Story by Carl Wepking
“Why do we engage in the practice of agriculture?” is a central thesis of Mark Bittman’s Animal, Vegetable, Junk: A history of Food, from Sustainable to Suicidal. This not-as-rhetorical-as-you’d-think question is asked from an economic and justice perspective: do we practice agriculture to 1) provide the food, fiber, and materials needed for people to thrive; or 2) to trade commodities on a global marketplace with the goal of squeezing every last dime out of the transaction?
Superficially, this question has an obvious answer – to feed ourselves, duh! After all, that’s what we hear time and time again: American and Midwestern farmers feed the world. And while most of us would agree that it should be the former, it’s undoubtedly the latter. How we settled on this wrong answer, and how to correct course is a fundamental question that we as a society need to reckon with, especially while a new Farm Bill is in the works.
If we’re in agreement that we practice agriculture to provide for one another, here’s the next question: do we need anything else from our agricultural landscapes? Is it just the provisioning of food, fiber, and raw materials? These landscapes, like all landscapes, are multifaceted. Focusing on a single metric – production in this case – has unintended consequences on how a piece of land functions. We need food, sure, but we also need drinkable water, breathable air, and a whole suite of services that are often overlooked. These many services, of which food production is one, are termed ecosystem services, and these services connect to processes and functions that are carried out on a given piece of land.
A team of Grassland 2.0ers decided to poke at this second question. We focused on a handful of farms within the Learning Hubs we’re engaged with and explored the ramifications of a couple common agricultural practices in the upper-Midwest (continuous corn, a corn-soy rotation, and perennial grassland) on a range of ecosystem functions and services. Using simulation models, we compared food-energy production, nutrient retention, and water dynamics across these three scenarios.
Most functions were dramatically improved in the perennial grassland compared with continuous corn. Both nitrate leaching and total phosphorus loss were reduced by roughly 90 percent. Drainage (the amount of precipitation that the soil could absorb) was increased by about 25 percent and evapotranspiration (water loss from the plants on the landscape) was reduced by nearly 30 percent.
The corn-soy rotation performed slightly better than the continuous corn system for the services listed above (nitrate leaching, total phosphorus loss, water dynamics), but both annual systems were generally quite similar compared to the perennial grassland.
On the food front, the corn-soy rotation was no different than perennial grassland for food-energy production. And yes, the continuous corn system did produce more food-energy than the grassland system – corn is quite high energy after all.
These findings point to a couple of key take-homes:
- A focus on production alone comes at the expense of other equally important ecosystem functions
- Across the metrics measured, the grassland system provides the most balanced portfolio of functions and services
Lastly, let’s revisit total phosphorus. Total phosphorus loss numbers are driven in large part by sediment phosphorus loss – which walks hand-in-hand with soil loss. The two annual systems (continuous corn and corn-soy rotation) lose soil. This is not surprising, and much research has shown how much soil has been lost since the plow arrived in the Midwest.
Perennial grasslands on the other hand build soil. Perennial grasslands are why we have rich soils in the upper-Midwest to begin with! Harkening back to Mark Bittman’s subtitle, a history of food from sustainable to suicidal, the current dominant agricultural system quite literally starts a countdown on the number of years of agricultural productivity we have left for a given piece of land, while the perennial one does not. The perennial one has the potential to be regenerative. In other words: no ticking clock, no countdown.
What our agricultural lands can provide (nutrition, clean water, healthy soils, etc.) is so much more valuable to society than the wealth that they can generate through the trading of commodities on a global marketplace. Continuing to prioritize the latter over the former will continue to degrade our agricultural land, and ourselves. After all, caring for the land is caring for ourselves.
Carl is the program manager for Grassland 2.0 based out of UW-Madison. His research has been primarily focused on soil and microbial ecology, soil biodiversity, and the ecosystem services provided by the life in soil. He is interested in how human activities affect soils and their associated functioning, both positively and negatively. Particularly, his research has focused on the unintended consequences of livestock antibiotics and the effect these antibiotics have on soil microbes and the functions they regulate. Carl received his BS in Environmental Science from St. Norbert College and his PhD in Biology from Virginia Tech.