The benefits of soil health practices — such as no-tillage, cover crops and biodiversity — have long been studied and promoted. But a new study of their effects on hydrologic processes sheds light on how soil management can mitigate the negative effects of climate change and severe weather.

Sequestration of carbon through soil management can help offset climate change, but new assessments goes well beyond that important factor, experts say. It focuses on how soil health regulates the movement of water.

“One of the driving factors that influences soil hydrology in terms of soil health practices is its influence on soil organic matter, which in turn increases the ability of soil to retain water,” said Briana Wyatt, assistant professor of soil physics and hydrology at Texas A&M University and chairman of the Council for Agricultural Science and Technology’s task force.

Increased infiltration

Soil health increase aggregate stability, which influences soil structure. Improved soil structure reduces soil loss due to rainfall, increases water infiltration in the soil and reduces the amount of surface runoff — keeping rain where it falls, she said.

“Once that water infiltrates into the soil, it continues to be redistributed throughout the soil profile. Typically, soil health practices lead to a lower bulk density and a greater water-holding capacity,” she said during a CAST webinar on Thursday

Soils are one of the largest reservoirs of fresh water on Earth. But the impacts of climate change and rising temperatures has significant impacts on the hydrologic cycle, she said.

Those include an expected increase in evapotranspiration, as well as an expected increase in precipitation intensity and variability and surface runoff — including flooding. The impacts also include an expected decrease in soil water storage and groundwater recharge.

“All of these things interact together to result in a decrease in the amount of water that’s available for plants, both native plants and agricultural crops,” she said.

Natural disasters

“We also expect to see an increase in the occurrence and the severity of natural disasters like severe weather, drought and floods,” she said.

Since about the year 2000, the number of major, costly disasters in the U.S. has increased significantly, and this has serious impacts, she said.

While certain areas of the world might become more suitable for agriculture, overall agricultural productivity is expected to decline, she said.

“The world’s three major food crops, that is maize, wheat and rice, are all expected to see yield declines in the future. Similarly, corn, soybean and cotton yields are expected to decrease anywhere from 30 to 82% depending on the level of warming,” she said.

Increased disease and pest pressure as well as livestock heat stress are also expected, she said.

“But there is still hope. There’s potential for these soil health practices to help us mitigate some of these negative impacts of climate change,” she said.

Organic matter

For example, 1 acre-foot of soil can hold an extra 16,500 gallons of plant-available water for every 1% increase in soil organic matter. So properly managing soils will increase organic matter, helping soil to store more water, she said.

There are economic and social implications of not adopting soil health practices. The cost of poor soil health on global food production has been estimated to range from $15 billion to $40 billion a year. The estimated cost of soil degradation on agricultural production, impact to infrastructure and reduced air and water quality is estimated at $3 trillion every year, she said.

The study also explores the impacts of urbanization, infrastructure and manipulation of historical hydrologic flow paths and assesses the role of the private sector and governments in incentivizing soil health practices.