Spring 2009

[ BACK ]

Iowa Should Make Soil Quality a Priority

By Kendall Lamkey

While visiting the exhibit Dig It! The Secrets of Soil at the Smithsonian National Museum of Natural History during a recent trip to Washington, D.C. I learned a number of ways soil is involved in our daily lives that even I as an agronomist did not know. The exhibit, sponsored by the Soil Science Society of America and others, does an outstanding job relating our personal and global relationship to soils.

I was surprised to find out the primary source of phosphorous in the Amazon rain forest is dust storms in the Sahara desert. I was impressed by the sheer diversity and quantity of life found in the soil. And I discovered the impact soil has on something that seems as simple as building a house. The exhibit also touched on the role of soil in climate change, a topic of world-wide public interest.

Soil interacts with our climate in many ways, but one of the most important is its role in the carbon cycle as the largest terrestrial reserve of carbon on the planet. How we humans interact with our soil directly impacts how much carbon in the soil enters the atmosphere as carbon dioxide.

Iowa soils contain only 50 percent as much carbon today as compared to when they were first plowed 150 years ago. Cropping systems, drainage systems, tillage, rainfall, temperature and other factors all contribute to a reduction in soil organic matter.

The amount of soil carbon is largely in the hands of humans. If soil carbon continues to decrease, the bountiful harvests Iowa has enjoyed will become increasingly costly to sustain. Further decreases in soil carbon will force Iowa farmers to increase external inputs into the cropping system to maintain production levels. But to increase soil carbon our society will have to change its priorities and habits. We will have to change our cropping systems, tillage practices and drainage systems. This means becoming more intentional about the mix of annual and perennial crops planted in Iowa. Recent studies at Iowa State University show putting as little as 10 percent of our row crop landscape into perennials could reduce erosion by as much as 80 percent – even in flood years like 2008. The planting of perennials, coupled with changes in our cropping system like cover crops, perennial ground covers and increased use of reduced or no tillage practices, will not only result in decreased erosion but also will have a huge impact on the carbon balance in Iowa’s soil. This all would result in the added benefit of increasing the quality of life for all Iowans through cleaner water and a more diverse landscape.

It does not mean, however, that we need to sacrifice production of crops and the livestock and poultry that depend on them for feed, or even ethanol and biodiesel. It means we will have to increase corn and soybean production on the remaining 90 percent of the acres through better agronomics – genetics, fertilizer management, pest control and how these factors interact with our weather. It means we will have to better integrate our crop, livestock and poultry systems. It means we never leave our soils bare through the winter.

I believe Iowa should lead the way in making soil health our number one priority. We can start by adopting zero tolerance for soil particulates in our streams, rivers and lakes. Soil is the number one water pollutant in our state according to the Iowa Department of Natural Resources.

The Natural Resource Conservation Service’s 2003 Annual National Resource Inventory shows Iowa has 128 million tons per year of water erosion, making Iowa number one in the nation for soil erosion by water. By making significant changes in our production systems Iowa can lead the nation in crop and livestock production and lead the nation in clean water.

Let’s make this our top priority and reward those who take the initiative. The future of Iowa depends on it. More importantly, the future of agriculture depends on it. Because Iowa is agriculture.

STORIES online Extra:

Dig It! The Secrets of Soil

Dig It! The Secrets of Soil at the National Museum of Natural History is open until January 2010.