That is a fact.
The point of my remarks today was, in a way, to say that it is laudable to try to tax nitrogen, for example, so as to attempt to reduce its use, but it is also important to understand that the more compact the soils are, the more fertilization, and in particular nitrogen fertilization, is required to sustain production. This is due to the phenomenon of nitrogen loss from a lack of oxygen in the soil owing to compaction.
To answer your question more specifically, I would say that research efforts have not been sustained in the past. There was a lot of effort in the 1980s and into the mid-1990s. After that, the teams were virtually all disbanded.