Soil Resource Protection and Monitoring

1.1. Soil as a Unique Natural Resource

Soil is not merely a substrate for growing plants. It is a complex bio-abiotic system that has formed over millennia under the influence of climate, topography, parent material, and living organisms (Eash et al., 2016). As German soil scientists vividly put it, soils form the "skin of the Earth"—a thin and vulnerable envelope whose thickness ranges from a few centimeters to several tens of meters, while the Earth's radius reaches 6,370 km (Scheffer et al., 2018). This metaphor emphasizes the main point: the soil cover is a resource that is not only valuable but also extremely fragile.

Unlike air and water, soil is practically non-renewable on the scale of a human lifetime. The rate of soil formation is extremely slow: forming a 1 cm layer (about 150 t/ha) in temperate latitudes takes centuries, and in tropical regions—decades (Weil & Brady, 2017). At the same time, soil losses from erosion can amount to tens of tons per hectare in a single year. This fundamental mismatch between the rate of formation and the rate of destruction of soil is the main reason why soil needs protection.

1.2. Natural and Accelerated Soil Dynamics

It is important to distinguish between two types of changes in soil cover.

Natural (geological) erosion is a process that occurs in nature without human intervention. It shapes the landscape: river valleys, ravines, deltas, levels mountains, and fills depressions. Under undisturbed vegetation, such as in forests or steppes, geological erosion is negligibly small—averaging less than 0.1 t/ha per year (Weil & Brady, 2017). Soil formation proceeds faster than removal, and the soil profile is preserved.

Accelerated erosion is the result of human activity. When people cut down forests, plow land, overgraze livestock, or build roads, they expose the soil. The rate of erosion increases by 10–1000 times compared to geological rates (Weil & Brady, 2017). On agricultural lands in Africa, Asia, and South America, average annual soil losses from water and wind erosion are 30–40 t/ha. In North America, cropland loses about 7 t/ha from water erosion and 5 t/ha from wind erosion. In some years, losses can be significantly higher.

Erosion is only one of many degradation processes. However, it is responsible for approximately 85% of all cases of soil degradation worldwide (Weil & Brady, 2017). According to FAO data, about 2 billion hectares of land globally are degraded to some degree, and erosion plays the main role in most of these territories (Fig. 1). Approximately 10 million hectares are so severely degraded that their restoration is impossible (Weil & Brady, 2017).

1.3. Main Threats to Soil Resources

Soil degradation is a process leading to the deterioration of their composition, properties, and functions (Mukha et al., 2003). Modern classification identifies several main types of degradation (Valkov et al., 2004; Mukha et al., 2003):

1. Physical degradation:

• Water erosion—the washing away and scouring of soil by meltwater and rainwater. Includes sheet erosion (uniform removal of the top horizon), linear erosion (formation of gullies and ravines), as well as irrigation erosion.
• Wind erosion (deflation)—the blowing away of soil particles. Particularly dangerous on light soils in arid regions. Begins at wind speeds exceeding 5 m/s.
• Technological degradation—deterioration of physical properties as a result of agricultural activities: compaction (including by the running gear of heavy machinery), destruction of structure, and agro-exhaustion.
• Industrial erosion—destruction of soils during mining, construction, and road laying.

2. Chemical degradation:

• Salinization—accumulation of readily soluble salts in the root zone. Especially dangerous under irrigation without proper drainage. When salt content exceeds 0.15–0.35%, most crops suffer (Mukha et al., 2003). At 0.7% salts, only very salt-tolerant species survive.
• Alkalization (sodication)—accumulation of exchangeable sodium in the soil exchange complex. When exchangeable Na⁺ content exceeds 10–15% of the cation exchange capacity, plants develop poorly, and at 20–35%, they are severely inhibited.
• Acidification—decrease in soil pH, often associated with the application of physiologically acidic fertilizers and acid precipitation.
• Contamination with heavy metals, petroleum products, pesticides, radionuclides, as well as excessive accumulation of nutrients (nitrogen, phosphorus) due to improper fertilizer application.

3. Biological degradation:

• Loss of humus (dehumification)—one of the most dangerous phenomena. In arable soils, humus reserves can decrease by 25% or more (Mukha et al., 2003).
• Decline in the abundance and diversity of soil microorganisms and mesofauna.
• Deterioration of microbiological activity—suppression of nitrification, ammonification, cellulose decomposition, and soil enzyme activity (Valkov et al., 2004).
• General depletion of soil biota as a critical component ensuring nutrient cycling and maintaining fertility.

4. Comprehensive landscape degradation—particularly characteristic of permafrost regions, where disturbance of vegetation cover leads to ground thawing, erosion development, and soil destruction (Valkov et al., 2004). Military actions can also cause large-scale destruction of soil cover and radioactive contamination.

1.4. Consequences of Soil Degradation: On-site and Off-site Effects

The damage from soil degradation is divided into two categories: on-site and off-site (Weil & Brady, 2017).

On-site consequences (local):

• Decline in fertility and productivity. Losses of humus, nitrogen, phosphorus, potassium, and micronutrients with eroded material significantly exceed their concentration in the remaining soil (enrichment ratio). Organic matter and nitrogen in eroded material can be 5 times higher than their content in the original soil (Weil & Brady, 2017).
• Deterioration of physical properties: compaction, crust formation, reduced water permeability and water-holding capacity.
• Reduction in the depth of the root zone.
• On slightly eroded soils, yields decrease by 10–20%, on moderately eroded soils—by 30–40%, and on severely eroded soils—by 50–60% compared to non-eroded analogs (Mukha et al., 2003). On deflated soils, yield losses are 10–25% less, but still significant.
• Formation of ravines that dissect fields and make machinery use impossible.

Off-site consequences (external):

• Silting of rivers, reservoirs, and canals. Billions of tons of sediment enter water bodies worldwide annually. Reduced reservoir capacity, silting of ports and shipping channels.
• Water turbidity, deterioration of drinking water quality. Sedimentation on fish spawning grounds, death of aquatic organisms.
• Contamination of water bodies with nutrients (nitrogen, phosphorus), causing eutrophication.
• Air dust pollution. PM₁₀ and PM₂.₅ particles generated by wind erosion pose a serious danger to human health (respiratory diseases, cardiovascular pathologies). Some estimates suggest that mortality from inhaling fine dust may exceed traffic fatalities (Weil & Brady, 2017).
• Economic damage amounts to tens of billions of dollars annually in the US alone, and globally—over $500 billion annually (Weil & Brady, 2017).

1.5. Soil in the Context of Global Challenges: The Anthropocene

Soil scientists increasingly speak of the onset of a new geological epoch—the Anthropocene (from Greek anthropos—man), in which human activity becomes the main factor of planetary change (Richter & Tugel, 2012). And soils are no exception. Today, more than half of the 13 billion hectares of land are somehow affected by human activity: plowed, used for pastures, forests, built up, disturbed by mining, or contaminated (Richter & Tugel, 2012).

"Global soil change" is not a metaphor but a reality. Soils have ceased to be only "natural bodies"; they have become cultural-historical systems to which humans contribute as a sixth factor of soil formation (Richter & Tugel, 2012). In essence, humans themselves have become an agent of soil formation—and far from always a beneficial one.

This is precisely what makes soil protection not just an agronomic task but a strategic necessity for the survival of humanity.

1.6. Ecological Specificity of Fertility

It is important to understand: there is no "generally fertile soil." Fertility is always specific and tied to a particular plant (Valkov et al., 2004). Pliny the Elder in the 1st century AD noted: "The soil which is adorned with tall and stately trees is far from being the best, if one considers its suitability for the trees themselves."

Different plants have different requirements for soil conditions. Tea and lupine grow only on acidic soils; alfalfa prefers neutral and slightly alkaline ones. Cereals need heavy structural soils; potatoes and melons need light ones. On rich soils, grapes and tobacco deteriorate in product quality, while hemp and vegetables, on the contrary, require very rich soils. Therefore, the same soil may be fertile for some plants and low-fertility for others.

This feature is directly relevant to soil protection. If we lose a certain soil type, we lose not just "fertility in general" but the ability to grow specific crops adapted to that soil type. The reduction in soil diversity also reduces the diversity of possible agroecosystems. This is why soil protection includes not only protection from erosion and pollution but also the preservation of soil diversity.

1.7. Irreversibility of Many Processes

Of particular concern is the irreversibility of many degradation processes. As Richter and Tugel (2012) emphasize, the most important criterion for the danger of soil change is its reversibility.

• Erosion leads to the irreversible loss of the top, most fertile horizon. Even if erosion is stopped, restoration of the soil profile will take centuries.
• Acidification (for example, in forest soils under the influence of acid precipitation) can lead to the destruction of clay minerals and the release of toxic aluminum (Al³⁺), which irreversibly changes the chemical properties of the soil for decades and longer (Scheffer et al., 2018).
• Salinization without drainage is often irreversible without large-scale and expensive reclamation.
• Contamination with heavy metals at high concentrations makes soil unsuitable for agricultural use almost forever, since metals do not decompose.
• Loss of humus reduces cation exchange capacity, water-holding capacity, and biological activity; restoration of organic matter requires a long time (decades) and properly organized management.

Thus, soil protection is not just about caring for the current harvest. It is an investment in the future, a guarantee that future generations will have the same opportunities for food production as we do.

1.8. Soil and Food Security

In the context of global population growth—according to UN forecasts, by 2050 there will be about 9.5–10 billion of us—the problem of soil conservation becomes critical. Estimates indicate that by 2050, to provide food, it will be necessary to increase global food production by 35–70% (Scheffer et al., 2018; Weil & Brady, 2017).

At the same time, new lands for agriculture are practically exhausted. Most suitable lands are already in use, and further development is associated with loss of forests and biodiversity, which entails additional environmental risks. The only path is to increase yields on existing areas. But this is impossible without maintaining and improving soil fertility. And fertility is a direct function of soil condition: its physical, chemical, and biological properties.

In addition, soils perform a number of ecosystem functions that must also be preserved (Richter & Tugel, 2012; Weil & Brady, 2017):

• Water regime regulation: filtration, storage, and purification of water.
• Carbon sequestration: soils are the largest terrestrial reservoir of organic carbon, and their degradation leads to CO₂ emissions into the atmosphere, intensifying the greenhouse effect.
• Biodiversity conservation: soil is a habitat for a quarter of all known species.
• Cultural and historical function: soil is an archive of the past, storing information about climate, vegetation, and human activity.

It is this multifunctionality of soils that makes their protection a task extending far beyond agriculture.

To summarize:

Soils need protection because:

1. They are a non-renewable resource on the scale of human life: the rate of soil formation is thousands of times lower than the rate of erosion.

2. Soil degradation (erosion, salinization, acidification, contamination, loss of humus and biodiversity) is increasing, and this is largely the result of anthropogenic activity.

3. Soil losses are not limited to reduced fertility on-site—they cause large-scale off-site effects (siltation of water bodies, air and water pollution, economic losses).

4. Many degradation processes are irreversible or reversible only over centuries.

5. In the context of population growth and limited land resources, soil conservation is a condition for food security and sustainable development of civilization.

6. Soils perform many ecosystem functions beyond production, and their loss means the loss of these essential "services."

Thus, the question "how to understand whether soil retains its functions?" becomes central to assessing the effectiveness of environmental protection measures and the sustainability of land use. The answer is provided by soil monitoring systems and the development of objective soil condition indicators, which will be the focus of the following sections of this lecture.

2.1. The Precautionary Principle (Preventiveness)

The precautionary principle (German Vorsorgeprinzip) is the cornerstone of modern soil protection policy. Its essence is simple: it is much more effective and cheaper to prevent degradation than to fight its consequences (Scheffer et al., 2018; Weil & Brady, 2017).

In Germany, this principle is directly enshrined in the Federal Soil Protection Act (BBodSchG, 1998), which states the need "to prevent harmful changes to soils" and "to take measures against adverse effects on soils in good time" (Scheffer et al., 2018). Similar provisions are contained in Russian legislation—in the Land Code of the Russian Federation and the Federal Law "On Environmental Protection," where land protection is defined as a system of measures aimed at the rational use, reproduction, and preservation of soils.

Why is this important? Because:

• Restoration of degraded soil requires decades and enormous costs (sometimes exceeding the value of the land itself).
• Contamination with heavy metals, petroleum products, or radionuclides is in many cases irreversible in the foreseeable future.
• Preventive measures—for example, preserving vegetation cover, proper tillage, regulating grazing—are many times cheaper than subsequent reclamation or combating siltation of water bodies.

Thus, preventiveness means that all types of economic activity should be planned and carried out so as to minimize the risk of soil degradation, rather than "treat" already arisen problems.

2.2. The Polluter Pays Principle (Verursacherprinzip)

This principle states: the economic responsibility for preventing, reducing, and eliminating harm caused to soil lies with the one who caused this harm (Scheffer et al., 2018; Weil & Brady, 2017). In German legislation, it is enshrined as the obligation of the "culprit" (or their successor) to carry out remediation of contaminated sites.

In practice, this means:

• The land user who applies agrochemicals, fertilizers, and heavy machinery must bear the costs of monitoring their impact and, in case of violation, restoring the soil.
• Industrial enterprises that contaminate soils with emissions or waste are obliged to finance cleanup and monitoring.
• The state can apply economic levers: taxes, fines, payments for excessive pollution (Mukha et al., 2003).

In Russia, the polluter pays principle is implemented through a system of payments for negative environmental impact, environmental fines, and mechanisms for compensation of harm (Mukha et al., 2003). However, in practice, its application is often hampered by the complexity of identifying pollution sources and assessing long-term damage.

Nevertheless, economic responsibility is a powerful incentive for implementing environmentally safe technologies and for abandoning risky land use practices.

2.3. The Principle of Sustainability (Non-depleting Use)

Sustainability (sustainability) is the ability of a system to maintain its functions over a long period without irreversible degradation. Applied to soils, this principle means that the intensity of soil use should not exceed its capacity for self-restoration (White, 2006; Weil & Brady, 2017).

In practical terms, this is expressed in:

• Preventing exceedance of permissible soil loss rates (T-values) . In the US, for most agricultural soils, allowable losses are set within 5–11 t/ha per year (Weil & Brady, 2017). This means that erosion should not exceed the rate of soil formation.
• Maintaining the balance of nutrients: removal with harvest should not exceed input (from fertilizers, atmospheric precipitation, biological nitrogen fixation, etc.). Otherwise, agro-exhaustion—loss of fertility—occurs (White, 2006).
• Preserving organic matter at a level that ensures sustainable functioning of soil biota and physicochemical processes.

More broadly, sustainability is interpreted in the concept of Sustainable Land Management (SLM) , proposed by FAO and developed in the work of many scientists (White, 2006). SLM considers not only productivity but also environmental, social, and economic aspects, including biodiversity conservation, water and air purity, and the well-being of local communities.

It is important to emphasize: sustainability is not a static state but a dynamic process of adaptation to changing conditions (climate, technologies, markets). It requires constant monitoring and adjustment of management decisions.

2.4. The Principle of Preserving All Soil Functions

Earlier (in Section 1), we spoke about the multifaceted nature of soil functions: productive (plant growth), ecological (filtration, buffering, nutrient cycling, habitat), and cultural-historical (archive of the past). The principle of multifunctionality requires that soil protection not be reduced only to protecting agronomic fertility but encompass the entire spectrum of these functions (Scheffer et al., 2018; Weil & Brady, 2017).

The German Federal Soil Protection Act (BBodSchG) directly lists the protected functions:

• Natural functions: basis of life and habitat for humans, animals, plants, and soil organisms; participation in the water and nutrient cycles; filtering, buffering, and transformation capacity (especially for groundwater protection).
• Archive function: soil as a repository of information about the natural and cultural history of the landscape.
• User functions: raw material resources, area for construction and recreation, as well as for agricultural and forestry production (Scheffer et al., 2018; also section 11.7 in Scheffer).

Thus, when assessing soil condition and making decisions, all these aspects must be considered. For example, even if soil yields well but loses its buffering capacity (for example, due to acidification and leaching of cations) or loses biodiversity, this is an alarm signal. Protection must be comprehensive.

2.5. The Principle of Scientific Validity and Systemic Monitoring

Soil protection cannot be successful without a deep understanding of soil processes and without objective information about the current state. This principle requires that all environmental decisions be based on data from soil surveys, monitoring, and scientific research (White, 2006; Weil & Brady, 2017).

This includes:

• Conducting large-scale soil surveys and compiling soil maps containing information on soil type, texture, humus content, pH, cation exchange capacity, groundwater depth, and other key indicators (Mukha et al., 2003).
• Organizing systematic monitoring (regular observation of changes in soil indicators over time). Without monitoring, it is impossible to assess whether soil conditions are improving or worsening and to adjust management in time.
• Using scientifically based soil condition indicators (about them—in Section 4) that allow objective and quantitative characterization of soil quality and their ability to perform functions.
• Applying mathematical models to forecast soil changes under the influence of climate, land use, and other factors.

As Richter and Tugel (2012) note, in the Anthropocene epoch, science must move from studying "natural" soils to studying anthropogenically modified systems and develop methods for predicting their behavior on time scales of decades and centuries. This requires an interdisciplinary approach combining soil science, ecology, climatology, economics, and social sciences.

2.6. The Principle of Integration with Protection of Other Natural Environments

Soil does not exist in isolation. It is connected to the atmosphere (gas exchange, precipitation, dust deposition), hydrosphere (water filtration, groundwater), and biosphere (living organisms). Therefore, soil protection is inseparable from the protection of water, air, and biodiversity (Scheffer et al., 2018; Weil & Brady, 2017).

Examples of such interconnections:

• Combating water erosion simultaneously protects rivers and water bodies from siltation and nutrient contamination.
• Preventing soil contamination with heavy metals and pesticides protects groundwater and food chains.
• Restoration of forest belts and natural vegetation increases carbon sequestration and improves microclimate.
• Proper pasture management reduces deflation and preserves biodiversity both in the soil and aboveground.

In the concept of ecosystem services, soils are considered a key component providing many "services" (regulation of water runoff, water purification, carbon sequestration, biodiversity support), and soil protection is simultaneously the protection of these services (White, 2006; Weil & Brady, 2017). Therefore, intersectoral cooperation—between agriculture, forestry, water management, and urban planning—is a mandatory condition for successful protection.

2.7. The Principle of Fertility Reproduction and Reclamation

This principle is closely related to the principle of sustainability but emphasizes the active role of humans: it is not enough to simply "do no harm"—it is necessary to purposefully restore and improve soils where they have been disturbed (Valkov et al., 2004; Mukha et al., 2003; Weil & Brady, 2017).

This includes:

• Reproduction of fertility in agroecosystems: application of organic and mineral fertilizers, liming, gypsum application, use of green manures and proper crop rotations, return of organic matter (crop residues, straw, manure).
• Reclamation of disturbed lands—a set of measures to restore the productivity of lands affected by industrial erosion (quarries, dumps), construction, and pollution. Reclamation includes two stages: technical (planning, chemical reclamation, application of humus layer) and biological (creation of vegetation cover, most often through sowing grasses and planting trees) (Valkov et al., 2004; Mukha et al., 2003).
• Restoration of soils affected by salinization, alkalization, and acidification through chemical amendments (gypsum, lime, acid-forming substances), deep ripping, leaching, drainage, and selection of tolerant crops.

It is important that reclamation is a long and costly process, often requiring several decades. Therefore, the precautionary principle here acts as an economically more profitable alternative.

2.8. The Principle of Environmental and Social Justice

Although this principle is more often discussed in a socio-economic context, it is directly relevant to soil protection. Soil degradation usually hits the poorest segments of the population hardest, who depend on subsistence agriculture and lack the resources for reclamation technologies or transitioning to other activities (Weil & Brady, 2017; White, 2006). At the same time, the benefits of intensive use (for example, in large agricultural holdings) are often received by some, while the consequences (water pollution, land degradation) affect others, including neighbors and future generations.

Consequently, soil protection must take into account social justice: access to knowledge, technologies, and resources for sustainable land use should be equal, and responsibility for degradation should be fairly distributed. This aligns with the UN Sustainable Development Goals and the tasks of the Global Soil Partnership (more details in Section 6).

Link Between Principles and Monitoring

All of the above principles cannot be implemented without an information base. How can the precautionary principle be applied without knowing which soils are vulnerable to erosion? How can sustainability be ensured without data on humus dynamics or biological activity? How can the polluter's guilt be proven without systematic observations?

This is precisely why the next section of our lecture—on soil monitoring—is a logical continuation of the protection principles. Monitoring provides that objective picture without which all principles remain mere good intentions.

To summarize:

The principles of soil protection form an interconnected system that requires:

• Prevention of degradation (prevent, do not repair).
• Economic responsibility (polluter pays).
• Sustainability (non-depleting use).
• Comprehensive approach to preserving all soil functions (not only productive).
• Scientific validity and regular monitoring.
• Integration with protection of other environments (water, air, biodiversity).
• Active reproduction of fertility and reclamation of disturbed lands.
• Social justice in the distribution of benefits and responsibilities.

These principles serve as a guide for the development of national and international soil protection strategies and underlie modern monitoring systems and indicators, which we now turn to.

3.1. Definition and Purpose of Soil Monitoring

Soil monitoring (from Latin monitor—one who reminds, warns) is a system of regular, repeated observations of the state of the soil cover, its properties, and processes occurring in soils, with the aim of timely detection of changes, their assessment, and forecasting (Valkov et al., 2004; Mukha et al., 2003; Richter & Tugel, 2012).

In a broader sense, monitoring is the information base for soil quality management. It allows:

1. To record the current state (to provide a "baseline").

2. To detect changes (both natural and anthropogenic) at early stages.

3. To assess trends (improvement, deterioration, stabilization) and the rate of changes.

4. To identify causes of observed changes (linking them to factors—climate, land use, pollution, etc.).

5. To forecast future changes under various management scenarios.

6. To evaluate the effectiveness of environmental protection measures and adjust them if necessary.

As White (2006) and Weil & Brady (2017) emphasize, monitoring is not a one-time survey but a continuous process covering long periods (years, decades). That is precisely why it requires special organization, standardization of methods, and long-term funding.

3.2. Why Monitoring is Needed: Link with Protection Principles

Monitoring is a tool without which none of the protection principles can be implemented in practice. Let's examine this connection in more detail:

Thus, monitoring is the "eyes and ears" of the soil protection system. Without it, all efforts to protect soils become no more than intuitive guesses.

3.3. Objects and Levels of Monitoring

Soil monitoring can cover different objects and be conducted at different levels (Mukha et al., 2003; Weil & Brady, 2017; Richter & Tugel, 2012).

Objects of monitoring:

• Soil profile (specific location, pit)—detailed study of all horizons.
• Soil cover (territory, landscape)—study of spatial heterogeneity.
• Individual properties and processes—for example, monitoring of humus, acidity, heavy metal content, biological activity, erosion processes.

Levels of monitoring (by scale):

1. Local (field) level—observations on a specific field, plot, or in a crop rotation. Most often tied to economic activity (monitoring the effectiveness of fertilizers, pesticides, erosion assessment).

2. Regional level—covers administrative districts, regions, natural zones. Allows identification of regional trends (for example, changes in soil acidity in areas of acid precipitation, spread of salinization in irrigated areas).

3. National level—nationwide observation system. In Russia—this is the state land monitoring conducted by Rosreestr and Rosselkhoznadzor. In Germany—this is the federal and state soil monitoring systems (Bodenzustandserhebung). In the US—the National Resources Inventory (NRI), conducted by NRCS (Weil & Brady, 2017).

4. Global level—international programs aimed at assessing the state of the planet's soils as a whole (for example, FAO's Global Soil Partnership, GLOSIS—Global Soil Information System).

Each level has its own tasks, methods, and frequency of observations. For example, local monitoring can be conducted annually or even more frequently, while global monitoring—at intervals of 5–10 years, using remote sensing data and modeling.

3.4. Types of Monitoring by Purpose

Depending on what exactly is being tracked, several types of monitoring are distinguished (Richter & Tugel, 2012; White, 2006; Weil & Brady, 2017):

1. Background (baseline) monitoring—observations on reference, minimally disturbed territories (nature reserves, reference sites). The goal is to obtain "normal" (reference) values of indicators for specific soil types and natural zones. These data serve as a baseline for assessing anthropogenic changes.

2. Impact monitoring—observations in areas of active anthropogenic impact (industrial zones, intensive agricultural lands, irrigation areas, municipal solid waste landfills, mining sites). The goal is to assess the scale and direction of changes caused by a specific type of activity.

3. Pollution monitoring—systematic observation of the content of pollutants (heavy metals, pesticides, petroleum products, radionuclides, nitrates, etc.) in soils and adjacent environments (water, plants, air).

4. Fertility (agrochemical) monitoring—regular monitoring of basic fertility indicators: humus content, pH, available forms of nitrogen, phosphorus, potassium, and micronutrients. This is the basis for developing fertilization and liming systems.

5. Degradation process monitoring—tracking erosion, deflation, salinization, alkalization, acidification, compaction, loss of biological diversity, and other processes of soil deterioration.

6. Restoration (reclamation) monitoring—monitoring the dynamics of soil properties on disturbed territories during their recovery.

In practice, these types often overlap. For example, agrochemical monitoring on arable lands can simultaneously serve as fertility monitoring and early detection of pollution (if anomalous accumulation of heavy metals is recorded).

3.5. Organization of Monitoring: Spatial and Temporal Aspects

Spatial organization of monitoring (where and how to take samples) is critically important because soils have enormous spatial variability (Richter & Tugel, 2012; Weil & Brady, 2017). Even within one field, soil properties can vary significantly.

Main approaches to spatial placement of observation points:

• Regular grid—observation points are placed at equal distances from each other (for example, every 1–2 km). Convenient for regional and national systems but may miss characteristic areas.
• Stratified sampling—the territory is divided into homogeneous areas (according to soil maps, topography, land use), and points are established in each. This approach provides more representative data for different soil types and conditions.
• Reference (benchmark) sites—permanent plots where long-term observations are conducted. They can be part of a network or independent objects (for example, long-term stationary experiments).

It is important that the location of monitoring points be permanent over time. Only repeated measurements at the same sites allow detecting changes rather than just spatial heterogeneity. This requirement is enshrined in the methodological documents of most countries.

Temporal organization (how often to conduct observations) depends on:

• The rate of change of the indicator (rapidly changing properties require more frequent monitoring).
• Monitoring objectives.
• Available resources.

Richter & Tugel (2012) distinguish three main temporal scales of changes in soil properties:

Accordingly, observation frequency varies:

• For rapidly changing indicators (nitrates, available phosphorus, microbial biomass)—annually or even several times per season.
• For moderate-speed indicators (humus, bulk density, pH, heavy metals)—every 3–5 years.
• For "conservative" properties—less frequently, as needed (for example, repeated soil survey every 10–20 years).

However, it is important to understand that climatic variability (dry and wet years) can strongly influence many indicators, masking long-term trends. Therefore, monitoring programs aim to conduct observations over a sufficiently long period (at least 10 years) and account for weather conditions when interpreting data (White, 2006; Weil & Brady, 2017).

3.6. Methods and Approaches of Monitoring

Soil monitoring uses three main approaches, each with its own strengths and weaknesses (Richter & Tugel, 2012; Weil & Brady, 2017).

3.7. Monitoring Data: From Points to Maps

The results of monitoring are usually a set of data at individual points. To make them useful for decision-making (at the field, district, or country level), they need to be interpolated and mapped using GIS technologies (geographic information systems) (Weil & Brady, 2017; White, 2006; Mukha et al., 2003).

Modern Soil Information Systems (SIS), such as SOTER (World Soil and Terrain Digital Database) or national systems (for example, NIBIS in Lower Saxony, Germany), allow:

• Storing and processing observation data.
• Integrating them with other information layers (soil maps, digital elevation models, climate data, remote sensing data).
• Building thematic maps (for example, maps of humus content, pH, erosion hazard).
• Conducting spatial analysis and modeling.
• Providing information in a user-friendly format (web portals, interactive maps).

In Russia, regional and federal soil information systems are also being created and developed (including based on the Unified State Register of Land—EGRZ data), although their completeness and accessibility still lag behind Western counterparts.

3.8. Problems and Challenges of Monitoring

Despite its obvious importance, soil monitoring faces serious problems (Richter & Tugel, 2012; White, 2006; Weil & Brady, 2017):

1. High cost and duration. Systematic observations require continuous funding over many years, which is difficult to ensure amid shifting priorities and budget constraints. Long-term experiments are often at risk of closure (Richter & Tugel, 2012).

2. Lack of standardization. Different countries, and often different regions within one country, use different sampling, sample preparation, and analysis methods. This complicates data comparison and the creation of a global picture. Standardization efforts (for example, through ISO, CEN, and international projects) are important but still incomplete.

3. Complexity of data interpretation. Soil properties depend on many simultaneously acting factors (weather, management, natural variability). Separating their influence on the observed trend is a complex statistical task. This is especially true for LTRM data, where there are no control plots.

4. Incomplete coverage. In many regions of the world, soil monitoring is practically absent (developing countries, inaccessible territories). Even in developed countries, coverage may be uneven (for example, predominance of data on arable land with a lack of data on forests, pastures, urban soils).

5. Lack of biological indicators. Physicochemical indicators are monitored relatively well, while biological ones (microbial biomass, enzymatic activity, diversity of soil fauna) are monitored significantly worse. Yet it is biological properties that are often the most sensitive to changes and first signal degradation (Richter & Tugel, 2012; Weil & Brady, 2017).

Despite these difficulties, monitoring remains indispensable. Without it, it is impossible to answer the main question: "Does the soil retain its functions?" And it is precisely to answer this question that we need soil condition indicators, which we turn to in the next section.

To summarize:

Soil monitoring is a system of regular observations of soil condition, which provides the information base for implementing all protection principles. It covers different scales (from field to planet), different types (background, impact, pollution, fertility, etc.), and uses various approaches (long-term experiments, space-for-time substitution, resource monitoring, modeling). The organization of monitoring requires careful planning of spatial and temporal grids, standardization of methods, and integration of data into soil information systems. Despite high costs and methodological difficulties, monitoring is the "eyes and ears" of the soil protection system, without which it is impossible to objectively assess either risks or the effectiveness of environmental protection measures.

Key terms (for memorization):

• Soil monitoring
• Background, impact, agrochemical monitoring
• Long-Term Soil-Ecosystem Experiments (LTSE)
• Space-for-Time Substitution (SFTS)
• Long-Term Resource Monitoring (LTRM)
• Soil Information Systems (SIS)
• Dynamic and conservative soil properties
• Standardization of monitoring methods

4.1. What Are Indicators and What Criteria Should They Meet?

A soil quality indicator is a quantitatively measurable soil property that is sensitive to changes (natural or anthropogenic) and correlates with one or more soil functions (productive, ecological, buffering, etc.) (Weil & Brady, 2017; White, 2006). An indicator should be:

1. Sensitive—noticeably changing under the influence of pressures or improvements in management.

2. Interpretable—changes should have a clear meaning (for example, a decrease in humus is a deterioration).

3. Measurable—using available, reproducible, and not too expensive methods.

4. Representative—reflecting the overall condition of the soil, not just a narrow local effect.

5. Predictive—allowing forecasting of future changes and risk assessment.

It is important to understand: no single indicator provides a complete picture. As in medicine, where a doctor looks not only at temperature but also at pulse, blood pressure, and blood tests, soil science requires a set of indicators covering different aspects—physical, chemical, and biological (Weil & Brady, 2017; Richter & Tugel, 2012; Valkov et al., 2004).

4.2. Classification of Indicators: Physical, Chemical, Biological

In modern soil science, indicators are conventionally divided into three large groups (Weil & Brady, 2017; White, 2006; Richter & Tugel, 2012). Each group reflects its own "slice" of soil condition:

In recent years, increasing attention has been paid to integral indices that combine several indicators into a single assessment of "soil quality" (Soil Quality Index—SQI) (Weil & Brady, 2017). This allows comparison of different sites and tracking of overall dynamics. However, individual indicators also retain their value, especially for diagnosing specific problems.

Below we examine in detail the key indicators most commonly used in monitoring, which serve as the "calling card" of soil condition.

4.3. Organic Carbon (Humus)

Organic carbon (total or active) is one of the most important and informative indicators (Weil & Brady, 2017; White, 2006; Valkov et al., 2004; Mukha et al., 2003; Scheffer et al., 2018). It is often called the "heart of fertility" because it affects almost all soil functions:

• Physical properties: improves aggregation, reduces density, increases water permeability and water-holding capacity (Weil & Brady, 2017).
• Chemical properties: increases cation exchange capacity (CEC), serves as a source of nutrients (N, P, S) after mineralization, participates in acid buffering.
• Biological properties: is the main source of energy for soil microorganisms, supports food webs.

What does a change in organic carbon content indicate?

• Sustained decline—an alarming signal: soil is losing fertility, its structure is deteriorating, and its capacity to retain moisture and nutrients is decreasing. Typical causes: erosion, intensive tillage (mineralization), removal with harvest without organic matter return.
• Stability or growth—a good sign: soil maintains or increases its fertility potential. This is achieved through the application of organic fertilizers, green manures, minimum tillage, and retention of plant residues.

Normal values strongly depend on soil type and climatic zone. In chernozems, organic carbon content can reach 5–8% or more; in soddy-podzolic soils—1–3%; in tropical Ferralsols—often less than 1% (Weil & Brady, 2017).

Special attention in modern literature is given to active (labile) organic carbon—the part that decomposes rapidly and participates in plant and microbial nutrition. This fraction is the first to respond to changes in management and serves as an early indicator of degradation or improvement (Weil & Brady, 2017).

4.4. Structure and Aggregate Stability

Soil structure is the mutual arrangement and mode of bonding of soil particles into aggregates (crumbs, clods, grains, prisms, etc.) (Scheffer et al., 2018; Weil & Brady, 2017). Good structure (granular, crumbly) is one of the main conditions of fertility because it:

• Provides an optimal ratio of solid, liquid, and gaseous phases.
• Creates a system of macro- and micropores through which water and air can penetrate and move.
• Is resistant to destruction by water (water stability of aggregates), which prevents crust formation and erosion.

Measured through:

• Aggregate analysis—separation of soil into fractions by aggregate size (usually >0.25 mm are considered agronomically valuable).
• Water stability of aggregates—the ability of aggregates not to disintegrate when immersed in water. This indicator is especially sensitive to tillage and organic matter content.
• Visual assessment using scales (for example, the method of field structure evaluation).

Loss of structure (dispersion, slaking, crust formation) leads to deterioration of water permeability, water stagnation, overheating, reduced aeration, and consequently, reduced yields.

4.5. Bulk Density

Soil bulk density (ρ) is the mass of dry soil per unit volume, including pores, in g/cm³ or t/m³ (Scheffer et al., 2018; Weil & Brady, 2017; Valkov et al., 2004). It is a direct indicator of compaction and porosity.

Optimal values depend on soil type and texture:

• For sandy and loamy sand soils—1.4–1.6 g/cm³.
• For loamy soils—1.2–1.4 g/cm³.
• For clayey soils—1.0–1.3 g/cm³.
• For peat soils—0.2–0.5 g/cm³.
• Density above these values indicates overcompaction.

Compaction is one of the most common forms of physical degradation, especially under intensive agriculture with heavy machinery. Compaction:

• Reduces macroporosity, impairs aeration and drainage.
• Increases root penetration resistance.
• Reduces water permeability, promoting surface runoff and erosion.
• Deteriorates conditions for soil fauna (especially earthworms).

Bulk density can change during the season (plowing loosens, precipitation and compaction restore), so for monitoring, it is important to take measurements at the same time of year and under comparable moisture conditions (Weil & Brady, 2017).

4.6. Soil pH (Acidity)

pH is a measure of hydrogen ion concentration in the soil solution, determining the soil reaction (Scheffer et al., 2018; Weil & Brady, 2017; Valkov et al., 2004). It is one of the most "manageable" and yet sensitive indicators.

Influence of pH on soil processes:

• At low pH (<5.0), the solubility of toxic forms of aluminum (Al³⁺) and manganese increases, which inhibits root growth and reduces the availability of phosphorus, calcium, and magnesium.
• At pH 5.5–7.0 (neutral or slightly acidic)—optimum for most agricultural crops. Availability of major nutrients is maximum, microorganisms are active.
• At pH >7.5 (alkaline)—availability of micronutrients (Fe, Zn, Mn, Cu) decreases, formation of poorly soluble calcium phosphates is possible.

pH trends in monitoring:

• Decrease in pH (acidification)—often associated with the application of physiologically acidic fertilizers (especially ammonium-based), acid precipitation, and removal of bases with harvest. Acidification is a serious problem for many arable and forest soils (Scheffer et al., 2018; White, 2006).
• Increase in pH (alkalization)—can occur as a result of salinization (accumulation of carbonates and bicarbonates), irrigation with alkaline waters, application of high doses of sodium-containing fertilizers (for example, some phosphorus fertilizers).

For agronomic purposes, pH is usually measured in a soil suspension with water (pH H₂O) or in 0.01 M CaCl₂ (pH KCl, giving more stable values). In monitoring programs, it is important to follow a uniform methodology (Weil & Brady, 2017).

4.7. Cation Exchange Capacity (CEC)

Cation Exchange Capacity (CEC) is the ability of soil to retain exchangeable cations (Ca²⁺, Mg²⁺, K⁺, Na⁺, NH₄⁺, Al³⁺, H⁺) on its solid particles (especially on colloids—clay minerals and humus) (Scheffer et al., 2018; Weil & Brady, 2017; Valkov et al., 2004). Expressed in cmol(charge)/kg or meq/100 g of soil.

Significance of CEC:

• The higher the CEC, the more nutrient cations can be retained in a plant-available form and the better the buffering capacity against acidification.
• Low CEC (in sandy soils with low humus content) means that soil easily loses nutrients through leaching and requires more frequent fertilization.
• High CEC in chernozems and clayey soils ensures their high natural fertility.

Change in CEC in monitoring:

• Decrease in CEC is often associated with loss of humus or destruction of clay minerals (for example, during acidification).
• Increase may result from accumulation of organic matter or (in alkaline soils) accumulation of sodium, which is undesirable as it deteriorates structure (alkalization).

CEC is a relatively stable characteristic, but in long-term monitoring (10–20 years), its changes can be significant, especially under intensive agriculture and reclamation.

4.8. Biological Activity

Biological indicators are the "living pulse" of the soil. They are particularly valuable because they respond to changes faster than many chemical and physical indicators and reflect the integral state of the soil ecosystem (Weil & Brady, 2017; Richter & Tugel, 2012; Valkov et al., 2004).

Main biological indicators:

• Microbial biomass—the total mass of living microorganisms in the soil. Often determined by the fumigation-extraction method or substrate-induced respiration. A decrease in microbial biomass is an early sign of degradation, toxic pollution, or depletion of organic matter. Normal values: 100–1000 mg C-microbial biomass per kg of soil (Weil & Brady, 2017).

• Soil respiration (basal and substrate-induced) —CO₂ emission by microbes and roots. A decrease in respiration may indicate inhibition of biota (pollution, compaction, desiccation). Too high respiration (at high temperature and moisture) may indicate intensive mineralization of humus—loss of organic matter.

• Enzymatic activity—activity of soil enzymes (dehydrogenase, urease, phosphatase, β-glucosidase, etc.) that catalyze key reactions of nutrient cycling (cellulose decomposition, nitrogen and phosphorus transformation). A decrease in enzymatic activity is a reliable signal of chemical pollution or physical degradation (Valkov et al., 2004; White, 2006).

• Abundance and diversity of soil fauna—earthworms, springtails, mites, nematodes. Earthworms are particularly indicative: their absence or low numbers indicate structural disturbance, overcompaction, acidification, or pesticide contamination (Weil & Brady, 2017).

• C:N ratio in organic matter or microbial biomass—reflects the availability of nitrogen for decomposition and the balance between mineralization and immobilization.

Biological indicators have one serious drawback: they are subject to seasonal variability (temperature, humidity) and therefore require strict standardization of sampling time (for example, always in spring or autumn, at a specific plant growth stage) (White, 2006; Weil & Brady, 2017).

4.9. Integral Indices and Soil Quality Assessment Systems

Individual indicators are useful, but to answer the question "does the soil retain its functions?" an integral assessment is often needed. This is why Soil Quality Indices (SQI) have been developed (Weil & Brady, 2017; White, 2006).

How SQI is constructed:

1. A set of indicators relevant to specific soil functions is selected (for example, for agroecosystems—productive, water-holding, buffering).

2. Each indicator is measured and normalized (reduced to a dimensionless scale, usually 0–10 or 0–1) using "scoring curves" that reflect which value is optimal, critical, or limiting (Weil & Brady, 2017).

3. Normalized scores are averaged (sometimes with weighting coefficients if some indicators are more important than others)—yielding an overall index.

4. The index allows comparison of sites over time and space and assessment of management effectiveness.

Examples of such systems:

• SMAF (Soil Management Assessment Framework)—widely used in the US (Weil & Brady, 2017).
• MicroLEIS (Mediterranean Land Evaluation Information System)—applied in Europe.
• In Russia, for soil rating, point assessments based on humus content, pH, and horizon thickness are used (Valkov et al., 2004; Mukha et al., 2003).

The disadvantage of integral indices is their dependence on the choice of indicators and weights. Different systems may give different assessments for the same site. Therefore, they do not replace detailed analysis of individual indicators but complement it (White, 2006).

4.10. Indicators as a Basis for Decision-Making

The main purpose of indicators is to support decisions in land use and soil protection. In practice, this looks like this:

• If pH drops below a critical level (for example, pH KCl < 4.5 for cereals), liming is required.
• If humus content is falling, a review of the crop rotation (introduction of green manures, increase in perennial grass proportion) or application of organic fertilizers is needed.
• If bulk density exceeds limits (for example, >1.5 g/cm³ for loam), measures for loosening and reducing load on the soil are necessary.
• If biological activity is reduced, pesticide use should be excluded or limited, and aeration improved.
• When heavy metals accumulate above background levels—limit the use of chemical fertilizers contaminated with metals, or even switch to phytoremediation.

Thus, indicators are not just "dry numbers" in a report. They are the language in which the soil "speaks" to the agronomist and ecologist, signaling problems and successes. And the better we learn to understand this language, the more effectively we will manage soil resources.

4.11. Selection of Indicators: Practical Recommendations

In practice, for monitoring a specific territory, it is not necessary to measure all possible indicators. A Minimum Data Set is recommended, which includes the most informative indicators for the given purpose (Weil & Brady, 2017; White, 2006). For example:

This approach allows saving resources and focusing on the most significant indicators without losing informativeness.

To summarize:

Soil condition indicators are measurable properties that allow objective assessment of whether soil performs its functions. They are divided into physical (structure, bulk density, water permeability), chemical (pH, humus, CEC, nutrients, pollutants), and biological (microbial biomass, respiration, enzymatic activity, fauna). For comprehensive assessment, integral soil quality indices (SQI) are used, but individual indicators remain an important diagnostic tool. A properly selected set of indicators is the basis for timely management decisions: liming, fertilization, tillage selection, reclamation, etc. Indicators are the "language" in which the soil signals its condition, and the ability to read it is a key competence of the modern agronomist and ecologist.

5.1. Local (Field) Level

This is the most detailed level of monitoring, directly linked to economic activity (Weil & Brady, 2017; Mukha et al., 2003). Its main task is to provide field-level management: diagnosis of current soil condition, assessment of agronomic practice effectiveness, and timely adjustment of fertilization, tillage, and irrigation systems.

Who conducts it?

• Agronomists, farmers, specialists of agrochemical services, soil laboratories.

What is monitored?

• Main agrochemical indicators: pH, humus content, available forms of N, P, K, and micronutrients.
• Physical properties: bulk density, moisture, structure (visually or using simple field methods).
• Biological activity (less frequently—at the farm level, more often—in scientific experiments).
• For intensive systems—nitrate content in the soil profile (leaching control).

Frequency:

• Agrochemical analysis—annually or every 2–3 years (depending on crop and fertilization system).
• Physical properties—as needed (for example, after use of heavy machinery, upon signs of compaction).
• Rapid tests (pH, nitrates)—can be conducted several times per season.

Examples of local monitoring:

• Precision agriculture system—sampling on a regular grid (for example, 1 sample per 1–2 ha) with subsequent construction of field maps and differentiated application of fertilizers and liming materials (Weil & Brady, 2017; White, 2006).
• Pollution control at a specific site—for example, around an industrial enterprise or along a highway.
• Long-term stationary experiments (LTSE)—although they belong more to scientific monitoring, they are often established at the field level and provide unique information on long-term trends (Richter & Tugel, 2012; Weil & Brady, 2017).

Limitations of local monitoring:

• Results are tied to a specific site and are not always representative of other fields or the region as a whole.
• Requires significant time and financial costs if conducted systematically and with high detail.

5.2. Regional Level

Regional monitoring covers administrative districts, regions, and natural-economic zones (for example, forest-steppe, steppe, dry-steppe zones) (Mukha et al., 2003; Weil & Brady, 2017; White, 2006). Its goal is identification of regional trends, assessment of the scale of degradation or improvement, and justification of regional agriculture and soil protection programs.

Who conducts it?

• Regional agrochemical service centers, Rosselkhoznadzor departments, research institutes, universities, land services (in Germany—state soil protection agencies, in the US—NRCS at the state level).

What is monitored?

• The same indicators as at the local level, but with less detail and on a representative network of points (stratified sampling, regular grid).
• Special attention—degradation indicators: erosion, salinization, acidification, humus loss, contamination with heavy metals and pesticides.
• Often include vegetation condition indicators (yield, species composition, projective cover), as they are closely linked to soil condition.

Frequency:

• Usually every 3–5 years (for soil properties) or every 5–10 years (for larger surveys, such as repeated soil mapping).
• In Europe, for example, repeated soil surveys within the ICP Forests program are conducted at 5–10 year intervals (Scheffer et al., 2018).

Examples of regional monitoring:

• Fertility monitoring of arable soils in the Russian Federation—conducted by agrochemical services as part of state land monitoring (Mukha et al., 2003).
• Monitoring of acidity of forest soils in Central Europe—under the influence of acid precipitation and land-use changes (Scheffer et al., 2018).
• Monitoring of salinization of irrigated lands in regions with intensive irrigation (for example, in the Volga region, in Central Asia) (Valkov et al., 2004).

Significance of the regional level:

• Allows detecting problems (for example, zones of acidification, pollution hotspots) before they become irreversible.
• Serves as the basis for regional programs of liming, gypsum application, and erosion control measures.
• Provides material for scientific generalizations (link between soil changes and climatic trends, changes in land-use structure).

5.3. National Level

National monitoring is a systematic assessment of the state of the country's entire soil resources (Weil & Brady, 2017; White, 2006; Richter & Tugel, 2012). Its goal is to provide an objective picture of national resources, their dynamics and threats, and to serve as the information base for state policy in soil protection, land use, agriculture, and environmental protection.

Who conducts it?

• State bodies (in the US—USDA-NRCS, in Germany—the Federal Environment Agency together with the states, in Russia—Rosreestr, Rosselkhoznadzor, Roshydromet, as well as scientific institutions of the Russian Academy of Sciences and the Ministry of Agriculture).

What is monitored?

• Key indicators of soil condition on a representative national network (usually several thousand points).
• Mandatory inclusion: humus content, pH, available forms of major nutrients, heavy metals (in risk zones), radionuclides (for some territories), erosion processes, area of disturbed and reclaimed lands.
• In some countries (US, Germany, UK), national soil resource inventories are also conducted (National Resources Inventory—NRI in the US), which include not only chemical but also physical and biological indicators (Weil & Brady, 2017).

Frequency:

• National inventories are usually conducted at 5–10 year intervals (in the US, NRI—every 5 years).
• More frequent observations of individual indicators (for example, pollution monitoring) can be conducted continuously at reference stations.

Examples of national monitoring systems:

• US: National Resources Inventory (NRI), which provides assessment of erosion, soil cover condition, and land-use changes at the national level (Weil & Brady, 2017).
• Germany: Soil Condition Survey (Bodenzustandserhebung) in forests and agricultural lands, with repeated measurements every 5–10 years (Scheffer et al., 2018).
• UK: Countryside Survey—regular inventory of soils, vegetation, and waters.
• Russia: State land monitoring (including fertility monitoring of arable soils) is conducted by Rosreestr and agrochemical services. Fertility data (humus, pH, P, K) are collected and summarized at the federal level, but their accessibility and analytical processing still lag behind Western counterparts (Mukha et al., 2003).

Significance of the national level:

• Allows assessment of national resources and comparison with other countries.
• Serves as the basis for state policy formulation in sustainable land use, subsidizing soil protection, and land market regulation.
• Provides material for reporting to international organizations (FAO, UN) and fulfillment of international obligations (for example, on sustainable development goals, combating desertification).
• Provides an information base for national-scale scientific research (for example, assessment of climate change impacts on soil resources).

5.4. Global Level

Global monitoring is not a single "satellite-based" observation system but a collection of national and regional data coordinated by international organizations, with the aim of assessing soil condition at the planetary level (Weil & Brady, 2017; Richter & Tugel, 2012; White, 2006). Its goal is to identify global trends, assess the scale of degradation worldwide, and support international agreements and initiatives.

Who coordinates?

• Food and Agriculture Organization of the United Nations (FAO).
• UN Environment Programme (UNEP).
• World Meteorological Organization (WMO).
• International Union of Soil Sciences (IUSS).
• European Soil Bureau (within the European Commission).
• And other international organizations.

What data are used?

• National soil maps and databases (for example, the European Soil Bureau database, FAO's Soil Map of the World at 1:5,000,000 scale) (Weil & Brady, 2017).
• Results of national monitoring programs (aggregated to the level of countries or regions).
• Remote sensing data (satellite imagery)—allow assessment of changes in vegetation cover (as an indicator of degradation), erosion processes, area of arable land, etc., especially in inaccessible regions (Weil & Brady, 2017; White, 2006).
• Data from long-term experiments and models—for assessment of global cycles of carbon, nitrogen, and other elements.

Main global projects and initiatives:

• Global Soil Partnership (GSP) — FAO's Global Soil Partnership (founded in 2011)—one of the key international structures (more details in Section 6).
• GLOSIS (Global Soil Information System) —a global soil information system being created under the auspices of GSP, which should integrate national soil databases into a single global platform.
• World Soil Day (December 5)—an annual campaign to raise awareness of soil issues.
• Global Assessment of Soil Degradation (GLASOD) —the first global assessment of soil degradation (completed in 1991), showing that over 2 billion hectares of land worldwide are degraded (Weil & Brady, 2017). Subsequently supplemented by the WAD (World Atlas of Desertification) project and others.
• UNCCD (UN Convention to Combat Desertification) —the UN Convention to Combat Desertification, under which countries report on land condition and take measures to combat degradation.

Challenges of global monitoring:

• Data heterogeneity. Different countries use different methods, classifications, and observation frequencies. This hinders direct comparison. Harmonization efforts (through international standards, ISO) are a key direction of GSP's work.
• Data scarcity from developing countries. Many regions (Africa, parts of Asia, South America) have very low density of observation points and weak laboratory infrastructure.
• Funding. Global programs require significant resources, which are not always allocated in sufficient volume.

Nevertheless, even with all limitations, the global level of monitoring provides indispensable information on the scale of problems (for example, assessment of global erosion, carbon loss, spread of salinization) and serves as the basis for international policy in environmental protection and sustainable development.

5.5. Interconnection of Levels: From Field to Planet

It is important to understand that monitoring levels do not exist in isolation. They form a hierarchical system where data from lower levels are aggregated and generalized for upper levels, while decisions at the upper level (policy, standards, funding) influence conditions at the lower level (Weil & Brady, 2017; White, 2006).

This hierarchy can be represented as a "pyramid" (Fig. 1):

1. Field level: detailed point data (hundreds of samples).

2. Regional level: aggregation (for example, average values for administrative districts).

3. National level: synthesis of regional data into national reports and maps.

4. Global level: integration of national data and use of satellite imagery to create global maps (for example, the world soil degradation map).

Example of level interconnection:

• A farmer notices a yield decline in one part of the field.
• They take soil samples (local level) and identify acidification.
• The result is reported to the regional agrochemical service.
• The service, having data from hundreds of fields, identifies that acidification is a mass phenomenon in the region (regional level).
• This information enters the national soil condition report (national level).
• Based on such reports and other data, FAO scientists assess that the area of acidified soils is growing globally (global level).
• In response, FAO initiates a liming and sustainable agriculture program, which is then translated into national and regional projects.

Thus, local observations have global significance, and global initiatives have local impact. This is the interconnection without which the modern soil protection system would be incomplete.

5.6. Problems of Data Integration Between Levels

Despite the obvious necessity, integration of data between scales faces serious problems (Richter & Tugel, 2012; Weil & Brady, 2017; White, 2006):

1. Different purposes and methods. At the field level, measurements are made for operational management and often do not conform to standards adopted at the regional or national level (different methods, different sampling depths, different frequencies).

2. Different levels of detail. Field data cannot always be aggregated to the regional level due to spatial variability; regional averages may not reflect real diversity.

3. Lack of standardization (especially at the international level)—a problem that GSP and the development of international standards (for example, ISO for analytical methods) are trying to address.

4. Confidentiality and data availability. Farm data are often commercially sensitive and cannot be passed to higher levels without consent. This limits the completeness of national and global databases.

5. Lack of analytical capacity in developing countries, reducing the quality and quantity of data for global generalizations.

Despite these problems, integration work is ongoing, and in the coming decades, significant progress can be expected in creating a truly global soil monitoring system, especially through the development of digital technologies (Big Data, artificial intelligence) and remote sensing.

To summarize:

Soil monitoring is conducted at four main levels (field, region, country, world), each with its own tasks, methods, frequency, and users. These levels form a hierarchy where data from lower levels are aggregated to upper levels, and decisions at upper levels influence practice at lower levels. Local monitoring provides information for operational crop and fertilization management. Regional and national monitoring provide the basis for policy, programs, and trend assessment. Global monitoring allows assessment of the scale of global threats (degradation, loss of fertility, pollution) and coordination of international efforts. However, data integration between levels faces challenges of standardization, accessibility, and methodological differences, requiring international cooperation and technological development.

6.1. Global Soil Partnership (GSP)

The Global Soil Partnership was established in 2011 under the auspices of the Food and Agriculture Organization of the United Nations (FAO) (Weil & Brady, 2017; Richter & Tugel, 2012). It is the main international platform uniting governments, scientific institutions, non-governmental organizations, and the private sector for joint action on soil protection and sustainable use.

Main objectives of GSP:

• Promote sustainable management of soil resources at all levels.
• Ensure that soils are at the center of the global agenda on food security, climate change adaptation, and sustainable development.
• Create a Global Soil Information System (GLOSIS) —a unified platform integrating national databases.
• Promote standardization of monitoring and soil assessment methods.
• Raise public awareness of the importance of soils (for example, through the annual World Soil Day—December 5).

Key achievements of GSP:

• Adoption of the Voluntary Guidelines for Sustainable Soil Management (VGSSM) in 2016—a set of recommendations for countries on maintaining soil health.
• Establishment of a network of soil laboratories (GLOSOLAN) for harmonization of analytical methods and quality improvement.
• Launch of the Global Soil Organic Carbon Map—the first global map of soil organic carbon stocks.
• Development of indicators for assessing progress towards Sustainable Development Goals (SDGs) related to soils.

GSP is not a supranational regulator but a platform for voluntary cooperation. However, its role in coordinating global efforts and drawing attention to soil issues cannot be overstated.

6.2. UN Sustainable Development Goals (SDGs)

In 2015, the UN General Assembly adopted 17 Sustainable Development Goals (SDGs) for the period up to 2030. Although soils are not directly mentioned in all goals, they are of key importance for achieving many of them (Weil & Brady, 2017).

The most directly relevant to soils are:

• SDG 2 (Zero hunger, food security, and sustainable agriculture)—directly depends on maintaining soil fertility.
• SDG 15 (Protect and restore terrestrial ecosystems, combat desertification, land degradation, and biodiversity loss)—includes target 15.3: "By 2030, combat desertification, restore degraded land and soil, including land affected by desertification, drought, and floods, and strive to achieve a land degradation-neutral world" (Land Degradation Neutrality—LDN).

The concept of "Land Degradation Neutrality" (LDN) is an ambitious idea that by 2030, the area of degraded land should not increase but should be offset by restoration of equivalent areas. This requires reliable monitoring and indicators—exactly what we discussed in the previous sections (Weil & Brady, 2017).

Other SDGs indirectly related to soils:

• SDG 6 (Clean water and sanitation)—soils regulate water runoff and filter pollutants.
• SDG 13 (Climate action)—soils are the largest terrestrial carbon reservoir, and their protection contributes to climate mitigation.
• SDG 1 (No poverty) and SDG 10 (Reduced inequalities)—soil degradation disproportionately affects the poorest populations.

6.3. UN Convention to Combat Desertification (UNCCD)

The United Nations Convention to Combat Desertification (UNCCD) was adopted in 1994 and entered into force in 1996. It is one of the three "Rio Conventions" (along with the UN Framework Convention on Climate Change and the Convention on Biological Diversity) (Scheffer et al., 2018; Weil & Brady, 2017).

The main goal of UNCCD is to combat desertification and mitigate the effects of drought in countries, particularly in Africa, through effective measures at all levels, supported by international cooperation.

Link to soils:

• Desertification is land degradation in arid, semi-arid, and dry sub-humid areas, caused inter alia by erosion, salinization, and vegetation loss.
• UNCCD requires member countries to develop national action plans to combat desertification and monitor land condition.
• Under UNCCD, a Global Mechanism was created to mobilize resources, and indicators for assessing land degradation were developed, aligned with SDG 15.3 (Land Degradation Neutrality).

UNCCD is a legally binding agreement, and member countries report on progress. This makes it a powerful tool for drawing attention and resources to soil problems in vulnerable regions.

6.4. European Initiatives

In Europe, soil protection is actively developing at the European Union level, although a unified pan-European "Soil Directive" has not yet been adopted (the 2006 proposal did not receive unanimous support). Nevertheless, there are a number of important initiatives and structures:

• European Soil Bureau (ESB) —a scientific coordination center located at the Joint Research Centre (Ispra, Italy). It develops pan-European soil maps (based on the European Soil Database), standards, assessment and monitoring methodologies (Scheffer et al., 2018).

• European Soil Data Centre (ESDAC) —a public portal collecting soil data for Europe (maps, models, indicators). This is the European equivalent of GLOSIS.

• ICP Forests (International Co-operative Programme on Assessment and Monitoring of Air Pollution Effects on Forests)—a forest monitoring program in Europe, including regular (5–10 years) soil monitoring (including chemical condition) at over 6,000 sites in 38 countries (Scheffer et al., 2018). This is one of the best examples of regional monitoring, providing valuable data on acidification, eutrophication, and pollution of forest soils.

• European Green Deal and the Farm to Fork Strategy include targets for reducing fertilizer and pesticide use, increasing organic farming area, and restoring biodiversity—all directly affecting soil condition.

• EU Soil Mission—an ambitious European Union program under Horizon Europe, aimed at creating 100 "living labs" and lighthouses for soil health restoration by 2030.

6.5. International Union of Soil Sciences (IUSS)

IUSS (International Union of Soil Sciences) is the oldest (founded in 1924) and most authoritative international scientific organization in the field of soil science (Weil & Brady, 2017; Richter & Tugel, 2012). It unites national soil societies and individual scientists.

Main areas of IUSS activity:

• Organization of World Soil Congresses (every 4 years).
• Development and improvement of international soil classification systems (for example, World Reference Base for Soil Resources—WRB, which is a global language for describing and classifying soils, complementing national systems) (Weil & Brady, 2017; Scheffer et al., 2018).
• Promotion of scientific research across all branches of soil science, including monitoring and protection.
• Cooperation with FAO, UNEP, UNCCD, and other organizations in developing global soil strategies.

IUSS does not have political or legal authority, but its scientific authority and expertise make it a key partner for all international soil initiatives. Many experts developing monitoring standards and indicators are members of IUSS.

6.6. Other Important Initiatives

In addition to those listed, there are several other international efforts related to soils:

• International Biogeochemical Cycles Program (for example, the Global Carbon Project)—includes assessment of soil carbon stocks and their role in climate.
• UN Environment Programme (UNEP) —conducts global environmental assessments, including soils (for example, the Global Environment Outlook—GEO).
• World Meteorological Organization (WMO) —participates in monitoring droughts and their impact on soils.
• FAO, in addition to GSP, develops global soil maps (for example, maps of salinization, erosion), publishes guidelines on sustainable soil management, and provides technical assistance to developing countries in organizing monitoring and reclamation (Weil & Brady, 2017).

6.7. The Role of International Initiatives in Solving Local Problems

At first glance, international initiatives may seem far removed from the reality of a specific field or region. However, they have a real impact on the local level through:

1. Funding—international projects (for example, the Global Environment Facility—GEF, EU programs) allocate funds for monitoring, reclamation, and farmer training in developing countries.

2. Standards and methods—international guidelines (for example, GSP's Voluntary Guidelines) help countries develop national soil protection programs, use unified indicators, and compare data.

3. Political goals—Sustainable Development Goals (SDGs) and UNCCD commitments compel governments to take specific measures and report on them. This creates "demand" for monitoring and stimulates its development.

4. Knowledge exchange—international networks of scientists and practitioners facilitate the dissemination of best practices (for example, in minimum tillage, precision agriculture, use of organic fertilizers).

Thus, international initiatives serve as an "umbrella" under which national and regional soil monitoring and protection systems receive support, coordination, and impetus for development.

6.8. Connection of International Initiatives with Monitoring and Indicators

As has been emphasized many times, all these international initiatives rely on monitoring and require objective indicators:

• To assess progress on SDG 15.3 (Land Degradation Neutrality), reliable data on the area of degraded and restored lands, as well as on the dynamics of key soil indicators (humus, pH, erosion, etc.), are needed.
• To fulfill UNCCD commitments, countries must conduct national inventories and use agreed degradation indicators.
• To create global maps (for example, carbon, salinization), data collected using standardized methodologies from multiple countries are needed—and GSP (through GLOSIS) is precisely engaged in harmonizing these data.

Thus, international initiatives are both "consumers" of monitoring results and "drivers" of its development. They set the agenda, require data, and create mechanisms for collection and exchange.

To summarize:

International initiatives play a key role in coordinating soil protection and monitoring at the global level. FAO's Global Soil Partnership (GSP) is the main platform for cooperation, standard development, and information systems. The UN Sustainable Development Goals (SDGs) , especially SDG 15 (combating land degradation), set political guidelines, including the concept of "Land Degradation Neutrality" (LDN). The UN Convention to Combat Desertification (UNCCD) is a legally binding mechanism for countries affected by drought and desertification. In Europe, the European Soil Bureau, ICP Forests, ESDAC, and new initiatives under the Green Deal and the Soil Mission play important roles. The International Union of Soil Sciences (IUSS) provides the scientific foundation and classification systems. All these initiatives are interconnected: they stimulate the development of national and local monitoring systems, require standardization of indicators, and provide a platform for data and experience sharing. Without international cooperation, it would be impossible to assess the global scale of soil degradation or develop coordinated measures for their protection.

7.1. What Does "Strategic Resource" Mean?

A strategic resource is a resource that:

1. Is critically important for the survival, security, and development of society (Weil & Brady, 2017).

2. Is limited in quantity and cannot be replaced in the foreseeable future.

3. Is unevenly distributed across the planet, creating potential conflicts.

4. Requires long-term planning and protection at the state and international levels.

Such resources traditionally include water, energy (oil, gas), minerals, and food. But soil possesses all these characteristics to no lesser degree (Richter & Tugel, 2012; Weil & Brady, 2017; White, 2006).

Soil is:

• The foundation of food security (95% of our food is produced on soils) (Weil & Brady, 2017).
• The largest terrestrial carbon reservoir (more than the atmosphere and vegetation combined) (Weil & Brady, 2017; White, 2006).
• A regulator of the water cycle and water quality.
• A library of biodiversity (soil is a habitat for more than 25% of all species on Earth) (Richter & Tugel, 2012; Weil & Brady, 2017).
• An economic asset, the value of which is difficult to overestimate (loss of fertility costs humanity hundreds of billions of dollars annually) (Weil & Brady, 2017).

7.2. Soil and Food Security: A Global Challenge

As we noted in the first section, by 2050, the Earth's population will reach 9.5–10 billion people. To feed everyone, food production will need to increase by 35–70% (Scheffer et al., 2018; Weil & Brady, 2017). At the same time:

• New agricultural lands are practically exhausted.
• Existing arable lands are losing fertility due to erosion, salinization, acidification, and humus loss (Weil & Brady, 2017; White, 2006).
• Climate change creates additional risks (droughts, floods, shifts in agro-climatic zones).

Under these conditions, maintaining and increasing soil fertility becomes not just an agronomic task but a condition for survival (Weil & Brady, 2017; Richter & Tugel, 2012). Every percent of fertility loss means millions of tons of unproduced grain, hunger, and social instability in vulnerable regions.

As W.C. Lowdermilk noted back in 1953 in his famous work "Conquest of the Land Through 7,000 Years" (cited in Weil & Brady, 2017): many ancient civilizations (Mesopotamia, Greece, Rome) declined not so much because of wars or epidemics but because of exhaustion and erosion of their soils. They "ate" their land. We have no right to forget this lesson of history.

7.3. Soil and Climate Change: The Role of Carbon

Soils are the largest reservoir of organic carbon in terrestrial ecosystems. Estimates suggest that soils contain about 1500–2500 Gt (gigatons) of carbon—2–3 times more than the atmosphere (about 800 Gt) and 3–4 times more than terrestrial vegetation (about 560 Gt) (Weil & Brady, 2017; White, 2006; Scheffer et al., 2018).

What does this mean?

• If soils degrade (erosion, intensive tillage, peatland drainage), they lose carbon as CO₂ and CH₄, intensifying the greenhouse effect. Carbon losses from soils can account for up to 1–2% of global CO₂ emissions annually (Weil & Brady, 2017).
• Conversely, if we restore soils (increase organic matter input, apply minimum tillage, retain plant residues), we can sequester additional carbon in soils, mitigating climate change.

This is precisely why the "4 per mille" (4 per 1000) concept, proposed at the COP21 conference in Paris in 2015, attracted so much attention (Weil & Brady, 2017). It states: if we annually increase soil organic carbon stocks by 0.4% (4 per mille), this could fully offset the current increase in atmospheric CO₂ concentration. This is an ambitious goal, but it shows what a huge role soils can play in climate policy.

7.4. Soil and Biodiversity: Invisible Wealth

Soil is not just a medium for plants. It is the richest ecosystem in terms of species diversity after tropical rainforests (Richter & Tugel, 2012; Weil & Brady, 2017). In 1 gram of fertile soil, up to 10⁹–10¹⁰ bacteria, 10⁵–10⁶ fungi, and thousands of other microorganism species can live, many of which are still undescribed (Scheffer et al., 2018). In addition, soil is a habitat for a huge number of invertebrates—earthworms, springtails, mites, centipedes, etc. (Weil & Brady, 2017).

Significance of soil biodiversity:

• Ensures nutrient cycling (decomposition of organic matter, transformation of nitrogen, phosphorus, sulfur) (White, 2006).
• Supports plant health (through symbiotic relationships, suppression of pathogens, improvement of soil structure) (Weil & Brady, 2017).
• Serves as a genetic reserve for biotechnology (search for new antibiotics, enzymes, genes resistant to drought or salinity) (Richter & Tugel, 2012).

Loss of soil biodiversity is an irreversible loss not only for the ecosystem but also for future generations who could have used this genetic wealth. Therefore, soil protection is not only protection of fertility but also protection of the "invisible heritage" of evolution.

7.5. Soil and Human Health

The link between soil and human health is much deeper than commonly thought (Weil & Brady, 2017; White, 2006; Valkov et al., 2004).

Direct link:

• Pathogenic microorganisms in soil—causative agents of tetanus, botulism, anthrax, gas gangrene, intestinal infections. In soils, they can persist for years (Valkov et al., 2004; Mukha et al., 2003). Sanitary-bacteriological monitoring of soils is an important part of public health protection.
• Contamination with heavy metals, pesticides, petroleum products, radionuclides—through plants, water, and dust enters the human body, causing poisoning, oncological, neurological, and other diseases (Valkov et al., 2004; Scheffer et al., 2018; Weil & Brady, 2017).

Indirect link:

• Quality of food products directly depends on soil. Deficiency or excess of micronutrients (iodine, selenium, iron, zinc) in soils leads to deficiency or toxicity of these elements in plants and food, causing endemic diseases (White, 2006).
• Dust storms (a product of wind erosion)—source of PM₁₀ and PM₂.₅, causing respiratory and cardiovascular diseases (Weil & Brady, 2017).

Thus, soil protection is direct care for human health, not just for future harvests.

7.6. Soil as an Economic and Social Asset

The economic value of soils is enormous, although difficult to measure directly (Weil & Brady, 2017; White, 2006). Some estimates:

• Annual damage from erosion worldwide—over $500 billion (only direct and indirect losses, not counting health) (Weil & Brady, 2017).
• In the US, annual costs associated with erosion (on-site and off-site) are estimated at $22–90 billion (Weil & Brady, 2017).
• Fertility losses in Africa due to land degradation cost 1–5% of GDP annually (White, 2006).

Soil is also a social asset. Access to fertile land determines the well-being of millions of rural families, especially in developing countries. Soil degradation leads to impoverishment, migration, and social conflicts (White, 2006; Weil & Brady, 2017). Conversely, sustainable soil management contributes to stability and development of rural areas, creates jobs, and reduces dependence on food imports.

In Russia, according to state monitoring data, annual humus losses from arable soils amount to tens of millions of tons, equivalent to multi-billion losses in monetary terms (Mukha et al., 2003). At the same time, many soils require liming, gypsum application, organic matter application—resources that are either not allocated or used inefficiently.

Thus, soil should be considered national wealth requiring no less careful treatment than reserves of minerals or forest resources.

7.7. Soil and Geopolitics: Resource of the Future

In the coming decades, competition for access to fertile soils and clean water may become one of the main geopolitical challenges (Weil & Brady, 2017; Richter & Tugel, 2012). Already now:

• Many countries (especially in the Middle East, North Africa, Central Asia) depend on food imports, while their own soils are degrading.
• Major global players (China, Gulf countries, South Korea) are buying or leasing land in other countries (in Africa, Latin America) for food production—"land grabbing" (Weil & Brady, 2017).
• Climate change will shift agro-climatic zones, creating new "food baskets" while making other regions unsuitable for agriculture.

In this context, soil becomes a strategic resource comparable in importance to oil or gas. Countries that preserve their soil resources will have a competitive advantage in the 21st century. Conversely, loss of soil fertility can lead to loss of food independence, economic and political instability.

7.8. Soil and the Future: Legacy for Generations

In the Anthropocene epoch, humans have become the main force changing the face of the planet (Richter & Tugel, 2012). We leave behind not only cities and technologies but also degraded, eroded, polluted, structureless soils. This is a legacy that our children and grandchildren will not be able to quickly fix.

As Richter & Tugel (2012) note, the main criterion for sustainable soil management is not today's yield but the soil's ability to retain its functions for future generations. Therefore, the question "Does the soil retain its functions?" is not only a question of current agronomy. It is a question of moral and strategic responsibility.

Each of us—farmer, agronomist, student, politician, consumer—makes daily choices that affect soil condition: which fertilizers and pesticides to use, how to till the land, what to buy for lunch, which laws to support. And the future of our planet in 10, 50, 100 years depends on these choices.

7.9. How to Understand Whether Soil Retains Its Functions? — Final Answer

Concluding the lecture, we return to the main question. The answer is multi-level:

1. At the field level—through regular monitoring of key indicators (pH, humus, bulk density, biological activity, nutrient content, pollutants) and their comparison with reference (baseline) values for the given soil type and climatic zone (Weil & Brady, 2017; White, 2006).

2. At the farm level—through assessment of the sustainability of agrotechnologies (nutrient balance, structure preservation, erosion prevention, biodiversity maintenance) (Mukha et al., 2003).

3. At the regional and national levels—through state monitoring, soil information systems, and soil quality indices (SQI), which allow identifying trends and making management decisions (Weil & Brady, 2017; White, 2006).

4. At the global level—through international programs (GSP, SDGs, UNCCD), which require reporting from countries and stimulate the implementation of monitoring standards (Weil & Brady, 2017; Richter & Tugel, 2012).

But the main criterion is the preservation or increase of natural capital that we pass on to future generations. If we are not only not losing soil fertility but also improving it (building up humus, restoring structure, reducing pollution), then we are on the right track. If we are "consuming" the soil (using its reserves faster than they are restored), then in the long term we are condemning ourselves and our descendants to hunger and environmental crisis.

Concluding summary:

Soil is a strategic resource on which food security, climate stability, biodiversity, human health, economic well-being, and the geopolitical position of countries depend. It is irreplaceable on the scale of human life, unevenly distributed, and vulnerable to anthropogenic impact. In the Anthropocene epoch, humans have become the main agent of soil formation—but far from always a constructive one. For soils to retain their functions, systemic monitoring at all levels (from field to planet) is needed, based on objective indicators (physical, chemical, biological), supported by protection principles (preventiveness, responsibility, sustainability), and coordinated by international initiatives (GSP, SDGs, UNCCD). Soil protection is not only an agronomic task but also a moral imperative requiring each of us to have a conscious attitude toward the "skin of the Earth."