Frankly, I was very suprised to hear this, too. I visited a rural family last year and we had a short chat about this. I had expected the subsidies are for machines etc., but influencing the choice of crops in this way seems really misguided. Whoever created this had good intentions, but the results are lamentable. (The family in question still have a large portion of land they cultivate in a more natural way, alternating the crops properly etc.)