Soil science is the study of soil as a natural resource on the surface of the earth including soil formation, classification and mapping; physical, chemical, biological, and fertility properties of soils; and these properties in relation to the use and management of soils. Sometimes terms which refer to branches of soil science, such as pedology (formation, chemistry, morphology and classification of soil) and edaphology (influence of soil on organisms, especially plants), are used as if synonymous with soil science. The diversity of names associated with this discipline is related to the various associations concerned.

Soil Biology

Soil biology is the study of microbial and faunal activity and ecology in soil. These organisms include earthworms, nematodes, protozoa, fungi and bacteria. Soil biology plays a vital role in determining many soil characteristics yet, being a relatively new science, much remains unknown about soil biology and about how the nature of soil is affected. We know that soil organisms break down organic matter, making nutrients available for uptake by plants and other organisms. The nutrients stored in the bodies of soil organisms prevent nutrient loss by leaching. Microbial exudates act to maintain soil structure, and earthworms are important in bioturbation. We have much work ahead to gain a better understanding of how soil biological components affect us and the planet they share with us. Soil biology involves work in the following areas: Modelling of biological processes and population dynamics; Soil biology, physics and chemistry: occurrence of physicochemical parameters and surface properties on biological processes and population behavior; Population biology and molecular ecology, methodological development and contribution to study microbial and faunal populations, diversity and population dynamics, genetic transfers, influence of environmental factors; Community ecology and functioning processes: interactions between organisms and mineral or organic compounds; involvement of such interactions in soil pathogenicity; transformation of mineral and organic compounds, cycling of elements; soil structuration Complementary disciplinary approaches are necessarily utilized which involve molecular biology, genetics, ecophysiology, biogeography, ecology, soil processes, organic matter, nutrient dynamics and 

Soil Conservation

Soil conservation Fudging is set of management strategies for prevention of soil being eroded from the earth’s surface or becoming chemically altered by overuse, salinization, acidification, or other chemical soil contamination. The principal approaches these strategies take are: choice of vegetative cover, erosion prevention, salinity management, acidity control, encouraging health of beneficial soil organisms, prevention and remediation of soil contamination, mineralization. Other ways are: no till farming, contour plowing, wind rows, crop rotation, the use of natural and man-made fertilizer, resting the land. Many scientific disciplines are involved in these pursuits, including agronomy, hydrology, soil science, meteorology, microbiology, and environmental chemistry. Decisions regarding appropriate crop rotation, cover crops, and planted windbreaks are central to the ability of surface soils to retain their integrity, both with respect to erosive forces and chemical change from nutrient depletion. Crop rotation is simply the conventional alternation of crops on a given field, so that nutrient depletion is avoided from repetitive chemical uptake/deposition of single crop growth. Cover crops serve the function of protecting the soil from erosion, weed establishment or excessm evapotranspiration; however, they may also serve vital soil chemistry functions. For example, legumes can be ploughed under to augment soil nitrates, and other plants have the ability to metabolize soil contaminants or alter adverse pH. The cover crop Mucuna pruriens (velvet bean) has been used in Nigeria to increase phosphorus availability after application of rock phosphate. Some of these same precepts are applicable to urban landscaping, especially with respect to ground-cover selection for erosion control and weed suppression. Windbreaks are created by planting sufficiently dense rows or stands of trees at the windward exposure of an agricultural field subject to wind erosion. Evergreen species are preferred to achieve year-round protection; however, as long as foliage is present in the seasons of bare soil surfaces, the effect of deciduous trees may also be adequate. Trees, shrubs and groundcovers are also effective perimeter treatment for soil erosion prevention, by insuring any surface flows are impeded. A special form of this perimeter or inter-row treatment is the use of a “grassway” that both channels and dissipates runoff through surface friction, impeding surface runoff, and encouraging infiltration of the slowed surface water.

Soil pH

Soil pH levels adverse to crop growth can occur naturally in some regions; it can also be induced by acid rain or soil contamination from acids or bases. The role of soil pH is to control nutrient availability to vegetation. The principal macronutrients (calcium, phosphorus, nitrogen, potassium, magnesium, sulfur) prefer neutral to slightly alkaline soils. Calcium, magnesium and potassium are usually made available to plants via cation exchange surfaces of organic material and clay soil surface particles. While acidification increases the initial availability of these cations, the residual soil moisture concentrations of nutrient cations can fall to alarmingly low levels after initial nutrient uptake. Moreover, there is no simple relationship of pH to nutrient availability because of the complex combination of soil types, soil moisture regimes and meteorological factors. The important observation is that pH is the regulatory mechanism to plant nutrient uptake, and that the theoretical concentration of soil nutrients is meaningless until pH levels are in the optimum range for uptake. Soil pH can be raised by amendment by agricultural lime; the pH of an alkaline soil is lowered by adding sulfur, iron sulfate or aluminium sulfate, although these tend to provide costly short term benefits. Urea, urea phosphate, ammonium nitrate, ammonium phosphates, ammonium sulfate and monopotassium phosphate also reduce soil