Issues

Agriculture is eroding much more than soil. It is accelerating climate change and fouling waterways. It is the single human activity most responsible for dismantling the biodiversity that makes life as we know it possible.

By using industrial techniques, agriculture is racing through resources future generations will need. It is no exaggeration to say that humans are destroying their future.

This is not a popular message. There are some who dismiss these warnings as evidence of a culture war over food and farming. They are not. The damage is real; here are some of the ways it occurs.

Bare-FieldSoil erosion and degradation

Estimates of the soil lost to erosion vary (here is an article that gives a good overview) but what is not debated is that more soil is lost to erosion on tilled fields than untilled. There’s a good reason that minimal-till and no-till farming — strategies that sharply reduce the amount of tillage – have gained in popularity: farmers understand all too well the implications of losing soil to erosion.

Soil is every bit as non-renewable as oil. Like oil, it accumulates on geologic, not human, timescales. Unlike oil, healthy soil has always been central to human survival. Unlike oil, soil has no substitute. Long-term soil studies show that no amount of fertilizer will preserve soil health when fields are planted with monocultures

Greenhouse gas emissions

Scientists have recognized for more than a century that atmospheric carbon dioxide has a greenhouse effect – it traps heat. About 50 years ago, it started to become clear that the quantity of oil and coal being burned is causing atmospheric carbon dioxide to build rapidly. What wasn’t recognized until more recently was the full extent to which agriculture contributed to this. We now know that land use, which includes agriculture, is second only to power generation as a greenhouse gas emitter, ahead of transportation.

It happens on many fronts. When the soil is disturbed, it stimulates microbial activity that allows the release of carbon. Current estimates are that at least one-third of the carbon has been lost from cropland.

Additional carbon is released simply due to the intensive use of energy. Each acre of corn typically requires the energy-equivalent of at least 35 gallons of diesel; burning that much diesel generates almost 800 pounds of carbon dioxide.

But it’s not just the carbon. Farmers put a lot of nitrogen on crops (112 million tons worldwide in 2011) to make up for fertility lost because they have replaced polycultures with monocultures. Typically less than half the nitrogen applied to fields is taken up by plants; the rest ends up somewhere else. Some escapes to the atmosphere in the form of nitrous oxide, a greenhouse gas 300 times more potent (by weight) than carbon dioxide.

Dead zones and other contamination

Some of the applied fertilizer is rinsed from fields by runoff, carried into lakes and the ocean. In freshwater bodies, such as Lake Erie, the phosphorous is spawning massive algal blooms. In the ocean, it is the nitrogen that creates dead zones that cover hundreds of square miles.

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