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Arable land is any land capable of being ploughed and used to grow crops. Alternatively, for the purposes of agricultural statistics, the term often has a more precise definition:
Arable land is the land under temporary agricultural crops, temporary meadows for mowing or pasture, land under market and kitchen gardens and land temporarily fallow. The abandoned land resulting from shifting cultivation is not included in this category. Data for 'Arable land' are not meant to indicate the amount of land that is potentially cultivable.
Evaporation is a type of vaporization that occurs on the surface of a liquid as it changes into the gas phase. A high concentration of the evaporating substance in the surrounding gas significantly slows down evaporation, such as when humidity affects rate of evaporation of water. When the molecules of the liquid collide, they transfer energy to each other based on how they collide. When a molecule near the surface absorbs enough energy to overcome the vapor pressure, it will escape and enter the surrounding air as a gas. When evaporation occurs, the energy removed from the vaporized liquid will reduce the temperature of the liquid, resulting in evaporative cooling.
Irrigation is the practice of applying controlled amounts of water to land to help grow crops, landscape plants, and 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 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.
Potash includes various mined and manufactured salts that contain potassium in water-soluble form. The name derives from pot ash, plant ashes or wood ash soaked in water in a pot, the primary means of manufacturing potash before the Industrial Era. The word potassium is derived from potash.
Evapotranspiration (ET) refers to the combined processes which move water from the Earth's surface into the atmosphere. It covers both water evaporation and transpiration. Evapotranspiration is an important part of the local water cycle and climate, and measurement of it plays a key role in agricultural irrigation and water resource management.
Potential evapotranspiration (PET) or potential evaporation (PE) is the amount of water that would be evaporated and transpired by a specific crop, soil or ecosystem if there was sufficient water available. It is a reflection of the energy available to evaporate or transpire water, and of the wind available to transport the water vapor from the ground up into the lower atmosphere and away from the initial location. Potential evapotranspiration is expressed in terms of a depth of water or soil moisture percentage.
No-till farming is an agricultural technique for growing crops or pasture without disturbing the soil through tillage. No-till farming decreases the amount of soil erosion tillage causes in certain soils, especially in sandy and dry soils on sloping terrain. Other possible benefits include an increase in the amount of water that infiltrates into the soil, soil retention of organic matter, and nutrient cycling. These methods may increase the amount and variety of life in and on the soil. While conventional no-tillage systems use herbicides to control weeds, organic systems use a combination of strategies, such as planting cover crops as mulch to suppress weeds.
Drip irrigation or trickle irrigation is a type of micro-irrigation system that has the potential to save water and nutrients by allowing water to drip slowly to the roots of plants, either from above the soil surface or buried below the surface. The goal is to place water directly into the root zone and minimize evaporation. Drip irrigation systems distribute water through a network of valves, pipes, tubing, and emitters. Depending on how well designed, installed, maintained, and operated it is, a drip irrigation system can be more efficient than other types of irrigation systems, such as surface irrigation or sprinkler irrigation.
Soil conservation is the prevention of loss of the topmost layer of the soil from erosion or prevention of reduced fertility caused by over usage, acidification, salinization or other chemical soil contamination.
Soil moisture is the water content of the soil. It can be expressed in terms of volume or weight. Soil moisture measurement can be based on in situ probes or remote sensing methods.
Deep ocean water (DOW) is the name for cold, salty water found in the deep sea, starting at 200 m (660 ft) below the surface of Earth's oceans. Ocean water differs in temperature and salinity. Warm surface water is generally saltier than the cooler deep or polar waters; in polar regions, the upper layers of ocean water are cold and fresh. Deep ocean water makes up about 90% of the volume of the oceans. Deep ocean water has a very uniform temperature, around 0–3 °C (32–37 °F), and a salinity of about 3.5% or, as oceanographers state, 35‰.
Tile drainage is a form of agricultural drainage system that removes excess sub-surface water from fields to allow sufficient air space within the soil, proper cultivation, and access by heavy machinery to tend and harvest crops. While surface water can be drained by pumping, open ditches, or both, tile drainage is often the most effective means of draining subsurface water.
An atmometer or evaporimeter is a scientific instrument used for measuring the rate of water evaporation from a wet surface to the atmosphere. Atmometers are mainly used by farmers and growers to measure evapotranspiration (ET) rates of crops at any field location. Evapotranspiration is a measure of all of the water that evaporates from land surfaces plus the water that transpires from plant surfaces. Based on the amount of water that does evaporate and transpire, the user can water crops correspondingly, which results in less water use and possibly increased crop yields. Companies that currently sell atmometers include C&M Meteorological Supply and Calsense.
Agricultural soil science is a branch of soil science that deals with the study of edaphic conditions as they relate to the production of food and fiber. In this context, it is also a constituent of the field of agronomy and is thus also described as soil agronomy.
Dryland salinity is a natural process for soil, just like other processes such as wind erosion. Salinity degrades land by an increase in soil salt concentration in the environment, watercourse or soil in unirrigated landscapes, being in excess of normal soil salt concentrations in dryland regions.
Soil salinity control refers to controlling the process and progress of soil salinity to prevent soil degradation by salination and reclamation of already salty (saline) soils. Soil reclamation is also known as soil improvement, rehabilitation, remediation, recuperation, or amelioration.
The Penman–Monteith equation approximates net evapotranspiration (ET) from meteorological data, as a replacement for direct measurement of evapotranspiration. The equation is widely used, and was derived by the United Nations Food and Agriculture Organization for modeling reference evapotranspiration ET0.
Transpiration is the process of water movement through a plant and its evaporation from aerial parts, such as leaves, stems and flowers. It is a passive process that requires no energy expense by the plant. Transpiration also cools plants, changes osmotic pressure of cells, and enables mass flow of mineral nutrients. When water uptake by the roots is less than the water lost to the atmosphere by evaporation plants close small pores called stomata to decrease water loss, which slows down nutrient uptake and decreases CO2 absorption from the atmosphere limiting metabolic processes, photosynthesis, and growth.
This page shows statistical data on irrigation of agricultural lands worldwide.
Irrigation is the artificial abstraction of water from a source followed by the distribution of it at scheme level aiming at application at field level to enhance crop production when rainfall is scarce.
Sustainable Water and Innovative Irrigation Management (SWIIM) is a farm-optimization and water-conservation system owned by SWIIM System, Ltd. that was developed by Regenesis Management Group, LLC., a Denver, Colorado-based incubator that focuses on natural resource conservation and optimization technology.
References
This article incorporates public domain material from Jasper Womach. Report for Congress: Agriculture: A Glossary of Terms, Programs, and Laws, 2005 Edition (PDF). Congressional Research Service.
