In Mexico and in the world, agricultural and livestock activities are the economic sector with the greatest scope in the transfiguration of the planet, of landscapes and ecosystems, and with the greatest environmental impacts, in addition to being one of the most relevant in total emissions. of greenhouse gases. This worrying reality is rarely recognized, given the enormous difficulty of designing and applying effective policies, in the prolix social and cultural complexities of the rural world. The truth is that agriculture and livestock are the most important vector of deforestation and destruction of biodiversity, extinction of species, depletion of water and soil resources, and pollution of the seas by agricultural runoff. Also, as we now know, around a quarter of the gas emissions that cause global warming are the responsibility of this sector. On the one hand, due to methane emissions originating from cattle, as well as from rice crops. On the other hand, agriculture, particularly cereals, is the cause of the largest emissions of Nitrous Oxide (N2O), a gas that is 265 times more powerful than CO2 in its potential to warm the planet’s atmosphere in a period of 100 years. The concentrations of this gas in the atmosphere, which had previously been underestimated due to methodological calculation errors (including in the emissions inventory of Mexico), have increased considerably in recent years, and explain up to 7% of the total warming observed on the planet. (Mexico is the tenth largest emitter of greenhouse gases in the world).
This is due to the massive and excessive use of nitrogenous fertilizers. An obvious example of this is the Yaqui Valley, in Sonora, a region with highly productive irrigated agriculture – the granary of Mexico – that produces wheat for export that literally feeds hundreds of millions of people, mainly in Africa and various countries. from Latin America. The Yaqui Valley was one of the preferred technological development and experimentation centers of Norman Bourlag, Nobel Peace Prize winner, who from the middle of the 20th century conceived the so-called Green Revolution, which with new varieties, synthetic fertilizers and pesticides made it possible to increase The yield per hectare of corn and wheat crops is spectacular. In particular, he managed to develop a type of wheat with more and larger grains, and a shorter stem to prevent the plant from bending and spoiling with the weight. With this, he saved thousands of millions of humans in Asia, Africa and Latin America from famine and death.
However, this historic achievement has had a dark side unforeseen by the Nobel Prize. Farmers, like those in the Yaqui Valley, spread up to 300 kilograms per hectare of nitrogen, in the form of urea granules, before sowing, which remains useless for days or weeks in the soil. They then pump anhydrous ammonia into the irrigation water once the wheat germinates and begins to grow. These practices are prohibited in various developed countries. It is estimated that the farmers of the Yaqui Valley apply more than double the nitrogenous fertilizer that is actually required, this, due to the desire to take the yield per hectare to the maximum possible, due to cultural inertia and lack of support and technical extensionism on the part of the farmers. of the authorities. Wheat plants only use about half of the applied nitrogen; the rest is processed by soil microbes from which they obtain nutrients, which generates the relentless Nitrous Oxide gas that is released into the atmosphere. Farmers perceive the cost and risk of under-fertilizing to be much higher than over-fertilizing – since environmental and climate costs are not taken into account. Recent research by the admirable Bourlag-founded International Maize and Wheat Improvement Center (CIMMYT, located in Texcoco, Mexico) has shown that the problem is orders of magnitude greater than previously believed, as the ratio of nitrogen applied to the soil and Nitrous Oxide emissions is not linear, but exponential.
Furthermore, agricultural return water that drains into the Sea of Cortez is saturated with nitrogen and phosphorus, in addition to pesticide residuals, which causes tidal death zones for plankton and photosynthetic algae induced by excess nutrients, which it depletes dissolved oxygen in the water, and kills fish, crustaceans, and mollusks. This ends fishing and the ways of life of riverside fishing communities. Apparently no one else cares.
Civil Engineer and Economist
Mexican politician, liberal environmentalist and researcher, he has served as a public official and activist in the private sector. He was the candidate of the Nueva Alianza party for President of Mexico in the 2012 elections.
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Agriculture, the Dark Side