The Soil and Soil Survey Investigation

Contributed By Fikadu Kassa

The "Soils" is defined as a three dimensional body, occupying the uppermost part of the earth's crust, having properties differing from the underlying rock material and relief as a result of interactions between climate, living organisms, parent material, relief and man for over period of time.

 It is distinguished from other soils' interms of differences in internal characteristics and/or interms of gradient, slope-complexity, macro-topography and stoniness and rockiness of the surface.

Without soil there is no life on planet earth and soil ,indeed, is SOUL (S) OF (O) INFINITE (I) LIFE (L), an invaluable gift of God to life on earth and unless we manage it intelligently, humanity has no future.

Historical Perspective

One of the earliest land evaluation systems that incorporated a soil classification was established during the Vao dynasty (2357-2261 B.C.) in China.

Soils were graded into nine classes, based on their productivity.

It has been suggested that property taxes were based on the size of the individual land holding and soil productivity (Lee, 1921).

In former times (< 1600 A.C.), soil was solely considered as a medium for plant growth.

Knowledge of soil behavior and crop growth was passed from generation to generation gained by observation.

For example, in the Middle Ages it was well known that manure applied to soils improved crop growth.

There was a close relationship between plant and animal production.

For instance, the "Plaggen cultivation" was practiced for a long time in Europe, which left "Plaggen soils": The top of grassland was peeled off and used as litter in the stables.

This material mixed with manure was applied to arable land to improve crop production.

In 1840, the German chemist Justus von Liebig initiated a revolution in soil science and agriculture.

He proved that plants assimilate mineral nutrients from the soil and proposed the use of mineral fertilizers to fortify deficient soils.

Crop production was increased tremendously using mineral fertilizers.

Another effect was the shift from extensive to intensive techniques in agriculture, which influenced soils.

Thaer (1853) published a classification that combined texture as a primary subdivision with further subdivisions based on agricultural suitability and productivity.

Several classifications based largely on geologic origin of soil material were also proposed in the 19th century (Fallou, 1862; Peters et al., 1885; Richtofen, 1886).

From the 1660s onwards, various members of The Royal Society of London proposed schemes of soil classification that incorporated elements of a natural or scientific approach in their criteria (Boyle, 1665; Lister, 1684).

From this period on, the disciplines of agricultural chemistry (with a strong focus on soil fertility), geography, and geology provided a broad but somewhat fragmented background from which pedology emerged as a separate discipline in the late 19th century more or less independently in Russia (Dokuchaev and colleagues) and in the United States (Hilgard and colleagues).

In 1883, Dokuchaev carried out a comprehensive field study in Russia, where he described the occurrence of different soils thoroughly using soil morphologic features.

Due to his observations in the field he hypothesized that different environmental conditions result in the development of different soils.

He defined soil as an independent natural evolutionary body formed under the influence of five factors, of which he considered vegetation and climate the most important.

Dokuchaev is generally credited with formalizing the concept of the "five soil forming factors", which provides a scheme for study of soils as natural phenomena.

The soil classification developed by Dokuchaev and his colleagues (Glinka, Neustruyev) was based on the soil forming factors -> soil forming processes -> and diagnostic horizons / soil properties.

The focus in his soil classification approach was in soil genesis, therefore the classification system is called "genetic".

The Soil Survey Description

"A soil survey describes the characteristics of the soils in a given area, classifies the soils according to the standard system of classification, plots the boundaries of the soils on a map, and makes predictions about the behavior of soils. The different uses of the soils and how the response of management affects them are considered [in designing and carrying out the survey]. The information collected in a soil survey helps in the development of land-use plans and evaluates and predicts the effects of land use on the environment."

The Purpose of Soil Surveys

It is apparent that "soil" is a narrow concept than the "land": soil is one of the several attributes of the land.

However, as soil genesis and the resulting soil characteristics are the result of several factors that also play a role in the properties of the land, there is a certain overlap between the two concepts.

The term " Soil Resource Survey" refers to the field investigation of the soils and other important land attributes of a specific area or tract of land in order to show the variability of land characteristics and distribution of different land units on a map, and to describe, classify and interpret these units for certain purposes of use in the form of a report.

The soil resource surveys may have many objectives.

The one most common and the main objective is to assess the potential and limitations of the resources and predict their response under different kinds of use and management.

Such information is of basic importance in developing land use plans an alternatives involving land management systems as well as in evaluating and predicting the effects of a proposed land use alternative.

The important areas in which the need for soil resource surveys is realized include the following.

  • Selection of the areas which can be developed for agriculture, forestry or rangeland etc.
  • Allocation of areas to different kinds of major land use i.e., irrigated agriculture, rainfed agriculture, timber forestry, woodland forestry, grazing/ livestock production, water catchment conservation, industrial and residential settlements, etc.
  • Selection of promising land use alternatives and suitable crops for cultivation in different parts of an area, and formulation of appropriate cropping patterns.
  • Prediction of crop yields and agricultural productivity of an area or region and long-term planning for the national/ regional food and fiver needs.
  • Prediction of possible changes or environmental hazards like soil erosion, drought, salinization, waterlogging, etc with the proposed development of an area or with future changes in land use.
  • Prescription of land management recommendation for maximum agricultural outputs and land resource conservation.
  • Formulation of land development projects.
  • Estimation of land development requirement and costs of a selected project area.
  • Determination of water requirements for irrigation of a selected project area.
  • Estimation of expected income and net financial benefits of the implementation of a selected project.
  • Land appraisal for consolidation, taxation and advancement of agricultural credits.
  • Planning for rehabilitation of degraded lands i.e., the lands affected by soil erosion, soil salinity/ acidity, water logging, etc.
  • Rational distribution of irrigation water resources.
  • Sitting agro-based industries.
  • Alignment and designing of roads, railway lines, irrigation canals, drainage channels, etc.
  • Field application of the results of agri-research conducted at experimental farms/research stations.
  • International coordination in agricultural research and soil management technology.
  • Acquisition of development funds from international aid-giving agencies.

Soil Survey Consumers

The information consumer is a person or organization or community which needs to know something about soil properties, as outlined in the previous section.

For the soil resource, these consumers include:

  • Land managers: farmers, ranchers, foresters, plantation managers… This group decides what to do with each land area, i.e. what to use it for, and under what management system.
  • Advisors to land managers: extensionists.

This group advises land managers.

  • Service industries related to land use: e.g. agricultural credit agencies, banks, investment groups.

This group facilitates land use and needs to know if their investment will be productive.

  • Land-user planners: rural, suburban, peri-urban, urban.

This group prohibits, advises, or facilitates certain kinds of land use in different areas.

  • Regulatory agencies: a sub-group of land-use planners, but with a specific legal authority to regulate land use.

Example: in the Netherlands, the amount of animal manures that can be applied to a hectare of land is determined by the soil type; the purpose of this regulation is to avoid ground-water pollution.

  • Taxation authorities: in some countries, land is taxed on its productive potential.

The outstanding example is Germany, following the 1934 law designed to insure fair land valuation for taxation and fair compensation for land reallocation.

  • Environmental managers who use the soil as an element of landscape ecology.
  • Researchers on the land's response to various land uses and management strategies: e.g. agricultural experimentalists; they expect that different soil units respond differently to management
  • Researchers on the land's contribution to various natural and human processes: hydrologists, geographers.
  • Engineers such as irrigation, civil
  • Bankers, Investors, Land Appraisers, Credit Agencies and Directors of Tax Equalization

FAO IDEPSA, 1990- Collection and Utilization of Land Resources Data for Feasibility Studies of Agricultural Development Project, Adiss Ababa.

Kevin Mcsweeney, Sabin Grunwald, 1999 Soil Morphology Classification and Mapping University of Wisconsin Madise Department of Soil Scince.