Quora Question: What We Aren't Saying About Sustainable Food

Farmer-dead crops
Farmer Matt Johnson pauses while in a dead area of his popcorn crop fields on his family's farm in Redkey, Indiana, June 28, 2012 Brent Smith/Reuters

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Answer from Miriam Horn, author of the recently published Rancher, Farmer, Fisherman: Conservation Heroes of the American Heartland:

The focus on pesticides and synthetic fertilizer has been crucial: 50 years ago, EDF was founded out of the fight alongside Rachel Carson against the spraying of DDT, which was decimating birds of prey. Today, EDF is leading efforts to reduce the air and water pollution caused by the excess use of fertilizer, which worsens climate change and causes huge dead zones in places like the Gulf of Mexico.

But other equally crucial issues have gotten far less attention.

First among these is soil health. Though we treat it like dirt, soil is among our most precious resources. It’s the largest reservoir of biodiversity, containing a third of the world’s organisms, including thousands of species of microbes which play essential roles for life on earth: capturing and ferrying nutrients to plants; protecting plants and animals (including humans) from pests and disease; sustaining photosynthesis, the source of all of our oxygen and all of our food.

Soil is also the planet’s second largest carbon repository, storing twice as much as our atmosphere and every plant combined.

But soil is also terribly endangered. It is essentially nonrenewable, taking some 500 years to build an inch. Every year, we suffer a net loss worldwide of 23 billion tons: 1 percent of the world’s total agricultural soil inventory.

Much of that loss is caused by the most traditional of farming practices: plowing. Tillage can leave soil stripped and highly vulnerable to erosion, or collapsed into a hard-pan impermeable to water. Tillage can also do great harm to those microbial communities, scrambling and separating them from their symbiotic partners, overfeeding them in ways that stimulate bacteria and crowd out more valuable fungi.

A second issue that gets too little attention is biodiversity. Agriculture has already taken over half of all ice-free land on earth, and continues to encroach on the remaining forests and grasslands. We need to limit or even shrink its footprint, by being as productive as possible on every acre we use; and we need to farm and ranch and fish in ways that maximize biodiversity on those productive lands and waterways. That includes protecting soil microbes, moving from monoculture to rotation and cover cropping, restoring our vanishing coastal wetlands, critical nurseries for most of our seafood, and revising management of our deepwater fisheries to bring back ocean abundance.

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