Physics deals in general with the forms and interactions of matter and
energy, the Soil Physics deals
specifically with the state and movement of matter and with the fluxes and
transformations of energy in the soil. Soil physics is one of the major subdivisions
of soil science. It seeks to define, measure, and predict the physical
properties and behavior of the soil, both in its natural state and under the
influence of some human activity. The fundamental study of soil physics aims at
understanding the mechanisms governing processes such as terrestrial energy
exchange, the cycles of water and of transportable materials, and the growth of
plants in the field. On the other hand, the practical application of soil
physics aims at the proper management of the soil by means of cultivation,
irrigation, drainage, aeration, improvement of soil structure, control of
infiltration and evaporation, regulation of soil temperature, and prevention of
erosion. Soil physics is thus both a basic and an applied science, with a very
wide range of interests.
The study of soil science in general and of
soil physics in particular is driven not only by the innate curiosity that is “our
species” main creative impulse, but also by urgent necessity. The intensifying
pressure of population and development has diminished the soil resources of our
small planet and has led to their unsustainable use and degradation in too many
parts of the world. Since the soil is not an isolated medium but is in constant
dynamic interaction with the larger environment, soil physics is an aspect of
the more encompassing field of environmental physics (sometimes called
biospheric physics) and of the overall science of geophysics. The early soil
physicists were interested primarily in the engineering and the agricultural
aspects of their discipline, hence their research focused on the soil as a
material for construction or as a medium for the production of crops.
Recent decades have witnessed an increasing
emphasis on the environmental aspects and applications of soil physics.
Consequently, Physicists have expanded its scope to include phenomena
related to natural ecosystems and to processes affecting the quality of the
environment. Processes occurring in the soil are now seen to affect the entire
terrestrial environment, including local and regional climates, the natural
food chain, biodiversity, and the fate
of the voluminous waste products of our
civilization (among which are many pathogenic and toxic agents). Increasingly,
the main concern of soil physics has shifted from the laboratory to the field
and from a restricted one-dimensional view to an expansive three-dimensional
view interfacing with the domains of sister disciplines such as meteorology and
climatology, hydrology, ecology, and geochemistry. The larger domain of soil
physics now encompasses greater complexity and variability in space and time,
the treatment of which requires reliance on stochastic as well as deterministic
methods. Consequently, the science is becoming ever more interesting and relevant.
The task of soil physics has become difficult
by the enormous and baffling intricacy of a medium containing myriad mineral
and organic components, all irregularly fragmented and variously associated in
a geometric pattern that is so complex and liable to challenge our imagination
and descriptive powers. Some of the spil solid material consists of crystalline
particles, while some is made up of amorphous gels that may coat the crystals
and modify their behavior.
The solid phase in the soil interacts with
the fluids, water, and air that permeate soil pores. The entire soil is hardly
ever in equilibrium as it alternately wets and dries, swells and shrinks,
disperses and flocculates, hardens and softens, warms and cools, freezes and
thaws, compacts and cracks, absorbs and emits gases, adsorbs and releases
exchangeable ions, dissolves and precipitates salts, becomes acidic or
alkaline, and exhibits aerobic or anaerobic conditions leading to chemical
oxidation or reduction. Hence the Physics of crystalline and amorphous
materials is an interesting aspects of soil for Physics researchers. They can
measure, compare and speculate the mechanism of formation of such ensembles and
associate them with geological findings. Hence for Physics researchers it gives
an excellent avenue that can lead to
direct applications and directions that are valuable to protect one of
the most valuable component of our eco system.
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