Crop yield

In agriculture, crop yield (also known as "agricultural output") refers to both the measure of the yield of a crop per unit area of land cultivation, and the seed generation of the plant itself (e.g. if three grains are harvested for each grain seeded, the resulting yield is 1:3). That figure, 1:3, is considered by agronomists as the minimum required to sustain human life.[1]

One of the three seeds must be set aside for the next planting season, the remaining two either consumed by the grower, or one for human consumption and the other for livestock feed. The higher the surplus, the more livestock can be established and maintained, thereby increasing the physical and economic well-being of the farmer and his family. This, in turn, resulted in better stamina, better over-all health, and better, more efficient work. In addition, the more the surplus the more draft animals—horse and oxen—could be supported and harnessed to work, and manure, the soil thereby easing the farmer's burden. Increased crop yields meant few hands were needed on farm, freeing them for industry and commerce. This, in turn, led to the formation and growth of cities.

Formation and growth of cities meant an increased demand for food stuffs by non-farmers, and their willingness to pay for it. This, in turn, led the farmer to (further) innovation, more intensive farming, the demand/creation of new and/or improved farming implements, and a quest for improved seed which improved crop yield. Thus allowing the farmer to raise his income by bringing more food to non-farming (city) markets.

Measurement

The unit by which the yield of a crop is measured is kilograms per hectare or bushels per acre.

History

Historically speaking, a major increase in crop yield took place in the early eighteenth century with the end of the ancient, wasteful cycle of the three-course system of crop rotation whereby a third of the land lay fallow every year and hence taken out of human food, and animal feed, production.

It was to be replaced by the four-course system of crop rotation, devised in England in 1730 by Charles Townshend, 2nd Viscount Townshend or "Turnip" Townshend during the British Agricultural Revolution,[2] as he was called by early detractors.

In the first year, wheat or oats were planted; in the second year, barley or oats; in the third year, clover, rye, rutabaga and/or kale were planted; in the fourth year, turnips were planted but not harvested. Instead, sheep were driven on to the turnip fields to eat the crop, trample the leavings under their feet into the soil, and by doing all this, fertilize the land with their droppings. In the fifth year (or first year of the new rotation), the cycle began once more with a planting of wheat or oats, resulting, on average, a thirty percent increased yield.

See also

Notes

  1. ^ Pipes, Richard, Russia under the Old Regime (Charles Scribner's Sons, NY 1974) p.8
  2. ^ Durant, Will, The History of Civilization: Vol. IX The Age of Voltaire p.47
Agricultural economics

Agricultural economics is an applied field of economics concerned with the application of economic theory in optimizing the production and distribution of food and fiber. Agricultural economics began as a branch of economics that specifically dealt with land usage, it focused on maximizing the crop yield while maintaining a good soil ecosystem. Throughout the 20th century the discipline expanded and the current scope of the discipline is much broader. Agricultural economics today includes a variety of applied areas, having considerable overlap with conventional economics. Agricultural economists have made substantial contributions to research in economics, econometrics, development economics, and environmental economics. Agricultural economics influences food policy, agricultural policy, and environmental policy.

Crop insurance

Crop insurance is purchased by agricultural producers, and subsidized by the federal government, to protect against either the loss of their crops due to natural disasters, such as hail, drought, and floods, or the loss of revenue due to declines in the prices of agricultural commodities. The two general categories of crop insurance are called crop-yield

insurance and crop-revenue insurance. On average, the federal government subsidizes 62 percent of the premium. In 2014, crop insurance policies covered 294 million acres. Major crops are insurable in most counties where they are grown, and approximately 83% of U.S. crop acreage is insured under the federal crop insurance program. Four crops—corn, cotton, soybeans, and wheat— typically account for more than 70% of total enrolled acres. For these major crops, a large share of plantings is covered by crop insurance. In 2014, the portion of total corn acreage covered by federal crop insurance was 87%; cotton, 96%; soybeans, 88%; and wheat, 84%.

Grapevine leafroll-associated virus

Grapevine leafroll-associated virus (GLRaV) is a name for a group of viruses infecting grapevine in the genus Closterovirus.Obscure mealybugs (Pseudococcus viburni) feed on the phloem of vines and woody-stemmed plants, especially pear and apple trees and grape vines. Some individuals are vectors for infectious pathogens and can transmit them from plant to plant while feeding; mealybug-spread grapevine leafroll associated virus type III (GRLaV-3), in particular, has wreaked havoc among the grapes of New Zealand, reducing the crop yield of infected vineyards by up to 60%.Leafroll viruses are associated with rugose wood condition of grapevine.

High-yielding variety

High-yielding varieties (HYVs) of agricultural crops are usually characterized by a combination of the following traits in contrast to the conventional varieties:

higher crop yield per area (hectare)

dwarfness

improved response to fertilizers

high reliance on irrigation and fertilizers - see intensive farming

early maturationMost important HYVs can be found among wheat, corn, soybean, rice, potato, and cotton.

HYVs become popular in the 1960s and play an important role in the green revolution, although their ancestral roots can be older.

Hybrid seed

In agriculture and gardening, hybrid seed is used produced by cross-pollinated plants. Hybrid seed production is predominant in modern agriculture and home gardening. It is one of the main contributors to the dramatic rise in agricultural output during the last half of the 20th century. The alternatives to hybridization are open pollination and clonal propagation.All of the hybrid seeds planted by the farmer will produce similar plants, while the seeds of the next generation from those hybrids will not consistently have the desired characteristics. Controlled hybrids provide very uniform characteristics because they are produced by crossing two inbred strains. Elite inbred strains are used that express well-documented and consistent phenotypes (such as high crop yield) that are relatively good for inbred plants.Hybrids are chosen to improve the characteristics of the resulting plants, such as better yield, greater uniformity, improved color, disease resistance.

An important factor is the heterosis or combining ability of the parent plants. Crossing any particular pair of inbred strains may or may not result in superior offspring. The parent strains used are therefore carefully chosen so as to achieve the uniformity that comes from the uniformity of the parents, and the superior performance that comes from heterosis.

Lists of cultivars

The lists of cultivars in the table below are indexes of plant cultivars, varieties, and strains. A cultivar is a plant that is selected for desirable characteristics that can be maintained by propagation.

The plants listed may be ornamental, medicinal, and/or edible. Several of them bear edible fruit. Plants are selectively bred for phenotypic traits (such as flower colour) and other hereditary traits. When developing a new variety, a plant breeder might value such characteristics as appearance, disease resistance, and hardiness. In the cultivation of edible fruit and vegetables, nutritional value, shelf life, and crop yield are also among the potential considerations.

Some of the lists use the word variety instead of cultivar. In most of these lists, variety refers to a cultivar that is recognised by the International Union for the Protection of New Varieties of Plants (UPOV). A cultivar must meet certain criteria in order to be recognised by UPOV as a named variety.

In a few lists, variety means something else: a taxonomic rank below that of species (a kind of subspecies). If the species' binomial name is followed by the word var. and another name, that is a botanical variety, not a cultivar.

Management science

Management science (MS) is the broad interdisciplinary study of problem solving and decision making in human organizations, with strong links to management, economics, business, engineering, management consulting, and other sciences. It uses various scientific research-based principles, strategies, and analytical methods including mathematical modeling, statistics and numerical algorithms to improve an organization's ability to enact rational and accurate management decisions by arriving at optimal or near optimal solutions to complex decision problems. Management sciences help businesses to achieve goals using various scientific methods.

The field was initially an outgrowth of applied mathematics, where early challenges were problems relating to the optimization of systems which could be modeled linearly, i.e., determining the optima (maximum value of profit, assembly line performance, crop yield, bandwidth, etc. or minimum of loss, risk, costs, etc.) of some objective function. Today, management science encompasses any organizational activity for which the problem can be structured as a functional system so as to obtain a solution set with identifiable characteristics.

Midge

Midges are a group of insects that include many kinds of small flies. They are found (seasonally or otherwise) on practically every land area outside permanently arid deserts and the frigid zones. The term "midge" does not define any particular taxonomic group, but includes species in several families of Nematoceran Diptera. Some midges, such as many Phlebotominae (sand fly) and Simuliidae (black fly), are vectors of various diseases. Many others play useful roles as prey items for insectivores, such as various frogs and swallows. Others are important as detritivores, participating in various nutrient cycles. The habits of midges vary greatly from species to species, though within any particular family, midges commonly have similar ecological roles.

One type of midge ceratopogonid midges (a type of fly in the family Dipteran) is a major pollinator of Theobroma cacao (cocoa tree) because of its unique morphological and behavioral characteristics. Having natural pollinators has beneficial effects in both agricultural and biological production because it increases Theobroma cacao crop yield and also density of predators of the midges (still beneficial to all parties).Examples of families that include species of midges include:

Blephariceridae, net-winged midges

Cecidomyiidae, gall midges

Ceratopogonidae, biting midges (also known as no-see-ums or punkies in North America, and sandflies in Australia)

Chaoboridae, phantom midges

Chironomidae, non-biting midges (also known as muckleheads or muffleheads in the Great Lakes region of North America)

Deuterophlebiidae, mountain midges

Dixidae, meniscus midges

Scatopsidae, dung midges

Theumaleidae, solitary midges

Peonidin

Peonidin is an O-methylated anthocyanidin derived from Cyanidin, and a primary plant pigment. Peonidin gives purplish-red hues to flowers such as the peony, from which it takes its name, and roses. It is also present in some blue flowers, such as the morning glory.

Like most anthocyanidins, it is pH sensitive, and changes from red to blue as pH rises because anthocyanidins are highly conjugated chromophores. When the pH is changed, the extent of the conjugation (of the double bonds) is altered, which alters the wavelength of light energy absorbed by the molecule. (Natural anthocyanidins are most stable in a very low pH environment; at pH 8.0, most become colorless.) At pH 2.0, peonidin is cherry red; at 3.0 a strong yellowish pink; at 5.0 it is grape red-purple; and at 8.0 it becomes deep blue; unlike many anthocyanidins, however, it is stable at higher pH, and has been isolated as a blue colorant from the brilliant "Heavenly Blue" morning glory (Ipomoea tricolor Cav cv).

Because of its unusual color stability, a cafeyl-acylated buffered formulation of it has been patented for use as food coloring.

Peonidin, like many anthocyanidins, has shown potent inhibitory and apoptotic effects on cancer cells in vitro, notably metastatic human breast cancer cells.

A very large question, however, has been raised about anthocyanidins' penetration and retention in human cells in vivo, due to their rapid elimination from the human body.

By far the greatest dietary source of peonidin is raw cranberries, which contain 42 mg per 100 g of fruit. Blueberries, plums, grapes, and cherries also contain significant amounts, ranging from 5 to 12 mg/100 g. Only fresh fruit has been shown to contain significant peonidin; frozen blueberries have been shown to contain almost none. Peonidin has been found in concentrations of up to 40 mg per 100 g (cooked) of certain cultivars of purple fleshed sweet potatoes; the amount of peonidin varies greatly across cultivars. It has also been isolated from raw black rice and black bananas.

The higher level of peonidin in fresh fruit corresponds to the rule of thumb that more natural fruit is healthier. Specifically, the amount of phenolic compounds in cranberries has been found to be inversely correlated with fruit size and crop yield.

Planet Labs

Planet Labs, Inc. (formerly Cosmogia, Inc.) is an American private Earth imaging company based in San Francisco, CA. The company designs and manufactures Triple-CubeSat miniature satellites called Doves that are then delivered into orbit as secondary payloads on other rocket launch missions. Each Dove is equipped with a high-powered telescope and camera programmed to capture different swaths of Earth. Each Dove Earth observation satellite continuously scans Earth, sending data once it passes over a ground station. Together, Doves form a satellite constellation that provides a complete image of Earth once per day at 3–5 m optical resolution.The images gathered by Doves, which can be accessed online and some of which is available under an open data access policy, provide up-to-date information relevant to climate monitoring, crop yield prediction, urban planning, and disaster response. With acquisition of BlackBridge in July 2015, Planet Labs had 87 Dove and 5 RapidEye satellites launched into orbit. In 2017, Planet launched an additional 88 Dove satellites, and Google sold its subsidiary Terra Bella and its SkySat satellite constellation to Planet Labs. The combined batches of Doves form the largest constellation ever put into orbit. By September 2018 the company had launched nearly 300 satellites, 150 of which are active.

Polyculture

Polyculture is a form of agriculture in which more than one species is grown at the same time and place in imitation of the diversity of natural ecosystems. Polyculture is the opposite of monoculture, in which only members of one plant or animal species are cultivated together. Polyculture has traditionally been the most prevalent form of agriculture in most parts of the world and is growing in popularity today due to its environmental and health benefits. There are many types of polyculture including annual polycultures such as intercropping and cover cropping, permaculture, and integrated aquaculture. Polyculture is advantageous because of its ability to control pests, weeds, and disease without major chemical inputs. As such, polyculture is considered a sustainable form of agriculture. However, issues with crop yield and biological competition have caused many modern major industrial food producers to continue to rely on monoculture instead.

Robusta coffee

Robusta coffee is coffee made from the Coffea canephora plant, a sturdy species of coffee bean with low acidity and high bitterness. C. canephora beans, widely known by the synonym Coffea robusta, are used primarily in instant coffee, espresso, and as a filler in ground coffee blends.

Robusta has its origins in central and western sub-Saharan Africa. It is easy to care for, has a greater crop yield, has almost double the amount of caffeine and more antioxidants, and is less susceptible to disease than arabica coffea. It represents approximately 40% of global coffee production, with arabica constituting the balance.

Seed drill

A seed drill is a device that sows the seeds for crops by metering out the individual seeds, positioning them in the soil, and covering them to a certain average depth. This makes sure the seed will be placed evenly.

The seed drill sows the seeds at equal distances and proper depth, ensuring that the seeds get covered with soil and are saved from being eaten by birds and being blown by the wind. This allows plants to get sufficient sunlight, nutrients, and water from the soil. Before the introduction of the seed drill, a common practice was to plant seeds by hand. Besides being wasteful, planting was usually imprecise and led to a poor distribution of seeds, leading to low productivity. The use of a seed drill can improve the ratio of crop yield (seeds harvested per seed planted) by as much as nine times.

Some machines for metering out seeds for planting are called planters. The concepts evolved from ancient Chinese practice and later evolved into mechanisms that pick up seeds from a bin and deposit them down a tube.

Seed drills of earlier centuries included single-tube seed drills in Sumer and multi-tube seed drills in China, and later a seed drill by Jethro Tull that was influential in the growth of farming technology in recent centuries. Even for a century after Tull, hand sowing of grain remained common.

Van Genuchten–Gupta model

The van Genuchten–Gupta model is an inverted S-curve applicable to crop yield and soil salinity relations.

Water table

The water table is the upper surface of the zone of saturation. The zone of saturation is where the pores and fractures of the ground are saturated with water.The water table is the surface where the water pressure head is equal to the atmospheric pressure (where gauge pressure = 0). It may be visualized as the "surface" of the subsurface materials that are saturated with groundwater in a given vicinity.The groundwater may be from precipitation or from groundwater flowing into the aquifer. In areas with sufficient precipitation, water infiltrates through pore spaces in the soil, passing through the unsaturated zone. At increasing depths, water fills in more of the pore spaces in the soils, until a zone of saturation is reached. Below the water table, in the phreatic zone (zone of saturation), layers of permeable rock that yield groundwater are called aquifers. In less permeable soils, such as tight bedrock formations and historic lakebed deposits, the water table may be more difficult to define.

The water table should not be confused with the water level in a deeper well. If a deeper aquifer has a lower permeable unit that confines the upward flow, then the water level in this aquifer may rise to a level that is greater or less than the elevation of the actual water table. The elevation of the water in this deeper well is dependent upon the pressure in the deeper aquifer and is referred to as the potentiometric surface, not the water table.

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).

Yaogan

Yaogan (Chinese: 遥感式卫星; pinyin: yáogǎnshì wèixīng; literally: 'Remote Sensing Type Satellite"; sometimes written YaoGan) refers to a series of Chinese reconnaissance satellites launched in the early 21st century.

Chinese media describe the satellites as intended for "scientific experiments, land survey, crop yield assessment, and disaster monitoring". Western analysts suspect that they are also used for military purposes. Analysts believe that each satellite employs either optical or synthetic aperture radar (SAR) sensors and that the SAR satellites are of the Jian Bing-5 series.The SAR satellite was developed by the Shanghai Academy of Space Flight Technology(SAST). The electro-optical digital imaging satellite was developed by the China Academy of Space Technology (CAST). It is carried into space atop a Chang Zheng (Long March) rocket.Yaogan satellites have been launched from both the Taiyuan Satellite Launch Center in China's northern Shanxi province and the Jiuquan Satellite Launch Center in China's northwestern Gansu province.

Yield (wine)

In viticulture, the yield is a measure of the amount of grapes or wine that is produced per unit surface of vineyard, and is therefore a type of crop yield. Two different types of yield measures are commonly used, mass of grapes per vineyard surface, or volume of wine per vineyard surface.The yield is often seen as a quality factor, with lower yields associated with wines with more concentrated flavours, and the maximum allowed yield is therefore regulated for many wine appellations.

Yield mapping

Yield mapping or yield monitoring is a technique in agriculture of using GPS data to analyze variables such as crop yield and moisture content in a given field. It was developed in the 1990s and uses a combination of GPS technology and physical sensors, such as speedometers, to track crop yields, grain elevator speed, and combine speed.

This data produces a yield map that can be used to compare yield distribution within the field from year to year. This allows farmers to determine areas of the field that, for example, may need to be more heavily irrigated or are not yielding any crop at all. It also allows farmers to show the effects of a change in field-management techniques, to develop nutrient strategies for their fields, and as a record of crop yield to use in securing loans or renters.

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