- Tropical agriculture
Worldwide more human beings gain their livelihood from
agriculturethan any other endeavor; the majority are self-employed subsistence farmersliving in the tropics. While growing food for local consumption is the core of tropical agriculture, Cash crops (normally crops grown for export) are also included in the definition.
When people discuss the tropics, it is normal to use generalized labels to group together similar tropical areas. Common terms would include the
humid-tropics ( rainforests); the arid-tropics ( desertsand dry areas); or monsoonzones (those areas that have well defined wet/dry seasonsand experience monsoons). Such labeling is very useful when discussing agriculture, because what works in one area of the world, will normally work in a similar area somewhere else, even if that area is on the opposite side of the globe.
Most temperate zone agricultural techniques are inappropriate for tropical areas. The second half of the 20th century saw many attempts to duplicate in the tropics
farmingpractices that had been successful in temperate climates. Due to differences in climate, soils, and patterns of land ownership, these largely failed. When they did succeed they tended to heavily favor farmers with substantial land holdings, as a high percentage of temperate agricultural practices are economically"scale-based" and favor large scale production. This in turn pushed many small-scale farmers on to ever more marginal land, as the better quality land was consolidated into larger farms.
Green Revolution" is the name given to the most successful agricultural improvement program ever undertaken in the tropics. Funded initially by the Rockefeller Foundation, it aimed to improve corn, rice, and other cerealcultivators – breeding plantsthat would produce more grain for the same amount of effort.
From that point it expanded out to improved basic farming practices, particularly for rice farmers. The growth of crop yields was such that agriculture was able to outstrip population growth — per capita production increased every year following 1950 - with
Asialeading the way. One of the more remarkable aspects of the Green Revolution is that the total cost of the program by 1990 was approximately US$100 million, less than what a single Boeing 747airliner costs in 2005.
It can be concluded that the
green revolutionwas a success, with only a minor flaw: although the crops gave more yield, they were more subject to disease since this was not a primary concern in the program.In order to address this problem together with an approach to more small-scale farming crops, there is today substantial interest in creating a second Green Revolution, based on sustainable agricultural practices and geared towards (small-scale) farmers with limited financialresources (who make up the bulk of farmers in the
Many tropical food plants are propagated by
cuttings. Seeds are necessary for plant embryosto survive the winter and other harsh conditions such as drought. However, where the weather is normally conducive to growth year-round, it is often advantageous for plants to reproducethrough means other than seeds. By bypassing the seed stage plants can greatly accelerate their reproductive cycle. Despite this, anyone who wishes so, may still grow tropical crops (eg fruit, ...) from seed. To do so, some special seed germination techniques to germinate it more quicker may be best used.
A particularly good description of plant defenses can be found at [http://www.wischik.com/marcus/essay/def.html How and why do plants defend themselves?] that states in part:
:"Plants are faced with a dilemma; while they need to attract beneficial pollinators and seed dispensers, they must also minimize the damage caused by the marauding army of herbivores. Without some form of protection the trees would be stripped bare and smaller plants would be completely devastated, and because plants stand still, they cannot run away. This is as true in Amazonian rainforest as it is in Northern coniferous forest." - Marcus Wischik.
Many (tropical) plants use
toxinsto protect themselves. Cassava, one of the most important tropical food crops, produces cyanideupon ingestionif improperly processed. Other plants are high in oxalates (the agent that binds calciumto form kidney stones); castor beans are the source of ricin, one of the most powerful poisonsin existence; and velvet beans contain 7-10% L-dopa. The list of toxic plants is long, but toxicity does not always mean a particular plant should be avoided, the knowledge needed to render toxic plants safe to use already exists in most communities.
The contents of a bag of commercial
fertilizeris described in terms of NPK - nitrogen(N), phosphorus(P) and potassium(K); with nitrogen being the main component of most commercial fertilizers. Oxygenis only a small part of the air; the largest component of air is nitrogen. Nitrogen is the main building block of protein; musclein mammalsand plant tissue in plants. If you increase the nitrogen in the soil, you significantly increase plant growth. Legumesare a group of plants that interact with bacteria( rhizobia) in the soil to fix nitrogen from the air, and deposit the nitrogen into the soil where it is available for other plants to use. The nitrogen deposited by legumes can be readily converted into larger harvests. Green manures are plants grown to improve the soil, suppress weeds, limit erosion, and - when legumes are used - to increase the nitrogen content of the soil. The most common type of green manure used in the tropics is Velvet bean. It produces a thick blanketof vines and leavesthat in addition to infusing the soil with nitrogen also smother most weeds. In addition it has reasonable tolerance to drought, low soil fertility, and highly acidicsoil. Alternatives to the Velvet bean include the Lablab bean, the Jack bean, and for use above 500 m altitude, the Scarlet runner bean.
Once the blanket is several centimeters thick, it is chopped down with a
machete, and the vines are chopped up. This produces thick mulchon top of the ground that both inhibits weed growth and adds vital nutrientsto the soil. Corn or other crops are then planted directly into this mulch.
Slash/mulch is popular in southern
Mexico, Guatemala, and Honduras; and in recent years has gained a following in many areas of the tropics, from Brazilto central Africa. Where it has been embraced it has pushed aside slash and burnagriculture, and allowed farmers to utilize the same land continuously for many years.
[http://ppathw3.cals.cornell.edu/mba_project/moist/home2.html Cornell University] has taken a leading role in
researching the effects of mulches and slash/mulch practices in the tropics.
In most places in the tropics sufficient precipitation occurs to grow enough food to feed the
local population; however, it many not fall in a timely or convenientmanner. Making maximum use of the waterthat does fall is an ongoing challenge.
Water is a particularly important issue in
dryland farming. The ability to collect and store water at a low cost and without damaging the environment, is what opens up deserts and other aridregions to farmers. When it rains in dryland areas, the rain storms are normally heavy, and the soil unable to absorb the large amounts of rain that comes down. This leads to excessive surface run-off that needs to be captured and retained.
Commercial farms growing cash crops often use irrigation techniques similar to or identical to what would be found on large scale commercial farms located in temperate regions; as an example, the Israeli drip-irrigation lines.
Water harvesting pits
One of the simplest forms of
irrigation- the farmer digs bathtubsized pits into his fields and lines them with plastic sheets to collect rainwater. Then once the dry seasonsets in the farmer uses the collected water to irrigate his crops. The technique is especially useful in mountainousareas, where rapid run-offwould otherwise occur.
During years with normal precipitation the growing season can be increased by an extra month or more by using harvesting pits. An extra month in many places means an extra crop can be grown. For instance if the local
growing seasonis 5 months long, and the farmers main crop takes 3 or 4 months to grow, an extra month may be enough time to grow a secondary crop. During times of drought, what rain does fall can be collected in the pits and used to secure the farmer's main crop.
Bucket drip irrigation
An irrigation system consisting of a
buckethung from a pole, with a hose coming out of the bottom, and holes punched into the hose. The bucket is filled, and gravityfeeds the water to the plants. As a rule about 40 litersof water per day are needed for every 100 plants, although this can vary depending upon what is being grown.
treadle pumpis a human-powered pump designed to lift water from a depth of seven meters or less. A treadle is lever device pressed by the foot to drive a machine, in this case a pump. The treadle pump can do most of the work of a motorized pump, but costs considerably less to purchase, and needs no fossil fuelas it is driven by the operators body weight and leg muscles. It can lift five to seven cubic meters of water per hour from wellsand boreholes up to seven meters deep and can also be used to draw water from lakesand rivers. Most treadle pumps used are of local manufacture, as they are simple and inexpensive to build.
Standard treadle pumps are
suctionpumps, and where first developed in the early 1980s in Bangladesh. Most treadle pumps manufactured in Africaare pressuretreadle pumps; a modification to the original design that means water is forced out of the pump under pressure. Pressure treadle pumps are more versatile as they allow farmers to pump water uphill, or over long distances, or fill elevated tanks.
Crop rotationis the cornerstone pest controlin the tropics. When a single crop is planted repeatedly in the same soil, insectsand diseasesthat attack that crop are allowed to build up to unmanageable levels, greatly reducing the farmer’s harvest.
The most basic form of crop rotation is also the simplest: never plant the same thing in the same place twice. This results in naturally breaking the cycles of
weeds, insects and diseases that attack food crops. Rotations are used to prevent or at least partially control several pests and at the same time to reduce the farmer’s reliance on chemical pesticides. Crop rotations often are the only economically feasible method for reducing insect and disease damage.
Crop rotation replaces a crop that is
susceptibleto a serious pest with another crop that is not susceptible. Each food crop comes with its own set of pests that attack that particular crop. By planting a different crop each time, the farmer is able to starve out those pests. Often a set of three or four crops are planted on a rotating basis, ensuring that by the time the first crop is replanted, the pests that attack it are substantially reduced.
Another side benefit of crop rotation is it improves the soil. Constantly growing the same crop in the same location will strip the soil of the
nutrientsthat particular crop requires. Rotating to a different crop will reduce the pressure placed on the soil. Or if a green manure is used as part of the rotation sequence, the soil can actually be improved.
Integrated pest management
Integrated Pest Management(IPM) was developed as an alternative to the heavy use of chemical pesticides. Eliminating all insect pests requires the extensive use of chemical pesticides, which over time can become self-defeating. Farmers end up using more and more chemicals with diminishing effect as pests quickly adapt –while at the same time natural predatorinsects are eliminated from the farm. Under IPM chemicals should be a secondary line of defense, while building up the number of natural predators on a farm is the main goal. The IPM approach calls for keeping the pest populationsbelow the levels at which they cause economic injury, not total eradication.
IPM in its pure form is extremely complex, and beyond the ability of most farmers to manage; however, the underlying principals have gained widespread acceptance in the tropics, with most governments sponsoring IPM educational programs.
ystem of Rice Intensification and other sustainable agricultural systems
IPM, there are also completely biological systems (not using pesticides at all) which are used in the developing world, mostly the System of Rice Intensificationand Organic farming. In the World of Organic Agriculture 2007, we can clearly see that in Oceania and Latin America, organic farming is matching the organic farming in the developed world.
Winters are mild in the tropics; there is no
frost, no snow, and no ice, so the insect population flourishes year-round. In temperate areas winter eliminates most insect pests prior to the emergence of new crops, so plants coming up in the spring have a chance to take hold and grow prior to being attacked. In the tropics plants enter a world already full of hungry adult insects.
Soils in the humid tropics are normally highly acidic and nutrient poor;
decompositionis rapid because of high temperatures, high humidity, and frequent heavy rains. Heavy rains, especially monsoon rains, lead to rapid nutrient leaching, and chemical weatheringof the soil. Standard temperate strategiesfor improving nutrient poor soil, such as composting, have limited application in such an environment due to rapid leaching. Aluminumis the most common metalfound in the Earth’s crust. It is found in all soils and in all environments, from temperate to tropical. In a solublestate it is highly toxicto plant life, as it inhibits rootgrowth; however, in neutral and alkalinesoils common to the temperate zones it is insolubleand therefore inert. Soil fertilityis directly influenced by how acidic it is, as the more acidic the higher the level of aluminum toxicity; in areas where the pHdrops below 5, aluminum becomes soluble and can enter into plant roots where it accumulates.
Approximately a third of all tropical soils are too acidic to support traditional food crops. These highly acidic tropical soils represent the largest untapped
arable landleft in the world, and therefore more productive utilization of these lands is key to expanding the world food supply.
Winrock International states "In the humid tropics, the relative importance of acid soils is greatest in Latin America (81%), but also significant in Africa (56%) and Asia (38%)" [http://www.winrock.org/forestry/FACTPUB/AIS_web/AIS10.html] .
Traditionally on commercial farms aluminum toxicity is countered by adding lime to the soil, which neutralizes the acid and renders the aluminum inert. However, many small land holders and resource-poor farmers cannot afford lime, and instead rely on slash-and-burn agriculture. As the original plant life is burnt, the ash acts to neutralize the acidic soil and makes the area acceptable for food plants. In time acidity increases and only plants will grow, forcing the farmer to move on and clear a new area.
Soil color in humid areas is related to the level of
oxidationthat has occurred in the soil, with red soil being the result of ironoxidation, and yellow soil being the result of aluminum oxidation.
Salinizationoccurs naturally in arid areas where not enough rain falls to wash soluble salts down and out of the root zone. Irrigation makes the situation worse, since surface water and groundwater contain more salt than rainwater does. Salt tends to build up in the soil as water is added through irrigation. As water is used by plants and evaporatesfrom the soil surface, the salt in the water concentrates in the soil. The high temperatures and low humidity in arid regions means that salinization often accompanies irrigation.
Day-length sensitive plants
Some plants have a photoperiod (
photoperiodism) requirement for a certain number of hours of daylight before they will grow, flower, or produce fruit. Without this they will not complete their life-cycleand will not produce fruit and seeds. For this reason seeds brought from the temperate zones may not perform as expected, or at all in the tropics. Some plants are genetically keyed to only start producing when a certain number of hours of daylight is reached, the same number of hours as is found in their native habitat. With the shorter daylight hours experienced in the tropics, that switch never gets thrown.
Logging of rainforest/tropical forests to produce food
Throughout the tropics and predominantly in
Indonesia, and certain South-East Asian Countries, a lot of forest is being cleared to produce food. Major examples are the oil palmplantations in Indonesia and the dry rice farmingtechniques using slash and burn-method in Southeast Asia. This of course adds to global warming(as trees collect CO2 in life and release it in death) and increases the decline in biodiversity. It has been argued that although tropical crops should be grown, it should be done in regions under threat (e.g., regions at risk of desertification, salination, ...)
Low economic input in Africa, constraining the export of tropical crops
In certain tropical places (predominantly the entire continent of Africa), there are very few (registered) African companies at all to sell their products trough the normal ways, let alone that they are capable of exporting products beyond their borders/continent. This phenomenon can be clearly seen if one walks into a supermarket (not a normal market, where this isn't the case) in the developing world (e.g., Africa); almost all products come from Western companies.
As such, tropical crops (vegetables, grain, fruit), although it has high value at European markets (very low production, increasing the demand and unknown products), are not sold at all (most crops) or very limited (certain tropical fruit as papaya, guave, mango, cacao by mostly Western companies and representing only a few percentages of the entire bunch of crops).
At the country of origin, predominantly at normal markets (not supermarkets), these food items are available, but only within the season and not always the crops of the entire country (rather only the ones grown locally). Of course because the demand and availability are closer together in these places, prices are lower and farmers are not capable of getting as high returns as if they would in the West.
Availability of inexpensive Western crops and food
Western food, as it is subsidized by the
EUand the USA, is for certain products, such as chicken, cheaper than it's counterparts in the developing world. Besides the matching food products being cheaper, the availability of Western surrogates for certain food has also proven disastrous. At least in certain continents as Africa, Western surrogate foods are thought to be 'better' and more modern by African people, who thus switch from their traditional ingredients and meals to Western counterparts (see article below).
This availability of inexpensive foreign food is not only damaging to the indigenous economy, but also for the
healthof the people themselves (sparking obesity, heart problems, and a lack of certain vitamins and minerals). This is believed to be because certain Western food (not only hamburgers but also the main staple food) is not qualified for them (as strange as it may seem). Because of these problems, the traditional African food is again slowly being distributed within the continent (e.g. in Nairobi, the Tusker Supermarket).
Pioneering crops are used in places where the land has been striped bare, and the
topsoilhas been entirely lost to erosion, or where desertificationhas started. The intent is not to grow food or cash crops, but to repairand reinvigorate the soil in order to prepare the way for the later planting of food or cash crops. Nitrogen fixingplants and trees normally form the basis of such a reclamationproject.
The hunger season is that period of time when all the food from the previous
harvesthas been consumed, and the next harvest is still some time away. Even in normal years, many households face an annual reduction in the amount of food they have available. Typically the hunger season will coincide with the start of plantingthe new crop, or shortly thereafter. So farmers are faced with a shortage of food at the very time they are expected to perform their heaviest labor.
One way of mitigating the effects of the hunger season is growing some non-seasonal crops close to the family home, such as
bananas in humid areas, or cassava where it is arid. As an example, a family that has ten banana plants producing fruit during the hunger season is unlikely to experience excessive hardship. Sweet potato, pigeon pea, and Moringa oleiferashould also be considered.
Common tropical horticulture crops
* Palms (mainly oil palm)
Common agricultural crops
* [http://www.echotech.org/network/modules.php?name=AZ Amaranth to Zai Holes - Ideas for Growing Food Under Difficult Conditions]
* [http://www.winrock.org/forestry/factnet.htm Forest, Farm, and Community Tree Network]
* [http://cidicco.hn/newcidiccoenglish/index.htm International Cover Crops Clearinghouse (CIDICCO)]
* [http://ppathw3.cals.cornell.edu/mba_project/moist/home2.html Management of Organic Inputs in Soils of the Tropics (MOIST)] - Cornell University
* [http://www.mekonginfo.org/mrc_en/doclib.nsf/0/1C15891F0E9A47FEC7256604001580FC/$FILE/FULLTEXT.HTML Report on soil conservation, soil improvement and extension for the Song Da watershed and CARE projects]
* [http://www.agroforestry.net/overstory/ The Overstory]
*The Doubly Green Revolution: "Food for All in the Twenty-First Century"; by Gordon Conway, Cornell University Press (March, 1999) ISBN 0-8014-8610-6
*Two Ears of Corn: "A Guide to People-Centered Agricultural Improvement"; by Roland Bunch, World Neighbors; 3rd edition (June, 1995) ISBN 0-942716-03-5
* [http://www.globalhort.org/ Global Horticulture Initiative]
* [http://www.iita.org International Institute of Tropical Agriculture]
* [http://www.bioversityinternational.org/publications/Pdf/1090.pdf Benefits of traditional vegetables, over Western food]
* [http://www.ipgri.cgiar.org/Events/IFAD-NUS/pdf/Emile%20paper%20to%20the%20CBD%20on%20Nurtrition.pdf Article on the effects of Western food to Africans]
* [http://www.nap.edu/books/0309049903/html/Lost Crops of Africa: Vol 1 Grains ]
* [http://books.nap.edu/openbook.php?isbn=0309103339 Lost Crops of Africa: Vol 2 Vegetables]
* [http://www.soel.de/oekolandbau/weltweit.html Organic Farming Worldwide]
Wikimedia Foundation. 2010.
См. также в других словарях:
College of Tropical Agriculture and Human Resources — The College of Tropical Agriculture and Human Resources (CTAHR), established in 1907, is the founding college of the University of Hawaii at Manoa in Honolulu, Hawai‘i. CTAHR is dedicated to actively help[ing] Hawai‘i diversify its economy,… … Wikipedia
International Center for Tropical Agriculture — The International Center for Tropical Agriculture (known as CIAT from its Spanish language name Centro Internacional de Agricultura Tropical) is a nonprofit organization that conducts advanced research in social and environmental fields to… … Wikipedia
International Institute of Tropical Agriculture — The International Institute of Tropical Agriculture (IITA) was established in 1967 as a non profit organization to find solutions for hunger and poverty through research for development activities. IITA has its headquarters in Ibadan in Nigeria… … Wikipedia
International Institute of Tropical Agriculture — Das International Institute of Tropical Agriculture (IITA) ist eine international tätige Forschungseinrichtung. Ihr Ziel ist die Verbesserung der Lebensbedingungen in Afrika durch landwirtschaftliche Forschung. Der hauptsitz ist in Ibadan. IITA… … Deutsch Wikipedia
Agriculture and Food Supplies — ▪ 2007 Introduction Bird flu reached Europe and Africa, and concerns over BSE continued to disrupt trade in beef. An international vault for seeds was under construction on an Arctic island. Stocks of important food fish species were reported… … Universalium
Tropical Africa — is a diverse region of the African continent that falls between the Tropic of Cancer in the northern hemisphere, at approximately 23°26 (23.4°) N latitude, and the Tropic of Capricorn in the southern hemisphere at 23°26 (23.4°) S latitude. This… … Wikipedia
Tropical rainforest — Tropical rainforests are generally found near the equator. They are common in Asia,Australia, Africa, South America, Central America, and on many of the Pacific Islands. Within the World Wildlife Fund s biome classification, tropical rainforests… … Wikipedia
Agriculture in the Empire of Japan — (農業政策, Nōgyō seisaku?) was an important component of the pre war Japanese economy. Although Japan had only 16% of its land area under cultivation before the Pacific War, over 45% of households made a living from farming. Japanese cultivated land… … Wikipedia
Agriculture of Cuba — Agriculture in Cuba has played an important part in the economy for several hundred years. Agriculture contributes less than 10 percent to the gross domestic product (GDP), but it employs roughly one fifth of the working population. About 30… … Wikipedia
Agriculture in Haiti — Agriculture continued to be the mainstay of the economy of Haiti in the late 1980s; it employed approximately 66 percent of the labor force and accounted for about 35 percent of GDP and for 24 percent of exports in 1987 (see fig. 14). The role of … Wikipedia