Land Capability Classification (PDF)

Land Capability Classification Land use- Land Cover… Dr. Gopal Kumar, ARS Ph.D. (Agril. Physics) Principal Scientist (Soil Physics, Soil and Water Conservation)...

Land Capability Classification Land use- Land Cover… Dr. Gopal Kumar, ARS Ph.D. (Agril. Physics) Principal Scientist (Soil Physics, Soil and Water Conservation) [email protected] ICAR-Indian Institute of Soil and Water Conservation, 218, Kulagarh Road, Dehradun-248195 1 18-Jan-21  Land Vrs. Soil Land: an area of ground, the solid surface of earth that is not permanently covered by water… includes. climate, relief, soil, hydrology, vegetation, minerals, landscapes, proximity, above and below ground entities.. to the extant that these influences the potential for land use (Soil +…) Soil: material on upper earth crust, primarily used for growing plants, made by weathering of rocks and minerals over the years by climate and vegetation conditioned by topography. Non-renewable (though formation takes place-too slow for human life span) Living entity-(most of the services governed) Can be sampled out (unlike to land) Polyphasic, 3-Dimensional Watershed: A geographical area (land) draining to a 18-Jan-21 common point (outlet) 2  Land cover is the physical material at the surface of the earth. - grass, asphalt, trees, bare ground, water, etc. Land use is a description of how people utilize the land and of socio-economic activity. A map that shows the types and intensities of different land uses - LU map. Urban and agricultural land uses are two of the most commonly known land use classes. Land Use Land cover Water storage Water spread, dried up area Agriculture Cropped land, barren areas Urban Buildings, road, Park, barren patch Recreation Vegetation, grassland, water cover Forest Trees, barren, Shrubs 18-Jan-21 3  “To use the land according to its capability and treat the land according to its need" LAND CAPABILITY CLASSIFICATION (L.C.C) Concept Land capability is the suitability of land for a specified use for maximum sustained production or returns. It is a systematic arrangement of different type of lands according to those properties which determine the ability of land to produce on virtually permanent basis, without causing damage to it due to erosion or other hazards. Class Col Area Position No. 1 G 2 Y 3 R 4 B 4 18-Jan-21 18-Jan-21 Purposes of land capability classification ▪ Land capability map makes available the technical data / information contained in a soil survey map, in a simple and practical language for application to the land use. ▪ It indicates the hazards of soil erosion and difficulties to be encountered in using the land. ▪ It indicates the most intensive, profitable and safe use of any piece of land ▪ It enables the land managers/ farmers to make the best use of research and experience in agriculture since the scientific and technical data are interpreted for each piece of land. 5  Parameter and permanent characteristics for LCC Soil parameters for soil functions: pH, EC, Texture, aggregation, water sable aggregates, BD, porosity, moisture holding capacity, permeability, erosion vulnerability................ Slope, soil texture, soil depth, effects of past erosion, permeability, water-holding capacity, type of clay minerals are considered permanent soil qualities and characteristics. Shrubs, trees, or stumps are not considered permanent characteristics 18-Jan-21 6 18-Jan-21 FACTORS DETERMINING LAND CAPABILITY 1. External features of land i. Slope ii. Erosion features iii. Water logging / wetness / marshy land etc 2. Internal / Inherent soil characteristics iv. Surface soil texture v. Effective soil depth vi. Permeability and internal drainage vii. Soil salinity and alkalinity, fertility, etc. 3. Environmental factors viii. Rainfall ix. Temperature x. Wind velocity, xi. Evapotranspiration 7 18-Jan-21 8 18-Jan-21 CLASSIFICATION LAND SUITABILITY GROUP A. Land suitable for cultivation B. Land not suitable for cultivation LAND CAPABILITY CLASSES I II III IV V VI VII VIII Increasing intensity of hazard and limitations of land use Suitable for cultivation Not suitable for cultivation 9  SUB-CLASSES: Kind of limitation / problem Limitation/hazards Symbol i. Erosion and runoff e ii. Excess water/wetness w iii. Root zone limitation s iv. Climatic limitations c LAND CAPABILITY UNITS Land capability unit - final step in the land capability classification. Within each sub-class the land that is suited for essentially the same kind of management and the same kind of conservation treatment is designated as a land capability unit. 18-Jan-21 10  The soils in a capability unit are sufficiently uniform to : Produce similar kinds of cultivated crops and pasture with similar management practices. Require similar conservation treatment and management under the same kind and condition of vegetation cover. Have comparable potential productivity (within 25% variation-10/20 years average). Land capability units are designated by ordinary numerals placed as subscript to the sub-class letters in the capability notation. For example, Class IIIs would show land with severe soil limitations. Soil limitations may arise because of one of the following reasons. Limitations of effective soil depth. Very heavy or light texture of soil. Nature of material restricting root zone. Salinity or alkalinity of soil. 18-Jan-21 11  Limitations of effective soil depth. Very heavy or light texture of soil. Nature of material restricting root zone. Salinity or alkalinity of soil. The above four soil limitations - need different management practices. These capability units will be indicated as: IIs1 IIIs2 IIIs3 IIIs4 18-Jan-21 12 18-Jan-21 Green Yellow Red Blue Dark green (Uncoloured) Orange Brown Purple 13 18-Jan-21 UPGRADATION AND DOWNGRADATION IN LAND CAPABILITY CLASS Optimum and well distributed rainfall throughout the year is required for classifying land under Class I, if there are no other limitations. Assured supply of irrigation: –no moisture deficit and drought conditions -upgrade the land by one class. Class upgradation is also considered when the suitable measures are taken for already existing problems or limitations of land. New problem: Water logging in terms of either surface water stagnation, seasonal overflow, or high water table and limited soil moisture or aridity – downgrade the land capability. 14 18-Jan-21 15  LAND CAPABILITY CLASSIFICATION : METHOD There are two ways to obtain information for land capability classes and sub-classes. Detailed soil survey maps - provide all information for land capability classification such as soil series, soil texture, effective soil depth, land slope and degree of erosion. Information - wetness, water logging, salinity, alkalinity, stoniness, rockiness, climate, etc. can be used for the land capability classification. In the absence of standard or detailed soil survey map, actual field survey has to be done to obtain information To begin- cadestral maps (village maps) or large scale toposheets can be used to serve as base maps. Google earth- for land cover, slope, erosion hazards 18-Jan-21 16  Steps in Land Capability Classification and Mapping of a Watershed Area Get familiar with the base map of the area A quick reconnaissance survey to ascertain ridge line, to have judgement about the physiography of the land. Survey work is started at one end of the watershed from a place of easily identifiable permanent features Take observation on texture of top soil, effective soil depth, land slope, erosion evidence any other relevant features or details at 3-4 locations in an area, more or less uniform with respect to physio-graphy record the observations in a tabular format. 18-Jan-21 17  Table for data collection Surve Soil Soil Slop Erosio Land use Land Management y/unit texture depth e n class Major Stat Measure Status No (cm) (%) cate. us 1 sl >90 17 e1 Ag C2 Terrace T2 2 cl >90 25 e2 Tea P1 Trenching Good 3 cl 60 35 e1 Forest F2 Nil - Rating chart to be used to determine land capability classes and sub-classes Confirm boundary of the mapping units and demarcate the boundary on the map. Minimum mapable area will depend upon the scale of the map. Area of each land capability class is determined by using Planimeter. 18-Jan-21 18  MAPPING UNITS OR SYMBOLS The collected information for classification is recorded as mapping unit in the following ways: Soil series - Texture of top soil - Effective soil depth Land Slope - Erosion hazard Simply it also can be written as, Texture - depth Slope - erosion The different information to be collected is as follows Texture of top soil - By Feel method Effective soil depth - By Screw Auger/road cuts Land slope - By Abney's level/Hand level Erosion hazard - By visual (eye) judgment. 19 18-Jan-21  Parameters Proposed Mapping unit LC Class LC Class with sub-class Texture- loam (l) I l -d4 IIs soil depth- (45-90 cm)-d4 II A-e1 Slope- 0-1% (A) I Erosion-Absent/very I slight(e1) Texture-clay loam(cl) I or II cl- d5 VIe Depth->90 cm (d5) I D – e3 Slope-5-10% (D) III Erosion-Severe (e3) VI Texture-silty clay (sil) I or II sil – d5 IIIe Depth->90 cm (d5) I D – e2 Slope- 5-10% (D) III Erosion-moderate (e2) III 18-Jan-21 20 18-Jan-21 RATING TABLE FOR LAND CAPABILITY CLASSIFICATION Class Soil Texture Soil depth Slope (%) Erosion status Other attributes Mapping (cm) colour Allu Black Red Deep Hima Effect of Succeptibili Permiabilit Con Climate vial soils soils red - past erosion ty to y (cm/hr) duct soils soils layas erosion ivity of EG Eg.,distanc (dS/ & e from m) WG active gully heads I sicl, cl, l, sl, >90 (d5) 0-1 0-1 0-1 0-1 0-1 e1 Upto ¼ Very far Moderate 0-2 Humid with well Green sil, scl top soil away (2-5) distributed rainfall lost-Sheet throughout the year II sicl, cl, sl, sil, 45-90 (d4) 1-3 1-3 1-3 1-3 1-3 e1 Upto ¼ Minimum Mod.slow 2-4 Humid with Yellow scl top soil 60 m (0.5-2) occasional dry spell; lost-Sheet Mod.rapid sub-humid; crop yield (5-12.5) frequently reduced by drought III sc, sic, c, ls 22.5-45 3-5 3-5 5-10 5-10 3-5 e2 ¼ to ¾ Between Slow 4-8 Sub-humid; crop Red (d3) 5-10 10-15 top soil 6-60 m for (0.125-0.5) yield frequently lost-rill 0-3% slope Rapid reduced by drought; (12.5-25) semi-arid IV s, c 7.5-22.5 10-15 5-10 5-10 15-25 10-15 e3 ¾ top ----- Very slow 8-16 Semi arid and arid Blue (d2) 25-33 15-25 soil and ¼ (25) V Same characteristics as class I land except for one or more limitation of Gullied Marginal -- >16 --- Dark wetness or stoniness or rockiness or adverse climatic conditions. It has no land or land ( 6m green hazard of erosion like class I land. sand dunes wide strip (Uncolou (e4) near gully red) land) VI 25 >50 >100 >100 Bad lands Gully sides Purple 3 and beds 21  DETERMINATION OF SOIL TEXTURE BY FEEL METHOD Sl.No. Soil Texture Feel by fingers Ball formation Stickiness Ribbon formation 1. Sand Very gritty Does not form Does not stain No ball fingers 2. Loamy sand Very gritty Forms very easily Very little-stains No broken ball fingers slightly 3. Sandy loam Moderately gritty Forms very firm Definitely stain No ball but easily fingers broken. 4. Loam Neither very Forms firm ball Definitely stain No gritty nor very fingers smooth 5. Silt loam Smooth or slick Forms firm ball Definitely stain Slight tendency to buttery feel fingers ribbon with flaky surface 6. Clay loam Slightly gritty Moderately hard Definitely stain Ribbons out on ball when dry fingers squeezing but the ribbons breaks easily 7. Silty clay Very smooth Moderately hard Definitely stain Shows some loam ball when dry fingers flaking on ribbon surface similar to silt loam 8. Clay Very smooth Forms hard ball Definitely stain Squeezes out at when dry, cannot fingers right moisture be crushed by into long (1”-3”) 18-Jan-21 fingers 22  LCC under different textural classes Texture class Symbol Proposed LC class Sand..... s IV Loamy sand..... ls III Sandy loam..... sl I, II Loam.... l I Clay loam..... cl I, II Sandy clay loam..... scl I, II Silt..... si I Silty loam..... sil I,II Silty clay..... sic II, III Silty clay loam..... sicl I,II Sandy clay.... sc III Clay..... c III, IV 18-Jan-21 23  SOIL DEPTH CLASSES Depth range Symbol Description Proposed LC class ----------------------------------------------------------------------------------------------- Above 90 cm d5 Very deep I 45 - 90 cm d4 Deep II 22.5 - 45 cm d3 Mod. Deep III 7.5 - 22.5 cm d2 Shallow IV 7.5 cm or less d1 Very shallow VI, VII ----------------------------------------------------------------------------------------------- SLOPE CLASSES -------------------------------------------------------------------------------------------------------- Class of slope Range of slope(%) Proposed LC class --------------------------------------------------------------------------------------------------------- A - 0- 1 I B - 1- 3 II C - 3- 5 II D - 5 – 10 III E - 10 – 15 III F - 15 – 25 IV G - 25 – 33 IV H - 33 – 50 VI I - 50 – 100 VII J - >100 VIII --------------------------------------------------------------------------------------------------------- 18-Jan-21 24  EROSION CLASSES Erosion class symbol and description Proposed LC class --------------------------------------------------------------------------------------------- - e1 No erosion or slight erosion I,II e2 Moderate erosion – sheet and rill III e3 Severe erosion – incipient of gullies. IV e4 Very severe erosion - shallow and deep gullies VI,VI --------------------------------------------------------------------------------------------- - Climate Humid with well distributed rainfall I throughout the year Humid with occasional dry spell; sub-humid; II crop yield frequently reduced by drought Sub-humid; crop yield frequently reduced by III drought; semi-arid Semi arid and arid IV 18-Jan-21 25 Salinity and Alkalinity: Free, Slight, Moderate, Strong Drainage: Good, Wetness which can be corrected by drainage, Wetness which continue after drainage, Excessive wetness 18-Jan-21 26 18-Jan-21 Land capability classification in ravine lands (Tejwani 1975). Land form Slope Distance Land (%) from gully capability rim (m) class Table land 0-1 >60 I Table land 1-3 >60 II Table lands and wide humps in between 0-3 6-60 III(a) wide gullies Table lands 3-5 >6 III (b) Table lands 5-10 >6 III © Table lands 10-15 >6 IV Marginal land between the gully rim and 0-15 9 m SS: vary SS: vary LCC for ravines most steep Class I Class II Slope: 0-1% Class III Slope: 1-3% D> 60m VI D > 60m 0-3% (6-60m) 3-10% (> 60 m) 0-15 % ≤ 6m 28 18-Jan-21 Area occupied by each mapping unit will have the following details:- Boundary of the area by black line. Mapping unit with Symbol. Land capability class and sub-class symbol. Slope direction shown by arrows with exact degree of slope in per cent. Standard colour of land capability class. 29 18-Jan-21 Green Yellow Red Blue Dark green (Uncoloured) Orange Brown Purple 30 Thank You