Soil is a natural resource that supports human civilization and plays a vital role in global food security. So, while we may not be ranchers, crop growers or researchers, we all have a vested interest in soil — especially soil health.

Soil health, as defined by a team of researchers in the College of Agricultural, Consumer and Environmental Sciences at New Mexico State University, is “the state of the soil being in sound physical, chemical, and biological condition, having the capability to sustain the growth and development of land plants.”

Rajan Ghimire, a cropping systems agronomist at the Agricultural Science Center in Clovis, put it more simply: “Healthy soil leads to healthy human beings.”

But soil degradation is becoming a growing concern. Worldwide, cropland, forest land, grassland and rangeland areas are declining in productivity due to degrading soil, according to the United Nations. If left unaddressed, soil degradation may affect food production systems that feed the human population.

“We have many degraded soils across the globe that are no longer productive and can only be regenerated to a fruitful state by applying soil health principles,” said John Idowu, an agronomist in the Department of Extension Plant Sciences.

“There has been an increasing demand from stakeholders to know more about soil health,” Idowu added, “and this demand has led NMSU to increase research and Extension efforts on soil health assessment and management.”

Idowu and other ACES researchers have identified several management strategies that will improve soil health. These methods include crop rotation, cover cropping, diversifying production, adding organic amendments, integrating livestock, reducing soil disturbance, using diverse plant species and practicing sustainable grazing.

But before committing to a management strategy, Idowu said, crop and rangeland producers should first assess the physical, chemical and biological attributes of their soil. Soil health management is a long-term strategy that requires education, thinking, planning, reading, discussion and investment, he added.

“Since each farm and ranch is unique,” he said, “the specific soil health practices that will deliver optimal performance will differ from place to place. Farmers and ranchers need to inform themselves and carefully plan an appropriate soil health management strategy that will work for their specific conditions.”

Idowu encourages land users and managers in New Mexico to connect with their local Cooperative Extension Service office when seeking guidance on soil health practices. 

Health and sustainability

In eastern New Mexico, Ghimire is leading research projects that aim to understand the linkages between soil health and sustainable crop production, using soil organic matter as the centerpiece of his research.

“Sustainable agriculture aims to optimize resource use while maximizing crop production, economic profitability and environmental quality,” he said. “Healthy soils provide a foundation not only for better crop production but also for improving environmental quality through reduced soil erosion, improved organic matter and nutrient storage.”

Ghimire is studying how various tillage, fertility, crop rotation, cover cropping and crop residue management practices affect different soil organic matter fractions. He’s also looking at the rate of carbon sequestration, nutrient cycling, greenhouse gas emissions and soil microbial activity related to cycling of essential nutrients as indicators of soil health in grain- and forage-based cropping systems.

In agronomic settings, Ghimire said, soil health is more important in soils that have eroded, have low fertility, or have other less-ideal crop-growing conditions, such as high variability in precipitation and temperature. These conditions exist in New Mexico.

“With the rapid rate of decline in water level in the Ogallala Aquifer,” he said, “producers in eastern New Mexico are facing challenges in irrigated crop production, which include increased fallow frequency, increased erosion, lost soil organic carbon and nutrients, and reduced production potential of the land.”

The soil health management practices Ghimire is studying could reduce such losses and maintain crop production and help farmers stay in business, he added.

“Our study finds a loss in soil organic carbon and nitrogen by 24 percent to 36 percent after the conversion of irrigated crop fields into dryland production, and crop production went down by at least the same proportion,” he said. “The loss of soil organic carbon and nutrients have both agronomic and environmental impacts. The part of lost carbon and nitrogen goes into the atmosphere as CO2 and N2O, potent greenhouse gases that cause global warming.”