In April and May, Northeast China enters its spring planting season. Farmers rush to plant rice and sow seeds in their fields, their busy pace continuing from the early spring preparations. "The hardworking farmers' spring plowing has transformed the soil from black to yellow," Fang Jian captured in mid-March, capturing scenes of plowing and straw burning. While traveling from Taiwan to Northeast China to promote the "Small Farmers Planting Carbon" project, he also witnessed warning signs of soil degradation.
Food is a vital global strategic resource. Amidst recent tariff wars and geopolitical pressure, China has been actively upgrading its food security initiatives. In early March, it announced an expansion of its agricultural reserve budget and raised its 2025 grain production target to 700 million tons, significantly higher than the 650 million tons set for 2024. The goal is also to reach 745 million tons by 2030. At the end of March, China released a new agricultural development blueprint, aiming to build 90 million hectares of high-standard farmland by 2030, a major step toward strengthening food security.
Northeast China is a vital grain-producing region in China, accounting for one-fifth of the country's arable land and producing a quarter of the nation's grain. Soil is considered the lifeblood of grain production, and as Northeast China's black soil gradually turns to loess, achieving grain production targets becomes increasingly challenging.
Soil degradation is an issue of international concern, especially in Northeast China, which is one of the three largest black soil regions in the world," said Chen Zunxian, professor emeritus of agricultural chemistry at National Taiwan University. In 2017, he was invited to the Harbin Academy of Agricultural Sciences and the Harbin Institute of Soil and Fertilizer to participate in a forum on soil organic carbon. "At that time, we discussed the significant decline in black soil fertility and organic carbon. After the meeting, we also visited the Wanmutian experimental area."
Opening the "Northeast Black Soil White Paper" released by the Chinese Academy of Sciences in 2021, it is found that in the past 60 years, the organic matter content of the cultivated layer of black soil in Northeast China has dropped by one-third, and in some areas it has even dropped by 50%. Moreover, the thickness of the black soil layer in some local areas has dropped from 60 to 80 cm in the 1950s to the current 20 to 40 cm. This series of figures means that the black soil has become "thin" and "thin", and its productivity has been greatly reduced.
The topsoil is the most fertile soil layer containing the most organic matter. Chen Zunxian pointed out that the topsoil 30 centimeters thick accounts for about 50% to 60% of the total carbon stock or soil fertility at a one-meter profile depth, and the topsoil 50 centimeters thick accounts for about 75% of the total carbon stock or soil fertility. In other words, the most fertile part of the entire soil layer is the topsoil 30 centimeters deep.
"Internationally, the extent of black soil degradation is assessed by soil erosion rate and soil carbon content or storage. These three indicators have all decreased significantly in Northeast China," said Chen Zunxian, who further analyzed data from the Black Soil White Paper. "Over the past 60 years, nearly 40 centimeters of topsoil have been lost. This translates to approximately 88 tons of topsoil being removed each year. Internationally, this is considered a severe level of loss."
Chen Zunxian referred to the book "Black Soil of Northeast China" published by China Agricultural Press in 2017. The book mentioned that the organic carbon content of the cultivated layer of the Northeast black soil is about 4%, and the total carbon storage of 30 cm thick topsoil is about 144 tons. In the past 60 years, organic carbon has decreased by 30%. In this way, about 0.72 tons of carbon are lost per hectare each year, and the loss of carbon stocks is quite serious.
Soil carbon storage not only helps mitigate climate change but also helps ensure food production. As early as the 2015 UN Climate Change Conference, the "4/1000 Initiative" was proposed, aiming to offset annual human carbon dioxide emissions by increasing soil organic carbon content by 0.4% annually. "To achieve the 4/1000 target, an increase of approximately 1 to 2 tons of organic carbon per hectare per year would be sufficient," Chen Zunxian explained. "However, the organic matter content of the topsoil of Northeast China's black soil has decreased by one-third, to approximately 0.72 tons per hectare per year. Therefore, under these conditions, soil carbon storage is unlikely to increase."
Three years ago, Fang Jian, Chairman of the Green Consumers Foundation, threw himself into the "Small Farmers Planting Carbon" project, actively responding to the "0.4% Initiative" - planting carbon back into the soil. This is also the world's first project to officially enter the international certification of soil organic carbon reduction. He started in Taiwan and gradually expanded to Ishikawa Prefecture on the Noto Peninsula in Japan and Wuchang City in Heilongjiang Province, China.
From last autumn to this year's spring plowing season, Fang Jian traveled extensively across Northeast China collecting samples from the black soil, conducting a baseline survey. "The organic matter content in the soil varies greatly, ranging from high to low." He observed this variability in his initial sampling. "In the same plot, we might measure 3% or 6%, but there's a lot of uncertainty."
A team of experts from the Chinese Academy of Sciences pointed out that "irrational reclamation and farming are the main causes of black soil degradation." Since the 1950s and 1960s, the development and utilization of the black soil in Northeast China has accelerated, from the "Great Northern Wilderness" to the "Great Northern Granary". In 2005, the sown area of grain crops was about 19.1 million hectares, and in 2021 it increased to 28.66 million hectares, an increase of more than 50%.
However, long-term high-intensity development has caused the soil fertility to be continuously weakened. Relevant research shows that corn yields show a clear downward trend as the thickness of black soil decreases. For every 1 cm of topsoil eroded, corn yields per hectare decrease by 123.7 kg.
"I visited their experimental fields and saw their actual operations. The farming machinery and equipment were enormous, operating like a vast army across the vast expanse of Beida Cang, and almost all of it was fully automated," said Chen Zunxian, discussing the large-scale modern agriculture in Northeast China. "Lower corn yields indicate significant topsoil loss, so soil and water conservation management is crucial."
Furthermore, the large-scale reclamation of arable land can exacerbate the development of gullies. A 2019 study published in the Journal of Geography found that gully erosion in Northeast China's black soil region is becoming increasingly severe, with erosion occurring fastest and covering the largest area on cultivated land. Chen Zunxian warned that sloping land is also a deadly threat to black soil, exacerbating erosion during heavy rains.
Straw residues leaving the fields are a common phenomenon in the area. "I asked why these crop residues couldn't be returned to the fields, and they told me there were two reasons. One is that corn stalks are very thick and large, and returning them to the fields would affect subsequent planting," Chen Zunxian said with deep emotion. "Another reason is that farmers take the corn stalks away and sell them to coal producers, where they can be used as fuel, which directly benefits the farmers."
Chen Zunxian explained that the weight ratio of corn kernels to crop residue is 1:1, meaning that for every 10 tons of corn harvested per hectare, 10 tons of crop residue will also be present. These crop residues protect the soil and also serve as fertilizer, generally providing about 180 kilograms of nitrogen fertilizer, 90 kilograms of phosphorus fertilizer, and at least 50 to 60 kilograms of potash fertilizer. When you remove them, you also remove organic carbon, nitrogen, phosphorus, and potassium nutrients.
He took the black soil area along the Mississippi River in the United States as an example. There were also problems with soil erosion and reduced yields, especially after the flood, when soil erosion was severe. Later, farmers harvested corn and chopped the corn stalks at the same time, returning them to the soil. This served as a good soil protection and nutrients could also return to the soil.
Can fertilizer enrich black soil?
"Modern agriculture strives for maximum yield, but does maximum yield ultimately translate into maximum value? You might have excellent yields for the first five or ten years, but then you'll have to rely on heavy fertilizers and pesticides to maintain them." Fang Jian points out the vicious cycle of overuse of land. "Excessive fertilizer use acidifies the soil, and crop quality deteriorates because more organic matter adds flavor to your crops."
According to statistics, fertilizer use in Northeast China increased by 62% from 4.57 million tons to 7.42 million tons between 1980 and 2021. However, excessive fertilizer use can harm the soil, exacerbating farmland degradation and reducing farmers' income from growing crops.
Wuchang is known as the producer of China's finest rice, earning it the nickname "the aristocrat of rice" for its high value. While interacting with farmers, Fang Jian heard about their problems: "The original aroma of Wuchang rice doesn't seem as fragrant as it used to be, and the taste isn't as good as it used to be."
In recent years, farmers in Northeast China have also found that the roots of corn and soybeans are not deep enough in the soil, and the seedlings that grow are thin and yellow. Excessive tillage is also a prominent problem.
In early spring of this year, Fang Jian took a high-speed train from Harbin to Dalian. Outside the train window, he watched the busy scenes of land preparation and tillage shift. The exposed soil had a yellow-brown hue, and the microbial ecosystem within it was dying. He was deeply moved, saying that tilling destroyed the ecological habitat of microorganisms. Under the influence of ultraviolet rays from the sun, large numbers of microorganisms died, emitting carbon dioxide.
"Every year, NASA releases time-lapse footage of changes in carbon dioxide concentrations in Earth's atmosphere, with concentrations peaking between March and May," he said, citing scientific evidence. "This increase in carbon dioxide is due to emissions from soil disturbance caused by spring plowing."
What is unfolding now is not only a fierce storm of black soil degradation, but also a raging climate change crisis, which clearly exposes the fragility of food security.
