Improving Our Understanding of Soil

August 10, 2015

The United Nations has designated 2015 the "International Year of Soils," focusing on challenges surrounding food, energy and the environment. Since 1997, Project GREEEN has been confronting these issues and their impacts on plant agriculture.

For nearly two decades, Project GREEEN has been influencing the plant agriculture industry through innovative and transformative research. But a truly significant impact would be impossible without dedicated researchers pushing the boundaries of the field.

Kurt Steinke, an assistant professor of soil fertility and nutrient management at Michigan State University, has been the beneficiary of Project GREEEN funding since joining the Department of Plant, Soil and Microbial Sciences in 2011. His first Project GREEEN initiative focused on improving the ecological efficiency of sugarbeet production. Sugarbeets are a specialty crop without as heavy of a research focus as larger-acreage cash crops.

Steinke found that while genetics and yields of the crop have changed dramatically over the past 10 to 15 years, nutrient recommendations have not. It used to be common that sugarbeets would follow dry beans in the field. Now they may routinely follow corn and wheat, two higher-density crops that produce greater biomass and more carbon, which affects the soil’s composition. By improving and updating nutrient recommendations, growers continue to see increases in yield and efficiency of fertilizer applications.

With the assistance of Project GREEEN funding in 2013, 2014 and 2015, Steinke has completed two additional projects. Since the early 1980s, atmospheric sulfate deposition has dropped nearly 75 percent due to pollution control measures. This has decreased the freely available sulfates from the atmosphere. Steinke and his team sought to determine the relationship between sulfur and nitrogen use efficiency in corn production.

“We found that adding sulfur helped nitrogen use efficiency, agronomic efficiency and corn yield but only at extremely low nitrogen rates and where organic matter levels were less than 2.8 percent,” Steinke said. “If growers were below the MSU recommendation for nitrogen, they saw a response to sulfur. If they were above, we did not see a response.”

In a second project, Steinke studied soil health by testing whether management practices impacted the biomass and diversity of soil microbial communities. Soybeans were preceded by three cover crop scenarios: no crop, oilseed radish (a rooting crop) and hairy vetch (a leguminous crop). Various organic and inorganic fertilizers were applied to all three, and samples were taken for DNA sequencing tests.

“The biggest question is, do we need to grow two crops to harvest one?” Steinke said. “The first crop is the soil microbial community, and the second is the cash crop of interest. Microbes rule the world. They dictate nutrient cycling. They mineralize nutrients. So if we have a healthy microbial community, does that translate into our crops having better access to a nutrient pool?”

Data analysis continues, and while preliminary findings indicate that management has a definite impact on microbial communities, there are several changes in the biomass that are out of growers’ control.

Steinke was awarded just over $130,000 for research on the two projects but was able to leverage more than $250,000, a tribute to the relevance of his work.

“Not many states have a program similar to Project GREEEN,” Steinke said. “I know a couple of other states are looking at the Project GREEEN model. The diversity of crop production in Michigan really plays a role in the program’s importance, and we’re fortunate to conduct research that helps growers well beyond our state.”