Imagine you’re visiting a carrot farm. Your friend, the farmer, hands you a freshly pulled carrot to munch on. Would you eat it without washing it? Probably not! You would first wash it, worried about germs from the soil clinging to it.
And those concerns are valid. Studies show that just one gram of soil from the rhizosphere—the space around plant roots—can contain up to one billion bacteria. This region is bustling with countless other microbes too, including tiny worms called nematodes, fungi, algae, viruses, and parasites.
While we try to avoid these microbes, plants actually depend on them for their survival. In fact, without these microscopic helpers, plants as we know them wouldn’t even exist.
Scientists have been exploring the world of microbes for over four centuries, starting with Antonie van Leeuwenhoek in the late 17th century, who crafted microscopes to examine various materials, including soil. He discovered tiny living organisms and called them "animalcules" long before "microbe" was even in use.
This is where our journey begins—at the fascinating intersection of microbiology, soil science, plants, and agriculture. Let’s explore the vital roles that soil microbes play in the life of plants and how this knowledge has transformed agriculture.
Humans began cultivating plants about 23,000 years ago1, and soil fertility was key to early agriculture. Civilizations like Mesopotamia managed soil fertility over 6,000 years ago2, laying the foundation for soil science. In ancient Rome, Cato the Elder wrote about composting and using animal manure3. China’s oldest agricultural text, by Fan Shengzhi4, also emphasized enhancing soil fertility.
For centuries, soil was seen as a source of fertility, but it wasn’t until the late 19th century that scientists like Vasily Dokuchaev5 and Jean-Baptiste Boussingault6 recognized soil as a natural body worthy of study and identified nitrogen as essential for plant growth. Pioneering scientists like Martinus Beijerinck7 and Sergei Winogradsky8 later discovered bacteria that fix nitrogen, turning atmospheric nitrogen into a form plants can absorb. Beijerinck identified Rhizobium bacteria living on legume roots that form a mutually beneficial partnership with plants.
Winogradsky built on this, finding bacteria that convert ammonia into nitrates, forms of nitrogen plants can use. These discoveries paved the way for understanding how microbes like nitrogen-fixing bacteria and nitrifying bacteria support plant life.
But nitrogen-fixing is just one of the many critical roles that soil microbes play in supporting plant life. Since the 19th century, microbiologists have been delving into the fascinating world of soil microbes, uncovering numerous species that aid plants in various ways.
Soil is much more than just a base for plants to anchor their roots. Soil microbes play a crucial role in ensuring that plants grow strong and healthy. Let’s explore some of the key ways they help plants:
This article is part of The biosolutions bulletin. Want it in your inbox every month?
Humans have only begun to understand soil microbes and the complex relationships they have with plants. The world of soil microbes is immense. A recent study estimated that about 59 percent of all life on Earth may live in the soil9, including over 50 percent of all bacteria and 90 percent of fungi. This suggests there could be more than three trillion types of bacteria and over five million types of fungi in the soil!
Unfortunately, we’ve only identified a tiny fraction of these soil microbes. Despite this limited understanding, the knowledge we do have about soil microbes has already led to significant advancements in agriculture. What are these exciting changes? Welcome to the world of Biosolutions for Agriculture, in short BioAg.
Despite limited understanding of the vast world of soil microbes, scientists have made significant advances in agriculture. One of the earliest successes was the development of Nitragin in 1896, a microbial inoculant designed to boost legume yields by ensuring plants get a nitrogen boost. Nitragin, still in use today, contains nitrogen-fixing bacteria that coat seeds and help plants absorb nitrogen from the soil.
Beyond Nitragin, scientists are developing more BioAg products using microbes to help plants absorb nutrients and fight off harmful microbes. As research on soil microbes advances, more bacteria and even fungi are being made available as biosolutions for farmers. These solutions do more than just supply nitrogen; they help plants absorb more phosphorus, potassium, and other essential nutrients from the soil. Additionally, some biosolutions use beneficial microbes to act as a protective shield, fighting off harmful microbes that can cause diseases and infections in plants.
This new era in agriculture harnesses the power of soil microbes to improve sustainability and crop productivity.
You will never look at the humble soil the same way again, will you? Humans have come a long way from seeing soil merely as a medium for growing plants. Now, we recognize soil as a vibrant community filled with diverse microbes that are essential for plant health. Thanks to incredible advances in biotechnology, we’re not just studying these tiny helpers; we’ve begun harnessing their power to transform agriculture in the 21st century. This marks a new era where soil microbes are the source of revolutionary innovations. So let’s celebrate the thriving world of microbes beneath us!
1. Microbial conferences for crucial decision-making
If you’ve ever attended a meeting that required a quorum—where a minimum number of attendees is needed to make decisions—you’ll get the idea of "quorum sensing" in the soil, which is all about teamwork. When enough microbes gather, they can collectively decide to fix nitrogen for plants or take other important actions.
2. Fungi superhighways
Beneath the soil, fungi create extensive networks called mycelium, which are made up of thin, thread-like structures. These mycelial networks can stretch for kilometers and act like superhighways, transporting nutrients and water between plants and playing a crucial role in ecosystem health and connectivity.
3. The soil color code
The color of soil is like a secret code that reveals its composition and health. For example, dark brown or black soils often indicate a rich content of organic matter, which is vital for plant growth. On the other hand, reddish soils typically contain iron oxide, giving them that distinctive hue and often signalling good drainage properties.
4. Nature’s farmers
Earthworms are vital for keeping soil healthy and fertile. Often called "nature’s farmers," these amazing creatures dig through the soil, which helps improve drainage and lets air flow. This is great for plant roots and helps helpful microbes thrive in the soil.
5. Soil is a natural filter
Did you know that soil functions as a remarkable natural filter for water? When rainwater seeps into the ground, it passes through various soil layers that act like a sponge, trapping impurities and pollutants. This natural filtration process not only purifies the water but also enriches it with essential nutrients. As a result, clean water is made available for plants and replenishes aquifers, supporting entire ecosystems.
Sources:
1. The Origin of Cultivation and Proto-Weeds, Long Before Neolithic Farming, PLOS ONE
2. A Brief History of Soil Science, Eric C. Brevik
3. De Compostus: a Brief History of Putting Animal Poop on Plants
4. Fan Shengzhi shu
5. Vasily Dokuchaev (the 175th anniversary)
6. A Chronology of Human Understanding of the Nitrogen Cycle
7. Martinus W. Beijerinck
8. Sergei Winogradsky: A Founder of Modern Microbiology and the First Microbial Ecologist⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀
9. Enumerating Soil Biodiversity
The global population is projected to soar to about 10 billion people by 20501, posing a significant challenge: how do we farm enough food to feed everyone? This challenge is compounded by the impacts of climate change on agriculture, requiring solutions that not only boost food production but also protect the environment and lessen the burden on our planet.
Is there a solution that can help solve this complexity? Surprisingly, yes – it lies in the bacteria and fungi living in the soil. These tiny organisms are already making agricultural practices more environmentally friendly and helping farmers increase their crop yields.
Microbes and enzymes are tiny but mighty agents of change. For billions of years, they’ve enabled transformation in all living things through microbiology.
Get the answers to these questions and more from the monthly biosolutions bulletin. Whether you’re an expert who wants to keep on top of the latest innovations or just starting to learn about biosolutions, we’ve got you covered.
With stories ranging from the role of biosolutions in food security to how they enable NOMA-style dining experiences, there’s something for everyone.
Don’t miss out on the latest news about how biosolutions better our world. Sign up to get the biosolutions bulletin delivered directly to your inbox.
This form is hidden because Marketing Cookies are turned off. You can enable them in your cookie settings to continue.