Researchers examine role of perennial crops, other practices on climate resilience

Candace Krebs
Special to Ag Journal
Hardy native sunflowers are one of the perennial crops under development at the Land Institute in Salina, Kansas. Planting perennials is a way to minimize soil disturbance while maximizing soil surface coverage and root activity. The nonprofit Land Institute was founded by ecologically minded plant geneticist Wes Jackson in 1976.

A rash of natural disasters, including wildfires, hurricanes and a historically early ice storm, backlit by a contentious election season, are keeping climate change in the headlines, even as agricultural researchers and land managers are working to clarify its impact and determine how agriculture can be part of the solution.

The Climate Adaptation Research Center at the University of California-Davis hosted a series of thought-provoking webinars this fall, which covered everything from forward-looking practices to the role of public policy. The panels included at least two prominent scientists from the Mountain-Plains region.

Nathan Mueller is an assistant professor of ecosystem science and sustainability in the department of soils and crop sciences at Colorado State University, where he studies vulnerabilities and potential adaptations related to climate variability.

Most of the negative consequences of global warming on agriculture appear to be the result of indirect impacts, he said.

“When we look at warming, we do see some negative impacts on almond and walnuts, but then surprisingly a lot of other crops are pretty insensitive to warming,” he said. “This could have to do with the role of irrigation, and that does get us into looking at the sustainability of water supplies.”

“In the future we could be seeing much more runoff occurring when we don’t want it and less when we do want it,” he continued, noting that Colorado and California’s San Joaquin basin are two regions most at risk.

While most major crops don’t demonstrate a strong temperature response, some crops are sensitive to changes in ozone exposure, with grapes serving as a prime example.

“The ozone result is pretty interesting,” he said. “This shows us that continued air quality improvement could be an opportunity to increase yield.”

Monitoring production at dairy operations shows they are adapting to moderate climate shifts and even experiencing a net positive effect in northern states, he added.

Still, there’s a lot to consider beyond temperature itself, including changes in pest populations, risk of late and early freezes, water supply variability and the impact of heat stress, wildfire smoke inhalation and poor air quality on worker health and safety.

Mueller was joined on the panel by Carl Evers Jr., chief operations officer for Hancock Natural Resource Group’s western region, who talked about how the land management company is investing in “climate resilient agriculture.”

Snowpack is the region’s largest reservoir, he said, a recognition that led his company to experiment with recharging underground aquifers during periods of excess runoff and installing automated precision irrigation to optimize water use. He also predicted the push for electric vehicles in California will eventually lead to wider adoption of electric-powered tractors and machinery too.

Improving soil health is widely seen as one of the best ways to improve agricultural resiliency while preparing for an uncertain future. Tim Crews, director of research and lead scientist in the ecology program at the Land Institute, based at Salina, Kansas, outlined why perennial crop development could be a valuable tool.

The Land Institute has invested decades researching and developing several perennial crops, including a short-statured, deep-rooted sunflower native to the Great Plains (sometimes referred to as rosinweed) and Kernza, an intermediate wheatgrass that produces small grains. Scientists there are also experimenting with mixed cropping, such as inter-seeding alfalfa into Kernza to reduce the need for nitrogen fertilization.

Perennial cropping systems allow practitioners to hit all of the key soil health principles at once, including minimizing soil disturbance, keeping the soil covered and living roots growing, and diversifying plant populations, Crews said.

Studies show that carbon sequestration benefits do accrue from perennial plantings.

One study showed very substantial carbon accumulation in the soil during the first two years Kernza was planted, with slower but still significant additional sequestration over the following years. In fact, the soil underneath the Kernza crop stored an additional ton of carbon compared to annual grains, Crews said.

“We need to think about changing agriculture from a source to a sink of greenhouse gases,” he said.

The obvious question is whether perennial crops produce high enough yields to make them economically feasible. A plant typically puts energy into its roots at the expense of the seed that makes the grain. Crews said there were other tradeoffs to consider.

“An important exception to make is that perennials have much longer growing seasons,” he said.

With more total photosynthesis to work with over time, perennial crops can be competitive. He cited work being done in China, where a new perennial rice nearly matches the yields of annual rice after just six harvests.

With perennial wheat, “there’s a lot of potential photosynthesis occurring during a time when the ground is typically bare,” he explained. “And with the modern breeding tools we have, we can get there in decades as compared to the time it took to develop the crops we currently rely on.”