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What are Degradation of soil and Conservation Measures ??
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Fábio Carvalho Nunes, ... Majeti Narasimha Vara Prasad, in Climate Change and Soil Interactions, 2020
9.3 Soil Degradation: Impacts on Climate and Society
Soil degradation is the loss of the intrinsic physical, chemical, and/or biological qualities of soil either by natural or anthropic processes, which result in the diminution or annihilation of important ecosystem functions. The main causes of soil degradation and, consequently, the main threats to its ecological functions are erosion, organic matter decline, loss of biodiversity, compaction, sealing, point-source and diffused contamination, pollution, and salinization (Fig. 9.14) (Montanarella, 2007).
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Figure 9.14. Area with soil sealing and salinization. Municipality of Bom Jesus da Lapa, Bahia, Brazil
The severity of soil and landscape degradation depends on the initial status of the land, the magnitude of drivers that place pressure on land, the responses of the land system, and the impact of feedback from these responses on land resources (Juntti and Wilson, 2005).
Indicators of soil degradation can be visual, physical, chemical, biological, and integrative (Ribeiro et al., 2009). Visual indicators can be obtained from field observation or analysis of satellite images, radar, or aerial photographs. Observations include, for example, changes in soil color and forested area, evidence of ravines and gullies (Fig. 9.15), presence of weed species, monitoring of plant development, and sediment deposition.
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Figure 9.15. Road section showing advanced erosion. Municipality of Entre Rios, Bahia, Brazil
Physical indicators can be measured by analyzing the arrangement of the solid fractions (coarse and fine) of the soil (Ribeiro et al., 2009). These manifest themselves, for example, as plant growth limitation, horizon thickness, textural gradient, permeability, porosity, density, penetration resistance, aggregate stability, infiltration, surface runoff, compaction, entrapment, temperature, and plasma-skeletal disjunction of the soil (Fig. 9.16).
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Figure 9.16. Photo on the left indicates precipitation of clayey material in a subsuperficial horizon (1 and 2) from the plasma-skeletal disjunction of the superficial horizon. Arrow 2 indicates the location of the details shown in the photo on the right
Chemical indicators can be measured by monitoring soil pH, salinity (Fig. 9.17), organic matter content, cation and anion exchange capacity, nutrient cycling, and the presence of toxic or radioactive elements, while biological indicators may include measures of the presence of macro- and microorganisms, as well as their activities and byproducts.
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Figure 9.17. Area with salinized soil in Tatio, Andes Mountain Range, Chile
Integrative indicators, also called key indicators, are used to assess soil quality and degradation. An integrative or key indicator should gather basic information about the composition, structure, and functions of the soil system. The objective is to reflect the interactions between different biotic and abiotic processes that express spatiotemporal transformations in the soil system, such as enzymatic activities and aggregation (Ribeiro et al., 2009).
It is important to note that the measurement of each indicator should express the direction (positive, negative, increase or decrease, etc.) and magnitude (as a percentage relative to a reference value) of variation, as well as the intensity, duration, and extension of variation (Ribeiro et al., 2009), so that it can measure the stage of soil degradation.
According to several authors, among them (Snakin et al., 1996), there are different stages of soil degradation, namely not degraded, weakly degraded, moderately degraded, highly degraded, and extremely degraded. These categories were obtained from experimental indicators of productivity and expert estimates (Table 9.5).
➲ What are Degradation Of soil and Conservation Measures ???
Soil degradation :-
soil erosion of and depletion are the major threats to soil as a resources . Both human and natural factors Can lead to degradation are deforestation , OVergreazing, overuse of chemical feritilisers or pesticides, rain wash, landslides and flood.