It's easy to overlook soil's ill health because overall it still does what we want it to do: produce bumper crops. But as organic matter levels drop, those yields are increasingly reliant on fertilizers like nitrogen, and, as the Minnesota Pollution Control Agency reported in June, so much of this nutrient is escaping the land that 27 percent of lakes and rivers in the southern half of the state are too polluted to be used for drinking water. Removing nitrates from drinking water is costing the Des Moines Water Works $7,000 a day. It's a vicious cycle: more chemicals result in less of the kind of biological activity needed to maintain natural fertility, which means even more chemicals are needed to prop up yields, which sends more chemicals into our water.
But since soil organic matter levels are tied to biological processes, we can have a relatively quick impact on those processes. Creating a one-inch layer of soil can take centuries, if not more. But I've been on farms where organic matter has been increased in a matter of a few years through the use of crop plantings and rotational grazing systems that diversify the landscape -- above and below the surface -- while shielding soil from the elements beyond the standard corn-growing season. A USDA survey released in July found that planting soil-friendly cover crops not only protected the soil but actually boosted corn yields significantly in parts of the Midwest most heavily hit by drought in 2012. Soil scientists are monitoring this revitalized soil and finding it can not only cook up its own fertility and make use of moisture better, but develop a kind of shielding system that keeps it from being blown apart by heavy rains.
The other good news is that today's science is providing fascinating glimpses at an ecosystem that most of us probably consider dull as, well, dirt, but which is in fact the most diverse on the planet. An awareness of what we are losing and a realization that traditional conservation isn't enough has prompted natural resource agencies to rethink erosion control strategies. One USDA Natural Resources Conservation Service estimate is that if all of our nation's cropland was managed using traditional conservation measures, erosion would drop by 0.85 billion tons annually. Increasing organic matter on our cropland would drop erosion by 1.29 billion tons per year.
Creating healthier humus will require farm policy reforms, as well as market-based incentives and land grant university research/outreach initiatives that help farmers adopt innovative, financially-viable production systems. All this requires support from the non-farm public, a tall order for a society that's quite comfortable treating soil like dirt. But this isn't just about maintaining crop yields, or even cleaner water. Soil provides at least $1.5 trillion in services worldwide annually, including stockpiling more carbon than the Earth's atmosphere and all the plants on the planet. That makes it a key player in controlling greenhouse gases, among other things.
As the father of soil conservation, Hugh Hammond Bennett, wrote in 1928: "Farmers have only temporary control over their land … The public's interest, however, goes on and on, endlessly, if nations are to endure."
Brian DeVore works for the Land Stewardship Project, a nonprofit organization fostering sustainable agriculture since 1982. DeVore writes for and edits the group's publication, The Land Stewardship Letter.