I disagree with that. In Western countries typically half to two thirds of agricultural land are used for meat and dairy production. We have plenty of food available to sustain the current or even growing populations without depending on mineral fertilizers. Farming techniques have significantly evolved over the past two hundred years and the crop yield of an intelligently managed field without mineral fertilizers is not signficantly lower than what is achieved by conventional farming. With the added difference that conventional farming is actively destroying the soil and killing the insects that are vital to maintaining agriculture.