Climate resilient plants: Scientists reveal the key lies in the soil

Climate resilient plants: Scientists reveal the key lies in the soil

Since the Climate change threatens the ability of farmers to provide food for the world to produce, researchers and environmental activists believe they have found a solution: playing in the dirt.

They report increasing experimental evidence that improving soil quality can make crop yields more resilient to droughts and extreme weather - and are calling on governments to offer financial incentives to farmers who practice regenerative agriculture to make farmland climate resilient. These practices include the promotion of Soil microbiome – i.e. the microbial community in the soil – by rotating plants between fields and adding “cover crops”. These plants are not necessarily harvested, but they prevent soil erosion and boost nutrients in the soil.

“There are many ripple effects of climate change that are creating challenges for our food system,” says Rob Myers, director of the Center for Regenerative Agriculture at the University of Missouri in Columbia. “The methods to counteract this are biological diversity, more organic matter in the soil – and integrated approaches.”

However, transitioning to such practices requires an initial investment. Researchers and farmers who spoke to Nature confirm that regenerative agriculture works, but it can take a few years for farms to see profits. In the United States, advocates are calling on Congress to include more subsidies for regenerative agriculture in the Farm Bill, a comprehensive legislative package updated every five years that includes funding for disaster relief and farmer training. The most recent version expired on September 30th. Meanwhile, the latest version of the European Union's Common Agricultural Policy came into force last year and included funding for farmers who adopt such sustainable practices.

Floor care

Industrial agriculture typically relies on fertilizers, pesticides and machinery to produce high-yield monocultures – such as corn or wheat. Excessive use of chemicals in these crops disrupts ecological processes in the soil and is a leading cause of water pollution in the United States. Unhealthy soil has difficulty absorbing water or storing nutrients.

An estimated 8,505 million tons of topsoil on U.S. farmland was lost to erosion between 2013 and 2017. The Food and Agriculture Organization of the United Nations warns that more than 90% of the world's soil is at risk of being degraded by 2050; this could lead to an increase in famines.

While regenerative agriculture has no formal definition, scientists who spoke to Nature say its general goal is to rebuild healthy soil. This starts with increasing the amount of organic matter – including living roots and manure – to nourish the soil microbiome and recycle nutrients for plants.

Although the term is modern, the principles of regeneration are ancient. Implementing them represents “a return to some of the practices that we as humanity have relied on for thousands of years,” says Rich Smith, an agroecologist at the University of New Hampshire in Durham.

Cover crops

One practice that is considered regenerative is growing cover crops: planting species that are not typically harvested, such as clover, when the main crop is out of season, rather than leaving the ground unplanted. The roots of cover crops prevent erosion and absorb excess nitrate from fertilizers that would otherwise leach into streams and groundwater. When a farmer cuts back the cover crop in preparation for the next planting of the main crop, it is incorporated into the soil where it feeds the bacteria and invertebrates in the soil and improves soil fertility. In 2022, only about 5% of cultivated land in the United States was under cover crops, but this figure has been increasing; In 2022, cultivation was 17% higher than in 2017.

During a severe drought that devastated corn and soybean crops in the U.S. Midwest in 2012, Myers heard from farmers who said fields with cover crops weren't affected as badly as those without. So he worked with the Conservation Technology Information Center, a nonprofit organization in West Lafayette, Indiana, that promotes conservation in agriculture, and a U.S. Department of Agriculture (USDA) sustainable agriculture program, to create the National Cover Crop Survey. Researcher surveyed around 700 farmers and found that corn yields were, on average, 9.6% higher and soybean yields were 11.6% higher when cover crops were planted in these fields.

This was surprising because “at the time, a lot of people thought cover crops were draining moisture” and not leaving enough for the main crops, Myers said.

The USDA offers subsidies to farmers who use cover crops. Of farmers who participated in the 2022-23 National Cover Crop Survey and received payments for growing cover crops, 90% said they would likely continue the practice after funding ceases.

Appreciate diversity

There is also evidence that crop rotation can improve soil quality and resilience. Growing different crops, rather than growing the same monoculture in the same field for years, can improve soil quality without sacrificing productivity, Smith said.

This can be accomplished by rotating different crops, including cover crops, in the same field over time, or by planting multiple crops simultaneously in the same field, including the “three sisters,” corn, beans, and squash, which have been cultivated by some Native American tribes for centuries.

A review of 20 studies that analyzed the effects of crop rotation on soil life found that multispecies rotation increased the number of microorganisms in soil by about 15% compared to monoculture fields and increased microbial diversity by more than 3% 1. Growing two or more different crops also produces more of the nutrients carbon and nitrogen in the soil than monocultures 2. A review of 33 papers examining fields where legumes and grains were grown together found an increase in the stability of yields from year to year compared to monoculture fields 3, suggesting that biodiverse farms could increase food security.

“Such systems can often be more resilient to weather variations and have improved disease resistance,” says Smith. “The evidence is relatively strong that they maintain, if not increase, returns.”

Innovative incentives

But the shift to regenerative agriculture can take about three years to pay off, say farmers and researchers who spoke to Nature.

Brandon Kaufman, a fourth-generation farmer in Moundridge, Kansas, rotates crops and lets cattle graze the fields in the fall and winter to fertilize the soil. When he started regenerative farming at the industrial farm he inherited, he said, he had “no safety net.” Government subsidies “challenged me to try some things and I gained a tremendous amount of knowledge as a result.”

Federal, state and corporate programs that provide incentives for planting cover crops typically end after farmers make the switch. To support the producers who supply the nation's food and implement these practices over the long term, the U.S. Farm Bill should include a measure to lower insurance premiums for farmers, Kaufman and others say. The USDA tested this idea during the COVID-19 pandemic by offering a $5 per acre insurance discount to farmers who planted cover crops. That federal program has since ended, but the states of Iowa, Wisconsin and Illinois have implemented their own versions.

Farmers can move away from industrial farming practices and toward healthier soil, Kaufman says. “It just takes time” and financial incentives to get producers to change their minds, he adds. This is important because “when you think about your children and grandchildren… where will their food come from in 100 years?”

1. Venter, Z. S., Jacobs, K. & Hawkins, H.-J. Pedobiologia 59, 215–223 (2016).

   Article
   
   Google Scholar

2. McDaniel, M. D., Tiemann, L. K. & Grandy, A. S. Ecol. Appl. 24, 560–570 (2014).

   Article
   PubMed
   
   Google Scholar

3. Raseduzzaman, M. & Jensen, E. S. Euro. J. Agron. 91, 25–33 (2017).

   Article
   PubMed
   
   Google Scholar

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