Tao Feng, a Ph.D. graduate from the Department of Earth System Science (DESS), Tsinghua University in 2023, studied in the School of Environmental Science and Engineering of Sun Yat-sen University. In 2018, he was recommended to study for a doctoral degree in the DESS, Tsinghua University. He studied under Professor Huang Xiaomeng from the DESS, Tsinghua University and Professor Luo Yiqi from Cornell University. His main research direction is global soil carbon cycle. During his doctoral studies he published research papers in Nature as the first author, won a scholarship from the National Fund for Studying Abroad, and won such honors as the 27th Rising Star Scholar  in Tsinghua University and Outstanding Graduate in Tsinghua University. He studied in a joint program with the Max Planck Institute of Biogeochemistry. After graduation, he will go to Cornell University for postdoctoral research.

Free exploration in no man’s land of scientific research

In ecology, the study of the soil system is considered the last frontier. Up to now, people still know little about the formation and development of soil and its interaction with other components of the Earth system. The study of organic carbon in soil began in Darwin's time, but some basic scientific problems are still inconclusive. With the remarkable influence of human activities on the global carbon cycle in the industrial revolution, it is becoming more and more imperative to understand the formation and storage of soil organic carbon, the largest carbon pool in terrestrial ecosystems.

Breakthrough of ancient research problems often calls for new ideas. Tao Feng began to study soil organic carbon under the guidance of Professor Luo Yiqi after he was determined to study in the doctoral program of the DESS, Tsinghua University. He first tried to optimize the process model to simulate the spatial distribution of global soil organic carbon. However, the traditional optimization method failed to significantly improve the simulation accuracy of the model. The huge heterogeneity of soil processes in different spaces made it difficult for the process model to accurately describe the key ecological processes through constant model parameters. A new method is needed to solve the above problems. “The turning point came from Professor Huang Xiaomeng's course, ‘Geoscience High Performance Computing and Big Data’. In this course, I saw a new possibility to solve my research problems by machine learning,” said Tao Feng. In the past, the machine learning method represented by deep learning was often used to directly predict the spatio-temporal values of the variables studied, so it was often questioned because “it only has high prediction accuracy but cannot give a mechanism explanation”. “Can we find a way for machine learning to explore the mechanism behind variables? Although this idea had never been explored in the field of soil carbon cycle by then, with the full support of my two mentors, I decided to break into this ‘no man’s land’,” said Tao Feng. After repeated attempts, Tao Feng developed the PROcess-Guided Deep Learning and DAta-Driven Modelling (PRODA), which organically combined the mechanism model, ecological big data, traditional data assimilation and artificial intelligence, systematically revealed the environmental dependence of parameters in the soil carbon cycle model, and improved the simulation ability of the process model to the level of pure machine learning results for the first time. “Although I dislike adventure in life, I enjoy the feeling of free exploration in scientific research. Lonely, but exciting,” said Tao Feng.

Tao Feng takes photos with his supervisors Professor Huang Xiaomeng (above) and Professor Luo Yiqi (below)

Grow strong in the hammering of life

Passion alone in scientific research is not enough. Faith provides the source of courage for Tao Feng to tackle daunting challenges in scientific problems, and it is also the driving force to support him in his research pursuit despite the lack of output over a long time. "External rewards and honors can bring happiness, but giving a complete answer to an important scientific question makes me happy," said Tao Feng. With such a mentality, Tao Feng did not rush to publish an article in the three years after completing the construction of PRODA methodology, but settled down to systematically and comprehensively explore the basic problem of controlling the key mechanism of global soil organic carbon formation and storage. Combining soil big data with a complex process model by PRODA method, through data assimilation, deep learning and meta-analysis, Tao Feng revealed for the first time that microbial carbon use efficiency (CUE) is the most critical among the seven mechanisms of soil organic carbon formation and storage that had been studied, and high microbial CUE mainly promotes soil organic carbon accumulation. This research result has promoted the transformation of the paradigm centre of soil organic carbon exploration from "plant carbon input-organic carbon degradation" to microbial process, providing a scientific theoretical basis for understanding the response of soil carbon cycle to climate change and improving soil carbon sequestration to achieve carbon neutrality.

The achievement and publication of this achievement was not smooth sailing. Over the past three years, Tao Feng has repeatedly verified the repeatability of the research results through various methods, and extensively discussed the scientific problems and conclusions with collaborators and reviewers. After one and a half years of article writing, one and a half years of submission, five rounds of peer review and more than fifty revisions, he finally managed to have his research results published in Nature. In the past three years, he had self-doubt and wanted to give up, but his supervisors’ trust and encouragement from beginning to end and his fascination with seeking answers to scientific questions kept him going to the end. “Looking back, the rough experience is a valuable asset for me, as what I have gained is not only an article, but also more thoughts on what is a good scientific problem and how to cultivate the ability to conduct research independently. At the same time, I have also trained my confidence and tenacity in the face of difficulties,” said Tao Feng frankly.

Tao Feng renders an academic report

Be a new geoscience scholar with a global vision

"For me, as a new generation researcher, the exploration of carbon cycle mechanism comes from my interest in exploring unknown problems in basic science, and it is also my responsibility as a new generation geoscientist in the 21st century to address the climate change crisis with scientific research results," noted Tao Feng. The experience of visiting the headquarters of the Food and Agriculture Organization (FAO) of the United Nations opened a window for Tao to study the impact of climate change on human society from a global perspective, and also made him truly realize for the first time that scientific research can play an active role in the policy formulation of international organizations and countries. Encouraged by this vision, Tao Feng deeply participated in the relevant work of the Global Soil Partnership during his visit to the FAO. He participated in the formulation of the technical route of the Global Soil Organic Carbon Map (GSOCmap), and made a report on behalf of the Global Soil Partnership Secretariat at the fifth working meeting of the International Network of Soil Information Institutions (INSII).

Tao Feng took a group photo with his colleagues during his visit abroad

During his study, Tao Feng's experience in international academic exchange activities helped him build an international cooperation network. With the vigorous support of his supervisors, Tao presented academic reports at two large-scale international conferences at least every year to exchange research progress and discuss emerging ideas with researchers all over the world. In this process, he could not only see the wonderful work of researchers from all over the world, but also deeply feel their sense of responsibility and commitment in tackling climate change.

After the midsummer, Tao Feng would bid farewell to the Tsinghua campus and embark on a new journey. Despite the varying research topics, the goal of exploring the frontiers of science and challenging his own limits remains unchanged; also constant is his initial aspiration to tackle climate change through scientific research.

Written by Tao Feng

Edited by Wang Jiayin

Reviewed by Chen Yawei, Lu Hui and Geng Rui