Agriculture & Natural Resources

Earth Day – every day, focus is on healthy soil

We walk, drive, work and play on it. Our food, fuel and fiber production rely upon it.  The various combinations of loam, sand and clay which form our Earth’s outermost layer, our soil, is the cradle of life for humans, animals and plants.  The Food and Agriculture Organization of the United Nations named year 2015 as the International Year of Soils. Beginning with Delaware Agriculture Week in January and continuing throughout the year, Delaware Cooperative Extension is reinforcing its efforts to promote soil health throughout the state.

Steve Woodruff, USDA-NRCS agronomist presents at last month's soil health field day at UD in Georgetown
Steve Woodruff, USDA-NRCS agronomist presents at last month’s soil health field day at UD in Georgetown

“Soil health is a topic being discussed nationally and internationally, but how it is implemented is going to be very specific to individual farms and fields,” says Mark VanGessel, UD Extension specialist in weed science.

“Working with farmers, the National Resource Conservation Service (NRCS) and the conservation districts, UD Extension is working on locally adapted practices that fit with Delaware soils, climate, and cropping systems. Getting farmers to think more about soil health an implement specific practices requires a collaborate effort on the part of USDA, conservation districts, Delaware Department of Agriculture, UD and DSU Delaware Cooperative Extension and most importantly, farmers,” VanGessel says.

Healthy soils are rich in organic matter with a high diversity of microbial activity and are more healthy if they are not over tilled, says Steve Woodruff.

Woodruff, an agronomist with the USDA -NRCS was the featured speaker at the Soil Health Field Day held on March 25, 2015 at the Carvel Research and Education Center in Georgetown. During the day-long seminar, Woodruff reflected on the change of mindset and cultural practices he has observed in agriculture. Growing up on a tobacco farm, Woodruff says the excessive tilling needed to grow tobacco has over time, ruined the soil’s function.

“Tobacco fields are starving for water today,” Woodruff says. “Humans have ruined what was a well-functioning system.”

Woodruff explains that farmers need to understand how soil functions so they can better use rainwater. Water that runs off, or just sits, is not a functioning system.

“Agriculture soils don’t have an erosion problem,” Woodruff adds. “But we have an infiltration problem.” Farmers need to stop focusing on the amount of rain, but instead, on how much rain gets to the crop.”

To illustrate his message, Woodruff often travels with his rain simulator, a messy, but effective device that distinguishes the way healthy and unhealthy soils accept or receive water during a rain event. In the video, Woodruff arranges soil profile samples to demonstrate a variety of soil quality and conditions. The soil profiles, from left to right are: 1. Low diversity and heavy tilled soil – less than 1% organic matter (unhealthy). 2. No-till – a section of soil with 25 years of diverse cover crops and organic matter equaling 4 to 4.5% (healthy). 3. Poor soil with a heavy residue cover (control). 4. Well-managed pasture with a diversity of cover crop (healthy) and, 5. Poorly-managed pasture – over grazed with biological disturbance – impaction (unhealthy). The results are clear.

The solution to the problem, Woodruff stresses, is creating healthy balance of organic matter in the soil. “Organic matter is the glue for soil strength,” Woodruff says.  Building that organic matter takes time. “We have to keep feeding the soil,” Woodruff explains. He concedes building organic matter in sandier soils can be tricky. Warmer soils, Woodruff emphasizes, need more microbial activity and less tillage.

Growing more cover crops is one solution. Understanding how these crops grow, use carbon and take up nitrogen, and eventually break down to form organic matter is vital knowledge for a farmer to put into practical use. Performance results of various cover crop species were made available at the field day.

Making the effort to understand how organic matter works and adding it to the soil also makes good economic and productive sense.

In farms where he is conducting research, adding one percent of organic matter in the top 12 inches of soil saved one farmer 16,500 gallons of water per acre, Woodruff says.

In one Michigan study, adding 1 percent of organic matter equaled a 12 percent increase in crop yield.

Most biological activity occurs in the top three inches of soil, Woodruff explains.

Healthy soils require microbial diversity. Woodruff compared a healthy soil in terms of human health. When humans are sick and take antibiotics, smart advice is given to replenish the diet with yogurt or pro-biotic additives to restore the “good stuff,” the microbes and bacteria the human body needs to thrive, Woodruff related. So too with plants. Plants and crops interact with particular microorganisms in the soil and help the plants to absorb nutrients better. A diversity of microbes need to exist in order to convert plant material into organic matter. In addition to cover crops, adding compost and strategic applications of poultry litter are natural and effective amendments.

For agricultural soils, Woodruff advocates planned and lengthened crop rotations along with the implementation of a variety of cover crops.

“Diverse soils are more resilient,” Woodruff explains, “and the crops that grow from that soil have a better chance to resist diseases, pest insects, climate change and other stresses.” As a result, Woodruff explains, there is less reliance and need for the “cides”  – pesticides, fungicides, herbicides, nematicides, etc. Prevention, avoidance, and monitoring should be undertaken before suppression and spraying for pest populations, Woodruff said.

“The impact of not building soil health is a $400 billion consideration,” Woodruff said. “Farmers need to know their main crops and understand the conditions that allow and provide the habitat for organisms to thrive in the soil.”

“Soil health is the continued capacity of oil to function as a vital living ecosystem that sustains  plats, animals and humans,” Woodruff featured in a slide presentation.

The Soil Health Field Day also covered presentations on the early establishment of cover crops with an air seeder, by Mike Willeke, Buckeye Soil Systems and included two field stations; the rain simulator and weed management in cover crops conducted by Mark VanGessel. The seminars were sponsored by the Sussex Conservation District, MRCS, DNREC and the University of Delaware


Article & media: Michele Walfred