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New doctoral grad researching ‘black box of soil’

Peng, holding computer in farm field
Taking samples at WSU’s Cook Farm, new doctoral graduate Qiuping (Ellen) Peng studies organic carbon deep in the soil, helping shed light on long-term sustainable practices.

Growing up in China’s Henan province, Qiuping (Ellen) Peng was drawn to agriculture while watching her parents care for their beautiful garden and grow food crops.

“The soil seemed to have magic power to grow all kinds of plants,” said Peng, who graduated this May with a doctorate in soil science from Washington State University. “My parents’ relationship with the land taught me that if you treat your soil well and work hard, you’ll always harvest what you plant.”

Agriculture, with its direct path from input to output, promised a fruitful field of study.

Unlocking the black box

During her undergraduate and master’s studies in China, Peng learned about the challenges farmers faced to maintain healthy soil, witnessed pollution from unsustainable practices, and noticed a lack of interest in agriculture in young people.

“The harmonious relationship between human beings and the soil, which I saw in hundreds of growers when I was little, was falling away,” Peng said.

Through her studies, she decided she might be able to help.

She focused her work on carbon and nitrogen cycling in soil with the greater goal of advancing sustainable agriculture. She chose to pursue a doctorate at WSU, advised by Dave Huggins, a USDA soil scientist and adjunct faculty member in the WSU Department of Crop and Soil Sciences.

All living things contain the element carbon. The carbon cycle is nature’s way of passing this element through plants, soil, air, and water. Carbon cycling impacts microbes and nutrients in the soil, plant productivity, water quality, and greenhouse gas emissions.

“Carbon is like a universal currency in the soil-plant-air continuum,” Peng said. “Understanding its cycle at the process level in larger time and space scales is a key to the black box of our soil system. It ultimately supports the sustainability of agriculture.”

Peng studied labile organic carbon—soil carbon that can be easily decomposed by microorganisms—in deep soil under long-term no-till practices at WSU. Working from the laboratory to the field scale, she compared the results with native prairie.

“Few researchers have delved deeply into the soil by combining very challenging laboratory and field measures to enhance our understanding of soil carbon cycling,” Huggins said. “Surprisingly, large quantities of labile soil carbon were found deep within the soil profile that are influenced by our agricultural practices.”

Peng’s comparisons and models help us understand the biological flow of carbon, and estimate annual carbon loss from soil. Her work helps find future avenues for research, helping evaluate the impacts, risks, and benefits of no-till farming.

Growing greater confidence

Peng also embraced personal growth. She worked hard to grow her English communications skills, overcoming her fear of speaking in public and learning how to understand the language in depth.

Peng challenged herself to ask questions in every class, no matter how simple or complicated, joined study groups, and volunteered to help organize events and activities for more chances to speak in public. She seized the opportunity to work as a teaching assistant in environmental biophysics.

“Ellen’s degree program required a broad understanding of not just soil carbon cycling, but other soil and agriculturally related disciplines, which is particularly challenging for graduate students and professors alike,” Huggins said. “It is very rewarding to experience a graduate student like Ellen, who persevered and was successful in meeting multiple challenges—scientific, cultural and personal. I think she has a very bright future ahead!”

“Listen and read a lot,” Peng advises fellow students. “I listen to at least one TED Talk a day, and read books, science related or not. Encouragement and friendliness from instructors, lab team members, and friends are a great help.”

Peng’s efforts helped grow confidence about her skills and knowledge.

“It took lots of time and mistakes,” she said. “Share and ask for help when you need to. Expose yourself to things you’re good at as well as those you’re challenged by—it’s a huge help that allows you to grow in multiple dimensions.”

“Keep your curiosity, openness, and learning attitude,” Peng said. “As graduate students, it’s so easy for us to just focus on the areas we’re studying. But innovation comes from the spark of interdisciplinary work and communication. Pay attention and take time to listen to different seminars, online courses, and talk with your colleagues—it may inspire you.”

The new graduate plans to continue working on field-scale studies, measuring different soil components’ contributions to soil respiration. She also envisions launching her own agriculture-related start-up enterprise in the future.