Anyone who has grown up in the Midwest can appreciate the wide-open spaces of the plains, the sweeping fields, and slight rolling hills. Now, imagine those fields of corn tassels and soybean stubble as a vast display of tall prairie grasses and flowers! Oh what a sight that would be! Back in the early 1800s, it was quickly realized that these prairie landscapes were nutrient-rich and perfect for agriculture – which is why only 0.01% of the tallgrass prairies remain. If we compare pictures from the 1800s and today, we can see the dramatic landscape shift that took place as the prairie landscape was farmed. But all we can visibly see is the aboveground change – I want to bring us belowground, to the real heart of the prairie: the soil (and everything that lives in it). What would you see if you could wear x-ray goggles and look underground beneath all those plants!? Roots! Worms! Insects! And…if you had a microscope…. you could see trillions of bacteria and fungi. So…now, with our belowground x-ray vision, how would those pictures from the early 1800s and today differ? First, the roots: prairie grasses have really deep roots, extending nearly 15 feet belowground! They use these deep roots to reach water during dry, summer months. Corn, on the other hand, has shallower roots that average around 5 feet deep. Corn cannot tolerate extreme drought like the prairie grasses which were adapted to these regions. Not only do these roots provide the plants with their water and nutrients, but the roots get broken-down (decomposed) by microbes which releases beneficial nutrients into the soil. So the larger the root system, the more nutrients are going to get released by the microbes and recycled to increase the soils nutrients. What’d I tell ya? The heart of the prairie lies belowground! Now, if we pull out our microscope, we could see trillions of bacteria and fungi swarming along the roots of the plants. Did you know there are more microbes in a teaspoon of soil than there are people on earth?! If there are so many microbes – the roots must be interacting with them! The plants’ roots secrete sugars to feed the microbes and, in turn, the microbes help the plants access nutrients and water, ward off diseases or pathogens, and even increase their growth! Pretty neat partnership, huh? The cool thing is that the prairie plants and their microbes have been growing and evolving together over hundreds of years – they had time to really fine-tune their relationship! Corn, on the other hand, was first brought to the Midwest from Mexico and didn’t have this long legacy of microbial relationship building (co-evolution) and, so, corn was likely not as well-suited to secrete the right sugars to the Midwest prairie microbes. In addition to introducing corn, farmers started to apply fertilizers - and lots of them! Yields increased, and corn production started to dominate the Midwest! However, little did we know that adding fertilizers also affected this cool plant-microbe relationship!1,2 You see, when plants are given the nutrients they need from fertilizers, they don’t need to work with their microbial partners. The ties are weakened and so is the growth, nutrient, and protection benefits that the plants gained from their microbes. Studies have shown that agricultural practices (such as fertilizers and tillage practices) drastically change the microbial communities in the soil.3 This isn’t to say that change is bad – but that it needs to be considered. So often, when we compare the Midwest landscape from the early 1800s to today, we think about the loss of prairies and natural habitat. This is all true – but I encourage us to also think about the belowground connections and habitats that are changing. It was, in fact, the nutrient-rich soil that brought about the Midwest corn belt in the first place, so the soil must not be forgotten. My next blog post will be about how new research and agriculture companies are trying to harness these beneficial plant-microbe partnerships to develop more sustainable agriculture practices! References: 1 - Liu, W., Jiang, L., Hu, S., Li, L., Liu, L., & Wan, S. (2014). Decoupling of soil microbes and plants with increasing anthropogenic nitrogen inputs in a temperate steppe. Soil Biology and Biochemistry, 72, 116-122. 2 - Wei, C., Yu, Q., Bai, E., Lü, X., Li, Q., Xia, J., ... & Han, X. (2013). Nitrogen deposition weakens plant–microbe interactions in grassland ecosystems. Global change biology, 19(12), 3688-3697. 3 - Mbuthia, L. W., Acosta-Martínez, V., DeBryun, J., Schaeffer, S., Tyler, D., Odoi, E., … Eash, N. (2015). Long term tillage, cover crop, and fertilization effects on microbial community structure, activity: Implications for soil quality. Soil Biology and Biochemistry, 89, 24–34.
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AuthorTayler Chicoine - In addition to being a PhD student in Integrative Biology at Michigan State University, I'm a curious, nature-loving plant nerd, who's seeking to understand how plant-microbial interactions can be managed to make this world a better place. ArchivesCategories |