As long as the two different crops are compatible yields tend to be the same or better if symbiotic. Problem is for economical harvesting you need to spread the

As long as the two different crops are compatible yields tend to be the same or better if symbiotic. Problem is for economical harvesting you need to spread them out which also lowers density on a field. Which also lessens the symbiotic benefits as they now are further apart. Also density is important for grains/cereals since each plant produces so little. Honestly, while a nice idea I agree it wont really work at the scale we need. I think some genetic engineering would be more useful. Ideally a crop that also is not encumbered by patents like other enhanced crops.