Dr. Rattan Lal, a renowned soil scientist and the 2020 World Food Prize Laureate, spoke recently about agriculture’s role in sequestering carbon to help mitigate climate change.
He also talked about sequestration’s connection with maintaining healthy soil biology in a presentation at Pasa Sustainable Agriculture’s 2021 virtual conference. The webinar, which live-streamed on Feb. 1, was titled, “Leveraging Agriculture’s Best Tool for Climate Mitigation.”
Over several decades, Lal has developed and mainstreamed a soil-specific approach to conserving natural resources and mitigating climate change while increasing food production.
He is a distinguished professor of soil science and director of the Carbon Management and Sequestration Center at The Ohio State University as well as an adjunct professor at both the University of Iceland and at Punjab Agricultural University.
It is Lal’s belief that in addition to socioeconomic factors, food security research must also address environmental and resource management issues. People can’t have clean water or air without clean and healthy soil — but it’s been left out of the trilogy, according to Lal.
“We must think about soil as a bank account,” Lal said, with “deposits” for soil rejuvenation exceeding the “withdrawals” — withdrawals that have led to decomposition, leeching and the depletion of viable topsoil across the globe.
“We must improve, restore and manage resources,” he said.
Humans belong to nature, Lal said, and nature and humans must benefit together. Carbon sequestration, which is the process of transferring carbon from the atmosphere back into the soil, is a vital step to repairing this relationship.
Using a soil and seed-centric approach, repairing and establishing perennial forests, wetlands, prairies, and rangeland, and promoting no-till practices will create an environment that sustains humans, as well as the planet’s multitude of other ecosystems, said Lal.
“My philosophy has been that we should not have most of the land changed from natural to managed ecosystems,” Lal said. That percentage, about 50% natural lands, would maintain a buffer against pollutants, sediments and other degradation of soil.
Lal also spoke of regenerative agriculture, a system-based approach that reconciles the need to produce adequate nutritious food with the necessity of restoring the environment, making farming a solution to environmental issues.
System-based conservation includes no-till farming, mulching, cover cropping, integrated nutrient and pest management, complex crop rotations, and the integration of crops with trees and livestock.
With over 300,000 types of known soils in the world, humans need to study and implement a wide range of land management practices, he said, and there is no “one size fits all” model for such diverse soils and biomes.
Managed grazing, agroforestry, ley farming, fodder trees, silvopasture, and live fences are just a few ways to help put carbon back into the soil.
Organic agriculture is one of many components for these changes, Lal said, but not necessarily the answer to these worldwide concerns.
“Thou shall never do this,” is not the purist vision he sees as solving all of these problems. He doesn’t believe that putting restrictions on agriculture — considering the needs of a global community, especially where population density is high and soil is degraded — will solve food security, if current population projections remain accurate.
A soil’s organic matter remains key to building and maintaining healthy soil, particularly in terms of water retention. Lal’s experiences in 1971 in Nigeria determined that a no-till rotation from corn to beans with crop residue remaining left no runoff, even on a 15% slope.
Crop residue retention was important, and compensating with fertilizer didn’t compare when the crop residue was taken away. In one of his long-term experiments, a field of no-till corn with 100% residue left in the field over several decades, the soil became climate-change-resilient and held up during a massive 2012 drought.
When farmers consider the nutrient levels CNPK of their fields (adding in carbon as a focus to the traditional NPK concerns) their dependence on chemicals decreases, soils build high biodiversity, and the soils themselves become more disease-suppressant.
A Soil Act is needed, said Lal, one that is pro-farmer and pro-nature, with ways to compensate farmers who take risks with alternative land-management practices. At the same time, healthy, safe and adequate food supplies need to be produced to quell malnourished populations worldwide.
“The agriculture and forestry sectors hold the potential to serve as a critical climate solution,” he said.
The societal value of a soil’s organic carbon count must be measured, he said, and payments to farmers for this service by ecosystems services will propel this movement forward. The Growing Climate Solutions Act of 2020, which was introduced to the U.S. Senate by a bipartisan group of senators, is a step in the right direction, said Lal.
“I think it was most important that Dr. Lal’s decades of field research lead to the conclusion that healthy living soils are essential for clean air, water and food,” said Eli Stogsdill, a Northampton County farmer who participated in the webinar. “As a species, we won’t survive without it. At the very least, this must be incorporated as the foundation of farm policy and compliance with clean air and water acts.”
Many of the concepts Lal has studied and promotes are embedded deep into civilization. And, with better land management to build soil capacity, he predicts that hundreds of gigatons of carbon could be taken out of the atmosphere and put back into the Earth’s soils.
Optimistically, if 2-1/2 gigatons were sequestered in soil annually, problematic atmospheric carbon could be mostly sequestered by the end of this century.
But, at the current rate that soil is being degraded, humans can’t undo this damage unless alternative energy sources are pulled to the forefront.
“I hope it can be done,” Lal said.