Soil quality is key to helping some U.S. crops withstand heat stress

Soil’s ability to hold water will be critical in determining how well farms in certain regions of the United States are handling the problem of prolonged heat stress due to climate change, a new study suggests. The newspaper Frontiers of sustainable food systems published the finding, based on analysis of 30 years of data on four major US crops: corn, soybeans, cotton and wheat.

“As farmers face more extreme weather events caused by climate change, they face the growing problem of land degradation,” says Debjani Sihi, first author of the study and assistant professor in the Department of Environmental Sciences. from Emory University.

Sihi is a biogeochemist who studies environmental and sustainability issues at the intersection of soil, climate, health and policy.

Globally, according to Sihi and his co-authors, 750 million people were undernourished in 2019 due to the effects of climate change, including reduced food production, food price increases and competition. increased for land and water. And the problem of global food security is set to intensify. Global agricultural yields are expected to decline by 25% overall over the next 25 years due to climate change, yet global food production is expected to double by 2050 to fuel projected human population growth.

“Keeping soil healthy is a key element needed to adapt to the climate crisis,” says Sihi.

Healthy soil contains microbes that provide the nutrients needed to grow healthy plants, she explains, while also helping to make the plant foods we eat more nutritious. The presence of these microbes also improves the soil’s ability to sequester carbon. According to the Food and Agriculture Organization of the United Nations, the top 30 centimeters of the world’s soil contains approximately twice as much carbon as the entire atmosphere, making soil the second largest sink of carbon. natural carbon after the oceans.

Rising average temperatures, however, are contributing to declining soil moisture in some regions, which can impact agricultural production while degrading soil in the long term.

For the present article, researchers sought to quantify the long-term impact of climate and soil properties on yields of corn, soybeans, cotton, and wheat across the continental United States. They relied on county-level data from the U.S. Department of Agriculture from 1981 to 2015. Their dataset contained precipitation rates and average daily temperature accumulation over the growing season of a crop, called growing degree days. The data also took into account soil variations, including water-holding capacity, organic matter texture (the percentage of sand, silt and clay), pH, slope, erodibility and tolerance to soil loss.

The researchers used an explainable machine learning approach to assess the impact on crop yields of each of these climate and soil variables.

The results identified growing degree days as the most important climatic factor and water-holding capacity as the most influential soil property for crop yield variability.

“The take-home message,” says Sihi, “is that farmers in regions facing additional heat stress to their crops may want to proactively focus on the water-holding capacity of their soil.”

Clay soils and soils rich in organic matter hold water better than sandy soils, she explains. So, farms with sandy soil, or with soils with less organic matter, may want to add more amendments to improve the soil’s water-holding capacity. Another possible adaptation is to use more mulch to reduce evaporation.

The researchers hope their findings will help farmers, land managers and policy makers in making decisions related to long-term, sustainable soil, water and crop management practices.

Study co-authors include Kanad Basu and Abraham Peedikayil Kuruvila of the University of Texas at Dallas; Biswanath Dari from North Carolina Agricultural and Technical State University and Gaurav Jha from Montana State University.

Funding for the work was provided by Emory University, North Carolina Agricultural and Technical State University, and Montana State University.

– This press release originally appeared on the Emory University website

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