scale of agriculture whereby the soil is used to its maximum capacity in the short term but becomes exhausted over time. That's as opposed to conservation farming and some practices that are fairly well documented and established, whereby farming is practised in such a way as to leave behind carbon that could have been extracted and exported, as well as some soil, and to leave behind some water, even though it could have led to a marginal increase in productivity.
On December 7th, 2017. See this statement in context.