Regression and degradation are evolutionary processes associated with a loss of balance of a previously stable ground.
Types of degradation
One often distinguishes regression and degradation, which can be combined.
Regression of a floor is mainly due to erosion. It corresponds to a rejuvenating phenomenon of soil (back to the opposite state to the climax stage).
The degradation of soil often results from a combination of factors, possibly including regression, leading the floor to a different evolution of the natural evolution linked to climate and local vegetation. It is usually directly related to human action via for example:
replacing the diverse original vegetation (called climax) by secondary vegetation (monoculture in the worst cases), which amends the humus and soil formation.
a decrease in organic matter caused by overuse of the soil (no return, or insufficient return of the exported material) leaching ..
the destruction of humus and insoluble clay-humus complexes by plowing that buries and destroys the living upper soil layers, or by excessive work (too heavy or too frequent) from the floor.
acidification, salinisation and possibly desertification can be induced or exacerbated by climate change, but also by the irrigation and drainage;
erosion (water and / or wind); it was facilitated by plowing and / or weed control and overgrazing that leave the soil bare for too long (they are then deconstructed and degraded by the action of drought and / or the impact of the rains that wash instead of penetrating.
pollution by heavy metals or biocides (pesticides or other pollutants) that would kill the organisms essential to maintain cohesion and capillary soil (fungi, earthworms ...).
compaction (soil compaction) and asphyxiation. It is often accompanied by the appearance of a plow in the case of plowed soil; The settlement which indicates a strong decline in natural porosity of the soil is one of the most serious and most common of land degradation. Soil compaction (especially rich in clay and / or silt) and their aggregates has a negative, direct and lasting impact on their biological activity and their hydrological characteristics. The compacted soils are less productive, more sensitive to erosion and contribute less to purifying functions and "buffer" of soil. Around the world, the soils used by humans tend to pack, losing their porosity, often 10 to 50 cm. This compaction is mostly due to agricultural and forestry machines, but overgrazing and overcrowding of a middle man can contribute locally. Finally, excessive or inappropriate use of chemical fertilizers and soil (as manure, compost, and other organic fertilizer improved soil quality) they contribute to deconstruct and compact the soil (for breakdown of aggregates and reduction of biological activity), always at the expense of penetration of root networks that normally - with burrowing organisms - décolmatent and build soils.
Action: The settlement can be assessed by physical measures (including density and electrical resistivity of the ground), but should ideally be able to compare each parameter in the same soil not compacted or non-degraded, which is not always possible
symptoms
The compacted soils - by nature - are identified by various symptoms:
floristic changes (sickly plants less resistant to drought, less green, abnormally varying sizes, occurrence of species adapted to compact soils with such reeds growing in the ruts in temperate forest), lifting delayed ..
poor penetration of water (puddles or persistent surface water in the area several hours after a heavy rain, several minutes after a thunderstorm).
slaking crust
ploughpan
areas presence compacted under the topsoil layer (plow pan)
Plant residues or crop decompose evil, even months after their incorporation into the soil
abnormal erosion phenomena, muddy water in ditches and hollows
The coordinates of the cache will take you to an information panel
1- Explain why it is a case of degradation and not of regression (a photo will help y)
2- What type of degradation occurred in this place? What signs helped to understand?
3- What actions were then set up to solve this problem?
You can directly logguer this cache after sending me the answers. I will contact you in case of problems.