• Women in Ag Science Team

Soil, The Finite Resource That Sustains Life

Updated: Dec 19, 2020

By: Noelymar González Maldonado, Zoelie Rivera Ocasio, and Patricia Marie Cordero Irizarry

Soils are alive!

There is a huge difference between dirt and soils. Dirt is defined as soil that has lost the characteristics that give it the ability to support life (SSSA). Dirt is dead; however, soils are alive. Soils support and sustain the lives of millions of living organisms responsible for essential processes of the Earth. Here, we aim to increase awareness of the importance of maintaining soils life to promote healthy ecosystems and humanity's well-being.



Why are soils important?

Picture courtesy of @zoils.pr

Soils are unique and dynamic entities. Soils have their origins and formation as a combination of physical, chemical, and biological interactions between five factors: parental material, climate, topography, organism, and time (Coleman et al., 2006). Differences in these factors will result in different soil properties, giving a different identity to soil entities.


Soils are the foundation of life, they promote and sustain life in many ways. Have you ever wondered how our lives would be if we did not have soils? From food production to forest establishment and community development, soils are the fundamental base for multiple essential everyday necessities and activities on this planet. These important functions of soils are commonly described as soil ecosystem services which include provisional, regulative, supporting (processes), and cultural services (source). Let’s look into each one of these.

1. Provisional Services: Habitat, Food, Fiber, and Materials

Soils function as the primary foundation for fiber and food production. They allow a habitat for root growth, water, and nutrients for plants. Moreover, soils are essential for growing crops and feeding a healthy diet to livestock and people. Grazing and forage lands on US farms supply feedstuff for approximately 90 millions head of cattle (USDA-NASS, 2014) In addition, many construction materials like wood are also obtained from trees grown in soils.


2. Regulative services: Carbon sequestration and Pest Suppression


Soils participate in climate regulation through carbon sequestration and water purification. Carbon sequestration is the process where carbon dioxide is removed from the atmosphere and stored in the soil. The soil carbon pool is approximately three times larger than the carbon in the atmosphere (Oelkers and Cole, 2008). However, many conventional management practices deplete soil carbon stocks which can lead to soil degradation and greenhouse gasses emissions. A decline in the soil’s condition due to improper use and management leads to serious environmental issues (NSW Government). Soils can serve as climate change mitigators since they have the potential to reduce carbon footprints through sustainable management practices.

Soils also act on disease and pest control and suppression for crops. For example, entomopathogenic nematodes are ubiquitous in soils and are important natural enemies of a key citrus pest, the weevil larvae (Dolinkski et al., 2012). This is one of the reasons why soil must be alive because the soil food web is tightly connected with pest-disease complexes.


3. Supporting services: organic matter and nutrient cycling, soil formation processes

Soils provide the space for the organic matter turnover and stabilization dynamics and cycling of nutrients which are essential processes for nutrient availability for plants and other soil organisms. Other processes that soils support are soil formation processes which are essential for the development and establishment of soils.

Casabe soil series. Courtesy of @zoils.pr

4. Cultural Services: Art, religion/spirituality, recreation, culture


In addition to ecological processes, soils play a key role in human lives through cultural, recreational, religious/spiritual, services. From art to literature, to music and forensics, soils are present in all aspects of human life. It’s been documented that clay tablets were considered the first portable pieces for writing and painting (Sindelar 2015). Colorful minerals of the soil also serve as sources of dyes and paints.

A Samoan 'umu at the early stage of heating the rocks. The soil acts as an oven to cook some traditional Samoan foods.

Cultural utilization of soil as pigments has been documented since 100,000 years ago. Projects like Arte-Suelo-Ser aim to communicate the importance of soils conservation through arts; nourishing the general public's appreciation for soils. Even Johnny Cash dedicated an entire album to soils, called Songs of Our Soil! Modern crime investigations look for footprints in the soil to gather more clues to help find suspects (Sindelar 2015).





Not just soils, but healthy soils


We cannot emphasize enough that soils are extremely important and play a key role for our planet and our everyday lives. However, over the past decades, many intensive and irresponsible soil management practices have led to the erosion and degradation of soils, significantly limiting their capacities to provide these essential services. Soils are a finite resource, implying that they take thousands of years to form and recover. We cannot continue harming and degrading our soils as we are doing because they might not be able to recover within our lifespan! This is highly detrimental for the environment, and ultimately for ourselves. Therefore, it is crucial to build healthy soils now and we provide 3 reasons to support this statement:


There is an urgent need to adopt strategies to protect soil and improve its quality. Although their integration will differ from field to field, there are some common approaches that are beneficial for building healthy soils:


1. Cover crops

These are a living ground cover planted into or after cash crops (Hartwig and Ammon, 2002). cover crops protect the soil’s surface from unfavorable conditions while enhancing its physical, chemical, and biological properties (Lu et al., 2000).


2. Reducing/Eliminating Tillage

Reducing soil disturbance reduces soil erosion and favors conditions to the vital soil organisms that are protagonists in most soil processes, like fungi. Also, reduced tillage and no-till can help to build soil organic matter and reduce greenhouse gas emissions.



3. Crop Rotations

It’s been shown that continuous monoculture is dangerous for food security because it makes the ecosystem susceptible to pests and diseases (Crews et al., 2018). Also, continuous monoculture suppresses soil biodiversity and biological processes.



4. Crop diversity

Increased aboveground diversity favors belowground biodiversity and activity. This favors soil services such as pest suppression, nutrient cycling, and increases soil resilience to erosion and degradation.

Soil health recognizes the soil as a living system, where biodiversity is fundamental to execute functions in soil. Soil organisms influence soil physical and chemical properties. They are principal participants in the cycling and regulatory processes. Microbial communities benefit crops by maintaining soil fertility through their influence on nutrient fluxes.


Because soils are home to a large proportion of the Earth’s genetic diversity, today we celebrate the life that soils sustain and support this year’s FAO World Soil Day theme: “Keep soil alive, protect soil biodiversity.”


Without soils, where would humanity stand?


This article was written by WAGS members Noelymar González Maldonado and Patricia Marie Cordero Irizarry in collaboration with Zoelie Rivera Ocasio, founder of @zoils.pr and @arte.suelo.ser, a project that highlights the relationship between soils and humanities.


References


Coleman, D., D.A. Crossley, and P. Hendrix. 2004. Fundamental of Soil Ecology. Second Edition. Georgia, U.S.


Crews, T.E., W. Carton and L. Olsson. 2018. Is the future of agriculture perennial? Imperatives and opportunities to reinvent agriculture by shifting from annual monocultures to perennial polycultures. Global Sustainability 1, e11, 1–18. https://doi.org/10.1017/sus.2018.11.


Dolinski, C., Choo, H.Y., Duncan, L.W., 2012. Grower acceptance of entomopathogenic nematodes: case studies on three continents. Journal of Nematology 44, 226–235.


Hartwig, N. and H. Ammon. 2002. Cover crops and living mulches. Weed Science. 50:688-699.


Lu, Y., K. Watkins, J.R. Teasdale, and A.A. Abdul-Baki. 2000. Cover crops in sustainable food production. Food reviews International. 16:121-157.


Oelkers, E. H. & Cole, D. R. 2008. Carbon dioxide sequestration: a solution to the global problem. Elements 4, 305-310.


Sinderlar, M. 2015. Soils, Culture, and People. Soil Science Society of America. https://www.soils.org/files/sssa/iys/december-soils-overview.pdf.


USDA National Agricultural Statistics Service, 2014. Cattle – final estimates 2009-2013. Statistical Bulletin Number 1034.



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