Chinese Scientists Combat Soil Disease to Protect 45 Million Mu of Greenhouse Crops

“In the past, when the fields were hit by disease, the yield per mu was no more than 8,000 jin, and crop rotation and fallowing didn't help either. Now with soil fumigation technology, the annual yield per mu can reach around 13,000 jin.” Wang Wengang, a farmer from Shidui Town, Anqiu, Shandong, who has grown ginger for ten years, told reporters.

Old Wang's story of increasing income is inseparable from the current application of soil-borne disease control technology in China. Facing increasingly severe soil-borne diseases, Chinese scientists are stepping up research and promotion efforts, declaring war on soil disease, and have already achieved remarkable results.

(Subheading) Soil Can Also Get Sick   Soil-borne diseases become the invisible killer of greenhouse crops

People can get sick, and soil can get sick too.

There is a scientific term related to soil disease, called soil-borne disease. It refers to soil diseases caused by pathogens living in the soil that, when conditions are suitable, invade crops from the roots or stems, mostly occurring in greenhouses and often bringing about root rot, wilting and so on in crops; in the eyes of local farmers, it is a kind of soil disease. Continuous cropping of the same crop, improper fertilization, and soil nematode infestation are the three main causes that trigger soil-borne diseases.

“When a single crop is continuously cultivated in one field for a long time, soil-borne diseases easily appear. In the last 10 years, with the rapid development of China's protected agriculture, soil-borne diseases have shown a trend of high incidence. This kind of disease cannot be seen or touched, and is the invisible killer that gives greenhouse farmers the biggest headache.” Cao Aocheng, chief scientist of the soil fumigation technology project and a researcher at the Institute of Plant Protection of the Chinese Academy of Agricultural Sciences, told reporters.

In recent years, with the intensive cultivation of high-value crops such as greenhouse vegetables in China, soil-borne diseases have become increasingly prominent, and their destructive power against protected agriculture such as greenhouses and vinyl houses is especially obvious. Statistics show that usually after 3 to 5 years of planting, soil-borne diseases begin to appear, and the yield and quality of crops are then seriously affected, generally causing a yield reduction of 20% to 40%, and sometimes even resulting in total crop failure.

(Subheading) Scientists Team Up to PK Soil Disease   “Specialist” chloropicrin answers the call in a crisis

Reporters learned that after soil-borne diseases appear, local farmers often use crop rotation or soil replacement to control them. But the result of crop rotation is a sharp decline in farmers' income, while the soil replacement method is labor-intensive and laborious, and in today's rural areas where labor is becoming more and more expensive, it is almost unfeasible.

“In areas where soil-borne diseases occur severely, crop rotation is mostly used, but rotating high-value crops with low-value crops not only yields low economic benefits, but also destroys some traditional advantage industries.” Cao Aocheng said.

In desperation, some local farmers turn to any remedy when sick. There were once farmers who used “black drugs (pesticides banned by the state)” to control devastating soil-borne diseases, resulting in the well-known “toxic ginger” incident, which caused serious impacts on the ecological environment and consumer health.

There is also soilless cultivation as a control method. Although it is rather high-end, it still does not fit China's current agricultural production conditions.

How to effectively solve problems such as the increasingly serious soil-borne diseases in crop production and promote sustainable agricultural development has become a key major issue in agricultural production. In response to the currently intensifying soil-borne diseases in China, the Institute of Plant Protection of the Chinese Academy of Agricultural Sciences, in cooperation with many related units, has declared war on soil-borne diseases and developed and promoted soil fumigation, a soil-borne disease prevention and control technology suited to China's national conditions.

“Because the fumigant used in the key technology has a small molecular weight and degrades quickly, there are no groundwater pollution or pesticide residue problems, which is conducive to environmental protection and food safety and significantly enhances the competitiveness of China's vegetables and high-value crops in the international market.” Cao Aocheng said.

Reporters learned that the key technology mentioned by Cao Aocheng has chloropicrin as its main component, and is hailed in the industry as the “specialist” of soil-borne control: it can both sterilize and also has a herbicidal effect, and can moreover stimulate soil vitality and reduce the application of chemical fertilizers and pesticides.

According to statistics from the Anqiu Plant Protection Station, in areas where this technology is applied, pesticide use decreased by an average of 23.75%, and chemical fertilizer use decreased by 16.5%.

In addition, because chloropicrin replaces methyl bromide, the main component of traditional fumigants that destroys the ozone layer, it is also of great significance for protecting the ozone layer.

(Subheading) Less Than 1% of Soil-borne Disease Control   Managing soil disease is a long and arduous task

“At present, this technology has been tested and demonstrated in more than 10 provinces and regions in China, including Shandong, Hebei, Beijing, Tianjin, Sichuan, Chongqing, Liaoning, and Inner Mongolia, and is widely used in protected crops such as ginger, strawberries, Chinese medicinal materials, protected vegetables, potatoes, and flowers, with remarkable results. Preliminary estimates show that the economic benefits increase by more than 3 billion yuan each year.” pointed out Chen Mengshan, Party Secretary of the Chinese Academy of Agricultural Sciences.

Chen Mengshan told reporters that China's current soil-borne disease prevention and control technology has approached the international advanced level, strongly supporting the development of China's protected agriculture, increasing farmers' income, and being welcomed by local farmers.

Cao Youyi, a strawberry grower in Pinggu, Beijing, has used soil fumigation technology to control soil-borne diseases since last year, with obvious returns. His family's 3 greenhouses (2.4 mu) of strawberries brought in 210,000 yuan, while his neighbor did not use this technology, and the strawberry greenhouses suffered soil-borne diseases, with the same 2.4 mu bringing in only 90,000 yuan.

It is worth mentioning that expert testing found that there is currently no secondary pollution from soil fumigation with chloropicrin, and long-term research in the United States, Canada and other places also shows that chloropicrin soil fumigation causes no groundwater pollution. This technology is widely used in developed countries such as the United States, Australia, Spain, and Japan, and has been used in large quantities in the United States for more than 60 years.

At present, China's protected agriculture covers 45 million mu, and half of it has continuously grown the same crop in protected facilities for more than 5 years, so soil-borne diseases will appear in a state of high incidence, but the land area used for soil-borne disease control technology is less than 200,000 mu, accounting for less than 1%. Strengthening the prevention and control of soil-borne diseases is a long and arduous task.