Healthy Soils Help Cities Deal with Floods

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Author: Ann Adams | Published: October 19, 2017

A recent article on the Union for Concerned Scientists website, titled “How Healthier Soils Help Farms and Communities Downstream Deal with Floods and Droughts,” was particularly timely given the recent hurricane damage that much of the southeast faced in late August and early September. It is no news to farmers and ranchers how devastating these events can be.

In the United States, floods and droughts together have done damage worth an estimated $340.4 billion since 1980 and taxpayers have paid $38.5 billion in crop insurance payouts from 2011 to 2016 (not to mention all the flood damage numerous cities have had to face). Luckily, the knowledge that soil can be a huge sponge to soak up rainfall is becoming more widespread as people learn about soil health and the power of soil carbon.

The full report noted in the article shares some of the key points learned from the Union’s review of scientific data. They also note that the key practices that increase soil health and resilience are:

  • Ecological grazing (planned grazing)
  • No-till cropping
  • Cover crops
  • Integration of livestock and cropping
  • Perennial cropping

The Union performed a rigorous review of prior field studies (150 experiments on six continents) that used any of those practices and focused on soil properties that improved water infiltration rate and water availability in the soil. Here’s some of the key findings:

  • Water infiltration rates improved by 59% with perennial crops, 35% with cover crops, and 58% with improved grazing practices.
  • The largest and most consistent improvements came from practices that keep live roots in the soil year round, such as cover crops, perennial crops, and planned grazing.
  • Heavy rainfall events – more than one inch of rain per hour – can be significantly offset with some of these practices, particularly perennials. In more than half (53%) of the experiments that compared perennial crops to annual crops, water entering the soil not only increased, but did so at a rate higher than a one-inch per hour rain event.

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