The aims of land evaluation
Land evaluation is concerned with the present land performance, change in the use of land and the land itself, and its effects taking into account land sustainability for future use. Other factors include the economics of the proposed enterprises, the social consequences for the people in the area and the country concerned, and the consequences, benefits or adverse, for the environment.
Questions answered by land evaluation:
? How the land is currently managed and the future prospects of the land if the present practices remain the same/don’t change
? What improvements in management practices are possible to implement within the present use
? What other uses of land that are physically possible, economically and socially relevant in the area
? Which uses offer the possibility of sustainable production and other benefits
? What recurrent input that are necessary to bring about the desire production and minimize the adverse effects. What are the benefits of each form of use?
However, if the introduction of a new use involves a significant change in the land itself, for example irrigation schemes, then land evaluation must be able to answer:
? What changes in the condition of the land are feasible and necessary, and how can they be brought about
? What non-recurrent inputs are necessary to implement these changes
The process of land evaluation provides data as a determinant to the decision-making process in land use and doesn’t determine itself the land use changes to be carried out. To be effective in this role, the output from an evaluation normally gives information on two or more potential forms of use for each area of land, including the consequences, beneficial and adverse, of each.
Land Evaluation and Land Use Planning
Land evaluation is a part of the process of land use planning and its precise role varies indifferent situations. In the contemporary framework it is satisfactory to represent the land use planning process by the following generalized sequence of activities and decisions:
1. Recognition of a need for change
2. Identification of aims
3. Formulations of proposals, involving alternative forms of land use, and recognition of their main requirements
4. Recognition and delineation of the different types of land present in the area
5. Comparison and evaluation of each type of land for the different uses
6. Selection of a preferred use for each type of land
7. Project design, or other detailed analysis of a selected set of alternatives for distinct parts of the area. This can take the form of a probability study in certain cases.
8. Decision to implement
10. Monitoring of the operation
Land evaluation plays a major role in stages 3, 4 and 5 of the above sequence and contributes information to the succeeding activities. Thus, land evaluation is heralded by the recognition of the need for some change in the use to which land is exposed to; which may be exposure to the development of new prolific uses, such agricultural development schemes or forestry plantations or the establishment of services, such as the designation of a national park or recreational area.
The recognition of this need is followed by identifying the aims of the anticipated alteration and formulation of the general and specific proposals. The evaluation process itself include the explanation of a range of promising categories of practice, and the assessment and comparison of these with respect to each type of land identified in the area leading to the recommendations involving one or a small number of preferred uses of land.
The Six-Factor Principles of Land Evaluation
There are basic fundamental principles that are considered in the approach and methods employed in land evaluation which include:
Assessment of land and classification.
This is a principle to determine land suitability. Land suitability is assessed and classified with respect to the specific kinds of use and this principle is embodied with the recognition fact that different land use production systems have different requirements.
For example, in areas that are affected by floods there are alluvial flood plains with impeded drainage and this can be utilized for or favors rice production than for forestry. The meaningfulness of the land suitability concept lies within the specific categories of land use, each with their own requirements, e.g. soil moisture, rooting depth etc.
The qualities of each type of land, such drainage, availability of moisture or liability to flooding are compared with the requirements of each use. This make the land and the land use to be equally fundamental to land suitability and evaluation.
Least cost principle of land production
Evaluation process requires a comparison of the benefits obtained and the inputs needed on different types of land. The productive potential of land is determined by the input installed in it, even in the collection of wild fruits input required is labor and the use of natural wilderness for nature conservation requires measures of protection.
The appropriateness for each practice is assessed by comparing the required input, such as labor, fertilizers or road construction, with goods produced or other benefits obtained.
The multidisciplinary approach system
A multidisciplinary approach is required where contributions are done from the fields of natural science, the technology of land use, economics and sociology to the evaluation process. Evacuating land according to the suitability principle of approach always incorporates economic considerations to a greater or lesser degree.
The degree of economic consideration in qualitative evaluation may be employed in general terms but without the calculation of costs and returns. In quantitative evaluation the comparison of benefits and inputs in economic terms plays a major role in the destination of suitability. The major role in the fortitude of suitability in quantitative evaluation is played by the comparison of benefits and inputs in economic terms i.e. the inclusion of cost and returns.
This principle follows that a team carrying out an evaluation and encompasses the study of land, land use, social aspects and economics. This however require a range of specialist which include geomorphologists, soil surveyors, ecologist who are specialist under natural science, agronomist, foresters, irrigation engineers, experts in livestock management, economist and sociologist.
Physical, economic and social context of the area
Under this principle evaluation is made in terms of the physical, economic and social context of the are concerned. The factors that form the context within which evaluation takes place include:
i. Regional Climate/Climatic conditions
ii. Standards of living
iii. Population Density
iv. Labor cost and availability
v. Potential market/Marketability – both local and export market
vi. Land tenure systems which are acceptable socially and politically
vii. Capital fluidity and accessibility
The assumptions in evaluation will differ from one country to another and to some extent also differs between areas of the same country. To avoid misunderstanding and to assist in comparisons between different areas many of these factors are often indirectly assumed and such assumptions should be explicitly stated.
Suitability refers to the use of land in a sustainable manner with respect to the aspect of environmental degradation. For example, some forms of lands use appear to be highly profitable in the short run economies of scale but likely to lead to soil erosion, progressive pasture degradation or adverse changes in river regimes downstream. These consequences will determine the fate of land use as they would outweigh the short-term profitability and cause the land to be classed as not suitable for such purposes.
This principle states the proper utilization of land through environment preservation for future use. Under normal circumstance agriculture is encompasses the replacement of the natural vegetation and normally soil fertility under arable cropping is either high or low depending on management but rarely at the same level as under the original vegetation.
The requirement is that, for any proposed form of land use, the probable consequence for the environment should be assessed thoroughly and accurately, and such assessments should be taken into consideration when determining suitability.
Best-Fit Principle of Analysis
The best-fit principle of analysis corelate the relationship between land use, population density and returns. In the context of agriculture, it corelates the relationship between land use, the factors influencing agricultural production which include (human, biotic, climatic and edaphic factors) and the tangible returns/profit realization.
Evaluation involves the comparison of more than a single kind of use and the comparison can be done for example, between two or more different faming systems, agriculture and forestry, or between individual crops. The reliability of land evaluation is dominated by the benefits and inputs from any given kind of use which can be compared to at least one and usually several different, alternatives. Considering only one use draws the danger that, whilst the land may be indeed suitable for that use, some other and more beneficial use may be ignored.
Levels of Intensity and Approaches
A number of activities are common to all types of land evaluation and in all cases, it commences with initial consultations, concerned with the objectives of the evaluation, assumptions and constraints and the methods to be followed. The details of the subsequent activities and the sequence in which they are carried out, vary with circumstances which include the level of survey intensity and the two overall approaches that have to be followed.
Level of Intensity
There are three levels of intensity that may be distinguished which are normally reflected in the scales of resulting maps
1. Investigation/Reconnaissance survey
The first level of intensity, reconnaissance, is more concerned with broad inventory of resources and development possibilities at regional and national levels. The evaluation of land is qualitative and economic analysis is only in very general terms. The results contribute to the creation of national plans, permitting the selection of development areas and priorities.
At semi-detailed or intermediate level of intensity, the level is concerned with more specific aims which include feasibility studies of development projects. The work includes farm surveys, economic analysis is considered more important and the evaluation of land is quantitative. Information provided at this level is for decisions on the selection of projects or whether a particular development or other change is to be applied.
The detailed level covers surveys for actual planning and design, or farm planning and advice, often carried out after the decision to implement has been made.
Two-stage and parallel approaches to land evaluation
The approaches to land evaluation adopted as shown in Fig. 7 below relates the relationship between of resource surveys and economic and social analysis, and the manner in which the kinds of land use are formulated depends on
1. A two-stage approach,
a. the first stage is mainly concerned with qualitative land evaluation,
b. the second stage consist of economic and social analysis.
The two-stage approach is often used in resource inventories for broad planning resources and in studies for the assessment of biological productive potential.
Classification in the first stage stages in land evaluation are based on the suitability of the land for the kinds of land use which are selected at the beginning of the survey e.g. arable cropping, dairy farming, maize or tomatoes.
Economic and social analysis contribution in the first stage is limited to a check on the relevance of the kinds of land use. However, it is utilized in the second stage either immediately or after an interval of time when the first stage has been completed ad its results presented in map and report form.
The basic components of land comprise the physical environment, including climate, relief, soils, hydrology and vegetation to the extent that these are influential factors for potential land use. It includes the past and present results of human activities e.g. reclamation from the sea, vegetation clearance, and also adverse results e.g. soil salinization.
A land mapping unit is a mapped area of land with specified characteristics. These land mapping units are defined and mapped by natural resource surveys, e.g. soil survey, forest inventory. The scale and intensity of study variates the degree of homogeneity or of internal variations. A single land mapping unit in some cases may include two or more distinct types of land, with different aptness e.g. a river flood plain, mapped as a single unit but known to contain both well drained alluvial areas and swampy depressions.
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