In Praise of Dirt
A soil scientist shares her journey from garden to academia
You may have heard the statement “Soil is the foundation of life on the Earth.” Unless you are an avid gardener or pay close attention to what soils are all about, you might not realize how significant a role soils play in our daily life, ranging from human history to food production to climate change!
I am often asked why I chose to study soil sciences and what it would take to become a soil scientist. For me, it all started from growing up gardening at home in Thailand with my grandmother. Our backyard had tropical fruit trees, a water lily pond and vegetable garden beds. I have many childhood memories of picking and eating the vine-ripened tomatoes and using fresh herbs in dishes like pad kra pao (basil stir-fry), tom yum soup or som tum (green papaya salad). That experience led me to enjoy being outside and to always be curious to learn more about nature, plants and animals. Therefore, I chose to earn my undergraduate degree in plant science.
Once I took my first soil science course, things started to make more sense scientifically. I learned about the biological, chemical and physical properties of soils. This eventually opened up my curiosity to study the connections between aboveground and belowground plant and soil systems, as well as their implications to our food production and environmental health.
Later, I moved to the United States to attend graduate schools at California State University–Fresno and the University of California–Santa Cruz. I took up a job working part-time for the U.S. Department of Agriculture (USDA), testing soil and plant samples in the analytical laboratory and conducting research on organic farms. It was amazing to be able to make connections between what I learned in the classroom and hands-on experience, and also their implications in the real world. My research focus was on sustainable agriculture, soil fertility and water management.
Eventually, our family with two young children moved to the Bay Area about a decade ago. In 2015, I decided to volunteer for the Master Gardener program of Santa Clara County to stay informed and share my soil science knowledge with our community. I’ve been volunteering ever since. I enjoy teaching gardening classes in topics related to making compost, improving soil fertility with organic methods, growing cover crops, preparing soils for seasonal gardening and regenerative gardening.
I teach them to think beyond what they can see above ground and to consider the importance of what is living below ground.
I worked as a farm educator for the Santa Clara Unified School District for about four years. Now I am a nature area curator teaching K–12 students who visit the Osborne Nature Area on field trips. We host about 2,500 students each school year. I also keep busy collaborating with middle- and high-school science teachers for the citizen science effort Project Monarch Health. There are class visits for special projects like the Pollinator Garden Design Challenge, Project Invent and AP Environmental Science that I lead. In addition, I oversee student and community volunteers helping with restoration projects at the Nature Area.
Some of us are quite familiar with the statement “Feed the soil, not the plant,” which often refers to the principle of organic farming practices. I always emphasize this term during my talks to encourage gardeners who want to improve their ability to grow their garden with minimal inputs of synthetic substances. I teach them to think beyond what they can see above ground and to consider the importance of what is living below ground. I then go in depth to give my audience scientific explanations about soil biology and introduce the Soil Food Web concept.
Scientists have studied living organisms below ground and identified how they influence soil fertility and improve crop productivity, proving this intricate Soil Food Web. One of the most-cited fun facts is that one teaspoon of healthy soil contains as many as one billion microbes, compared to only 500 microbes in unhealthy soil. Those microbes are members of bacteria, fungi and protozoa groups. They are the food of other organisms such as earthworms, nematodes and arthropods. We recognize the earthworm as a key living organism to show the sign of healthy and living soils. Other critters also play significant roles within the Soil Food Web and contribute to healthy plants by releasing important plant nutrients into plant roots.
Another important term is regenerative. It refers to the holistic approach of land management practices that emphasize maintaining healthy soils, improving soil carbon storage and reducing greenhouse gas emissions. Soil carbon storage has become an important topic due to our rising awareness of combating global climate change. For example, expanding and growing plants, trees and grasslands can capture carbon in plant tissues, as long as we don’t harvest them.
We recognize the earthworm as a key living organism to show the sign of healthy and living soils. Other critters also play significant roles within the Soil Food Web and contribute to healthy plants by releasing important plant nutrients into plant roots.
Numerous publications and documentaries present their points of view in regards to this topic of regeneration. The general consensus is that healthy soil can be another major carbon storage below ground to mitigate carbon dioxide emissions. There is no perfect solution but as citizens of this world, we can all play our part. Our decisions on gardening practices, food and composting influence our carbon footprint and will impact our future generations.
Sajeemas “Mint” Pasakdee is a plant and soil biologist working for the Santa Clara Unified School District as a curator for the Osborne Nature Area, and a member of the Association for Environmental & Outdoor Education (AEOE). She also teaches the Green Gardener certification course for landscape professional training. In addition, she is an active community volunteer member for both Master Gardener and Composting Education Programs of the UCCE in Santa Clara County.
Tony Tieu’s love affair with photography began when he was a professional skateboarder photographed doing stunts by top photographers. He applies techniques he learned from them to his own photography. He really enjoys finding something “ordinary” and then discovering a unique perspective to it.
