ABSTRACT
Few natural soils contain sufficient food for modern varieties of crops, efficiently cultivated by modern methods. The most hopeful way of increasing food supplies is by more intensive cultivation of the land already in use: this is true not only for the United Kingdom but for large parts of the rest of the world. Addition of antibiotics to the food has cut down the losses of young birds and increased the growth rate, especially when the ration is short in protein. The transformation has long been accomplished in the United Kingdom and North-West Europe; elsewhere it is in very different stages, in some countries it has hardly begun. Acidity and poverty in plant foods are easily remedied by dressings of chalk and of fertilizers; lack of organic matter presents greater difficulty, but fortunately is of less consequence for leguminous crops than for others.
