Nitrogênio em Mumford (1938)

During the last generation the whole field of improvement has widened: soil regeneration through the use of nitrogen-producing crops has come: likewise the improvement of plant and animal strains, selective breeding toward potency of growth; the utilization [341] of chemical wastes for soil enrichment; finally the intensification of crop yield, both as to time and space, through the cultivation of plants in specially prepared tanks, with scientific mixture of plant food, complete control of light and heat, and elimination of insect pests and blights. All these advances have, in one way or another, equalized agricultural advantages over greater areas and removed the incentives toward one-sided specialization. (Mumford 1938:340-1)

MUMFORD, Lewis. 1938. The Culture of Cities. San Diego: Harvest/HBJ.