Dartman - strangely enough, that’s precisely what is done to provide meat for consumption... huge fields are devoted to producing feed to provide to cows, chickens, sheep, pigs, etc. Without the global demand for meat, less land would need to be used to produce the equivalent amount of plant-based food…
However, going back to biofuels, one of the advantage is that the net CO2 from biofuels is much much lower than other fuel sources. Whilst we continue to burn things to produce energy, it’s better that it’s biofuels rather than fossil fuels. That being said, if we moved towards a more plant-based world, we could use some of the land currently used to grow animal feed to produce ethanol!