Long-term crop rotation and tillage effects on soil greenhouse gas emissions and crop production Illinois, USA (Research Summary)

Post submitted by Tianna Griffin, the Iowa Water Center’s Special Projects Assistant

A recent article by Behnke et al. (2018) evaluates the long-term effects of crop rotation and tillage practices on yield and greenhouse gas emission for corn (C), soybeans (S), and wheat (W). The rotations were CCC, CS, CSW, SSS, SC, WCS, with each rotation representing one year. Each rotation had a tilled (T) and no-till (NT) treatment. The study was conducted using a 15-year time span at the Northwestern Illinois Agricultural Research and Demonstration Center.

Behnke, et al’s research evaluated tillage practices and crop rotation on yield, greenhouse gas emission, and soil available Nitrogen (N). Behnke et al. hypothesized that crop rotations where less N fertilizer is used would result in lower greenhouse gas emissions, specifically nitrous oxide (N2O). They predicted that chisel tillage would cause an increase in N2O and CO2 (carbon dioxide) emissions caused by mineralization of decomposing residues (Behnke, et al 2018). From 2012-2015, greenhouse gas emissions were taken weekly during a period of four growing seasons. The data was grouped into three sets of sampling months: March-May, June-August, and September-November. Putting the data into groups allowed for analysis of seasonality on greenhouse gas emission. Soil samples were also taken from the 2013-2015 growing year to evaluate N concentrations.

A main finding of the study was that there wasn’t a significant difference on greenhouse gas emissions between continuous corn with tillage and continuous corn with no till. They found that there was a significant benefit of chisel tillage to corn and soybean yield in increasing organic matter and residue, but there was no increase of N2O and CO2 in the soil found in the study. Because corn typically benefits from high amounts of N, they observed that corn being part of a rotation was able to lower the amount of N2O in the soil. An important part of the research was that N2O emissions were higher at times of fertilizer application. During fertilizer application is when pollution (water and air) is more likely to occur. When fertilizer is applied in excess, plants don’t take up all of it; what is not taken up by the plant is volatilized (when a chemical converts to a liquid or gas) and/or runs off the field. Yields were higher with a diverse crop rotation, such as CS or CSW. Having a diverse cropping system also provides resiliency in yield during suboptimal weather conditions.

Agricultural practices are responsible for a lot of the pollution that occurs in the United States. According to Behnke et al. (2018), greenhouse gases emissions due to agricultural practices in the Unites States makes up 9% of the emitted greenhouse gases. Of that 9%, 81% is CO2, 11% is NH4 (methane), and 6% is N2O. Long-term research like this study can help evaluate ways to mitigate greenhouse gas emissions as well as determine the effects of some agricultural practices on greenhouse gas emissions as well as on improving yields. This research may lead to more long-term research on agricultural practices.


Tianna Griffin was the Iowa Water Center’s Special Projects Assistant. She recently graduated with an undergraduate degree in agronomy with emphasis in agroecology and and a minor in horticulture with an emphasis in fruit and vegetable production.

Why I am Getting into Soil and Water

Post submitted by Lindsay Brown, recent graduate from Iowa State University and member of Iowa State’s Soil and Water Conservation Club (SWCC)

My name is Lindsay Brown and I have recently graduated Iowa State University with a Bachelor of Science Degree in Biology and Environmental Science. I joined the Soil and Water Conservation Club (SWCC) in the fall semester of 2016 and it has provided me with vast amounts of knowledge surrounding the topic of soil and water conservation. Over the years I have heard many presentations from graduate students, professors and other professionals working in the field. The presentations range from land management and conservation to farming practices. Hearing from these various professionals has allowed me to diversify my knowledge about these topics and develop a better understanding on how conservation efforts can be implemented and managed. The SWCC does not only meet every other week and listen to presentations, but we also sell, assemble and present Groundwater Flow Models. These models visually represent how water moves throughout the ground. This visualization can help students, farmers, faculty, or really anyone to realize the importance of water movement on the surface and underground and how understanding its movement can lead to specific water management practices. The Groundwater Flow Models are sold and distributed nationally and internationally and the profits go toward club funds, which allows us to go on trips and attend conferences for professional experience.

The SWCC also has an annual publication called Getting into Soil and Water that is put together by the publication committee. Getting into Soil and Water is a publication that is composed of a variety of articles related to soil and water about local and international subjects written by professionals from various backgrounds. I have been an editor for this publication since August of 2016 and have learned a lot about the editing process, leadership skills, and how to communicate efficiently and effectively with my peers, authors and sponsors. At the beginning of the year, the publication committee discusses and brainstorms different possibilities for themes the publication could follow. After the theme is discussed and we’ve reached a consensus, authors are then contacted to see if they would like to write an article in the publication. After all the articles are retrieved, the editing process begins. Each article is edited many times by each member of the committee and compiled into a cohesive publication. Once the publications are printed, they are distributed to people all around the state of Iowa. Through my experience of being an editor, I learned how to delegate effectively and to recognize the value each person brings to a team in achieving a larger goal. Being an editor also gave me experience running meetings, helped me to develop confidence voicing my opinions in a group setting and allowed me to share ideas with my peers in the publication committee. All of these experiences will be useful for my future career goals and aspirations.

Since graduation I have moved to Minneapolis and now have an internship with the University of Minnesota partnered with the City of Woodbury leading a water conservation project. My future career goals are to work with environmental consulting to decrease environmental degradation and improve the health of communities and ecosystems. Being a part of the SWCC and the Getting into Soil and Water publication committee as an editor, has provided me with multiple years of experience learning about conservation practices as well as practical communication skills. I would definitely recommend students to get involved in student organizations like the SWCC on campus, because it provides you with lifelong practical skills for your future career.

Lindsay Brown is leading a water conservation project with the Minnesota Technical Assistance Program in Minneapolis, Minnesota. She has a B.S. in Biology and Environmental Science from Iowa State University. She is currently looking for full-time employment doing environmental consulting in the Twin Cities area.