Soil Conservation: Methods and Benefits

In the 1930s, the Dust Bowl taught Americans the importance of soil conservation, as drought, extreme heat, and short-sighted agricultural practices led to dust storms smothering much of the Great Plains. In 1935, Congress passed the Soil Conservation Act, establishing the Soil Conservation Service. Farmers were encouraged to plant grasses and crops that returned nutrients to the soil rather than deplete them—part of what we would call today regenerative agriculture.

With the growth of industrial agriculture and the increasing use of fertilizers, however, the lessons of the Dust Bowl have largely been forgotten. A recent study by geoscientists from the University of Massachusetts found that up to 46% of the original topsoil of the Corn Belt has been not just depleted, but completely lost.

The problem of soil loss, however, is a global one—and a global threat. According to the United Nations, without active measures of soil conservation and changes in how we grow food, the world's topsoil could be gone within 60 years.

Soil Conservation Methods

In the United States, the National Resources Conservation Service and the American Farmland Trust conduct soil surveys, support soil conservation programs, and promote agricultural practices that protect both farmland and farmers. Worldwide, organizations like the UN Food and Agriculture Organization (FAO)'s Global Soil Partnership and the World Association of Soil and Water Conservation, oversee efforts to restore productivity to degraded soils and prevent the loss of soil biodiversity.

Many of the methods for conserving soil are those known to farmers from time immemorial. Crop rotation helps prevent soil erosion by returning organic matter to the soil. The planting of root crops is especially destructive of soil structure because it requires deeper plowing. Rotating root crops with grains and cover crops on an annual basis helps preserve soil structure as well as the subterranean organisms that call it home.

Avoiding plowing altogether through no-till farming reduces evaporation and erosion, allowing soils to retain their organic matter and moisture. Buffer strips of deep-rooted natural vegetation growing between waterways and crops can help maintain river banks. Integrating livestock or crop farming with other agricultural practices like forestry or orcharding can use the deep roots of trees to maintain soil, retain moisture, and prevent erosion. And contouring or cross-slope farming, where rows of crops are grown around or perpendicular to the slope of a hill, reduces runoff and erosion—something rice farmers have known for centuries.

What We Don't Know, We Can't Protect

One-quarter of all species on Earth live in the soil, with some 170,000 species of soil organisms having been identified. More than 5,000 different kinds of creatures can be found in a single handful of soil. Yet nature conservation efforts focus primarily on land- and ocean-based flora and fauna, with little attention to soil conservation.

Making soil biodiversity a greater part of the UN Convention on Biological Diversity will focus more attention on the problem. Soil scientists recently launched Soil Bon, the Soil Biodiversity Observation Network, to measure essential biodiversity variables within the soil. The Global Soil Partnership of the FAO has also helped increase awareness of biodiversity loss. Fortunately, a “wealth of new scientific, technical and other types of knowledge relevant to soil biodiversity” has been published in the past two decades, culminating in the 2020 publication of the FAO's State of Knowledge of Soil Biodiversity. Now, what is needed is to incorporate that knowledge into conservation programs.

Benefits of Soil Conservation

Soil quality depends on a healthy, diverse ecosystem above ground. Plant biomass is the main source of energy for nearly all terrestrial life, including the many species of fungi, bacteria, worms, insects, nematodes, and other living organisms below ground. Maintaining plant biodiversity “in the face of environmental change is fundamental for maintaining terrestrial ecosystem functioning.” Soil conservation depends on ecosystem protection.

Yet, biodiversity below ground is also key to healthy ecosystems above ground. Indeed, their mutual relationship may even be at the origins of land-based plants. Without a diversity of life, soil is susceptible to erosion from water and wind, “one of the most serious threats facing world food production." Good quality soils also help regulate the climate by absorbing carbon dioxide, purifying groundwater, keeping soil-borne pathogens at bay, and lowering the incidence of human respiratory diseases caused by wind erosion. Soil conservation is one of the most vital and most often overlooked areas of ecosystem protection.