Increasing atmospheric CO2 is leading to micronutrient-poor crops
About 70 years ago, Weston Price found evidence that US soils were depleted. Writing about phosphorous, which is essential for mammalian health, he said ‘Now when we realize that a 60 bushel crop per acre of wheat or corn will remove from the soil about 25 pounds of phosphorous per acre, or one fortieth of the total content in the top 7 inches, we are immediately confronted with the fundamental, controlling problem that we have, accordingly, only enough phosphorous in the average soil for forty excellent crops ...’ The idea has been picked up by other writers (e.g., ‘Empty Harvest’) and by the organic movement which considers not only soil minerals, but also the way modern agriculture strips the soil of the humus and rich bacterial biomass (e.g., www.soilassociation.org) in which our food plants evolved and thrived.
Now comes a startling new line of research findings which, in a nutshell, demonstrates that the increase in atmospheric CO2 and the global warming which accompanies it, accelerates photosynthesis and causes plants to grow faster, but with a diluted micronutrient content as they can’t absorb micronutrients from the soil fast enough to match their increased production of cellulose. Organic gardeners and farmers had the answer to soil depletion: nurturing the soils under their control. But now they have no individualized answer to the deleterious effects of the changing air their plants breathe. There is nowhere to hide.
New Scientist magazine of 30 November 2002 has a feature on this research centred on the work of the Princeton biologist Irakli Loladze.
Loladze shows that plants grown under today’s atmosphere (with 30% more CO2 than 250 years ago) and the atmosphere predicted for the year 2100 (with 100% more CO2) have a significantly reduced micronutrient content, particularly iron, zinc, selenium and chromium. He has focused on the 32 elements of which all biomolecules are composed and homed in on the 24 that are essential for the human body. Pulling together all the relevant data he could find from experiments with doubled CO2 he found declines in almost every element studied. In one study on rice, for example, the research showed iron and zinc both down 17%, nitrogen down 14% and phosphorous down 5%.
So much for those fringe scientists in their think tanks who have been spruiking for the past few years that rising CO2, and the increased quantity of agricultural production which it is stimulating, is a free lunch. TINSTAFL!
The article tells us that iron deficiency is already the world’s most widespread health problem with 3.5 bn humans suffering some degree of mental and physical impairment as a result. Zinc deficiency, which leads to pregnancy complications and poor growth and health in childhood, may be just as widespread. This raises the question of the currency of USDA (and all other) food nutritional analyses, especially those of vital micronutrients.
What to do? New Scientist tells us that fertilizing the soil will not work, as farmers are driven by yield and there is no incentive at all to redirect fertilizer regimes away from plant growth into keeping crop composition optimal for human consumption. The article concludes by suggesting a causal link between this ‘hidden hunger’ and obesity: our bodies are identifying the need to eat more food bulk in order to satisfy our established physiological need for micronutrient levels our species have been evolutionarily adjusted to.
New Scientist refers to articles in:
• Global Change Biology, volume 6, page 43
• New Phytologist, volume 156, page 9
• Trends in ecology and evolution, volume 17, page 457