CANADIAN, Texas – Adam Isaacs was surrounded by cattle in an old pasture that had been overgrazed for years. It was now a mess of weeds.
“Most people would like to go out here and start spraying it” with herbicides, he says. “My family did that. It does not work.
Instead, Mr. Isaacs, a fourth-generation rancher on this hilly land in the northeast corner of the Texas Panhandle, will put his animals to work on the pasture, using portable electrified fences to confine them to a small area. so they can’t help but trample some of the weeds while they graze.
“We let the cattle trample a lot of things,” he says. This adds organic matter to the soil and exposes it to oxygen, which will help grasses and other more desirable plants take over. Eventually, with continued careful management of the pasture, the pasture will become healthy again.
“These cows are my land management tool,” said Isaacs. “It is much easier to work with nature than against it.”
His goal is to turn those 5,000 acres into something closer to the lush mixed grass prairie that thrived in this part of the Southern Great Plains for millennia and served as pasture for millions of bison.
Mr. Isaacs, 27, runs a cow-calf farm, with several hundred cows and a dozen bulls producing calves which he sells to the beef industry after weaning. Improving his land will benefit his business, through better grazing for his animals, less loss of soil and nutrients through erosion, and better water retention in an area where rainfall does not exceed in average only 18 inches per year.
But healthier ranches can also help the planet by sequestering more carbon, in the form of roots and other plant tissue that used carbon dioxide from the air for their growth. Storing this organic matter in the soil will prevent carbon from entering the atmosphere in the form of carbon dioxide or methane, two major contributors to global warming.
With the Biden administration offering to pay farmers to store carbon, soil sequestration has gained popularity as a tool to fight climate change. Done on a large enough scale, proponents say, it can play an important role in limiting global warming.
But many scientists say this claim is exaggerated, that soils cannot store nearly enough carbon, over a long enough period of time, to have a significant effect. And measuring carbon in soil is problematic, they say.
The soil improvement practices followed by ranchers like Mr. Isaacs are called regenerative grazing, part of a larger movement known as regenerative agriculture.
There are no clear definitions of the terms, but regenerative agriculture techniques include minimal or no tillage, crop rotation, planting crops to cover and benefit the soil after harvesting the main crop. , and greater use of compost rather than chemical fertilizers. .
Regenerative grazing means closely managing where and for how long animals feed, unlike a more conventional approach in which animals are left to graze more or less continuously on the same pasture. Pastoralists also rely more on the manure of their animals to keep their pastures healthy.
These practices are spreading among farmers and ranchers in the United States, spurred by environmental concerns about what industrialized agriculture and meat production have done to the land and agriculture’s contribution to global warming. In the United States, agriculture accounts for about 10 percent of greenhouse gas emissions.
Agri-food companies and large food producers are launching initiatives to encourage regenerative practices, as part of efforts to attract consumers concerned about climate change and sustainability.
And the Biden administration, in its early action to tackle climate change, cited agriculture as a “backbone” of its strategy. One idea is to allocate $ 1 billion to pay farmers $ 20 for each tonne of carbon they trap in the soil.
Proponents of regenerative agriculture have at times made extravagant claims about its potential as a tool in the fight against global warming. Among them is Allan Savory, a farmer from Zimbabwe and a leader of the movement, who in an oft-cited 2013 TED talk said he could ‘reverse’ climate change.
Some research has suggested that the widespread implementation of regeneration practices around the world could have a significant effect, storing up to 8 billion metric tonnes of carbon per year in the long term, almost as much as current annual emissions. from burning fossil fuels.
Although there is a large consensus that regeneration techniques can improve soil health and provide other benefits, some analysis has revealed that the potential carbon sequestration figures are vastly overestimated. Among the critics, the researchers point out that short-term studies can show large increases in soil carbon, but that these gains decrease over time.
“It’s really great to see the private sector and the US government take seriously reducing agricultural emissions,” said Richard Waite, senior researcher at the World Resources Institute, an environmental research organization in Washington. But for carbon sequestration in soils, the institute’s analysis suggests that “the opportunities for mitigation are rather modest”.
Focusing on soil carbon sequestration also risks drawing attention to other important ways to reduce agriculture’s carbon footprint, Waite said, including improving productivity, reducing deforestation and shifting food consumption towards more climate-friendly diets.
Jason Rowntree, a Michigan State University researcher who served as a science advisor for five years for an institute founded by Mr. Savory, said that while regenerative grazing “creates a cascade of good things,” his research and that of others have shown the amount of carbon sequestered can vary widely by region, affected largely by the amount of precipitation and nitrogen available in the soil.
“Based on the amounts of these products where you are, the ability to produce carbon can change dramatically,” he said. “It must be considered in a localized context.”
Additionally, Dr Rowntree said, using soil carbon as a basis for judging agriculture’s contribution to tackling climate change could be problematic because it is difficult to measure. As a metric, he said, “carbon is probably the worst we can find.”
Tim LaSalle, former executive director of Mr. Savory’s institute that later co-founded a sustainable agriculture program at California State University, Chico, said he viewed the movement as “a shift in vision for soil. and its potential ”.
“And this is where the science is lacking,” he said, arguing that most research focuses on one or two factors without considering the entire complex plant-soil system.
Dr. LaSalle and his colleagues are collecting research data that shows the benefits of regenerative practices, including field trials using compost inoculated with fungi and other microbes that reduces or eliminates the need for chemical fertilizers.
“We need to disseminate the data so that people understand better what is going on,” he said.
Mr. Isaacs, who studied ranch management at Texas Tech University and worked for two years for the Natural Resources Conservation Service of the US Department of Agriculture, performs measurements and analyzes to assess the effectiveness of His efforts.
“We do a lot of surveys,” he said, taking photos and samples to determine microbial activity in the soil, how well plants grow and how the mix of species changes. “That way you can see the trends,” he says. “When you’re here everyday it’s hard to see what you’re doing.”
It is certain that it builds more carbon in the soil and thus benefits the climate to some extent. But from a walk around his ranch, it’s clear that a great source of pride is the visible improvements he sees in the country.
Stopping in a pasture on his way back to the ranch house he shares with his wife, Aubrie, he pointed to a gentle slope with a mixture of vegetation.
As with other pastures on the ranch, Mr. Isaacs used his electrified fence to graze his cattle on small plots here for short periods – 200 head, perhaps, eating and stomping in a space no larger than a suburban owner. back yard for as little as half an hour. Moving the fences along the pasture to new plots allows the grazed land to regain time.
“That’s what the bison did,” he says. “They came in a million at a time, crushed everything and moved on to new pastures. And they wouldn’t come back until it’s time to graze again.
The work requires planning and frequent movement of livestock. But Mr Isaacs is helped by the technology – he uses a small drone to help keep the animals, and is investing in devices that will lift the fence gates on command from an app on his phone.
Cattle make a single pass through much of the ranch in the winter, preparing the land for spring growth. Other passes follow in spring or summer, the number depending largely on precipitation.
“In the spring, the forage grows really fast, so we turn the cows around the ranch very quickly,” Isaacs said. “As the summer progresses and it gets warmer and the growth slows, we slow down the cows.”
Mr. Isaacs noted several tall grass species growing among the smallest on the slope. Intensive grazing and scavenging has helped these tall grasses come back, he said, and cattle are devouring them. “During the growing season it’s as good as it gets,” he says.
“As I do better for the soil, it gradually gets better and better and you grow more grass,” Mr. Isaacs said. “And the more you grow more grass, you get better soils.”
“It never ends.”