ISU researchers explore the effects of biochar on downstream ecosystems

Eric Debner

Biochar may be a next-generation soil amendment utilized by farmers to increase agricultural productivity. 

While this biorenewable solution has potential for commercial use in the near future, there are aspects and variables that could be further explored to improve the capabilities of biochar.

Lori Biederman, adjunct assistant professor of ecology, evolution and organismal biology, and William Harpole, assistant professor of ecology, evolution and organismal biology, received a grant from the ISU-based Leopold Center for Sustainable Agriculture to experiment and research the effects of biochar on a restored native prairie plant species in Western Iowa. Harpole said the experiment will explore the downstream ecosystem impacts of biochar on native plants and biodiversity.

Biochar is a byproduct of a process called pyrolysis, that essentially turns biomass, such as corn stover and switchgrass, into a renewable source of energy. 

Harpole said biochar can be used as an additive to help strengthen soils by adding water retention properties and nutrients such as phosphorus, which helps farmers increase their crop yields.

“Biochar has been promoted as a win-win-win solution,” Harpole said. “You get energy, you improve soil conditions and increase crop yield.”

Harpole said this ideal scenario creates a fourth question: the environment. Is that a win, or is that a loss?

When applied to the landscape, Harpole said biochar is susceptible to erosion and win that can carry it into neighboring ecosystems. Harpole said some studies have shown that up to 50 percent of biochar can be transported away through erosion or wind.

“We have to be careful of protecting our buffers and understanding how biochar affects the perennial systems that are right next door to annual crops,” Biederman said. “[Biochar] blows everywhere, and can very easily end up in places where it was not applied.”

Biederman and Harpole conducted a process called meta analysis in which they collected all the published information on biochar experiments and put it into a data table. Harpole said most of the data showed biochar has, on average, positive effects with plant growth.

“It also points out what we don’t know,” Harpole said. “We don’t have much information about the impacts of [biochar] on downstream ecosystems.”

Harpole said the effects of biochar could play out in a number of ways. If biochar is beneficial for agricultural systems, then it could also benefit natural systems. Harpole said an alternative situation is biochar could negatively affect native plant species but positively affect exotic weedy species.

One aspect of downstream ecosystems that Biederman and Harpole want to explore is the effect biochar has on perennial plants compared with annual plants. 

Biederman said perennials are plants that persist for many growing seasons while annuals perform their entire life cycle, from seed to flower to seed, within a single growing season. Biederman said annual plants typically fared better in biochar-treated soils than perennials.

“There’s something about being a perennial and annual plant that makes them react differently to biochar,” Biederman said. 

It is important for researchers to investigate all aspects of biochar before applying it onto the field, to better understand how biochar affects the perennial systems right next door to annual crops.

“More information helps us make better decisions about how we use our landscape and what we’re trying to conserve and promote,” Harpole said.