SOIL MAGAZINE

2012

LUIS EDGARDO TREJO ESCALANTE, RITA GLORIMAR MONSALVE GARCIA

THE SOIL MAGAZINE

To begin to define soil is it Life-supporting upper surface of earth that is the basis of all agriculture

LETREJOESCALANTE_2011@HOTMAIL.COM 04267378871 02742214996

Soil, dirt, sediment, what’s the difference?

Depending upon whom you ask, you might get a radically different answer. Some sources state that the only difference between them has to do with their location: soil is the unconsolidated material on the ground, dirt is that same matter on your hands or clothes, and sediment is the same material on the bottom of a river or lake. .

W

HAT IS SOIL?

The unconsolidated mineral or organic material on the immediate surface of the Earth that serves as a natural medium for the growth of land plants. The unconsolidated mineral or organic matter on the surface of the Earth that has been subjected to and shows effects of genetic and environmental factors of: climate (including water and temperature effects), and macro- and microorganisms, conditioned by relief, acting on parent material over a period of time. A product-soil differs from the material from which it is derived in many physical, chemical, biological, and morphological properties and characteristics. ,

[NATURAL SYSTEM APPROACHES TO SOIL CLASSIFICATION, SUCH AS THE FRENCH SOIL REFERENCE SYSTEM (REFERENTIAL PÉDOLOGIQUE FRANÇAIS) ARE BASED ON PRESUMED SOIL GENESIS. SYSTEMS HAVE DEVELOPED, SUCH AS USDA SOIL TAXONOMY AND THE WORLD REFERENCE BASE FOR SOIL RESOURCES WHICH USE TAXONOMIC CRITERIA INVOLVING SOIL MORPHOLOGY AND LABORATORY TESTS TO INFORM AND REFINE HIERARCHICAL CLASSES.]

Soil resources are critical to the environment, as well as to food and fiber production. Soil provides minerals and water to plants. Soil absorbs rainwater and releases it later, thus preventing floods and drought. Soil cleans the water as it percolates. Soil is the habitat for many organisms: the major part of known and unknown biodiversity is in the invertebrates (earthworms, woodlice, millipedes, centipedes, snails, slugs, mites, springtail, enchytraeids, nematodes, protists), bacteria, archaea, fungi and algae; and most organisms living above ground have part of them (plants) or spend part of their life cycle (insects) interconnected, making soil protection of paramount importance for any restoration or conservation plan.

Soils filter and purify water and affect its chemistry. Rain water and pooled water from ponds, lakes and rivers percolate through the soil horizons and the upper rock strata; thus becoming groundwater. Pests (viruses) and pollutants, such as persistent organic pollutants (chlorinated pesticides, polychlorinated biphenyls), oils (hydrocarbons), heavy metals (lead, zinc, cadmium), and excess nutrients (nitrates, sulfates, phosphates) are filtered out by the soil.

This section addresses geologic formations, topography, and soils Marine geology, bathymetry, and sediment quality are addressed under Section 3.4, Water resources. The major earth resources of an area are its bedrock and soils. For the purpose of this environmental Impact Statement (EIS)/Overseas EIS (OEIS), the terms soil and rock refer to unconsolidated and consolidated materials, respectively.

CLIMATE

Soil Structure Soil structure is the size, shape and strength of the naturally occurring soil aggregates (called peds). Many things contribute to soil structure including texture, organic and mineral composition, water content, soil organisms, biological processes such as root growth etc.

The soil is ORGANIC TIME MATTER formed action of the five elements MINERAL RELIEF

The soil system Soil is a composite environment which is the result of abiotic factors (independent of human

actions),

that

is

to

say

of

alterations to the bedrock (which provides soil's

mineral

elements),

atmospheric

content (oxygen fixation, nitrogen cycle, water cycle) and biotic factors (linked to the actions of living things) such as the content

of

vegetation

cover

and

the

decomposition of living things. The analysis of a section of soil shows a superimposition of layers made up of different colours, different

chemical

different

sizes

superimposition

compositions

of of

pedological profile.

material.

layers

and Each

creates

a

Types of degradation Human activity is the main cause of soil degradation. Agriculture plays a large part in soil degradation, especially clearing, irrigation, the spreading of chemical fertilisers and pesticides, overgrazing and even the passage of heavy farming equipment.

The clearing and deforestation of large plots of land to increase the agricultural surface area change humus composition and soil formation. This is because of varied primitive vegetation being replaced by secondary vegetation (monoculture being the extreme).

Tillage destroys superior layers of soil as well as the layer of humus and can even cause a plough sole (lower layer of compact land) to form because of ploughs regularly passing through soil at the same depth. Farming equipment also contributes to soil compaction especially when it weighs more than 5 tons.

Irrigation and soil drainage can cause soil acidification and salination whilst the use of chemical fertilisers and pesticides contributes to reducing soil capillarity (runoff) as well as its consistency. Irrigation in the Aral basin caused the salination and flooding of soils (this can be attributed to canals not being covered and bad drainage). It also famously caused the Aral Sea to dry out.

By threatening the productive capacity and/or reproduction of vegetation, overgrazing strips soils thus making them more vulnerable to hydraulic erosion (this is the case for 56% of soil degradation) and wind erosion (28% of cases).

In urban areas, pollutants such as heavy metals which are dumped can affect soils, just as old industrial sites sometimes leave behind waste land with severely polluted soils.

TYPES OF SOIL DEGRADATION Loss of soil fertility (see lesson on nutrition) Erosion Salinity Soil compaction Soil acidification Build up of dangerous chemicals Erosion

CAUSES OF HUMAN EROSION Poor agricultural practices such as ploughing soil to poor to support cultivated plants or ploughing soil in areas where rainfall is insufficient to support continuous plant growth.

Exposing soil on slopes.

Removal of forest vegetation.

Overgrazing.

Altering the characteristics of streams, causing bank erosion.

Causing increased peak water discharges (increased erosion power) due to changes in hydrological regimes, by such means as altering the efficiency of channels (channel straightening); reducing evapotranspiration losses as a consequence of vegetation removal; and by the production of impervious surfaces such as roads and footpaths, preventing infiltration into the soil and causing increased runoff into streams.