A Bench Mark Soil is a reference point which is adequately characterised in terms of its properties and environmental conditions. The information about Bench Mark Soils can be extended to other soils closely related in classification and geography. The Bench Mark Soils are selected from among the existing and established soils that represent typical range of characters based on Major Land Resource Areas or Agroecological Zones. The Bench Mark soil list helps the research community to focus their investigative efforts on key soils that have the greatest potential for applying new technology across a large area, and also for transferring new technologies to similar soils, thereby optimizing cost-benefit ratios.
The criteria for grouping a soil as Bench Mark Soil, standardised by the United Sates Department of Agriculture, is listed below
Extent : The soil series that are selected as Bench Mark Soils are commonly of moderate or large extent in the Major Land Resource Area. Since Bench Mark Soils represent the soil series in classes of the higher categories of Soil Taxonomy, the soils selected as Bench Mark should collectively be considered representative of 60 to 80 per cent of all soils in the Major Land Resource Area. This kind of representation ensures that any collected data are widely applicable.
Key soils : Often, many of the series that share the same taxonomic family are expected to behave similarly. The research on these can be easily applied to other soils. Therefore, there is little advantage in assigning more than one series from a given family as a Bench Mark Soil. Instead, the procedure followed is to determine which series is most representative for the family, and assign Bench Mark status to that series only. Bench Mark soils in a Major Land Resource Area usually do not share the same family.
Unique soils: Certain soils are especially important because of their use for specific types of crops or specific management, required to make them suitable for raising crops or because of their unique location or special characteristics. If these soils are essential to the understanding of and interpretations for specialty crops, engineering, or other uses, they become Bench Mark Soils.
Existing data : Soil series for which there are large amounts of data have preference over equally suitable series for which there are less data. Data-completeness of correlated pedon data must be evaluated concurrently with analyses of series extent and taxonomic significance. Based on the above considerations, 82 soil series have been identified as Bench Mark Soils of Kerala. The morphological characters and chemical properties, hydro-physical properties, estimate of water balance and crop growing period of each soil and geology, geomorphology, climate, ground water resource, forest and forestry, agriculture and land utilisation of Kerala are detailed in the publication "Bench Mark Soils of Kerala".
BENCH MARK SOILS OF KERALA
Early farmers realized that the different soils and climates they encountered required them to grow certain types of crops in order to survive economically. ‘Major Land Resources Areas of Kerala’ is the brainchild of Sri. Hari Eswaran, Scientist, USDA conceived during the First International Forum on Soil Taxonomy and Sustainable Land Management held in February-March 1993. The basic concept was built up on by the department personnel who identified 27 resource areas in Kerala based on physiography, geology, climate, soils and crops as parameters.
Eighty two Bench Mark soils have been identified in the 27 different Major Land Resource Areas of Kerala for which soil monoliths were collected. A Bench Mark Soil is one that is widely extensive, holds a key position in the soil classification system and is of special significance to farming, engineering or other uses. The basic objective of Bench Mark Soil is to focus attention on extensively occurring soils and their agronomic concepts for wider acceptability of interpretations and for extrapolation of research data. The Bench Mark Soils are selected from among the existing and established soils that represent typical range of soil conditions within the state and having extensive coverage. It is the representative of the most extensive soils in major land resource area or agro ecological zone of the state and/or holding a key position in Soil Taxonomy. The selected soil should have large amount of research data for making transfer of agro technology feasible. Studies of Bench Mark Soils helps in soil correlation, standardization of legends, prediction of soil behaviour, agro technology transfer and planning further research in allied disciplines.