4.18.25

Farms in the fight against climate change

Caro working in the labs at the Kellogg Biological Station to confirm the % soil carbon measurements used in the study.

The activities are as follows:

Carbon, when it is found in the soil, has a lot of benefits. Soil carbon makes water more available to plant roots, supports microbes and insects, helps water move through the soil and not flood at the surface, and holds on to critical nutrients for plants, like nitrogen and phosphorus. It is a key measure of soil health used by farmers.

The more carbon stored in soils, the less that ends up in our atmosphere as greenhouse gas, which contributes to climate change. Farming practices that increase soil carbon are a double benefit – they help crop plants grow and produce more return for farmers, while also helping to fight climate change.

Yet, accumulating carbon in the soil is a slow and mysterious process. It can take decades to see greater levels of carbon in most agricultural soils. Farmers need information about which farming practices reliably and continually increase soil carbon.

View of the Long-Term Ecological Research experiment at the Kellogg Biological Station where plots have been growing with different agricultural and plant community treatments since 1989.

Caro is a soil scientist working with farmers to figure out how they can increase carbon in their soils. Her passion for soils brought her to the Kellogg Biological Station. This site is very special because it houses the Long-Term Ecological Research Program, which has been running the same experiment since 1989! When the study began, the soils were the same across the site. But, after decades of different treatments taking place in research plots, a lot has changed above and below ground.

In 2013, a team of scientists worked to sample soil carbon at this site, 25 years after the experiment began. The team processed the samples to determine the percent, by weight, of each soil sample that is made up of carbon. This is called % soil carbon. They collected samples from 4 different treatments, each with 6 replicate plots:
(1) Conventional: plots grown in a corn soybean-wheat crop rotation. The soil in these plots is tilled during spring, meaning they are disturbed and turned over. These plots represent how agriculture is conventionally done in the area with standard chemical inputs of fertilizer, herbicides, and pesticides.
(2) No-till: plots that are grown in the same way as conventional, but with one key difference. The soil in these plots is not tilled, meaning it has been undisturbed for 25 years at the time of sampling.
(3) Cover crops: plots grown similarly to conventional, with a few key differences. First, cover crops were added. Cover crops are plants that are planted alongside crops or at times of the year when the main crop is not growing. This means the soil has living plant roots year-round, not just during the season with crops. Second, this treatment had no chemicals added; all nutrients came from the addition of manure. These plots were tilled.
(4) Not farmed: non-agricultural plots growing in a diverse mix of plant species. Plots are unmanaged, but are sometimes burned to keep out woody species.

These 4 treatments represent different ways that land can be managed. The goal of the study was to see how different types of land management had changed % soil carbon over time. When Caro came to KBS in 2018, she was excited to see such a cool dataset waiting to be analyzed! She thought that keeping the soil undisturbed and having living roots in the soil for more of the year would increase soil carbon over time. This led her to predict that she would see higher % spoil carbon in the cover crop and no-till treatments, compared to conventional.

Featured scientist: Caro Córdova from University of Nebraska-Lincoln and the W. K.
Kellogg Biological Station Long Term Ecological Research Program.

Flesch–Kincaid Reading Grade Level = 4.1

Additional teacher resources related to this Data Nugget:

The results from this study are published and the article is available online.
Table 2 in the paper matches the dataset that students are working with in this activity.

If students want to read more about this paper, there is a blog post summarizing the study.

The full dataset is also available online in the Dryad Digital Repository. The file has lots of details about the variables measured and the different cropping systems studied. The first tab of the spreadsheet contains the data used in this activity, plus many more variables and treatments that students can explore to ask new questions!

More information on Regenerative Agriculture from MSU here.

These data are part of the Kellogg Biological Station Long Term Ecological Research Program (KBS LTER). To learn more about the KBS LTER, visit their website.

1.20.25

Microbes facing tough times

Jennifer sampling soil before the shelters were set up. Here you can see the control (left) and carbon addition (right) plots.

The activities are as follows:

As the climate changes, Michigan is expected to experience more drought. Droughts are periods of low rainfall when water becomes limiting to organisms. This is a challenge for our agricultural food system. Farmers in Michigan will be planting crops into conditions that make it harder for corn, soybean, and wheat to grow and survive.

Scientists are looking into how crop interactions with other organisms may help. Microbes are microscopic organisms that live in soils everywhere. Some microbes can help crops get through time times. These beneficial microbes are called mutualists. They give plants nutrients and water in exchange for carbon from the plant. Microbes use the carbon they get from plants as food. If plants are stressed and don’t have any carbon to give, microbes get carbon from dead plant material in the soil.

Jennifer is a biologist studying the role of microbes in agriculture. She has always been interested in a career that would help people. As a student, Jennifer thought she would have a career in politics. Along the way, she learned that a career in science is a great way to study questions that may lead to solutions for the challenges we are facing today. Jennifer was drawn to the Kellogg Biological Station, where she joined a team of scientists studying the impacts of climate change and drought on agriculture.

Jennifer and other scientists set out to test ways that we can give mutualists in the soil a boost. She thought, perhaps if we were to give microbes more food, they would be less stressed during a drought and would be able to help out crops growing in these stressful conditions.

To test this idea, Jennifer needed to test how well microbes were doing under different carbon and drought conditions. First, she set up treatments in soybean fields to manipulate the amount of carbon in the soil. She set up control plots where she left the soil alone. She also set up carbon treatment plots where dead plant litter was added to the soil to increase the carbon available to microbes.

Next, Jennifer manipulated the availability of water in her plots to test the microbes under stress. To do this, she set up her plots under shelters that kept out rain. The shelters had sprinklers, which were automated to add specific amounts of water to the plots. This design allowed Jennifer to control the watering schedule for each plot. One shelter treatment was a control, where water was added to the plots every week. This is similar to the schedules of local farmers who add water through irrigation. The other shelter treatment was drought, where plots received no water for six weeks. This experiment was replicated 4 times, meaning there were 4 shelters on the control watering schedule and 4 shelters that were under drought conditions.

A view of one of the shelters used in Jennifer’s experiment.

Finally, Jennifer had to measure how the microbes were doing in each treatment. She did this by measuring their enzyme activity. Enzyme activity is a measure of how active the microbes are. The higher the enzyme activity, the happier the microbes are. To measure this, Jennifer collected soil samples from each plot throughout the growing season and took them to the lab to measure enzyme levels in the soil samples. These enzymes are made by microbes when they are active. She then calculated the mean of all her samples for each treatment combination.

Jennifer predicted two things. First, if drought is harmful to microbes, then she would expect to see lower enzyme activity in the drought treatment compared to the irrigated treatment. Second, if adding carbon to the soil is a way to help microbes overcome the challenge of drought, she expected higher enzyme activity in the plots with plant litter added compared to the control treatment. Both of these taken together would indicate that drought is stressful for microbes, but we can help them out by adding resources like plant litter to soils.

Featured scientist: Jennifer Jones (she/her) from the Kellogg Biological Station Long Term Ecological Research Site. Written with Melissa Frost and Liz Schultheis.

Flesch–Kincaid Reading Grade Level = 8.2

Additional teacher resources related to this Data Nugget:

To introduce this Data Nuggets activity, students can watch a talk by Jennifer when she made a classroom visit to share her background and research interests. This video is a great way to introduce students to scientist role models and learn more about what a career in science looks like, as well as get an introduction to the themes in the research.

There is also a video of Jennifer and her scientist colleague, Grant Falvo, out in the field talking about their research under the rainout shelters.

For more information about the rainout shelter experiment, students can watch this short video featuring Jennifer Jones and another scientist on the team, Grant Falvo:

These data are part of the Kellogg Biological Station Long Term Ecological Research Program (KBS LTER). To learn more about the KBS LTER, visit their website.