Soil Taxonomy And Survey PDF

SOIL TAXONOMY And Soil survey  Soil Taxonomy This formal term refers to the system of classification developed by the USDA Soil Survey.  DEFINITION OF TERMS: Classification is a scheme of grouping objects or ideas in an...

SOIL TAXONOMY And Soil survey  Soil Taxonomy This formal term refers to the system of classification developed by the USDA Soil Survey.  DEFINITION OF TERMS: Classification is a scheme of grouping objects or ideas in an orderly manner. The purpose of soil classification is to group individual soil units found in nature so that their properties can be easily remembered, and facts known about them can be made useful to man. Pedon refers to the smallest unit of volume that may be called a soil. By definition, it is restricted to an area between 1 to 10 m2, the actual size depending on the character of the profile under consideration. Soil Individual  Polypedon is a collection of pedons sufficiently alike to be classed in the same soil. Soil series A soil series is a class of soils and the basic unit used to classify soils. Nearly 400 soil series in the Philippines. Class a group of individuals or other units similar in selected properties and distinguished from all other classes of the same population by differences in these properties. The principles of Soil Taxonomy are: Classify soils on basis of properties Soil properties should be readily observable or measurable Soil properties should either affect soil genesis or result from soil genesis Purpose of Soil Taxonomy 1. Organize knowledge about soils 2. Understand relationships among different soils 3. Establish groups or classes for practical purposes. a. predicting behavior b. identifying best uses c. estimating productivity d. extending research results Requirements Temperature Regimes – mean annual soil temperature measured at 50 cm from surface Moisture Regimes – number of days when soil contains available water during the period when soil temperature at 50 cm below the surface is above 5oC Diagnostic Horizons – distinct types of horizons that reflect nature of soil formation  Surface diagnostic horizons (Epipedon) Mineralogy –dominant type of clay minerals Particle size distribution – proportion of coarse fragments (2 mm – 74 mm size particles) in combination with fine fragments (6oC – 8oC Frigid A soil with a frigid temperature regime is warmer in summer than a soil with a cryic regime, but its mean annual temperature is lower than 8 oC and the difference between mean summer (June, July, and August) and mean winter (December, January, and February) SOIL TEMPERATURE REGIME 8oC – 15oC Mesic The mean annual soil temperature is 8 oC or higher but lower than 15 oC, and the difference between mean summer and mean winter soil temperatures is more than 6 oC either at a depth of 50 cm from the soil surface. SOIL TEMPERATURE REGIME 15oC – 22oC Thermic The mean annual soil temperature is 15 oC or higher but lower than 22 oC, and the difference between mean summer and mean winter soil temperature is more than 6 o C either at a depth of 50 cm from the soil surface. SOIL TEMPERATURE REGIME >22oC Hyperthermic The mean annual soil temperature is 22 oC or higher, and the difference between mean summer and mean winter soil temperature is more than 6 oC either at a depth of 50 cm from the soil surface.  SOIL MOISTURE REGIMES The soil moisture regime is an expression of the changes in soil water over time. It refers to the presence or absence of either groundwater or of water held at a potential of less or more than -1,500 kPa (-15 bars) by periods of the year.  Three soil water conditions are recognized: a. soil that is water saturated (wet soil), b. soil between saturation and the permanent wilting point (moist soil), and c. soil drier than the wilting point (dry soil). Aquic Moisture Regime Soils with aquic moisture regime are wet. At sometime during the year, the lower soil horizons are saturated. In many instances, the entire soil is saturated part of the year. Water saturation occurs because of the location of the soil in a landscape position that is naturally poorly drained or where an impermeable layer causes saturation. Aquic Moisture Regime Typically, the top of the saturated soil fluctuates during the year, being deeper during the driest part of the year. Artificial drainage is needed to grow plants that require an aerated root zone. Soils with an aquic moisture regime are unsuitable for building sites unless these soils are dewatered with a drainage system. Udic and Perudic Moisture Regimes Udic means humid. Soils with a udic moisture regime are not dry in any part of the moisture control section as long as 90 cumulative days inmost years. Udic moisture regimes are common in soils of humid climates that have well distributed precipitation. Udic and Perudic Moisture Regimes If the regime is characterized by very wet conditions, the regime is perudic. In the perudic regime, precipitation exceeds evapotranspiration every month in most years, water moves through the soil every month unless the soil is frozen, and there are only occasional periods when some stored soil water is used. Ustic Moisture Regime The concept of the ustic moisture regime relates to soils with limited available water for plants, but water is present at a time when conditions are suitable for plant growth. Soils with ustic moisture regime are dry in some part of the moisture control section for as long as 90 cumulative days in most years. Aridic Moisture Regime The driest soils have an aridic moisture regime. The subsoil, or moisture control section, is dry (permanent wilting point or drier) in all parts for more than half the growing season, and is not moist (wetter than the permanent wilting point) in some parts for as long as 90 consecutive days during the growing season in most years. Most soils with an aridic moisture regime are found in arid or desert regions with widely spaced shrubs and cacti as the native vegetation. Xeric Moisture Regime Soils in areas where winters are cool and moist and summers are hot and dry have a xeric soil moisture regime. This kind of climate is known as a Mediterranean climate. The precipitation occurs in the cool months when the evapotranspiration is low and surplus water may readily accumulate.  There are seven diagnostic epipedons that differ in thickness, color, structure, content of organic matter and phosphorus, mineralogy, and the degree of leaching. DIAGNOSTIC SURFACE HORIZONS Mollic Horizon The word mollic is derived from mollify, which means to soften. The mollic horizon is a surface horizon that is soft rather than hard and massive when dry. The major grassland soils of the world have mollic epipedons. Umbric and Ochric Horizons Umbric horizons form in some very humid forests. In most forests, the epipedon is thinner than is that of the umbric, is lower in organic matter, and is lighter in color. This epipedon is called ochric. Histic Horizon Where soil development occurs under conditions of extreme wetness, as in swamps or lakes, the epipedon is organic in nature and is, typically, a histic epipedon. Melanic Horizon Melanic epipedons are thick, black colored, and contain high concentrations of organic matter. The moist Munsell value and chroma are 2 or less, and the organic carbon content is 6 percent or more but less than 25 percent. Anthropic and Plaggen Horizons The anthropic and plaggen horizons are formed by human activity. The anthropic epipedon resembles the mollic horizon in color, structure, and organic matter content; however, the phosphorus content is 250 or more ppm of P2O5 equivalent soluble in 1 percent citric acid solution. Cambic Horizon The cambic horizon can form quickly, relatively speaking, because changes in the color and structure, and some leaching will convert the subsoil parent material into a cambic horizon. Cambic horizons are not illuvial horizons and, generally, they are not extremely weathered. A cambic horizon is a Bw horizon. A parent material with a texture of fine sand (or even finer) is required for the development of cambic horizons. Albic Horizon The loss by eluviation of sesquioxides and clay, during the formation of spodic and argillic horizons, tends to leave behind a light-colored overlying eluvial horizon called the albic horizon. Albic is derived from the word white. Oxic Horizon The oxic horizon (Bo horizon) is a subsurface horizon at least 30 centimeters thick that is in an advanced stage of weathering. Oxic is derived from the word oxide. Oxic horizons consist of a mixture of iron and/or aluminum oxides with variable amounts of kaolinite and highly insoluble accessory minerals such as quartz sand. Oxic Horizon Soils with oxic horizons have essentially reached the end point of weathering. Soil Taxonomy Soils are divided into six distinct categories based on diagnostic characteristics CATEGORIES OF SOIL TAXONOMY Soil order Sub-order Great group Sub-group Family Series  Soil Taxonomy 1. Orders – presence or absence of diagnostic horizons 2. Suborders – subdivide soil order based on moisture and temperature regime 3. Great Groups – subdivide suborder based on differences between soil horizons  Soil Taxonomy 4. Subgroups – typic (central concept of the great group); intergrades or transitional forms to other orders, suborders, or great groups; extragrades or additional properties not common to great group characteristics 5. Family –particle size, mineralogy, temperature regime, etc. 6. Series – parent material; kind, number and arrangement of horizons in the profile  12 Soil Orders Entisol Ultisols Inceptisol Oxisols Andisols Aridisols Spodosols Vertisols Mollisols Histosols Alfisols Gelisols Derivation and connotation of soil orders (Soil Survey Staff, 1975) ORDER CONNOTATION ent  Entisol - ent ❑Recent soils - minimal development, little ❑ Characteristically have A/C or horizonation, young A/R profiles, exhibit only soils. ephemeral soil development - largely confined to surface horizon. May have an Ap horizon. A R Derivation and connotation of soil orders (Soil Survey Staff, 1975) ORDER CONNOTATION ept  Inceptisol - ept ❑Inception - soil shows the beginning of horizon development, little or no illuviation, Derivation and connotation of soil orders (Soil Survey Staff, 1975) Derivation and connotation of soil order (Soil Survey Staff, 1975) ORDER CONNOTATION id  Aridisols - id ❑NaCl Salt ❑Arid regions of the world accumulates on (19%), < 10 in of rainfall, the surface and usually contain carbonates, in the subsurface. A Az Bw Bz Bk C1 C C2 Derivation and connotation of soil orders (Soil Survey Staff, 1975) ORDER CONNOTATION oll  Mollisols - oll ❑soils with thick, dark, soft surface ❑mollic + cambic, natric, argillic or none ❑high base saturation ❑soils of the grassland Derivation and connotation of soil orders (Soil Survey Staff, 1975) ORDER CONNOTATION od  Spodosols- od ❑acid sandy soils with thick E and red Bhs -ochric and spodic Derivation and connotation of soil orders (Soil Survey Staff, 1975) ORDER CONNOTATION alf  Alfisol -- alf ❑fertile forested soils with ochric and argillic - high base saturation ❑(> 35%) -forested soils Derivation and connotation of soil orders (Soil Survey Staff, 1975) ORDER CONNOTATION ult  Ultisols - ult A E ❑soils more weathered than Alfisols - ochric Bt1 and argillic - low base saturation < 35% - Bt2 redder and more acid than Alfisols BC Derivation and connotation of soil orders (Soil Survey Staff, 1975) ORDER CONNOTATION ox Oxisols - ox ❑Soils with Oxic horizon - highly weathered soils of the tropics. ❑low pH (acid soils); high in 1:1 clay minerals Derivation and connotation of soil orders (Soil Survey Staff, 1975) ORDER CONNOTATION ert hist Vertisol - ert ❑Inverted - soils with high clay content, large shrink swell potential - gradually invert on themselves, Histosols - ist ❑peat soils - organic material - histic ❑Peat – undecomposed to slightly decomposed o.m. in waterlogged areas ❑Muck – highly decomposed o.m. Derivation and connotation of soil orders (Soil Survey Staff, 1975) ORDER CONNOTATION and  Andisols - and ❑soils from volcanic volcanic ejecta (ash, cinder, pumice, basalt) : very light, low bulk A density ❑early-stage secondary Bw minerals (allophane, imogolite, ferrihydrite 2BC clays), ❑High P fixing capacity 2C Derivation and connotation of soil orders (Soil Survey Staff, 1975) ORDER CONNOTATION el Permafrost, often with Gelisol cryoturbation ( frost churning) Gelisol - el ❑New Order as of 1998 - soils with permafrost (formerly Cryochrepts - or frozen Inceptisols) ❑ Soils formed in cool climate (pergelic temperature regime) · Any parent material · Often: Glacial drift  An example naming a soil according to soil taxonomy: Name Category ULTISOL ORDER UDULT SUB-ORDER TROPUDULT GREAT GROUP TYPIC TROPUDULT SUB-GROUP TYPIC TROPUDULT, Clayey, Kaolinitic Isohyperthermic FAMILY ADTUYON CLAY SERIES Soil survey Soil Survey - Inventory of the Soil Resource 3 Main Elements: 1) a map showing the geographic relationships of each soil 2) a text describing the soils 3) tables giving physical and chemical data and interpretations for various uses. Practical purposes of soil survey include: 1. Rural land classification for rain fed and irrigated crops production. 2. Land appraisal. 3. Selection of new lands for settlement. 4. Land – use planning at local, regional and national level. Practical purposes of soil survey include: 5. Assessment of potentialities airports, highways, urban and industrial. 6. Forest management. 7. Designing and constructing airports, highways, urban and industrial structure, waste disposal facilities and recreational development. Soil Survey ❑ A soil survey describes the characteristics of the soils in a given area, Usually a Province is the unit of publication. ❑ Classifies the soils according to a standard system of classification, ❑ Plots the boundaries of the soils on a map, the map uses an aerial photo as the base ❑ Makes predictions about the behavior of soils, Map Scale ❑ Soil maps differ in their scale: ❑ Map scale refers to how many inches on the map represents inches on the ground – ❑ Scale of 1:24,000 says 1 inch on map = 24,000 inch on the ground. Orders of Soil Survey ❑ Order 1 = very detailed ❑ Order 2 = semi-detailed ❑ Order 3 = reconnaissance survey ❑ Order 4 = general soil map ❑ Order 5 = regional map  Orders of Soil Survey 1. First order: very intensive (detailed); experimental plots, building sites; minimum size delineation < 1 hectare 2. Second order: intensive (detailed); general agriculture, urban planning; minimum size delineation 0.6 to 4 ha. 3. Third order: extensive; rangeland, community area planning; min. size delineation – 1.6 to 16 ha.  Orders of Soil Survey 4. Fourth order: extensive (reconnaissance); for broad land use potential and general land management; min. size delineation – 16 to 252 ha. 5. Fifth order: exploratory; regional planning, national planning; min. size delineation – 252 to 4000 has Camansa Sandy Clay Loam pH - strongly acid NPK - low CEC - very high BS - medium Source of PM - shales and sandstones with water-worn gravel and sand Effective Soil Depth – shallow Soil Color - yellowish brown, light brown to brown Dominant Relief - hilly to mountainous Surface Drainage - well-drained Sub-surface Drainage - somewhat well-drained Flooding Hazard - none Camansa Tugbok Clay Land Characteristics : pH - strongly acid NPK - medium CEC - high BS - medium Source of PM - igneous rocks, predo- minantly andesite Effective Soil Depth - deep Soil Color - brown to weak reddish brown Dominant Relief - undulating to gently rolling Surface Drainage - well-drained Subsurface Drainage – well-drained Flooding hazard - none Tugbok LAND EVALUATION FOR DEVELOPMENT Land Is an area of the earth surface, the characteristics of which embrace all reasonably stable or predictably cyclic attributes of the biosphere vertically above and below this area including those of the atmosphere, the soil, and the underlying geology, the hydrology, the plant and animal populations, and the results of past and present human activities to the extent that these attributes exert a significant influence on present and future uses of the land by man (FAO, 1976). Land evaluation is the process of assessment of land performance when used for specified purposes. It involves the execution and interpretation of basic surveys of climate, soils, vegetation and other aspects of land in terms of the requirements of alternative forms of land use (FAO, 1976). Land evaluation is developed from soil survey interpretation and land classification. Land evaluation is only part of the process of land use planning. Land capability is viewed by some as the inherent capacity of land to perform at a given level for a general use, and land suitability as a statement of the adaptability of a given area for a specific kind of land use. Others see capability as a classification of land primarily in relation to degradation hazards, while some regard the terms suitability and capability as interchangeable.  Land capability classes Class I Class I land can be used to continuously for intensive crop production with good farming practices. Class II Class II land has more limitations than Class I land for intensive crop production, as to such characteristics as moderately steep slopes (2-5 %).  Land capability classes Class III Class III land has severe limitations and requires more special conservation practices than Class II land to keep it continuously productive. For example, the land may have shallow soil, slopes of about 6-10 %, or shallow water tables.  Land capability classes Class IV Class IV land has severe limitation for cropping use and needs a greater intensity of conservation practices for cultivated crops than Class III land. Most of the time this land should be in permanent crops such as pastures.  Land capability classes Class V Class V land is not likely to erode but has other limitations, such as boulders or wetness, which are impractical to correct, and thus the land cannot be cultivated. It should be used for pasture, range, woodland, or wildlife habitat.  Land capability classes Class VI Class VI is suitable for the same uses as Class V land, but it has a greater need for good management to maintain production because of such limitations as steep slopes of shallow soils. Class VII Class VII land has very severe limitations and requires extreme care to protect that soil, even with low intensity use for grazing, wildlife, or timber.  Land capability classes Class VIII Class VIII land has such severe limitations (steep slopes, rock lands, swamps, delicate plant cover) that it can be wisely used only for wildlife, recreation, watersheds, or aesthetic appreciation. Land suitability is the fitness of a given type of land for a defined use (FAO, 1976). It can also be stated at the applicability of a given type of land for a specified kind of land use. Land suitability classification is the appraisal and grouping of specific areas of land in terms of their suitability for defined uses. Land characteristic is an attribute of land that can be measured or estimated in a routine survey in any operational sense, including by remote sensing, census and natural resource survey. Land quality is a complex attribute of land that acts in a manner distinct from the actions of other land qualities in its influence on the suitability of land for a specified kind of use. Land quality refers to the ability of the land to fulfil specific requirements for a land utilization type.  Function, aims, and purposes of land evaluation The function of land evaluation (or land use planning) is to guide decisions on land use in such a way that the resources of the environment are put to the most beneficial use for man, while at the same time conserving those resources for the future. Land evaluation may be concerned with present land performance. Frequently however, it involves change and its effects; with change in the use of land and in some cases change in land itself.  Function, aims, and purposes of land evaluation Land evaluation takes into consideration the economics of the proposed enterprises, the social consequences for the people of the area and the country concerned, and the consequences, beneficial or adverse, for the environment. To be effective in this role, the output from an evaluation gives information on two or more potential forms of use for each area of land including the consequences, beneficial and adverse, of each. Land use Land use is the human use of land. Land use involves the management such as fields, pastures, and settlements. It has also been defined as ‘the arrangements, activities, and inputs people undertake in a certain land cover type to produce, change or maintain it’ (FAO, 1997). Land use planning Land use planning is the term used for a branch of public policy encompassing various disciplines which seek to order and regulate land use in an efficient and ethical way, thus preventing land use conflict.