Soils and the delivery of ecosystem services

A farmer ploughing a field
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Soils and the ecosystem

Soils are fundamental to the provision of a wide range of ecosystem services that are vital for human well-being and ecological balance. They serve as a critical interface between the atmosphere, hydrosphere, and biosphere, supporting processes that regulate water, nutrient cycles, and biodiversity. This overview discusses the key ecosystem services provided by soils, highlighting their importance in agricultural productivity, water filtration, carbon sequestration, and habitat provision.

Agricultural productivity

Soils are the foundation of terrestrial food production systems. They provide essential nutrients and a medium for plant growth, influencing crop yield and quality. Healthy soils contribute to sustainable agriculture by maintaining fertility through nutrient cycling and organic matter retention (Lal, 2004). Soil management practices, such as crop rotation and cover cropping, enhance soil health and resilience, further supporting agricultural productivity (Doran & Zeiss, 2000).

Water regulation and filtration

Soils play a crucial role in regulating the hydrological cycle. They facilitate groundwater recharge and surface runoff management, thereby mitigating flood risks and enhancing water availability (Davis & McCarty, 2008). Additionally, soils act as natural filters, removing contaminants and improving water quality through microbial processes and adsorption (Graham et al., 2005). This filtration capacity is vital for maintaining healthy aquatic ecosystems and ensuring safe drinking water supplies.

Carbon sequestration

Soils are significant carbon sinks, storing more carbon than the atmosphere and vegetation combined (Jobbágy & Jackson, 2000). Through the processes of photosynthesis and organic matter decomposition, soils sequester carbon, mitigating climate change by reducing greenhouse gas concentrations in the atmosphere. Soil management practices that promote organic matter retention, such as agroforestry and conservation tillage, enhance soil carbon sequestration potential (Lal, 2004; Powlson et al., 2011).

Biodiversity and fabitat provision

Soils support a vast array of organisms, from microorganisms to larger fauna, contributing to soil health and resilience. Biodiversity within soil ecosystems enhances nutrient cycling, disease regulation, and overall soil functioning (Giller et al., 1997). Diverse soil habitats are crucial for maintaining ecosystem stability and providing services such as pest control and pollination.

Cultural and aesthetic values

Beyond their physical and biological functions, soils also provide cultural and aesthetic services. They are integral to landscapes that support recreational activities, cultural practices, and traditional agricultural systems. The connection between communities and their soils fosters a sense of place and cultural identity, highlighting the socio-cultural dimensions of ecosystem services (Meyer et al., 2018).

Understanding the multifaceted roles of soils in delivering ecosystem services is essential for effective land management and conservation strategies. By recognizing the intrinsic value of soils, stakeholders can implement practices that enhance soil health, promote sustainable agriculture, and support ecosystem resilience. Integrating soil science into environmental policies and land-use planning is crucial for safeguarding the services that soils provide, ultimately contributing to human well-being and ecological sustainability.

Role of belowground biodiversity in ecosystem services

Belowground biodiversity, encompassing the diverse array of organisms residing in soil ecosystems, play a crucial role in the delivery of vital ecosystem services. These services, including nutrient cycling, soil structure formation, carbon sequestration, and disease regulation, are fundamental for maintaining ecosystem health and resilience. This overview establishes the significance of belowground biodiversity in ecosystem service provision and identifies key threats to soil biota.

Belowground organisms, including bacteria, fungi, protozoa, and invertebrates, are integral to nutrient cycling processes. They decompose organic matter, facilitating the release of nutrients essential for plant growth (Swift et al., 1998). For instance, mycorrhizal fungi form symbiotic relationships with plant roots, enhancing nutrient uptake—particularly phosphorus—while contributing to soil organic matter formation (Smith & Read, 2008).

Soil fauna, such as earthworms and arthropods, contribute to the physical structure and stability of soils. Their burrowing activities promote aeration and water infiltration, improving soil drainage and root penetration (Blouin et al., 2013). Additionally, soil organisms participate in the formation of soil aggregates, which protect organic matter and enhance soil fertility (Rillig, 2004).

Belowground biodiversity plays a significant role in carbon sequestration. The decomposition of organic materials by microbial communities leads to the stabilization of soil organic carbon, mitigating climate change by reducing atmospheric CO2 levels (Lal, 2004). The diverse microbial processes involved in carbon cycling are crucial for maintaining soil health and productivity.

A diverse soil microbiome can suppress plant pathogens through various mechanisms, including competition for resources and the production of antimicrobial compounds (Mazzola, 2004). This biocontrol function is essential for promoting plant health and reducing the reliance on chemical pesticides.

Threats to belowground biodiversity

The key threats to belowground soil biodiversity are:

Land use change

Intensive agricultural practices, urbanization, and deforestation significantly alter soil ecosystems, leading to habitat degradation and loss of biodiversity. The application of chemical fertilizers and pesticides can disrupt microbial communities and reduce overall soil health (Smith et al., 2015).

Climate change

Climate change poses a direct threat to belowground biodiversity through alterations in temperature and moisture regimes. These changes can impact the distribution and activity of soil organisms, potentially leading to declines in biodiversity and ecosystem functioning (Kardol et al., 2010). Furthermore, increased frequency of extreme weather events can exacerbate soil erosion and degradation.

Soil contamination

Pollution from heavy metals, plastics, and agrochemicals adversely affects soil organisms. Contaminants can reduce microbial diversity and alter community composition, impairing ecosystem services and soil health (Giller et al., 1998).

Invasive species

The introduction of non-native species can disrupt local soil ecosystems. Invasive organisms may outcompete native species for resources, leading to a decline in biodiversity and alterations in ecosystem functioning (Davis et al., 2011).

Conclusions

Establishing the importance of belowground biodiversity in delivering ecosystem services is critical for promoting sustainable land management and conservation strategies. Protecting soil biota from various threats is essential for maintaining soil health, resilience, and the myriad of services that support human and ecological well-being.

Life and soils

STARS PhD student, Paul George discusses life in soil. He explains how living organisms play crucial roles in maintaining soil health across the planet; providing plants and animals with the water, nutrients and habitat they need to survive. Greater understanding of these organisms and their interactions has the potential to promote sustainable and healthy agricultural systems.

Demonstrating the relationship between soil physical properties and ecosystem functioning

Soil physical properties are critical determinants of ecosystem functioning, influencing processes such as water retention, nutrient availability, and biological activity. Here we introduce the key physical properties of soil—texture, structure, porosity, and density—and their interconnections with various ecosystem functions.

Soil texture

Soil texture, defined by the proportions of sand, silt, and clay, significantly affects water retention and drainage, nutrient availability, and microbial activity. Soils with a good clay content generally exhibit greater water-holding capacity, which can enhance plant growth during dry periods (Hillel, 2004) and fertility by increasing the cation exchange capacity (CEC). In contrast a heavy clay soil can become waterlogged. Conversely, sandy soils drain quickly but are more prone to drought. This balance impacts ecosystem productivity and resilience, particularly under changing climatic conditions (Lal, 2004).

Soil structure

Soil structure refers to the arrangement of soil particles and the spaces between them. Well-structured soils facilitate root penetration, water infiltration, and aeration, which are vital for plant growth and soil microbial communities (Keller et al., 2016). Aggregate formation, influenced by organic matter content and microbial activity, enhances soil stability and decreases erosion risk (Rillig, 2004). Poorly structured soils can impede water movement and root development, leading to reduced ecosystem productivity.

Porosity and bulk density

Porosity, the volume of pore space in soil, is crucial for water and air movement. High porosity allows for better drainage and oxygen availability, supporting root respiration and microbial activity (Danielson & Sutherland, 1986). Bulk density, inversely related to porosity, provides insight into soil compaction. High bulk density can restrict root growth and reduce the capacity of the soil to store water, negatively impacting plant health and ecosystem stability (Baver et al., 1972).

Water holding capacity

The ability of soil to retain water is a key physical property that directly influences ecosystem functioning. Water holding capacity is affected by both texture and structure, impacting plant growth and the functioning of soil biota (Rayment & Higginson, 1992). Soils with adequate water retention support more diverse plant communities and contribute to higher ecosystem productivity.

Erosion and soil conservation

Soil physical properties are integral to erosion dynamics. Well-structured soils with high organic matter content are more resistant to erosion, promoting soil conservation and maintaining ecosystem integrity (Lal, 2003). Conversely, degraded soils with poor structure and low cohesion are more vulnerable to erosion, leading to loss of topsoil and nutrients, which can drastically alter ecosystem functions (Pimentel et al., 1995).

Implications for land management

Understanding the relationship between soil physical properties and ecosystem functioning is essential for effective land management practices. Soil conservation techniques, such as reduced tillage and cover cropping, can enhance soil structure and promote ecosystem resilience (Giller et al., 2011). Furthermore, integrating soil health assessments into land-use planning can facilitate the sustainable use of soil resources, enhancing ecosystem services.

Conclusion

The interplay between soil physical properties and ecosystem functioning underscores the importance of maintaining healthy soil systems for sustaining ecosystem services. By recognizing and managing these relationships, stakeholders can better protect and enhance ecosystem resilience, productivity, and overall environmental health.

Studying the fate of waste stream products in soil

The increasing prevalence of waste stream products, including metal nanoparticles and antibiotics, poses significant challenges to soil health and ecosystem functioning. Understanding the fate of these contaminants in soil systems is crucial for evaluating their environmental impacts and developing effective management strategies.

Metal Nanoparticles

Metal nanoparticles, such as silver (Ag), copper (Cu), and zinc (Zn) nanoparticles, are increasingly used in various industrial applications, including medicine and electronics. Once released into the environment, these nanoparticles can enter soil systems through various pathways, such as agricultural runoff, wastewater irrigation, and the deposition of urban waste (Mohan et al., 2018). In soils, the fate of metal nanoparticles is influenced by factors such as soil texture, organic matter content, pH, and microbial activity. They can undergo transformations, including agglomeration, dissolution, and adsorption to soil particles, affecting their bioavailability and toxicity (Khan et al., 2019).

Antibiotics

Antibiotics enter soil systems primarily through agricultural practices, particularly the application of manure from livestock treated with these substances (Dahlgren et al., 2015). In soils, antibiotics can persist for extended periods, with degradation rates influenced by soil properties and microbial communities. The presence of antibiotics in soils can disrupt microbial communities, potentially leading to the development of antibiotic-resistant bacteria (Bengtsson-Palme et al., 2018).

Effects on soil health

Metal nanoparticles and antibiotics can have a host of negative effects on soil health, disrupting a host of processes important to the maintenance of soil conditions.

Microbial communities

Both metal nanoparticles and antibiotics can have profound effects on soil microbial communities. Metal nanoparticles can be toxic to specific microbial populations, altering community structure and function (Kumar et al., 2021). For instance, Ag nanoparticles are known to inhibit bacterial growth, which can disrupt essential soil processes such as decomposition and nutrient cycling. Similarly, antibiotics can reduce microbial diversity and inhibit the growth of beneficial soil microorganisms, impairing soil health and functioning (Ghosh et al., 2018).

Nutrient cycling

The disruption of microbial communities by these contaminants can significantly affect nutrient cycling processes. Microbial activity is vital for organic matter decomposition, nitrogen fixation, and phosphorus solubilization. Altered microbial communities can lead to reduced nutrient availability, negatively impacting plant health and productivity (Nannipieri et al., 2003).

Soil structure and functioning

Heavy metals and nanoparticles can also influence soil physical properties. The accumulation of these contaminants can lead to soil compaction and reduced porosity, impacting water infiltration and retention (González et al., 2019). The changes in soil structure can further exacerbate issues related to erosion and runoff, leading to degraded soil health.

Management implications

Addressing the impacts of waste stream products on soil health requires effective management strategies. Practices such as soil remediation, careful management of waste disposal, and the use of bioremediation techniques can help mitigate the adverse effects of these contaminants. Additionally, implementing regulations on the use of antibiotics in agriculture and promoting sustainable practices can reduce the introduction of these substances into soil systems (Van Boeckel et al., 2015).

Conclusions

The fate of waste stream products like metal nanoparticles and antibiotics in soil systems is a growing concern for soil health and ecosystem functioning. Understanding their behaviour, effects, and management options is crucial for safeguarding soil quality and ensuring sustainable agricultural practices. Continued research is needed to assess long-term impacts and develop strategies for mitigating risks associated with these contaminants.

Antibiotic resistance on the farm

STARS PhD Student Alex Williams presents an insight from his research on antibiotic resistance in soils.

Soil knowledge