Land Evaluation Chapter 5 PDF

CHAPTER FIVE LAND EVALUATION  At the end of this chapter, you will be able to: Define land evaluation Identify land evaluation procedure knows the basic data for land evaluation prepare or develop land capability map  Land Evaluation  It is the proces...

CHAPTER FIVE LAND EVALUATION  At the end of this chapter, you will be able to: Define land evaluation Identify land evaluation procedure knows the basic data for land evaluation prepare or develop land capability map  Land Evaluation  It is the process of estimating the potential of land for alternative kinds of use.  Part of the process of land use planning  Land evaluation involves Assessment of spatial variation of land Assessment of sustainability of land uses Multi-disciplinarity Use of specialist as well as local knowledge  In land evaluation procedure there are two types of land classification. Land capability classification Land suitability classification  Land capability classification  The intention of this method was to classify  Land according to the degree of its limitations for sustained use.  Ranks land on the basis of its potential productivity and cropping flexibility.  Determined by the extent to which its physical characteristics( soil, climate &relief)  The method is relatively easy to handle  Depending on these, the land is classified in to 8 capability classes.  Land Capability Classification Approach  The method focuses on inventory of major characteristics of landforms, and soil physical properties  The major data required to employ the method are: classes of slope, soil depth, past erosion status, soil texture, soil infiltration rate, Stoniness and water logging condition of a land unit.  Cont..  Based on the above characteristics of an area mapping units can be determined by drawing boundaries following slope brakes.  In this system, land is often classified in eight classes according to its degree of limitation for a number of general land-use categories. Land capability classification class characteristics Class I lands  Has no much physical limitations that hinder annual crops production.  However soil fertility improving and soil conservation activities appropriate to the slope class might be beneficial in improving yield/ ha.  Eg. soil drainage on vertisols, fertilizers, and leguminous plants along field boundaries. Class II- IV lands  suitable for annual crop cultivation and other alternative uses,  their capacity of production/unit area will be lowered by factors that hinder to reduce productivity such as slope, soil depth and stones cover  productivity can be enhanced with interventions that can ameliorate levels of limiting factors Class I to IV lands are also suitable for any other development activities like: Livestock forest development if the planning team needs to choose and allocate as per the farmers or land users choices.  Class V lands  wet or swampy  requires a lot of investment to change its land uses other than dry season grazing and grass cutting.  draining the soil by making drainage ditches Class VI lands  constrained by slope and erosion  need intensive input and management techniques and practices to ameliorate and change them to annual crops production unit.  but by constructing appropriate physical and biological conservation measures, annual & perennial crops can be grown on bench terraces. Class VII & VIII lands developed by enclosing the area as: house of natural regeneration and biodiversity conservation perennial crops if: availability of moisture and suitable temperature relevant to the selected land uses.  LCC and physical resource evaluation Preparing Land Capability Map based on the Multi Criteria of Physical Evaluation after determination of land capability classes of mapping units of a planning unit area; a land capability map can be prepared with a legend that describes the land capability classes in terms of: area, recommended alternative land uses, corrective measures to be taken to improve limitations and possible regulation measures  LCC Principles The following principles are adopted: 1. LCC is an interpretative classification based on permanent qualities and characteristics of the land. Existing vegetation (including shrubs, trees, or stumps) is not considered a permanent characteristic 2. Land with a class is similar in the severity of limitations, but not necessarily in the kind of limitation or in the management practices required, so that for example, there may be quite different soils in the same class 3. LCC is not a productivity rating for specific crops, though the notion of input to output may help determine the class. 4. A moderately high level of management is assumed. 5. The system does not, in itself, indicate the most profitable use that could be made of the land. 12  LCC Principles 1. Where removal of limiting factors is feasible or has been carried out (e.g. drainage, irrigation, stone removal ) the land is assessed according to the limitations remaining after the improvements have been made. The cost of such improvement does not affect the assessment 7. The land capability assessment of an area may be changed by major reclamation projects that permanently change the nature and/ or extent of limitations, e.g. a large scale drainage, irrigation, or flood prevention schemes 8. Capability groupings are subject to change as new information about the behavior and responses of the soils become available. 9. Distance to markets, kinds of roads, size and shape of the soil area, locations within fields, skill or resource of individual operators, and other characteristics of the land ownership patterns are not criteria for capability groupings 13 Objective of classification: – to regionalize an area of land into units with similar kinds and degree of limitation 14  USDA-LCC Structure (General): Three 1. Land Capability Class: I, II, III, IV, V, VI, VII, VIII 2. Land Capability Subclass: designations identify the character of the soil’s limitation. Class I soils are not subdivided. Subclasses: e: erosion hazard or damage w: water in or on the soil interferes with arability s: root zone limitation: shallow, stony, saline, or droughty c: climatic limitations, usually very cold or very 3. Land Capability Units: same response to management and improvement practices and grow similar range of crops with comparable yields. 15  LCC Structure A. Capability Class: general degree of ‘goodness’ in the sense of ‘possible intensity of use: I, II, III, IV, V, VI, VII, VIII. I= best, VIII = worst. B. Capability Subclass: indicates the major limitations, by the use of one or more letters. 1. Slope (L), 2. Soil depth (D), 3. Past erosion (E), 4. Texture (T) 5. Water logging (W), 6. Infiltration (I), 7. Length of Growing Period (G) 8. Stoniness or rockiness (S), and 16  Capability subclass: Indicates the kind of limitation for agricultural use. defined on the basis of major conservation problems, a suffix notation is introduced provides information as to the kind of conservation problem or limitation If the necessary soil information is provided: map at 1;200 000 to 1:50 000 the Land Note: one or max. of two limiting factors following the Land Capability Class. 17 A. Capability Land Unit:  Is a group of soils with similar characteristics that respond in similar way to management and improvement practices, potential productivity and grow similar range of crops with comparable yields.  is the combination of Land Capability Class and Sub-class & Units. In other words, Land class units = SCRC + major limiting factor +Numerical values. Example: Land class units, IIL = II + slope (L) + 1 IIIL= III + slope (L) + 2 IVE = IV + past erosion (E) + 3 VIIIES = VIII + Past erosion (E) + Stoniness (S) + 4 18  Cont…  soils in a capability unit are sufficiently uniform to:  Produce a similar kind of cultivated crops and pasture plants with similar management practices;  Require similar conservation treatment and management;  Have comparable potential productivity.  It Capability Unit provides: – the most specific and detailed information. – it covers specific portion of a farm or ranch – greatly aid detailed farm planning. 19 Major limiting factors of capability classfication Texture Slope Depth SOIL Erosion Infiltration status Water logging  Characteristics of Classes Class Characteristics Recommended land Use/treatment I Deep, productive soils easily worked, on Use of fertilizer and lime, cover nearly level land, not subjected to overland crop, crop rotations required to flow, no or slight risk of damage when maintain soil fertility and soil cultivated without treatment structure II Productive soils on gentle slope, moderate May require drainage, Use crop depth subjected to occasional overland rotations, water control systems or flow, moderate risk of damage when special tillage practices to control cultivated without treatment erosion III Soils of moderate fertility on moderate Crop cover instead of row crops steep slopes, subjected to more sever erosion, subjected to sever risk of damage when cultivated without treatment IV Good soils on steep slopes, subjected to Pasture but a grain crop may grown sever erosion, very risk of damage when once in five or six years cultivated without treatment 21 Class Characteristics Recommended land Use/treatment Land is too wet or stony for cultivation Used for pasture or forestry but V but nearly level slope, subjected to only grazing should be regulated to slight erosion if properly managed prevent plant cover from being destroyed Shallow soils on steep slopes Used for grazing and forestry, VI grazing should be regulated to preserve plant cover, if plant cover is destroyed, use should be restricted until cover is re- established Steep, , rough, eroded land with shallow Strict grazing or forest VII soils, also including droughty and swampy management must be applied land, sever risk of damage even when used for pasture or forestry VIII Very rough land not suitable even for Reservation for wildlife, recreation woodland or grazing or watershed conservation 22 Class Suitable land use I Land suitable for annual crops II III IV V Land Wet land regularly may be suitable unsuitable for only for rice and temporary grazing annual crops VI Suitable for perennial crops or grazing VII Suitable for forestry VIII Land unsuitable for agriculture 23  1) Land slope (L) Slope classes % range Code Flat or almost flat 0-3% L1 Gentle sloping 3-8% L2 Sloping 8-15% L3 Moderately steep 15-30% L4 Steep 30-50% L5 Very steep >50% L6 24  2) Soil depth (D) Soil depth classes cm Code Very deep >150 D1 Deep 100 - 150 D2 Moderately deep 50 - 100 D3 Shallow 25 - 50 D4 Very shallow < 25 D5 25  3) Past erosion (E) Erosion classes Definition Code Nil No erosion noticeable E0 Surface wash & small rills Slight roots slightly exposed E1 slight top soil loss Rills cover most or the surface Moderate Roots are well exposed E2 Much top soil is removed in the upper part Shallow gullies are frequent Severe Tree/plant roots are frequent exposed E3 Most top soils are removed Most of the land is dissected by gullies Small top soil are present Very severe E4 Land consist of rock (parent material) as result of complete removal 26  Textural group 4)Textural Soil Texture class (T) Code Sand T1 Coarse Sandy Loam T2 Loam T3 Silt Loam T4 Medium Clay Loam T5 Clay, Silt Clay T6 Fine Heavy Clay T7 27  5) Water Logging (W) Water logging Definition Code No water logging Well drained soil W0 Imperfectly drained areas Intermittently water Water & logged during heavey W1 logged rains for a few days 1 week Poorly drained areas Regularly water Commonly folded during wet W2 logged season Very poor drained areas Swampy area Water table at or near the surface W3 during wet season 28  6) Surface Infiltration (I): Infiltration Definition Code classes Good The soil in the surface layer is porous or very permeable or has a good structure to absorb rapidly. When the dry soil is I0 ploughed it breaks into fine clods and grains. Moderate The soil in the surface layer has a massive structure or has a moderate to slow permeability; The surface has tendency to I1 compact and seal. When the dry soil is ploughed it breaks in to large clods; a good tilth is difficult to obtain; Moderate surface cover with plants or grass materials is observed; Poor In addition to a massive structure the soil has a strong tendency to seal on wetting or settling to almost I2 impermeable crust on drying. When dry, the soil does not show cracks at the surface. 29 6) Length of Growing Period- LGP (G): Length of Growing Code Period (Days) 240 G5 30  8) Surface Stoniness or rockiness (S) Stoniness classes Rockiness Area Cover Code (%) No Stone or few No rock or few 90 S4 31  7. LCC and physical resource evaluation: Table 7. 10: Land capability classification conversion table Land Land capability classes determining factors of land mapping units derived Capability Limiting Factors Slope/L 1 2 3 4 1-4 5 6 1-6 1-6 Soil depth/D 1 1-2 1-2 1-3 1-4 1-3 1-4 1-5 1-5 Erosion/E 0 0 0-1 0-2 0-2 0-3 0-3 0-4 0-4 Texture/T 3-5 3-6 3-7 2-7 2-7 2-7 2-7 1-7 1-7 Water 0 0 0-1 0-2 0-2 0-2 0-2 0-2 0-3 logging/W Infiltration 0 0 0-1 0-2 0-2 0-3 0-3 0-2 0-2 rate/I LGP/G 3,4 3,4 3,4 2-4 >G1 >G1 >G1 G1- G5 G1-G5 Stoniness/S 0 0-1 0-2 0-2 0-2 0-3 0-3 0-4 0-4 Land I II III IV VI VII VIII V Capability Land suitable for annual crops Suitable for Suitable for Not suitable Swampy Class Perennial Forest for crop land crops & development production grazing  Summary Class Major limiting factors Class Major limiting factors I No Limitation Slope (L) V Swamp's, river beds II Stoniness (S) Slope (L) Slope (L) III Erosion (E) VI Soil depth (D) Water logging (W) Stoniness (S) Infiltration (I) Slope (L) Stoniness (S) VII Soil depth (D) Slope (L) Erosion (E) IV Erosion (E) Soil texture (T) Soil depth (D) VIII Stoniness (S) Water logging (W) 33 LCC on the Landscape 34  Exercise 1 If the land – Slope: gentle slope, – Soil depth: deep, – Erosion: moderately eroded, – Texture: medium /Silt loam/, – Water logging: intermittently, – Infiltration: good, – Stoniness: stony. 1. Decide the limiting factor & Land class Unit. 2. What is the soil conservation requirement class? 3. For which land use system you recommend this land? 35  Solution Given Gentle slope = L2 Deep soil = D2 Moderately eroded = E2 Medium texture /Silt loam/ = T4 Intermittently water logged = W1 Good infiltration = I0 Stony = S2 36  Land capability classification criteria Limiting Factor Range of codes permitted in the column Slope (L)2 1 2 3 4 1-4 5 6 1-6 1-6 Soil depth (D)2 1 1-2 1-2 1-3 1-4 1-3 1-4 1-5 1-5 Past Erosion (E)2 0 0 0-1 0-2 0-2 0-3 0-4 0-4 Top soil texture (T)4 3-5 3-6 3-7 2-7 2-7 2-7 1-7 1-7 Water logging (W)1 0 0 0-1 0-2 0-2 0-2 0-2 0-3 Infiltration (I)0 0 0 0-1 0-2 0-2 0-2 0-2 0-2 Surface Stoniness 0 0-1 0-2 0-2 0-3 0-3 0-4 0-4 (S)2 Soil Con. Req. class I II III IV VI VII VIII V Land suitable for For For Unsuitable Swampy annual crops grazing or Forestry for areas, perennial Agriculture river beds, crops etc. 37  Exercise 2 If the land Slope: 20%, Soil depth:120cm, Erosion: surface wash, small rills & roots slightly exposed, Soil texture: silt loam, Wetness: well drained soil, Infiltration: moderate or slow & Stoniness: moderately rocky. 1. Decide the limiting factor & Land class Unit. 2. What is the soil conservation requirement class? 3. For which land use system you recommend this land? 38  Solution Given Slope 20% = L4 120cm soil depth = D2 Surface wash, small rills & roots slightly exposed = E1 Silt loam texture = T4 Well drained soil = W0 Moderate or slow infiltration = I1 Moderately Rocky = S1 39  Land capability classification criteria Limiting Factor Range of codes permitted in the column Slope (L)4 1 2 3 4 1-4 5 6 1-6 1-6 Soil depth (D)2 1 1-2 1-2 1-3 1-4 1-3 1-4 1-5 1-5 Past Erosion (E)1 0 0 0-1 0-2 0-2 0-3 0-4 0-4 Top soil texture (T)4 3-5 3-6 3-7 2-7 2-7 2-7 1-7 1-7 Water logging (W)0 0 0 0-1 0-2 0-2 0-2 0-2 0-3 Infiltration (I)1 0 0 0-1 0-2 0-2 0-2 0-2 0-2 Surface Stoniness (S)1 0 0-1 0-2 0-2 0-3 0-3 0-4 0-4 Soil Con. Req. class I II III IV VI VII VIII V Land suitable for For For Unsuitable Swampy annual crops grazing or Forestry for areas, perennial Agriculture river beds, crops etc. 40  Exercise 3 The land has 25% slope, 100cm soil depth, Erosion level is severe, Clay loam texture, Well drained soil, Surface infiltration is poor & Few or no rock. 1. What is the major limiting factor? 2. What is the SCRC? What is the land class system unit? 3. For What land use you recommend the land? 41  Solution Given Slope 25% = L4 100cm soil depth = D2 Erosion level severe= E3 Clay loam texture = T5 Well drained soil = W0 Surface infiltration is poor = I2 Few or no Rock = S0 42  Land capability classification criteria Limiting Factor Range of codes permitted in the column Slope (L)4 1 2 3 4 1-4 5 6 1-6 1-6 Soil depth (D)2 1 1-2 1-2 1-3 1-4 1-3 1-4 1-5 1-5 Past Erosion (E)3 0 0 0-1 0-2 0-2 0-3 0-4 0-4 Top soil texture (T)5 3-5 3-6 3-7 2-7 2-7 2-7 1-7 1-7 Water logging (W)0 0 0 0-1 0-2 0-2 0-2 0-2 0-3 Infiltration (I)2 0 0 0-1 0-2 0-2 0-2 0-2 0-2 Surface Stoniness (S)0 0 0-1 0-2 0-2 0-3 0-3 0-4 0-4 Soil Con. Req. class I II III IV VI VII VIII V VII e For For Unsuitable Swampy Land suitable for grazing or Forestry for areas, annual crops perennial Agriculture river beds, crops etc. 43  Integration of Natural Resource Information with Socio-economic Information Local level Participatory land use plans are prepared based on  natural resources,  social,  economics, and  environmental data collected and analyzed from planning units of mapping units by a participatory planning team.  Final land use plan  On each biophysical data type report is prepared that shows, problems constraints and land use options and given to land evaluator to be compiled.  Problem prioritization is made for the second time with PRA teams.  Last final draft land use plan prepared  The draft plan is commented by the general assembly  Final land use document prepared  n k s ! T h a