{"id":24661,"date":"2025-12-03T12:01:53","date_gmt":"2025-12-03T20:01:53","guid":{"rendered":"https:\/\/extension.wsu.edu\/kitsap\/?page_id=24661"},"modified":"2026-03-11T18:04:02","modified_gmt":"2026-03-12T01:04:02","slug":"backyard-composting-soil-and-decay","status":"publish","type":"page","link":"https:\/\/extension.wsu.edu\/kitsap\/backyard-composting-soil-and-decay\/","title":{"rendered":"The Science of Soil and Decay"},"content":{"rendered":"
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Soil and Decay<\/h1>\t\t\t\t
Soil is not static\u2014it forms slowly, is easily damaged, and is worth protecting. Understanding this helps relate to the unique soils in your own yard and landscapes.<\/div>\t\t\t\t\t\t\t<\/div>\n\t\t\t\t\t\t
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Soil Formation<\/h2>\n\n\n\n

The formation of soil happens in a series of steps. At it’s very start, it’s erosion of stone, rich in mineral formation that it will release throughout its existence. You will see later how these minerals are extracted through synergy with microorganisms that form bonds with these materials, helping in the transfer to larger organisms and eventually our food sources. <\/p>\n\n\n\n

The soil then, as you can imagine, forms slowly over time as rocks break down through weathering. During this time of accumulation, organic matter from plants, animals, and microorganisms living and dying, and decaying back into the cycle adding biological matter to the soil. Climate, living organisms, land geology and shape, as well as time interact to create distinct soil layers with different textures and nutrients. This ongoing process produces the living foundation that supports plant growth, water movement, and ecosystems. This process is known as the Five Factors of Soil Formation. <\/p>\n\n\n\n

Soil formation is driven by five interacting factors \u2014 parent material, climate, time, biota, and topography \u2014 which together shape how sand, silt, and clay develop through physical and chemical weathering. Particle size reflects the degree of weathering over time: sand is least weathered and largest, silt is intermediate, and clay forms through extensive chemical transformation that increases water and nutrient holding capacity. To explore how these factors influence soil texture and development in greater detail, visit The University of Maryland Soil Basics<\/a> for visual representation of this process. <\/p>\n\n\n\n

The Addition of Organic Matter and Soil Food Web<\/h2>\n\n\n\n

Organic matter is the cornerstone of a healthy soil ecosystem, providing the essential biological and chemical foundations necessary for sustainable plant growth. Biologically, it serves as the primary energy and food source for a vast community of microorganisms, including bacteria and fungi, which are the catalysts for nutrient cycling and disease suppression. <\/p>\n\n\n\n

The relationship between these organisms as they decompose organic materials, release critical nutrients such as nitrogen, phosphorus, and sulfur in forms that plants can easily absorb, effectively acting as a slow-release natural fertilizer. The soil food web is dynamic and integral to soil health. Chemically, organic matter significantly increases the soil’s cation exchange capacity (CEC), allowing it to hold onto positively charged nutrients like calcium and potassium, preventing them from leaching away while also buffering the soil against extreme pH fluctuations. <\/p>\n\n\n\n

Learn more about your soil texture in two easy ways by performing first a Hand Texture Estimate and then a Slake Test. First you are going to learn about the feel of the soil and the parent material. Then the slake test will show you how the soil holds together under stress. When you do the hand texture test, make a prediction for what might happen during the slake. Compare what you learned to the NRCS Soil Database that has cataloged soils across the U.S. This is building intuition with your soil. <\/p>\n\n\n\n

Physically, organic matter transforms the soil into a more resilient medium by dramatically improving its structure and water-handling capabilities. It acts much like a sponge, with the ability to absorb and hold up to 90% of its weight in water, which protects crops during dry periods and increases overall plant-available water by thousands of gallons per acre. This enhanced structure\u2014characterized by stable aggregates and increased pore space\u2014also promotes better aeration and faster water infiltration, which reduces the risk of surface crusting, runoff, and erosion. By darkening the soil, organic matter even helps it absorb more solar radiation, warming the ground more quickly in the spring to support earlier seed germination and more vigorous root development.<\/p>\n\n\n\n

Organic Matter and Soil Stabilization<\/h2>\n\n\n\n

Organic matter is the cornerstone of a healthy soil ecosystem, serving as the primary fuel for a complex cycle of biological and chemical stabilization. As microorganisms like fungi and bacteria feed on organic residues, they secrete substances such as glomalin\u2014a sticky, “soil-glue” protein that acts as a powerful short-term cementing agent to bind individual soil particles into stable aggregates. These microbial “organic glues,” combined with water-resistant substances produced by plant roots, provide the long-term structural integrity necessary for soil to resist erosion. Because these biological bonds take time to develop and are easily shattered, excessive tilling is discouraged; breaking up the soil physically disrupts these vital connections and rapidly reduces the soil’s ecological function. <\/p>\n\n\n\n

This biologically-driven structure is what allows soil to master the balance between gravity and water retention. While large “macropores” created by these aggregates allow for rapid drainage and aeration, the tiny “micropores” within the aggregates use capillary tension to hold water against the downward pull of gravity. Through adhesion\u2014water sticking to soil surfaces\u2014and cohesion\u2014water sticking to itself\u2014the soil acts like a sponge, locking in moisture that would otherwise run through. By fostering these stable aggregates through organic matter, the soil creates a resilient environment. By increasing the total surface area for adhesion and the volume of micropores, every 1% increase in organic matter can help an acre of soil store thousands of additional gallons of water.<\/p>\n\n\n\n

\"Illustration
Good soil structure has adequate space (pores) between aggregates to alleviate compaction so that air and water can reach plant roots. Glomalin acts as a glue that binds soil particles together, stabilising aggregates and enhancing soil structure.<\/em> Greenwood Nursery U.K. <\/figcaption><\/figure>\n\n\n\n

Composting Science<\/h2>\n\n\n\n

While nature\u2019s pace is slow and unmanaged, human-led composting optimizes the recycling of organic matter through two distinct scientific paths: active (hot) and passive (cold) methods. In nature, decomposition happens sporadically based on the weather, but in composting, we intervene to ensure that organic residues are transformed into stable nutrients rather than simply rotting or off-gassing into the atmosphere. The science of composting is essentially the art of managing microbial metabolism\u2014balancing air, water, and food to turn “waste” into a concentrated biological asset.<\/p>\n\n\n\n

Passive composting, mimics the natural forest floor but with a more intentional focus on moisture and volume. It operates at ambient temperatures and relies on a broader cast of characters, including “cool” microbes and macro-organisms like red wiggler worms and mites. While it lacks the speed and sanitizing heat of a hot pile, passive composting is scientifically valuable because it preserves certain heat-sensitive beneficial fungi and microbes that might perish in a hot system. Both methods serve to hone the natural cycle, ensuring that carbon is sequestered back into the soil as humus rather than escaping as greenhouse gases.<\/p>\n\n<\/div>\r\n\n\n

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Soil Health Resources<\/h2>\n\n\n\n

Did You Know?<\/h3>\n\n\n\n

Soil stability is a strong indicator of biological activity, energy flow, and nutrient cycling. Soil aggregates must be continuously rebuilt by living organisms\u2014and composting is one of the most effective ways to support this living system.<\/p>\n\n\n\n

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