PROJECT OUTCOMES

In this project we have pursued a better long-term understanding of the ecology of intensive row-crop agriculture typical of the US Midwest, with its outsized impact on human and environmental welfare. We have integrated experimental studies and long-term observations to reveal ways to use ecological knowledge to better manage annual and perennial field crops in order to make US agriculture more productive and sustainable. We have discovered ways that ecological knowledge can advance both crop productivity and environmental goals. In particular:

1) High crop yields are an important aspect of sustainability. We tested how ecological management can substitute for synthetic chemical inputs in high productivity corn, soybean, and wheat crops. We managed these crops in four different ways, ranging from conventional to organic. By not disturbing the soil, our no-till crops yielded 10-20% more than the conventional crops that were tilled. A reduced input system, with only 1/3 of conventional chemical inputs, yielded as much as the conventional system. The organic system had equivalent soybean but lower corn and wheat yields. Results show that management based on ecological principles—instead of relying solely on chemical inputs—can provide high yields.

2) Agriculture can contribute substantially to global greenhouse gas mitigation. By measuring the greenhouse gases CO₂, nitrous oxide, and methane from annual, perennial, and natural ecosystems we were able to evaluate the potential for different crops and farming practices to produce or consume greenhouse gases. We found that the way we farm annual crops such as corn, soybean, and wheat hugely affects agriculture’s climate impact. We also found that perennial crops grown as feedstock for cellulosic biofuels can be extremely mitigating when managed appropriately.

3) Healthy soils are key for attaining crop production and environmental stewardship goals. The soils under our annual crops grown without tillage had ~20% more carbon (organic matter) than did the conventional system with normal tillage. This higher level of carbon increased the soil’s ability to hold water and deliver nutrients to the crops. This was particularly important in drought years such as 2012, when conventional yields decreased by 50% but no-till yields by only 25%. Belowground, we discovered that long-term use of nitrogen fertilizers accelerated the evolution of beneficial soil microbes (rhizobium bacteria) that supply nitrogen to plants like soybeans, making the microbes less effective nitrogen providers. This rapid evolution was aided by horizontal gene transfer in soil and point mutations.

4) Understanding how agriculture affects the quality and quantity of water is important for environmental and human health. We measured the amount of nitrate flowing from our different annual and perennial crops. We found that organic and low-input management of corn, soybean and wheat reduced nitrogen pollution to groundwater. We were also surprised to find that water use was not different between various annual and perennial crops or vegetation types, which suggests that water dynamics across Midwest landscapes will not change much with different crops or climate variability.

5) In agricultural landscapes, plant and landscape diversity helps to control unwanted pests, provide sufficient pollination, and enhance soil health. By examining landscape level plant-insect dynamics, we discovered how the diversity of plants surrounding crop fields enhances habitat for predators of agricultural pests. Across the upper Midwest, we documented how beneficial ladybeetles that consume soybean aphids helped to reduce pesticide use and averted pesticide expense and yield losses worth millions of dollars annually. We also found that non-native, invasive ladybeetles were just as able to suppress the aphids. This highlights the importance of landscape-level research to help manage crops more sustainably.

6) There are many barriers to adoption of sustainable farming practices, including farmer costs and attidudes. Increasingly society is willing to pay farmers to protect natural resources. Our research revealed that farmers would accept low payments to provide environmental benefits that they valued, such as building soil organic matter and reducing nitrogen pollution to groundwater. However, farmers wanted higher payments for benefits not perceived as useful to their farm, such as greenhouse gas mitigation. Such findings can inform policies and incentives to promote wide-scale adoption of sustainable practices.

We have disseminated our findings widely within the scientific community and stakeholder groups. Research results have been reported in more than 315 peer reviewed journal articles between 2011 and 2017.  Thirty-seven graduate theses and dissertations were completed during this period. Every year we provided ~130 science teachers from 16 school districts multiple workshops to provide curriculum for teaching hands-on science. We developed classroom activities based on research results (called Data Nuggets) that allow students to learn by analyzing and interpreting real data. They have been used by over 9,000 teachers in 50 US states and 130 countries. We mentored over 43 undergraduate students, more than half from underrepresented groups. We engaged with agricultural professionals to discuss research findings and environmental journalists to promote science communication.

Last Modified: 05/01/2018
Modified by: G. Philip Robertson