Soil degradation affects one-third of the Earth’s surface, triggering dust storms, floods, and landslides. It is also a global threat to our food supply, and diminishes the soil’s ability to sequester carbon to mitigate climate change. China has only 0.21 hectares of agricultural land per person, which is well below the global average. Worse yet, over 40 percent of that land is already degraded.  

The need to protect soil is the focus of World Soil Day held every December 5th. At Ohio State University (OSU), the 2022 annual observance featured a discussion with Rattan Lal, 2020 World Food Prize winner, who reminded attendees that “soil is where food begins.” I first met him when we both joined the OSU faculty in the mid-1980s, and we share the view that soil acts as a bank account of sorts. Before we can withdraw environmental services from the earth, we must first provide the nutrients, organic matter and protect soil from compaction and pollution. 

Lal’s career demonstrates his powerful commitment to these issues, especially as they play out in the world’s largest agricultural nations: China and the United States. Themes of conservation agriculture and the role of soils in sustainable development shine through in his 1,000+ scientific articles.

Carbon Management and Sequestration

Lal’s humble beginnings growing up on a small farm in what is now Pakistan helped lead him to become an expert in this field. He first studied at the Punjab Agricultural University in Ludhiana, India, and while he was encouraged to study soil science by one of his professors, Lal did not need much convincing. As a farmer, he already knew how important it was to invest in improving the soil during good years to develop its capacity to provide food during bad years. 

Take Lal’s thoughts on the important topic of carbon sequestration. During a China Environment Forum Green Tea Chat, he noted that soil is the largest terrestrial source of carbon in the biosphere. Thus, carbon sequestration in soil is an important opportunity in sustainable development, as shown by a special report from the Intergovernmental Panel on Climate Change, which estimates that plants nurtured on even degraded soils could remove 63 billion tons of carbon from the atmosphere. As plant material decomposes, it recarbonizes the soil. Once healthy, soils retain this carbon and keep it underground and out of the atmosphere. 

As people use soil for agriculture and urban development, carbon escapes to the atmosphere. Chinese agricultural soils, for example, have lost about half of their stored carbon. Worldwide, soils have released about 133 billion tons of carbon.  

Conservation Agriculture is Needed

Cropland degradation is especially severe in China. Each hectare of farmland that is polluted by heavy metals, compacted by construction, and desertified due to poor water management and overgrazing has lost the ability to remove 12 kilograms of carbon from the atmosphere every year. This is a triple loss, damaging food production, the atmosphere, and the climate. To compensate for lost productivity, farmers increased nitrogen fertilizer application fourfold, increasing the risk of water pollution and emissions of nitrous oxide, a powerful greenhouse gas. 

In CEF’s Green Tea Chat, Lal zeroed in on how practicing conservation agriculture could reverse these soil degradation trends. Healthier soils can better store carbon and reduce nitrous oxide emissions. The five pillars of conservation agriculture are:

• Land is not tilled.
• Cropland is always covered with plants and/or crop residues. 
• Farmers follow a complex crop rotation, with cover crops planted in off-season.
• Crops are integrated with trees and livestock.
• Farmers practice integrated soil fertility management beyond just fertilizer application. 

Some farmers in China started practicing conservation agriculture in the mid-1980s. Yet, sadly, further adoption of these practices has been slow. In China, only 8 million hectares were using conservation agriculture in 2016 — a total that represents approximately the land area of South Carolina. 

Globally, conservation agriculture is only practiced on about 15 percent of total cropland, mainly in North and South America. Similarly, the use of conservation agriculture in the United States is not yet robust. One encouraging sign is that the U.S. Department of Agriculture estimates 40 percent of U.S. cropland is not tilled, and farmers leave crop residue on the ground through the winter. Taking the next step to plant a winter cover crop that can take carbon dioxide from the air and move it into the soil has not been widely adopted. It is only practiced on about 2 percent of U.S. cropland.

Improving Soil Health: A Call for Action

Lal’s soil science and carbon management activities are not limited to the academic sphere. He is also working to change policy. In 2015, for instance, Lal worked with the French Minister of Agriculture to formulate the “4 per 1000” initiative for food security and climate, proposed at the Paris climate summit (COP21). 

Since the soil already contains double to triple the amount of carbon found in the atmosphere, the initiative is key to the goal of making soil healthier. It seeks to support conservation agricultural practices by increasing the amount of carbon stored in the surface layer of soil by 0.4 percent per year (that is 4 parts per 1000). 

The “4 per 1000” initiative is considered a win-win to help stabilize carbon in the atmosphere while also ensuring sufficient food for everyone. In China, the potential for soil carbon sequestration is enough to offset 25 percent of the country’s annual fossil fuel emissions.

Lal has seen that conservation agriculture is not the same for all regions, or for all crops. Site specific recommendations are needed, requiring an army of agricultural specialists to work with farmers to tailor their conservation practices. If the work is not done carefully, crop yield might suffer, or air and water pollutants could be discharged from the soil.

In poverty-stricken areas of the world, added Lal, the soil mirrors the image of the people. If people in a particular place are desperate and starving, they pass on their suffering to the soil — and it reciprocates. Thus, it is critical to instill respect for the soil natural resource through practicing agroecology and adopting regenerative agriculture.

Lal pointed out in the Green Tea Chat that in the United States, the 1967 Clean Air Act and the 1972 Clean Water Act were a good start to improve environmental quality. To ensure agricultural sustainability, however, the United States needs to pass the Healthy Soil Healthy Climate Act (introduced in the U.S. Senate in 2020) to reward farmers for improving soil quality and sequester carbon. 

The world cannot sustain clean air and water without healthy soil. It is encouraging that the European Parliament is considering a similar act, and farm and business groups hope that the next U.S. Farm Bill considered by the Congress will also address this issue.

The next World Soil Day is December 5, 2023, a date that aptly coincides with COP28 in Dubai. Lal’s research shows that soil can definitely serve as a reservoir for carbon. Now is the time to start not only planning a celebration of healthier soil—but also taking action to make it a reality.

This blog is part of a new China Environment Forum-The Ohio State University project Cultivating U.S. and Chinese Climate Leadership in Food and Agriculture.