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Pedotransfer Function
In soil science, pedotransfer functions (PTF) are predictive functions of certain soil properties using data from soil surveys. The term ''pedotransfer function'' was coined by Johan Bouma as ''translating data we have into what we need''. The most readily available data comes from a soil survey, such as the field morphology, soil texture, structure and pH. Pedotransfer functions add value to this basic information by translating them into estimates of other more laborious and expensively determined soil properties. These functions fill the gap between the available soil data and the properties which are more useful or required for a particular model or quality assessment. Pedotransfer functions utilize various regression analysis and data mining techniques to extract rules associating basic soil properties with more difficult to measure properties. Although not formally recognized and named until 1989, the concept of the pedotransfer function has long been applied to estimate soi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Soil Science
Soil science is the study of soil as a natural resource on the surface of the Earth including soil formation, classification and mapping; physical, chemical, biological, and fertility properties of soils; and these properties in relation to the use and management of soils.Jackson, J. A. (1997). Glossary of Geology (4. ed.). Alexandria, Virginia: American Geological Institute. p 604. Sometimes terms which refer to branches of soil science, such as pedology (formation, chemistry, morphology, and classification of soil) and edaphology (how soils interact with living things, especially plants), are used as if synonymous with soil science. The diversity of names associated with this discipline is related to the various associations concerned. Indeed, engineers, agronomists, chemists, geologists, physical geographers, ecologists, biologists, microbiologists, silviculturists, sanitarians, archaeologists, and specialists in regional planning, all contribute to further knowledge ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Field Capacity
Field capacity is the amount of soil moisture or water content held in the soil after excess water has drained away and the rate of downward movement has decreased. This usually takes place 2–3 days after rain or irrigation in pervious soils of uniform structure and texture. The physical definition of field capacity (expressed symbolically as θfc) is the bulk water content retained in soil at −33 kPa (or −0.33 bar) of hydraulic head or suction pressure. The term originated from Israelsen and West and Frank Veihmeyer and Arthur Hendrickson. Veihmeyer and Hendrickson realized the limitation in this measurement and commented that it is ''affected by so many factors that, precisely, it is not a constant'' (for a particular soil), ''yet it does serve as a practical measure of soil water-holding capacity''. Field capacity improves on the concept of moisture equivalent by Lyman Briggs. Veihmeyer & Hendrickson proposed this concept as an attempt to improve water-use efficiency for ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Soil Functions
Soil functions are general capabilities of soils that are important for various agricultural, environmental, nature protection, landscape architecture and urban applications. Soil can perform many functions and these include functions related to the natural ecosystems, agricultural productivity, environmental quality, source of raw material, and as base for buildings. Six key soil functions are: #Food and other biomass production #Environmental Interaction #Biological habitat and gene pool #Source of raw materials #Physical and cultural heritage #Platform for man-made structures Food and other biomass production Soil acts as an anchor for plant roots. It provides a hospitable place for a plant to live in while storing and supplying nutrients to plants. Soil also functions by maintaining the quantity and quality of air by allowing to escape and fresh to enter the root zone. Pore spaces within soil can also absorb water and hold it until plant roots need it. The soil also moderat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nonlimiting Water Range
The non-limiting water range (NLWR) represents the range of water content in the soil where limitations to plant growth (such as water potential, air-filled porosity, or soil strength) are minimal. John Letey (1985) from UC Riverside introduced the NLWR concept in an attempt to integrate several physical properties associated with plant or root growth to refine the concept of available water capacity. Alvaro Pires da Silva, Bev Kay. and Ed Perfect (University of Guelph, Ontario) (1994) refined the concept and termed it ''least limiting water range'' (LLWR). The upper limit (wet end) of LLWR is determined not only at water content at field capacity (FC), but also the capability of providing adequate aeration for plant roots (usually taken as a minimum air filled porosity of 10%). The upper limit is then defined as: min q . Rather than air-filled porosity at 10%, LaoSheng Wu from UC Riverside proposed moisture content where Oxygen gas diffusion rate ODR value of 0.2 micro-g/cm2/mi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Moisture Equivalent
Moisture equivalent is proposed by Lyman Briggs and McLane (1910) as a measure of field capacity for fine-textured soil materials. Moisture equivalent is defined as ''the percentage of water which a soil can retain in opposition to a centrifugal force 1000 times that of gravity''. It is measured by saturating sample of soil 1 cm thick, and subjecting it to a centrifugal force of 1000 times gravity for 30 min. The gravimetric water content after this treatment is its moisture equivalent. This concept is no longer used in soil physics, replaced by field capacity. Lyman Briggs and Homer LeRoy Shantz (1912) found that: Moisture Equivalent = 0.02 sand + 0.22 silt + 1.05 clay Note: volume of water stored in root zone is equal to the depth of water in root zone (Vw=Dw) See also * Available water capacity * Field capacity * Nonlimiting water range * Pedotransfer function In soil science, pedotransfer functions (PTF) are predictive functions of certain soil properties using data ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Soil Inference System
Inference is a process of deriving logical conclusion from the basis of empirical evidence and prior knowledge rather than on the basis of direct observation. Soil inference system (SINFERS) is the term proposed by McBratney et al. (2002) as a knowledge base to infer soil properties and populate the digital soil databases. SINFERS takes measurements with a given level of certainty and infers data that is not known with minimal uncertainties by means of logically linked predictive functions. These predictive functions, in a non-spatial context are referred to as pedotransfer functions. The basic assumption underlying SINFERS is that if one knows or is able to predict the basic fundamental properties of a soil, one should be able to infer all other physical and chemical properties using PTFs. Pedotransfer functions relate basic soil properties to other more difficult or expensive to measure soil properties by means of regression and various data mining tools. Crucial to the operation ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Artificial Neural Network
Artificial neural networks (ANNs), usually simply called neural networks (NNs) or neural nets, are computing systems inspired by the biological neural networks that constitute animal brains. An ANN is based on a collection of connected units or nodes called artificial neurons, which loosely model the neurons in a biological brain. Each connection, like the synapses in a biological brain, can transmit a signal to other neurons. An artificial neuron receives signals then processes them and can signal neurons connected to it. The "signal" at a connection is a real number, and the output of each neuron is computed by some non-linear function of the sum of its inputs. The connections are called ''edges''. Neurons and edges typically have a ''weight'' that adjusts as learning proceeds. The weight increases or decreases the strength of the signal at a connection. Neurons may have a threshold such that a signal is sent only if the aggregate signal crosses that threshold. Typically ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
United States Department Of Agriculture
The United States Department of Agriculture (USDA) is the United States federal executive departments, federal executive department responsible for developing and executing federal laws related to farming, forestry, rural economic development, and food. It aims to meet the needs of commercial farming and livestock food production, promotes agricultural trade and production, works to assure food safety, protects natural resources, fosters rural communities and works to end hunger in the United States and internationally. It is headed by the United States Secretary of Agriculture, Secretary of Agriculture, who reports directly to the President of the United States and is a member of the president's Cabinet of the United States, Cabinet. The current secretary is Tom Vilsack, who has served since February 24, 2021. Approximately 80% of the USDA's $141 billion budget goes to the Food and Nutrition Service (FNS) program. The largest component of the FNS budget is the Supplementa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Soil Texture Classification
Soil texture is a classification instrument used both in the field and laboratory to determine soil classes based on their physical texture. Soil texture can be determined using qualitative methods such as texture by feel, and quantitative methods such as the hydrometer method based on Stokes' law. Soil texture has agricultural applications such as determining crop suitability and to predict the response of the soil to environmental and management conditions such as drought or calcium (lime) requirements. Soil texture focuses on the particles that are less than two millimeters in diameter which include sand, silt, and clay. The USDA soil taxonomy and WRB soil classification systems use 12 textural classes whereas the UK-ADAS system uses 11.''Soil Science Division Staff. 2017. Soil survey sand. C. Ditzler, K. Scheffe, and H.C. Monger (eds.). USDA Handbook 18. Government Printing Office, Washington, D.C.'' These classifications are based on the percentages of sand, silt, and cla ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Soil Organic Matter
Soil organic matter (SOM) is the organic matter component of soil, consisting of plant and animal detritus at various stages of decomposition, cells and tissues of soil microbes, and substances that soil microbes synthesize. SOM provides numerous benefits to the physical and chemical properties of soil and its capacity to provide regulatory ecosystem services. SOM is especially critical for soil functions and quality. The benefits of SOM result from a number of complex, interactive, edaphic factors; a non-exhaustive list of these benefits to soil function includes improvement of soil structure, aggregation, water retention, soil biodiversity, absorption and retention of pollutants, buffering capacity, and the cycling and storage of plant nutrients. SOM increases soil fertility by providing cation exchange sites and being a reserve of plant nutrients, especially nitrogen (N), phosphorus (P), and sulfur (S), along with micronutrients, which the mineralization of SOM slowly release ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Available Water Capacity
Available water capacity is the amount of water that can be stored in a soil profile and be available for growing crops. It is also known as available water content (AWC), profile available water (PAW) or total available water (TAW). The concept, put forward by Frank Veihmeyer and Arthur Hendrickson, assumed that the water readily available to plants is the difference between the soil water content at field capacity () and permanent wilting point (): :θa ≡ θfc − θpwp Daniel Hillel criticised that the terms FC and PWP were never clearly defined, and lack physical basis, and that soil water is never equally available within this range. He further suggested that a useful concept should concurrently consider the properties of plant, soil and meteorological conditions. Lorenzo A. Richards remarked that the concept of availability is oversimplified. He viewed that: the term availability involves two notions: (a) the ability of plant root to absorb and use the water with which i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bulk Density
Bulk density, also called apparent density or volumetric density, is a property of powders, granules, and other "divided" solids, especially used in reference to mineral components (soil, gravel), chemical substances, (pharmaceutical) ingredients, foodstuff, or any other masses of corpuscular or particulate matter (particles). Bulk density is defined as the mass of the many particles of the material divided by the total volume they occupy. The total volume includes particle volume, inter-particle void volume, and internal pore volume. Bulk density is not an intrinsic property of a material; it can change depending on how the material is handled. For example, a powder poured into a cylinder will have a particular bulk density; if the cylinder is disturbed, the powder particles will move and usually settle closer together, resulting in a higher bulk density. For this reason, the bulk density of powders is usually reported both as "freely settled" (or "poured" density) and "tappe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
