Nitrogen and the Carrying Capacity of the Earth

Abstract

What would be the population of the earth without “enrichment?” If that sounds like a strange question, consider the answer—perhaps three billion persons less than we have now, and that is because we would not have the food to feed us without the technology of soil nutrient enrichment. Vaclav Smil has written an excellent and crisply focused science and history story on the broader subject of human domination of the biosphere through agriculture. It is because of the discovery of the technical means to split the molecule of nitrogen—the most abundant element in the atmosphere and yet often most limiting in the soil home of the plant—which, thus, makes it reactive and so crucial in all of life′s processes. Left to nature, this enrichment could not occur, and human population numb- ers would be at levels—carrying capacities—that nature decrees. Exceeding natural carrying capacities for long terms has very certain ecological impacts and may also have evolutionary ones as well, such as causing species extinctions.