Tile systems that drain excess water from much of Iowa’s farmland yield dramatic improvements in plant health and productivity. But they also are often pointed to as the source of excess nutrients in streams, rivers, and coastal regions.
When farmers in my local watershed gathered 12 years ago to discuss these problems, we agreed nutrient loss is expensive. If we could understand ways to make our farm system less leaky, why wouldn’t we try?
A new way of thinking about soil — of the importance of life in that soil — leads to water and soil quality improvements. And good yields. But it takes patience, a willingness to listen to people who know more, and an ability to let go of things that turn out to be wrong.
I knew erosion below 5 ton/acre was sustainable. I learned soil regenerates from mineralization of subsoil and crop residues at this rate. But this is a decades-old standard based more on what farmers could achieve to comply with federal rules than actual sustainability. A nd a ny soil leaving my farm was carrying valuable nutrients away. I no longer accepted my 2- to 3-ton losses. Why would I?
Another thing I knew was I needed to till every few years to alleviate compaction, mix crop residue with soil so it could break down, and keep fertilizer mixed throughout the soil. But tillage perpetuates compaction, destroys soil structure and causes the soil surface to seal over when it rains reducing infiltration and increasing runoff. And tillage decimates diversity of life in healthy soil. I started to view tillage as damage.
Our mechanical way of thinking, trying to manage the physical and chemical environment that we grow our crops in has left our fields vulnerable to erosion and nutrient loss. Ignoring the biology of soil has left commercial agriculture with a leaky system that increases vulnerability to weather variability.
With other Practical Farmers of Iowa members, I was learning farming had to be about growing more than crops I could sell. I had to keep my farmland productive year around to produce enough food for worms and bugs that work deeper through my soil profile than any tillage tool. Winter small grains like wheat, rye, and barley scavenge nutrients which are then consumed, recycled and stored in organic matter. Some plants form mutually beneficial relationships with soil fungi,trading sugars for otherwise unavailable soil minerals, reducing the need for fertilizer. I no longer thought life in my soil was “stealing” nutrients from my cash crops.
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My willingness to commit to the Natural Resources Conservation Service Soil Health Program was encouraged by the Conservation Stewardship Program. I signed a 5-year contract agreeing to no tillage, multispecies cover crops, nutrient testing of soil and plants, and to add at least 20 acres of small grains to my corn and soybean rotation.
After 5 years of these practices, I can testify they really work. My yields did likely suffer from no-till until soil health improved, but my yields have rebounded as my soil gained structure and stability. In 2017 I had a 40-acre cornfield produce 20 bu/acre over my county average while weekly tests of tile lines never surpassed 5 ppm nitrate, half the drinking water standard.
I will never go back to farming without considering how my decisions affect soil health. Why would I?
• Dick Sloan farms in Buchanan County and has been involved in water quality work since 2006, when he was elected president of the Lime Creek Watershed Improvement Association.