- Researchers say a satellite imagery survey will help improve policymaking and crop management in the far west region
- China has had to redirect Xinjiang products to new markets since the US imposed an import ban
Researchers in China say that a detailed new mapping project of cotton production in Xinjiang could help improve crop management and farming output.
Xinjiang is the largest cotton producing region in China and using satellite images, the group of scientists have mapped and made public cotton growing distribution in the region from 2018 to 2021.
The images were obtained from the European Space Agency imaging missions Sentinel-1 and 2. Vegetation and soil are among the monitoring objectives of Sentinel-2.
“This is the first cotton mapping for the entire Xinjiang at 10-metre (32.8 feet) resolution, which can provide a basis for high-precision cotton monitoring and policymaking in China,” the team wrote in an article published in the peer-reviewed journal Scientific Data last month.
“The accurate and detailed mapping of cotton in Xinjiang is vital for cotton management, disease prevention and control, and yield forecast,” the team said, adding that the data set is available on the open repository Zenodo.
The researchers are from: the National Engineering Research Centre for Satellite Remote Sensing Applications under the Chinese Academy of Sciences; the Oasis Eco-Agriculture Key Laboratory, Xinjiang Production and Construction Corps, at Shihezi University in northern Xinjiang; and Canada’s University of Toronto.
China produces more than 20 per cent of the world’s cotton, mostly from the far western region of Xinjiang. Last year, the autonomous region produced 90 per cent of the country’s cotton, according to state news agency Xinhua.
Cotton output from the region is expected to drop by 11 per cent to 5.57 million tonnes this year compared to 2022, a year after the United States imposed a Xinjiang import ban, and as China pushes to improve quality and food and crop security. Climate shocks earlier this year were also likely to contribute to decreased yields.
Xinjiang products are being redirected to countries that are part of China’s Belt and Road Initiative following the US-led boycott over alleged forced labour. Beijing has consistently denied the allegations, describing Xinjiang cotton as “pure white and flawless”.
The US’ Uygur Forced Labour Prevention Act, which went into effect in June 2022, has effectively blocked American imports of all products wholly or partially sourced from Xinjiang. Cotton is among “high priority” sectors that will face scrutiny by US customs agents.
Without direct access, researchers in the West have used open-sourced and non-public Chinese government documents, academic sources, state media reports and satellite images to study Xinjiang.
In 2019, the think tank Australian Strategic Policy Institute (APSI) released a report analysing the expansion of textile factories, and a vocational skills education training centre in Xinjiang. Its author, who specialises in satellite data, said “satellite imagery provides unique insights into the increasingly securitised nature of the region”.
“The situation in Xinjiang is extremely opaque and investigation of what is occurring there is difficult. But collection and analysis of open-source information, including satellite imagery, provide an alternative window into what is happening on the ground,” APSI analyst Nathan Ruser wrote at the time.
In the new study, the scientists said it was key “to choose a suitable computing platform and remote sensing data for cotton mapping across Xinjiang, for satellite-based remote sensing imagery has been developed as the main data source for crop mapping in large spatial ranges”.
The analysis showed that cotton was mainly concentrated in southern and northern Xinjiang in the four-year period starting from 2018. The most densely distributed areas at the prefecture level were in Bortala, Tarbagatay, Changji, Aksu and Bayingolin.
They said their cotton maps “exhibited better spatial details and more realistic dynamics of cotton across Xinjiang” compared with other existing cotton mapping products.
The scientists said they could also use the method to build a map of more recent conditions.
“The proposed method can be transferred to cotton mapping in a new year [2022], and the published cotton maps data set can provide a basis for crop management and policymaking,” the researchers said.
Source: https://www.scmp.com/