Vegetal On The World

Experimental Crops

Experimental crops are foodstuffs with the potential to be grown in a sustainable manner, produce large yields, and reduce people’s reliance on the traditional crops wheat, rice, and corn.

Shifting from a hunter-gatherer society to an agrarian society led to increasingly larger-scale agricultural production that involved selecting local crops for domestication. In recent history there has been a reduction in the number of agricultural crops grown for human consumption.

There are estimated to be at least 20,000 species of edible plants on earth, out of more than 350,000 known species of higher plants. However, only a handful of crops feed most of the world’s people.

These include wheat, rice, corn, potatoes, sugar beets, sugarcane, cassava, barley, soybeans, tomatoes, and sorghum. Rice, wheat, and corn together account for a majority of calories consumed. In the effort to develop experimental crops, agricultural goals include expanding the diversity of plant food in the human diet.

Recent Successes

Soybeans (Glycine max) are a relatively newcrop that gained worldwide acceptance and widespread cultivation in the second half of the twentieth century. Originally cultivated in China, soybeans gradually spread throughout Asia and became a staple food there.

High in protein, soybeans were first grown in the Western world as animal feed. Concerted breeding efforts have resulted in many locally adapted varieties. Today, soybeans as both meal and oil are common place. Worldwide soybean production is now the greatest of any legume.

Triticale (x Triticosecale) is a hybrid created to combine the ruggedness and high protein content of rye (Secale cereale) with the high yield of wheat (Triticumaestivum). Triticale has not replaced wheat or rye in bread-making due to its rather low gluten content but is used to supplement bread flours. Triticale is also adaptable to marginal agricultural soils.

Kiwifruit (Actinidia deliciosa) is another recent success story. Apreviously little-known fruit originally called Chinese gooseberry, it was introduced to New Zealand at the turn of the twentieth century and renamed kiwifruit. The name change was a marketing strategy that led to worldwide popularity.

Kiwifruit farm

Today kiwifruit cultivation and consumption are increasing worldwide. Kiwifruit grows on a de- ciduous vine, much like grapes. It can be harvested and then stored for several months without loss of quality.

Grains and Cereals

Quinoa (Chenopodium quinoa) is a grain native to the Andes Mountains of South America. It has been a staple in the diets of people living in that region for centuries. Although the leaves are edible, it is principally the tiny seed which is consumed.

The seeds contain high amounts of protein, calcium, phosphorus, and the essential amino acid lysine, which is typically lacking in other cereals such as wheat, rye, and barley.

Quinoa seeds must be washed or otherwise processed to remove the bitter saponins contained in the pericarp and can then be cooked and eaten much like rice. Quinoa can also be ground into flour as a supplement for bread making. Cultivation and use of quinoa have increased steadily since the 1980’s.

Grain amaranths (Amaranth) are being rediscovered and developed as a potential new source of grain. Amaranth was a staple crop for centuries in Mexico, Central America, and South America. Amaranth is grown as an annual and yields thick, heavy seed heads containing numerous tiny seeds.

The hard seed coat is removed by heating or boiling and can be prepared much like corn. Amaranth is comparable to other grains in protein, contains high amounts of lysine, and can be consumed by those allergic to typical grains.

Breeding efforts over the last few decades involving A. hypochondriacus, A. cruentus, and A. hybridus have greatly increased seed yield as well as desirable plant growth habits. Another important characteristic is amaranth’s drought resistance.

Legumes

Legumes

Members of the Leguminosae family are particularly valuable as food sources because they contain high levels of protein. This is in part due to their ability to fix atmospheric nitrogen in root nodules that contain nitrogen-fixing bacteria. This symbiotic relationship with the bacteria means relatively little nitrogenous fertilizer is required for agricultural production of legumes.

Tarwi (Lupinus mutabilis) is a legume native to the South American Andes that has a high protein and oil content, similar to the soybean. Tarwi is also high in the essential amino acid lysine. It grows well in poor soils and is drought-resistant. Current breeding efforts focus on reducing the bitter alkaloids, which can be removed by rinsing in water.

The winged bean (Psophocarpus tetragonolobus), native of tropical Asia, is entirely edible—leaves, flowers, seeds, pods, and tuberous roots. Like most legumes, the winged bean has a high protein content. This species could have tremendous potential in many tropical regions of the world, rivaling the success of the soybean.

A native of North America, the groundnut (Apios americana)was a major food source of many American Indian tribes. It is purported to have been offered to the Pilgrims to avert starvation. The numerous underground tubers can be prepared (cooking is necessary) like potatoes yet have a much higher protein content.

Several other legumes whose use and acceptance are likely to increase include the tepary bean (Phaseolus acutiflius), the pigeon pea (Cajanus cajan), and the bambara groundnut (Voandzeia subterranea).

Other Crops

There are many other potential food crops. Most have been cultivated on a small scale for years and are being rediscovered and researched for commercial production. Some of these include potato-like oca tubers (Oxalis tuberosa), fruits such as cherimoya (Annona cherimola), pepino (Solanum muricatum), and feijo (Acca sellowiana), and nuts such as egg nut (Couepia longipendula).

agriculture , Economic botany and plant uses , history of plant science

Agricultural Revolution

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3:51 AM

Agricultural Revolution

The agricultural revolution marked the transition by humans from hunting and gathering all their food to domesticating plants for food.

People first obtained their food by scavenging kills made by other animals, by hunting animals, and by gathering wild food plants. Between ten thousand and twelve thousand years ago, people began to use plants in new ways. Some scientists and historians call this period of time the "agricultural revolution".

Agricultural Beginnings

Before the 1960’s,many scientists and historians believed that hunter-gatherers abruptly switched from foraging to farming. Those who thought that agriculture arose quickly coined the term "agricultural revolution".

They suggested that this revolution spread rapidly because it was a tremendous improvement over the old foraging lifestyle, with the availability of cultivated food sources far more dependable than those of wild sources.

Since the 1960’s, scientists and historians have challenged this view of agricultural beginnings. Later studies have shown that modern hunting-gathering societies have a remarkably sophisticated knowledge about native plants and plants’ life cycles.

Gatherers use a large number of plant species for food. Hunting and gathering cultures today do not have to plant seeds intentionally to keep from starving and most likely did not have to do so in the past.

Domesticated and Wild Plants

Domesticated plants are genetically distinct from their wild ancestors. Domestication involves processes by which a wild plant adapts to the needs of the farmer. The traits that make a plant desirable as a human food plant may not be ones that confer survival value on plants in their natural habitats and may actually be detrimental to the plant’s survival in the wild.

People who gathered wild plants looked for traits that made gathering easier and more profitable. They would have gathered grasses, for example, that had bigger seeds or plants, had more seeds or fruits or edible parts, or had seed heads that did not shatter easily. If seeds from such plants are the ones that were planted, accidentally or on purpose, their useful traits would be reinforced in successive generations.

The appearance of a domesticated plant in the archaeological record is the end result of generations of cumulative genetic transformations that might have taken hundreds or even thousands of years. Therefore, it becomes difficult to pick a single point in the past for any continent or geographic region that signals the beginning of an agricultural economy.

Geography of Agricultural Origins

Fertile Crescent

The area of the Middle East called the Fertile Crescent (between the Tigris and Euphrates Rivers in what is now Iraq) seems to be the first area where formal agriculture began. The native grasses were highly productive.

Wild wheat and barley grew in dense stands and were valuable food sources before cultivation began. It was this use of gathered wild grasses for food that probably led to their early domestication.

Along with the grasses, complementary sources of protein were adopted, namely leguminous crops such as pea and lentil, and animals were domesticated. The plants that were domesticated in the Middle East include einkorn wheat, emmer wheat, bread wheat, barley, lentil, pea, vetch, the fava (or broad) bean, chickpea, lupine, and flax.

Agriculture originated in northeast China with the Yang Shao culture around six thousand years ago and spread quickly into Korea and Japan. Some of the plants brought under cultivation include barley, barnyard millet, common or broomcorn millet, foxtail millet (or foxtail grass), soybean, adzuki and mung beans, hemp, buckwheat, bottle gourd, Chinese cabbage, great burdock, lacquer tree, paper mulberry, and a number of fruit trees, including apricot, pear, peach, and plum.

In Southeast Asia, as well as the Pacific Islands and India, cultivated plants included sesame, the pigeon pea, eggplant, rice, sugarcane, bananas, plantains, coconuts, oranges, mango, Asian yam, betel nut, pepper, taro, bitter gourd, winter melon, snake gourd, luffa, mangosteen, durian, rambutan, breadfruit, and bamboo.

In Africa, plant domestication took place south of the Sahara Desert and north of the equator. Many crops were grown, including various kinds of millet, sorghum, okra, coffee, watermelon, several species of yam, African rice, cowpea, African oil palm, and cola nut. In Ethiopia, Ethiopian oats, coffee, enset, tef, noog, and chat were cultivated.

In Central America, archaeological evidence suggests that squash and pumpkins may have been cultivated before corn, especially in the Oaxaca region. In Oaxaca and Tamaulipas, along with squash and pumpkins, people were cultivating beans and bottle gourds, followed later by corn.

In the Tehuacán Valley of Central Mexico, corn, chile peppers, avocado, beans, amaranth, and foxtail grass were among the very earliest cultivated plants.

Cultivated plants either originating or cultivated early in South America include quinoa, white potato, peanut, cacao, jicama, lima bean, common bean, pineapple, chile pepper, papaya, sweet potato, yucca, and avocado. Tomatoes were cultivated in both Central and South America.

In North America, prior to the diffusion of the corn-squash-beans complex from the southwest after 1000 c.e., Indians of Eastern North America were cultivating a number of plants, including bottle gourd, erect knotweed, sumpweed, goosefoot, maygrass, little barley, and sunflower.

agriculture , Economic botany and plant uses , food , water-related life

Marine Agriculture

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1:13 AM

Marine Agriculture

Marine agriculture uses techniques of artificial cultivation, such as growing, managing, and harvesting, and applies them to marine plants and animals. The products are then used for human consumption.

Marine agriculture is also known as mariculture or aquaculture, although aquaculture is a more general term referring to both freshwater and marine farming of organisms. The world’s oceans cover approximately three-fourths of the globe, including vast regions of unexplored life and landforms.

The potential for exploiting the oceans agriculturally is great but currently meets significant obstacles. Because of the expense of equipment and personnel involved, most marine species are not cultivated.

Coastal pollution, habitat destruction, competition for land use, and economics all limit mariculture programs. Nevertheless, mariculture does offer several food, medical, and other products that are currently being marketed.

Food

Seaweeds are edible, especially the red and brown algae. The three most common types of seaweeds are known by their Japanese names: nori (Porphyra), a red seaweed high in vitamin C and digestible protein; kombu (Laminaria); and wakame (Undaria), high in calcium.

They are eaten raw, cooked, or dried and have several vitamins and minerals as well as protein. Seaweeds are low in fats, and 35 to 50 percent of the dry weight of red seaweeds is protein.

Seaweeds can be used to add taste and variety to foods. They are used as a hot vegetable, boiled and formed into cakes and fried, in salads, and in preparing desserts, breads, soups, casseroles, sandwiches, teas, and candy.

The world’s yearly harvest of seaweeds is approximately 8.4 million tons of green seaweed, 2.8 million tons of brown seaweed, and 1.2 million tons of red seaweed. The total seaweed market in 1998 was worth more than $5 billion, with $600 million deriving from food additives alone.

China is the leading harvester and the world’s biggest seaweed consumer. Japan is the leading seaweed importer and, at the end of the twentieth century, employed more than thirty-five thousand people in the industry. Harvesting and marketing edible seaweed is a growing business in the United States, especially on the West Coast.

Seaweeds

Seaweeds produce several types of phycocolloids, starchlike chemicals used in food processing and manufacturing. An important type called algin, which makes up alginic acid and alginates, is used inmanufacturing dairy products such as ice cream, cheese, and toppings as well as to prevent frostings and pies from desiccation.

Another extract is agar, used to form jellies and protect fish and meats during canning. Agar is also used in low-calorie foods and as a thickener. Red algae is a source of the agglutinant carrageenan, which is used in many food products as an emulsifier to give body to dairy products and other processed foods, including instant puddings. Additionally, seaweed-based food additives are common in prepared and fast foods, including hamburgers and yogurt.

Kelp farming is a major livelihood in the eastern Pacific, with approximately 140,000 tons harvested each year for the extraction of alginates used in food and food additives. Kelp is a good source of calcium, potassium, iron, iodine, bromine, and zinc. It is also low-fat, has some protein, and is a natural tenderizer. Kelp flakes are used as a low-sodium salt substitute.

Medicine

The use of marine plants inmedicine is still in the early stages of exploration and faces many challenges, including identification of useful chemicals and the cultivation of significant quantities.

Dinoflagellates and other microalgae are being investigated for compounds that might fight cancerous tumors. Diluted algae toxins from red tides can be used to inhibit the growth of most bacteria. Green algae has halosphaerin, a strong antibiotic.

Seaweed is used in wound dressings in hospitals and as a source of iodine, A, B, D, and E vitamins, calcium, magnesium, potassium, sodium, sulfur, and trace antioxidants such as selenium and zinc. The seaweed extract agar is used in laxatives and as a medium to grow bacteria and molds.

Kelp is rich in chlorophyll, which can help detoxify the body, fight inflammations, and increase the formation of oxygen-carrying red blood cells. Chlorophyll is also used to fight bad breath and as an ingredient in deodorants.

Kelp is used to reduce cholesterol, treat gastrointestinal, respiratory, and genitourinary disorders, and lower blood pressure. The alginic acid produced by kelp can rid the body of radioactive strontium, the most dangerous to humans of all components in the fallout from atomic explosions.

Other Uses

Marine plants are used for a variety of other purposes. Seaweed is used as a component of many fertilizers, as a food additive in animal feed, and to reduce soil acidity.

Research on cattle and swine has revealed that the addition of seaweed to animal feed can enhance the immune system and makes the meat a more desirable color. It can also save cattle from the effects of fungus-infected grass.

Seaweed is used as an ingredient in cosmetics as well as to nourish, revitalize, condition, and improve the skin, hair, and body. It is used in cleansers, toners, moisturizers, scrubs, body lotions, and hair and bath products.

The giant kelp (Macrocystis) is a major source of algin for commercial uses, as is the brown algae Laminaria, which is harvested in the north Atlantic. Algin is used in shampoos, shaving cream, plastics, pesticides, rubber products, paper, paints, and cosmetics.

Additionally, kelp is used in emulsifiers for toothpastes and printing inks. Kelp has even been used to make fishing lines. Some research has been done on using kelp as a fuel to produce a clean-burning methane gas. Kelp can be used to ferment human waste and garbage, which can then be sold as fertilizers.

agriculture , Economic botany and plant uses , environmental issues

Modern Agriculture Problems

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9:20 PM

Modern Agriculture

Many current problems in agriculture are not new. Erosion and pollution, for example, have been around as long as agriculture. However, agriculture has changed drastically within its ten-thousand-year history, especially since the dawn of the Industrial Revolution in the seventeenth century.

Erosion and pollution are now bigger problems than before and have been joined by a host of other issues that are equally critical—not all related to physical deterioration.

Monoculture

Modern agriculture emphasizes crop specialization, also known as monoculture. Farmers, especially in industrialized regions, often grow a single crop on much of their land. Problems associated with this practice are exacerbated when a single variety or cultivar of a species is grown. Such a strategy allows the farmer to reduce costs, but it also makes the crop, and thus the farmand community, susceptible to widespread crop failure.

The corn blight of 1970 devastated more than 15 percent of the North American corn crop. The cornwas particularly susceptible to the harmful organisms because 70 percent of the crop being grown was of the same high-yield variety. Chemical antidotes can fight pests, but they increase pollution.

Maintaining species diversity or varietal diversity—growing several different crops instead of one or two—allows for crop failures without jeopardizing the entire economy of a farm or region that specializes in a particular monoculture, such as tobacco, coffee, or bananas.

Genetic Engineering

Growing genetically modified (GM) crops is one attempt to replace post-infestation chemical treatments. Recombinant technologies used to splice genes into varieties of rice or potatoes from other organisms are becoming increasingly common. The benefits of such GM crops include more pest-resistant plants and higher crop yields.

Genetic Engineering

However, environmentalists fear new genes could trigger unknown side effects with more serious, long-term environmental and economic consequences than the problems they were used to solve. GM plants designed to resist herbicide applications could potentially pass the resistant gene to closely related wild weed species that would then become "super weeds".

Also, pests, just as they can develop resistance to pesticides, may also become resistant to defenses engineered into GM plants. The high cost of recombinant technologies calls into question the feasibility of continuing development of GM plants.

Erosion

Erosion

An age-old problem, soil loss from erosion occurs all over the world.As soil becomes unproductive or erodes away, more land is plowed. The newly plowed lands usually are considered marginal, meaning they are too steep, nonporous or too sandy, or deficient in some other way.

When natural vegetative cover blankets these soils, it protects them from erosive agents: water, wind, ice, or gravity. Plant cover "catches" rainwater that seeps downward into the soil rather than running off into rivers. As marginal land is plowed or cleared to grow crops, erosion increases.

Expansion of land under cultivation is not the only factor contributing to erosion. Fragile grasslands in dry areas also are being used more intensively. Grazing more livestock than these pastures can handle decreases the amount of grass in the pasture and exposes more of the soil to wind, the primary erosive agent in dry regions.

Overgrazing can affect pastureland in tropical regions too. Thousands of acres of tropical forest have been cleared to establish cattle-grazing ranges in Latin America. Tropical soils, although thick, are not very fertile. After one or two growing seasons, crops grown in these soils will yield substantially less than before.

Tropical fields require fallow periods of about ten years to restore the soil after it is depleted. That is why tropical farmers using slash-and-burn agriculture move to new fields every few years in a cycle that returns them to the same place years later, after their particular lands have regenerated.

Where there is heavy forest cover, soils are protected from exposure to the massive amounts of rainfall. Organic material for crops is present as long as the forest remains in place.

When the forest is cleared, however, the resulting grassland cannot provide the adequate protection, and erosion accelerates. Lands that are heavily grazed provide even less protection from heavy rains, and erosion accelerates even more.

The use of machines also promotes erosion, and modern agriculture relies on machinery such as tractors, harvesters, trucks, balers, and ditchers. In industrialized nations, machinery is used intensely. Machinery use is on the rise in developing countries such as India, China, Mexico, and Indonesia, where traditional, nonmechanized farming methods are the norm.

Farming machines, in gaining traction, loosen topsoil and inhibit vegetative cover growth, especially when farm implements designed to rid the soil of weeds are attached. The soil is then more prone to erode.

Eco-fallow farming has become more popular in the United States and Europe as a way to reduce erosion. This method of agriculture, which leaves the crop residue in place over the fallow (non-growing) season, does not root the soil in place as well as living plants do.

As a result, some erosion continues. Additionally, eco-fallow methods require heavy use of chemicals, such as herbicides, to "burn down" weed growth at the start of the growing season. This contributes to increased erosion and pollution.

Pollution and Silt

Besides causing resistance among harmful bacteria, insects, and weeds, pesticides inevitably wash into, and contaminate, surface and groundwater supplies. Chemicals, although problematic, are not as difficult to contend with as the increasingly heavy silt load choking the life out of streams and rivers.

Accelerated erosion from water runoff carries silt particles into streams, where they remain suspended and inhibit the growth of many forms of plant and animal life.

The silt load in American streams has become so heavy that the Mississippi River Delta is growing faster than it once did. Heavy silt loads, combined with chemical residues, are creating an expanded dead zone. By taxing the capabilities of ecosystems around the Delta, sediments are filtered out slowly, plant absorption of nutrients is decreased, and salinity levels for aquatic life cannot be stabilized.

Most of the world’s population lives in coastal zones, and 80 percent of the world’s fish catch comes from coastal waters over continental shelves that are most susceptible to this form of pollution.

Pesticide Resistance

Pesticide Resistance

With the onset of the Green Revolution, the use of herbicides, insecticides, and other pesticides increased dramatically all over the world. An increasing awareness of problems caused by overuse of pesticides extends even to household antibacterial cleaning agents and other products. Mutations among the genes of bacteria and plants have allowed these organisms to resist the effects of chemicals that were toxic to their ancestors.

Use of pesticides leads to a cycle wherein more, or different combinations of, chemicals are used, and more pests develop resistance to these toxins. Additionally, the development of herbicide-resistant crop plants enables greater use of herbicides to kill undesirable weeds on croplands.

Increasing interest in biopesticides may slow the cycle of pesticide resistance. Types of biopesticides include beneficial microbes, fungi, and insects such as ladybugs that can be released in infested areas to prey upon specific pests. Biopesticides used today include naturally occurring and genetically modified organisms. Their use also avoids excessive reliance on chemical pesticides.

Fertilizers and Eutrophication

Increased use of fertilizers was another result of the Green Revolution. Particulate amounts of most fertilizers enter the hydrologic cycle through run-off. As a result, bodies of water become enriched in dissolved nutrients, such as nitrates and phosphates.

The growth of aquatic plants in rivers and lakes is overstimulated, and this results in the depletion of dissolved oxygen. This process of eutrophication can harm all aquatic life in these ecosystems.

Water Depletion

With an increasing reliance on irrigation, groundwater resources are mismanaged and overtapped. The rate of groundwater recharge is slow, usually between 0.1 and 0.3 percent per year. When the amount of water pumped out of the ground exceeds the recharge rate, it is referred to as aquifer overdraft. An aquifer is a water-bearing stratum of permeable rock, sand, or gravel.

In Tamil Nadu, India, groundwater levels dropped 25 to 30 meters during the 1970’s due to excessive pumping for irrigation. In Tianjin, China, the groundwater level declines 4.4 meters per year. In the United States, aquifer overdraft averages 25 percent over the replacement rate.

The Ogallala aquifer under Kansas, Nebraska, and Texas represents an extreme example of overdraft: Depletion is 130 to 160 percent above the replacement rate annually. At this rate, this aquifer, which supplies water to countless communities and farms, has been projected to become nonproductive by 2030.

Soil Salinization

In addition, continued irrigation of arid regions can lead to soil problems. Soil salinization is widespread in the small-grained soils of these regions, which have a high water absorption capacity and a low infiltration rate.

Some irrigation practices add large amounts of salts into the soil, increasing its natural rate of salinization. This can also occur at the base of a hill slope. Soil salinization has been recognized as a major process of land degradation.

Although surface and groundwater resources cannot be enriched by technology, conservation and improved environmental management can make the use of precious freshwater more efficient. In agriculture, for example, drip irrigation can reduce water use by nearly 50 percent. In developing countries, though, equipment and installation costs often limit the availability of these more efficient technologies.

Urban Sprawl

Urban Sprawl

As more farms become mechanized, the need for farmers and farm workers is being drastically reduced. From a peak in 1935 of about 6.8 million farmers farming 1.1 billion acres, the United States at the end of the twentieth century counted fewer than 2 million farmers farming 950 million acres.

Urban sprawl converts a tremendous amount of cropland into parking lots, malls, industrial parks, and suburban neighborhoods. If cities were located in marginal areas, then concern about the loss of farmland to commercial development would be nominal.

However, the cities attracting the greatest numbers of people have too often replaced the best cropland. Taking the best cropland out of primary production imposes a severe economic penalty.

agriculture , Economic botany and plant uses

Traditional Agriculture

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6:14 AM

Traditional Agriculture

Two agricultural practices that are widespread among the world’s traditional cultures, slash-and-burn agriculture and nomadism, share several features. Both are ancient forms of agriculture, both involve farmers not remaining in a fixed location, and both can pose serious environmental threats if practiced in a nonsustainable fashion.

The most significant difference between the two is that slash-and-burn is associated with raising field crops, while nomadism usually involves herding livestock.

Slash-and-Burn Agriculture

Farmers have practiced slash-and-burn agriculture, which is also referred to as shifting cultivation or swidden agriculture, in almost every region of the world where farming is possible.

Although at the end of the twentieth century slash-and-burn agriculture was most commonly found in tropical areas such as the Amazon River basin in South America, swidden agriculture once dominated agriculture in more temperate regions, such as northern Europe. Swidden agriculture was, in fact, common in Finland and northern Russia well into the early decades of the twentieth century.

Slash-and-burn acquired its name from the practice of farmers who cleared land for planting crops by cutting down the trees or brush on the land and then burning the fallen timber on the site. The farmers literally slash and burn.

The ashes of the burnt wood add minerals to the soil, which temporarily improves its fertility.Crops the first year following clearing and burning are generally the best crops the site will provide. Each year after that, the yield diminishes slightly as the fertility of the soil is depleted.

Farmers who practice slash-and-burn do not attempt to improve fertility by adding fertilizers such as animal manure to the soil. They instead rely on the soil to replenish it-self over time.

When the yield from one site drops below acceptable levels, farmers then clear another piece of land, burn the brush and other vegetation, and cultivate that site while leaving their previous field to lie fallow and its natural vegetation to return.

This cycle will be repeated over and over, with some sites being allowed to lie fallow indefinitely, while others may be revisited and farmed again in five, ten, or twenty years.

Farmers who practice slash-and-burn do not always move their dwelling places as they cultivate different fields. In some geographic regions, farmers live in a central village and farm cooperatively, with fields being alternately allowed to remain fallow and farmed, making a gradual circuit around the central village.

In other cases, the village itself may move as new fields are cultivated. Anthropologists studying indigenous peoples in Amazonia, for example, discovered that village garden sites were on a hundred-year cycle. Villagers farmed cooperatively to clear a garden site. That garden would be used for about five years; then a new site was cleared.

When the fields in use became an inconvenient distance from the village—about once every twenty years—the entire village would move to be closer to the new fields. Over a period of approximately one hundred years, a village would make a circle through the forest, eventually ending up close to where it had been located long before any of the present villagers had been born.

In more temperate climates, farmers often owned and lived on the land on which they practiced swidden agriculture. Farmers in Finland, for example, would clear a portion of their land, burn the covering vegetation, grow grains for several years, and then allow that land to remain fallow for five to twenty years.

Slash-and-Burn Agriculture

The individual farmer rotated cultivation around the land in a fashion similar to that practiced by whole villages in other areas but did so as an individual rather than as part of a communal society.

Although slash-and-burn is frequently denounced as a cause of environmental degradation in tropical areas, the problemwith it is not the practice itself but the length of the cycle.

If the cycle of shifting cultivation is long enough, forests will grow back, the soil will regain its fertility, and minimal adverse effects will occur. In some regions, a piece of land may require as little as five years to regain its maximum fertility; in others, it may take one hundred years.

Problems arise when growing populations put pressure on traditional farmers to return to fallow land too soon. Crops are smaller than needed, leading to a vicious cycle in which the next strip of land is also farmed too soon, and each site yields less and less. As a result,more and more land must be cleared.

Nomadism

Nomadic peoples have no permanent homes. They earn their living by raising herd animals, such as sheep, horses, or other cattle, and they spend their lives following their herds from pasture to pasture with the seasons, going wherever there is sufficient food for their animals.

Most nomadic animals tend to be hardy breeds of goats, sheep, or cattle that can withstand hardship and live on marginal lands. Traditional nomads rely on natural pasturage to support their herds and grow no grains or hay for themselves. If a drought occurs or a traditional pasturing site is unavailable, they can lose most of their herds to starvation.

Nomadism

In many nomadic societies, the herd animal is almost the entire basis for sustaining the people. The animals are slaughtered for food, clothing is woven from the fibers of their hair, and cheese and yogurt may be made from milk.

The animals may also be used for sustenance without being slaughtered. Nomads in Mongolia, for example, occasionally drink horses’ blood, removing only a cup or two at a time from the animal.

In mountainous regions, nomads often spend the summers high up on mountain meadows, returning to lower altitudes in the autumn when snow begins to fall. In desert regions, they move from oasis to oasis, going to the places where sufficient natural water exists to allow brush and grass to grow, allowing their animals to graze for a few days, weeks, or months, then moving on.

In some cases, the pressure to move on comes not from the depletion of food for the animals but from the depletion of a water source, such as a spring or well. At many desert oases, a natural water seep or spring provides only enough water to support a nomadic group for a few days at a time.

In addition to true nomads—people who never live in one place permanently—a number of cultures have practiced seminomadic farming: The temperate months of the year, spring through fall, are spent following the herds on a long loop, sometimes hundreds of miles long, through traditional grazing areas, then the winter is spent in a permanent village.

Nomadism has been practiced for millennia, but there is strong pressure from several sources to eliminate it. Pressures generated by industrialized society are increasingly threatening the traditional cultures of nomadic societies, such as the Bedouin of the Arabian Peninsula. Traditional grazing areas are being fenced off or developed for other purposes.

Environmentalists are also concerned about the ecological damage caused by nomadism. Nomads generally measure their wealth by the number of animals they own and will try to develop their herds to as large a size as possible, well beyond the numbers required for simple sustainability. The herd animals eat increasingly large amounts of vegetation, which then has no opportunity to regenerate. Desertification may occur as a result.

Nomadism based on herding goats and sheep, for example, has been blamed for the expansion of the Sahara Desert in Africa. For this reason, many environmental policy makers have been attempting to persuade nomads to give up their traditional life-style and become sedentary farmers.

agriculture , food

Agriculture: World Food Supplies

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4:28 AM

World Food Supplies

Soil types, topography, climate, socioeconomics, dietary preferences, stages in agricultural development, and governmental policies combine to give a distinctive personality to regional agricultural characteristics and, hence, food supplies in various areas of the world.

All living things need food to live, grow, work, and survive. Almost all foods that humans consume come from plants and animals. Not all of earth’s people eat the same foods, however. The types, combinations, and amounts of food consumed by different peoples depend upon historic, socioeconomic, and environmental factors.

History of Food Consumption

Early in human history, people ate what they could gather or scavenge. Later, people ate what they could plant and harvest and the products of animals they could domesticate. Modern people eat what they can grow, raise, or purchase.

Their diets or food composition is determined by income, local customs, religion or food biases, and advertising. There is a global food market, and many people can select what they want to eat and when they eat it according to the prices they can pay and what is available.

Historically, in places where food was plentiful, accessible, and inexpensive, humans devoted less time to basic survival needs and more time to activities that led to human progress and enjoyment of leisure.

Despite a modern global food system, instant telecommunications, the United Nations, and food surpluses in some places, however, the problem of providing food for everyone on earth has not been solved.

In 1996 leaders from 186 countries gathered in Rome and agreed to reduce by half the number of hungry people in the world by the year 2015. United Nations data for 1998 revealed that more than 790 million people in the developing parts of the world did not have enough food to eat. This is more people than the total population of North America and Europe at that time.

The number of undernourished people has been decreasing since 1990. Still, at the current pace of hunger reduction in the world, 600 million people will suffer from "acute food insecurity" and go to sleep hungry in 2015. Despite efforts being made to feed the world, outbreaks of food deficiencies, mass starvation, and famine are a certainty in the twenty-first century.

World Food Source Regions

World Food Source Regions - North America

Agriculture and related primary food production activities, such as fishing, hunting, and gathering, continue to employ more than one-third of the world’s labor force. Agriculture’s relative importance in the world economic system has declined with urbanization and industrialization, but it still plays a vital role in human survival and general economic growth.

Demands on agriculture in the twenty-first century include supplying food to an increasing world population of nonfood producers as well as producing food and nonfood crude materials for industry.

Soil types, topography, weather, climate, socio-economic history, location, population pressures, dietary preferences, stages in modern agricultural development, and governmental policies combine to give a distinctive personality to regional agricultural characteristics.

Two of the most productive food-producing regions of the world are North America and Europe. Countries in these regions export large amounts of food to other parts of the world.

North America is one of the primary food-producing and food-exporting continents. After 1940 food output generally increased as cultivated zacreage declined. Progress in improving the quantity and quality of food production is related to mechanization, chemicalization, improved breeding, and hybridization. Food output is limited more by market demands than by production obstacles.

Western Europe, although a basic food-deficit area, is a major producer and exporter of high-quality foodstuffs. After 1946 its agriculture became more profit-driven. Europe’s agricultural labor force grew smaller, its agriculture became more mechanized, its farm sizes increased, and capital investment per acre increased.

Foods from Plants

Foods from Plants

Most basic staple foods come from a small number of plants and animals. Ranked by tonnage produced, the most important food plants throughout the world are wheats, corn, rice, potatoes, cassava, barley, soybeans, sorghums and millets, beans, peas and chickpeas, and peanuts. Wheat and rice are the most important plant foods.

More than one-third of the world’s cultivated land is planted with these two crops. Wheat is the dominant food staple in North America, Western and Eastern Europe, northern China, the Middle East, and North Africa. Rice is the dominant food staple in southern and eastern Asia.

Corn, used primarily as animal food in developed nations, is a staple food in Latin America and southeast Africa. Potatoes are a basic food in the highlands of South America and in Central and Eastern Europe.

Cassava is a tropical starch-producing root crop of special dietary importance in portions of lowland South America, the west coast countries of Africa, and sections of South Asia. Barley is an important component of diets in North African, Middle Eastern, and Eastern European countries.

Soybeans are an integral part of the diets of those who live in eastern, southeastern, and southern Asia. Sorghums and millets are staple subsistence foods in the savanna regions of Africa and South Asia, while peanuts are a facet of dietary mixes in tropical Africa, Southeast Asia, and South America.

The World’s Growing Population

The World’s Growing Population

The problem of feeding the world is compounded by the fact that population was increasing at a rate of nearly 80 million persons per year at the end of the twentieth century. That rate of increase is roughly equivalent to adding a country the size of Germany to the world every year. Compounding the problem of feeding the world are population redistribution patterns and changing food consumption standards.

By 2001, the world had exceeded the six billion mark, and the world population was projected to reach approximately ten billion people by 2050—four billion people more than were on the earth in 2000. Most of the increase in world population was expected to occur within the developing nations.

Urbanization

Along with an increase in population in developing nations is massive urbanization. City dwellers are food consumers, not food producers. The exodus of young men and women from rural areas has given rise to a new series of megacities, most of which are in developing countries. By the year 2015, twenty-six cities in the world are expected to have populations of ten million people or more.

When rural dwellers move to cities, they tend to change their dietary composition and food-consumption patterns. Qualitative changes in dietary consumption standards are positive, for the most part, and are a result of educational efforts of modern nutritional scientists working in developing countries. During the last four decades of the twentieth century, a tremendous shift took place in overall dietary habits.

Dietary changes and consumption trends have contributed to a decrease in child mortality, an increase in longevity, and a greater resistance to disease. This globalization of people’s diets has resulted in increased demands for higher quality, greater quantity, and more nutritious basic foods.

Perspectives

Humanity is entering a time of volatility in food production and distribution. The world will produce enough food to meet the demands of those who can afford to buy food. In many countries, however, food production is unlikely to keep pace with increases in the demand for food by growing populations.

The food gap—the difference between production and demand—could more than double in the first three decades of the twenty-first century. Such a development would increase the dependence of developing countries on food imports. About 90 percent of the rate of increase in aggregate food demand in the early twenty-first century is expected to be the result of population increases.

Factors that could lead to larger fluctuations in food availability include weather variations, such as those induced by El Niño and climatic change, the growing scarcity of water, civil strife and political instability, and declining food aid.

agriculture , disciplines , Economic botany and plant uses , soil

Agronomy

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Agronomy

Agronomy is a group of applied science disciplines concerned with land and soil management and crop production. Agronomists’ areas of interest range from soil chemistry to soil-plant relationships to land reclamation.

The word "agronomy" derives from the ancient Greek agros (field) and nemein (manage) and therefore literally means "field management". The American Society of Agronomy defines agronomy as "the theory and practice of crop production and soil management". There are many specialties within the study of agronomy.

Agronomic Specialties

Agronomy is the family of disciplines investigating the production of crops supplying food, forage, and fiber for human and animal use. It studies the stewardship of the soil upon which those crops are grown. Agronomy covers all aspects of the agricultural environment, from agroclimatology to soil-plant relationships.

It includes crop science, soil science, weed science, and biometry (the statistics of living things) as well as crop, soil, pasture, and range management; turfgrass; agronomic modeling; and crop, forage, and pasture production andutilization.

Within each area are subdisciplines. For example, within soil science are traditional disciplines such as soil fertility, soil chemistry, soil physics, soil microbiology, soil taxonomy and classification, and pedogenesis, the science of how soils form.

Newer disciplines within soil science include such studies as bioremediation, or the study of how living organisms can be used to clean up toxic wastes in the environment, and land reclamation, the study of how to reconstruct landscapes disturbed by human activities, such as surface mining.

Scientific Goals

Chief among detrimental human activities is poor field management, which leads to reduced productivity and reduced environmental quality. Historical examples abound; one is that of the 1930’s Dust Bowl in the United States.

In the early 1900’s much of the American Southern Plains, which had been natural grassland, was converted to wheatland. Planting and plowing methods of the time did not enable wheat to protect the ground against winds. Additionally, overgrazing of livestock had destroyed what grassland remained by the 1930’s.

The soil eroded, drought conditions which would last for most of the decade set in, and a series of wind and dust storms whipped through the region. An estimated 50 million acres of land were destroyed before soil conservation measures, implemented under the administration of Franklin Roosevelt, began to improve the situation.

It is the role of agronomy to manage soil and crop resources as effectively as possible so that the twin goals of productivity and environmental quality are preserved.

Agronomy treats the agricultural environment as humankind’s greatest natural resource: It is the source of food, clothing, and building materials. The agricultural environment purifies the air humans and other animals breathe and the water they drink.

Scientific Goals

Agronomists, whatever their specific field, seek to utilize soil and plant resources to benefit society. Crop breeders, for example, use the genetic diversity of wild varieties of domesticated plants to obtain the information needed to breed plants for greater productivity or pest resistance.

Soil scientists study landscapes to determine how best to manage soil resources. Integrating agricultural practices with the environment maintains soil fertility and keeps soil in place so that erosion does not reduce the quality of the surrounding environment.

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