Photo courtesy of U. S. Department of Agriculture
Soil, often overlooked beneath our feet, plays a crucial role in sustaining life. A recent article written by SDSU extension specialist Hans Klopp, Anthony Bly and David Karli delves into the intricate components of healthy soil, shedding light on the factors that contribute to its vitality and productivity.
Unveiling the Foundations: Soil Composition
The article underscores that soil is not a mere combination of rocks and minerals. It comprises particles derived from geologic minerals, pore spaces holding water and air, living and dead organic materials, and dissolved chemicals. A healthy soil possesses a sound structure, facilitating nutrient cycling, effective water filtration and retention, easy plant root penetration, diverse organisms, and sufficient plant residues.
Decoding Soil Texture
The texture of soil, a result of geological processes over time, determines its composition. Sand, silt, and clay, with different particle sizes, define the soil's texture. The ideal soil, as commonly suggested, consists of 50% pore space, 5% organic matter, and 45% minerals. Organic matter and minerals combine to form soil aggregates, ranging in size, allowing optimal water infiltration and storage.
Organic Matter Dynamics
Organic matter, a dynamic aspect of soil, can be influenced by human management. The article highlights the role of practices chosen by land managers in returning or removing organic matter (carbon). The type and amount of soil carbon impact the composition of soil organic matter, which encompasses various elements such as dead plant material, living and dead roots, soil organisms, and different carbon compounds formed through biological activities.
The Symphony of Soil Life
Common organisms, from bacteria to mammals, thrive in the soil, each playing a crucial role in its functioning. The soil hosts an intricate web of life, with bacteria, fungi, protozoa, nematodes, worms, and larger organisms creating a balanced ecosystem. Their activities decompose organic materials, release nutrients for plants, and contribute to the overall health of the soil.
Unraveling Soil Carbon Mysteries
Soil carbon, a key player in soil health, poses mysteries yet to be fully understood. Estimates indicate that 2 to 5% of soil organic matter is microbial biomass, while a significant portion remains mineral-associated organic matter. Reactive carbon, actively changing and including soil microorganisms and decomposing plant materials, is a vital component. Laboratory procedures, such as permanganate oxidizable carbon and particulate organic matter carbon, measure the pool of reactive carbon, shedding light on soil health dynamics.
Crafting a Conclusion: The Essence of Healthy Soil
In summary, the article emphasizes that healthy soil is characterized by robust structure, allowing water infiltration and retention, a rich and diverse biological community, and adequate surface cover. It efficiently releases essential nutrients for plants while maintaining them near the soil surface for future use. Understanding the intricate dance of soil components, from texture to organic matter and the diverse community of organisms within, is crucial for sustainable land management. As we navigate agricultural and environmental practices, acknowledging the nuanced complexities of healthy soil is the first step toward nurturing the very foundation that sustains life on Earth.
References:
Brady, N.C. & Weil, R.R. 1999. The nature and properties of soils 12th ed.. Prentice-Hall Inc. Upper Saddle River, New Jersey.
Cai, A., Feng, W., Zhang, W., & Xu, M. (2016). Climate, soil texture, and soil types affect the contributions of fine-fraction-stabilized carbon to total soil organic carbon in different land uses across China. Journal of environmental management, 172, 2-9. -
Giannetta, B., Plaza, C., Galluzzi, G., Benavente-Ferraces, I., García-Gil, J. C., Panettieri, M., ... & Zaccone, C. (2024). Distribution of soil organic carbon between particulate and mineral-associated fractions as affected by biochar and its co-application with other amendments. Agriculture, Ecosystems & Environment, 360, 108777.
Sharma, V., Hussain, S., Sharma, K. R., & Arya, V. M. (2014). Labile carbon pools and soil organic carbon stocks in the foothill Himalayas under different land use systems. Geoderma, 232, 81-87.
Simonsson, M., Kirchmann, H., Magid, J., & Kätterer, T. (2014). Can particulate organic matter reveal emerging changes in soil organic carbon?. Soil Science Society of America Journal, 78(4), 1279-1290.
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