|
Waterlogging (agriculture)
Waterlogging water is the saturation of soil with water. Soil may be regarded as waterlogged when it is nearly saturated with water much of the time such that its air phase is restricted and anaerobic conditions prevail. In extreme cases of prolonged waterlogging, anaerobiosis occurs, the roots of mesophytes suffer, and the subsurface reducing atmosphere leads to such processes as denitrification, methanogenesis, and the reduction of iron and manganese oxides. All plants, including crops require air (specifically, oxygen) to respire, produce energy and keep their cells alive. In agriculture, waterlogging of the soil typically blocks air from getting in to the roots. With the exception of rice (''Oryza sativa''), most crops like maize and potato, are therefore highly intolerant to waterlogging. Plant cells use a variety of signals such the oxygen concentration, plant hormones like ethylene, energy and sugar status to acclimate to waterlogging-induced oxygen deprivation. In ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Irrigation
Irrigation (also referred to as watering) is the practice of applying controlled amounts of water to land to help grow Crop, crops, Landscape plant, landscape plants, and Lawn, lawns. Irrigation has been a key aspect of agriculture for over 5,000 years and has been developed by many cultures around the world. Irrigation helps to grow crops, maintain landscapes, and revegetation, revegetate disturbed soils in dry areas and during times of below-average rainfall. In addition to these uses, irrigation is also employed to protect crops from frost, suppress weed growth in grain fields, and prevent soil consolidation. It is also used to cool livestock, reduce dust, dispose of sewage, and support mining operations. Drainage, which involves the removal of surface and sub-surface water from a given location, is often studied in conjunction with irrigation. There are several methods of irrigation that differ in how water is supplied to plants. Surface irrigation, also known as gravity irri ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Watertable Control
Watertable control is the practice of controlling the height of the water table by drainage. Its main applications are in agricultural land (to improve the crop yield using agricultural drainage systems) and in cities to manage the extensive underground infrastructure that includes the foundations of large buildings, underground transit systems, and extensive utilities (water supply networks, sewerage, storm drains, and underground electrical grids). Description and definitions Subsurface land drainage aims at controlling the water table of the groundwater in originally waterlogged land at a depth acceptable for the purpose for which the land is used. The depth of the water table with drainage is ''greater'' than without. Purpose In agricultural land drainage, the purpose of water table control is to establish a depth of the water table (Figure 1) that does no longer interfere negatively with the necessary farm operations and crop yields (Figure 2, made with the SegReg mode ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Swamp
A swamp is a forested wetland.Keddy, P.A. 2010. Wetland Ecology: Principles and Conservation (2nd edition). Cambridge University Press, Cambridge, UK. 497 p. Swamps are considered to be transition zones because both land and water play a role in creating this environment. Swamps vary in size and are located all around the world. The water of a swamp may be fresh water, brackish water, or seawater. Freshwater swamps form along large rivers or lakes where they are critically dependent upon rainwater and seasonal flooding to maintain natural water level fluctuations.Hughes, F.M.R. (ed.). 2003. The Flooded Forest: Guidance for policy makers and river managers in Europe on the restoration of floodplain forests. FLOBAR2, Department of Geography, University of Cambridge, Cambridge, UK. 96 p. Saltwater swamps are found along tropical and subtropical coastlines. Some swamps have hammock (ecology), hammocks, or dry-land protrusions, covered by aquatic vegetation, or vegetation that tolerates ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Soil Salinity Control
Soil salinity control relates to controlling the problem of soil salinity and reclaiming salinized agricultural land. The aim of soil salinity control is to prevent soil degradation by salination and reclamation of already salty (saline) soils. Soil reclamation is also called soil improvement, rehabilitation, remediation, recuperation or amelioration. The primary man-made cause of salinization is irrigation. River water or groundwater used in irrigation contains salts, which remain behind in the soil after the water has evaporated. The primary method of controlling soil salinity is to permit 10-20% of the irrigation water to leach the soil, so that it will be drained and discharged through an appropriate drainage system. The salt concentration of the drainage water is normally 5 to 10 times higher than that of the irrigation water, thus salt export matches salt import and it will not accumulate. The soil salinity problem Salty (saline) soils are soils that have a high sal ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polder
A polder () is a low-lying tract of land that forms an artificial hydrological entity, enclosed by embankments known as dikes. The three types of polder are: # Land reclaimed from a body of water, such as a lake or the seabed # Flood plains separated from the sea or river by a dike # Marshes separated from the surrounding water by a dike and subsequently drained; these are also known as ''koogs'', especially in Germany The ground level in drained marshes subsides over time. All polders will eventually be below the surrounding water level some or all of the time. Water enters the low-lying polder through infiltration and water pressure of groundwater, or rainfall, or transport of water by rivers and canals. This usually means that the polder has an excess of water, which is pumped out or drained by opening sluices at low tide. Care must be taken not to set the internal water level too low. Polder land made up of peat (former marshland) will sink in relation to its previous l ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Environmental Impact Of Irrigation
The environmental effects of irrigation relate to the changes in quantity and quality of soil and water as a result of irrigation and the subsequent effects on natural and social conditions in river basins and downstream of an irrigation scheme. The effects stem from the altered hydrological conditions caused by the installation and operation of the irrigation scheme. Amongst some of these problems is depletion of underground aquifers through overdrafting. Soil can be over-irrigated due to poor distribution uniformity or management wastes water, chemicals, and may lead to water pollution. Over-irrigation can cause deep drainage from rising water tables that can lead to problems of irrigation salinity requiring watertable control by some form of subsurface land drainage. However, if the soil is under irrigated, it gives poor soil salinity control which leads to increased soil salinity with the consequent buildup of toxic salts on the soil surface in areas with high evaporation ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Effects Of Weather On Sport
The effects of weather on sport are varied, with some events unable to take place while others are changed considerably. The performance of participants can be reduced or improved, and some sporting world records are invalid if set under certain weather conditions. While outdoor sports are most affected, those played indoors can still be impacted by adverse or advantageous weather conditions. Temperature Temperature has a significant impact on the performance of athletes. High temperature can cause various heat illnesses such as heat cramps and heatstroke, while very low temperatures may lead to hypothermia. Training regimes may include methods of heat acclimatization, and regulations in some sports stipulate the intensity of some schedules. The National Collegiate Athletic Association (NCAA) in North America requires teams to build up the level of training in hot weather. Such preparation intends to improve performance and reduce the potentially fatal risk of heat stroke. High te ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Drainage System (agriculture)
An agricultural drainage system is a system by which water is drained on or in the soil to enhance agricultural production of crops. It may involve any combination of stormwater control, erosion control, and watertable control. Classification While there are more than two types of drainage systems employed in agriculture, there are two main types: (1) surface drainage and (2) sub-surface drainage. Figure 1 classifies the various types of drainage systems. It shows the field (or internal) and the main (or external) systems. The function of the ''field drainage system'' is to control the water table, whereas the function of the ''main drainage system'' is to collect, transport, and dispose of the water through an outfall or outlet. In some instances one makes an additional distinction between collector and main drainage systems. Field drainage systems are differentiated in surface and subsurface field drainage systems. Sometimes (e.g., in irrigated, submerged rice fields), a form ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Drainage Research
Drainage research is the study of agricultural drainage systems and their effects to arrive at optimal system design. Aspects to be covered Agricultural land drainage has agricultural, environmental, hydrological, engineering, economical, social and socio-political aspects (Figure 1). All these aspects can be subject of drainage research. The aim (objective, target) of agricultural land drainage is the optimized agricultural production related to: # reclamation of agricultural land # conservation of agricultural land # optimization of crop yield # crop diversification # cropping intensification # optimization of farm operations. Systems analysis The role of targets, criterion, environmental, and hydrological factors is illustrated in Figure 2. In this figure criterion factors are factors influenced by drainage on the one hand and the agricultural performance on the other. An example of a criterion factor is the depth of the water table: # A drainage system influences this de ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Drainage
Drainage is the natural or artificial removal of a surface's water and sub-surface water from an area with excess of water. The internal drainage of most agricultural soils is good enough to prevent severe waterlogging (anaerobic conditions that harm root growth), but many soils need artificial drainage to improve production or to manage water supplies. History Early history The Indus Valley civilization had sewerage and drainage systems. All houses in the major cities of Harappa and Mohenjo-daro had access to water and drainage facilities. Waste water was directed to covered gravity sewers, which lined the major streets. 18th and 19th century The invention of hollow-pipe drainage is credited to Sir Hugh Dalrymple, who died in 1753. Current practices Geotextiles New storm water drainage systems incorporate geotextile filters that retain and prevent fine grains of soil from passing into and clogging the drain. Geotextiles are synthetic textile fabrics specially ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gardening
Gardening is the practice of growing and cultivating plants as part of horticulture. In gardens, ornamental plants are often grown for their flowers, foliage, or overall appearance; useful plants, such as root vegetables, leaf vegetables, fruits, and herbs, are grown for consumption, for use as dyes, or for medicinal or cosmetic use. Gardening ranges in scale from fruit orchards, to long boulevard plantings with one or more different types of shrubs, trees, and herbaceous plants, to residential back gardens including lawns and foundation plantings, all the way to container gardens grown inside or outside. Gardening may be very specialized, with only one type of plant grown, or involve a variety of plants in mixed plantings. It involves an active participation in the growing of plants, and tends to be labor-intensive, which differentiates it from farming or forestry. History Ancient times Forest gardening, a forest-based food production system, is the world's oldest form ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
