The Philosophy of the Soil Sponge

Learning about soil health can be like cannon-balling into the deep end of a pool: there’s a lot to learn, and the details can get complex very fast. You know you need to care for your soil, but how do you know where to begin?

Elizabeth Murphy, author of Building Soil, brings expert clarity to understanding it all. She urges readers to simplify how we think about soil. Rather than a massive web of chemistry and biology, step back and think about soil as an ecosystem, one that—like all ecosystems—needs the basics of food, shelter, air, and water to live. This way, we can ask: What does the soil have and what does it need?

organic matter provides resources to living soil
Organic matter gives fertile soil its rich, black color. It’s the secret ingredient that makes soils into resource-retaining sponges, providing the living soil with food, shelter, water, and air.


Organic Matter: The Soil Sponge

Amazingly, there’s a single solution that provides food, shelter, water, and air for the living soil. The miracle cure is organic matter. Organic matter is anything living or anything dead that was once living. If it has the gooey, sticky signature of life, then it’s organic matter.

Organic matter is, essentially, the sponge of the soil. It captures and holds onto resources like water and nutrients. It changes soil structure and builds friable, loose soils. It provides basic food to plants and living organisms.

From an organism’s point of view, organic matter turns the soil environment from a disaster-relief shelter into a luxury condominium, leading to bigger, healthier, and more productive populations of living soil organisms.

soil sponge vs. soil sieve
Sustainable systems minimize what enters and leaves the system, relying on internal processes to recycle and retain resources. Non-sustainable systems don’t hold onto resources and require continual inputs from the outside.


Organic Matter is Food

First and foremost, I like to think of organic matter as food for the soil. When stranded on a deserted island, a person who is fed has the energy to make his or her own shelter, explore the island, and build signals to summon rescue help. If living organisms are fed, then they also have the energy to improve their own homes by improving soil condition.

Organic matter provides the raw materials for building the bodies and tissues of organisms and plants. Decomposition, the rotting of organic matter, is an important process in your soil, your compost pile, and sometimes your refrigerator. It starts when tiny microorganisms munch on raw organic matter and excrete it as something new.

This process of transformation releases important nutrients, such as phosphorus and potassium. It also releases a large amount of energy that fuels the living activity of the soil engine. Your plants and soils need this nutrition and energy to grow and thrive. In this way, when you feed the soil, you also literally feed your plants.

Does your garden hold onto water, nutrients, and other resources so that you add less and less over time, like a sponge? Or do these inputs simply pass through the garden like a sieve, continually requiring you to add more and more to meet plant demand?


Organic Matter Holds Water

In addition to being food for the soil, organic matter stores soil water. Like a sponge, it has a huge amount of pore space and a lot of surface area. It is able to absorb vast amounts of water to release when conditions become dry. Even a small amount of organic matter in the soil can greatly increase the amount of water your soil can hold after rain or irrigation to provide more water for microbes and plants in the living soil. This is particularly helpful for sandy soils with little water-holding ability.

Sustainable systems, like this old-growth forest, are self-perpetuating sponges. They are built to capture and hold onto sunlight and water. Nutrients are continually recycled between the active soil ecosystem below ground and the productive forest above ground, maintaining a productive, layered, and diverse forest ecosystem.
Sustainable systems, like this old-growth forest, are self-perpetuating sponges. They are built to capture and hold onto sunlight and water. Nutrients are continually recycled between the active soil ecosystem below ground and the productive forest above ground, maintaining a productive, layered, and diverse forest ecosystem.


Organic Matter Lets the Soil Breathe

Take a handful of mineral soil and a handful of well-rotted compost. Which is lighter? The properties of organic matter that make it a good sponge are the same properties that make it fluffy and full of air. All that space in between the little bits and pieces of soil organic matter, when they are not filled with water, are filled with air. This gives the soil more space to breathe, providing oxygen for living organisms and plant roots.

Adding fluffy organic matter to the soil, drainage and other problems of compaction are also improved. Since waterlogged soil limits the oxygen available to living organisms, improving drainage is an essential part of maintaining a well-aerated soil.

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This is your down-to-earth, complete manual for achieving great gardening results with your own rich, organic soil!

How do you recognize healthy soil? How much can your existing soil be improved? What are the best amendments to use for your soil? Let Building Soil answer your questions and be your guide on gardening from the ground up! Fertilizing, tilling, weed management, and irrigation all affect the quality of your soil. Using author Elizabeth Murphy’s detailed instructions, anyone can become a successful soil-based gardener, whether you want to start a garden from scratch or improve an existing garden.

If you want methods that won’t break your back, are good for the environment, and create high-yielding and beautiful gardens of all shapes and sizes, this is the book for you! Create classic landscape gardens, grow a high-yielding orchard, nurture naturally beautiful lawns, raise your household veggies, or run a profitable farm. A soil-based approach allows you to see not just the plants, but the living system that grows them. Soil-building practices promote more ecologically friendly gardening by reducing fertilizer and pesticide use, sequestering greenhouse gases, and increasing overall garden productivity.

Building Soil is a simple book full of practical, up-to-date information about building healthy soils. Simple methods perfect for the home gardener’s use put healthy, organic soil within everyone’s reach. You don’t need a degree in soil management to understand this book; you only need a yard or garden and the desire to improve it at the most basic level.

Elizabeth Murphy has a passion for growing food that led her to a master’s degree in soil science from University of California, Davis, where she researched soil organic matter storage and a farmer’s ability to improve it. She has worked as a faculty instructor for Oregon State University Extension’s Small Farms Program, where she taught and consulted with gardeners and farmers about best management practices to build healthy soils. Since 2006, she has owned a half-acre garden in southern Oregon, which she considers her laboratory for experimenting with sustainable soil management and gardening practices for landscapes and vegetables. Currently, she lives in Tacoma, Washington.