Crop rotation

Crop Rotation

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Crop rotation

Crop rotation or Crop sequencing is the practice of growing a series of dissimilar types of crops

Crop (agriculture)

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Crop rotation or Crop sequencing is the practice of growing a series of dissimilar types of crops

Crop (agriculture)

A crop is the annual or season's yield of any plant that is grown in significant quantities to be harvested as food, as livestock fodder, or for any other economic purpose....
in the same area in sequential seasons for various benefits such as to avoid the build up of pathogens and pests that often occurs when one species is continuously cropped. Crop rotation also seeks to balance the fertility demands of various crops to avoid excessive depletion of soil nutrients. A traditional component of crop rotation is the replenishment of nitrogen

Nitrogen

Nitrogen is a chemical element that has the symbol N and atomic number 7 and atomic mass 14.00674?. Elemental nitrogen is a colorless, odorless, tasteless and mostly inert diatomic gas at standard conditions, constituting 78% by volume of Earth's atmosphere....
through the use of green manure

Green manure

In agriculture, a green manure is a type of cover crop grown primarily to add nutrients and organic matter to the soil. Typically, a green manure crop is grown for a specific period, and then plowed under and incorporated into the soil....
in sequence with cereals and other crops. It is one component of polyculture

Polyculture

Polyculture is agriculture using multiple crops in the same space, in imitation of the diversity of natural ecosystems, and avoiding large stands of single crops, or monoculture....
. Crop rotation can also improve soil structure

Soil structure

Soil structure is determined by how individual soil granules clump or bind together and aggregate, and therefore, the arrangement of soil pores between them....
and fertility by alternating deep-rooted and shallow-rooted plants.

Method and purpose

Crop rotation avoids a decrease in soil fertility, as growing the same crop

Agriculture

Agriculture refers to the production of food and goods through farming and forestry. Agriculture was the key development that led to the rise of civilization, with the animal husbandry of domestication animals and plants creating food surpluses that enabled the development of more Population density and Social stratification societies....
repeatedly in the same place eventually depletes the soil

Soil

Soil is the naturally occurring, unconsolidated or loose covering on the Earth's surface. Soil is composed of particles of broken rock that have been altered by chemical and environmental processes including weathering and erosion....
of various nutrient

Nutrient

A nutrient is a chemical that an organism needs to live and grow or a substance used in an organism's metabolism which must be taken in from its environment....
s. A crop that leaches the soil of one kind of nutrient is followed during the next growing season by a dissimilar crop that returns that nutrient to the soil or draws a different ratio of nutrients, for example, rices followed by cottons. By crop rotation farmers can keep their fields

Field (agriculture)

In agriculture, a field refers generally to an area of land enclosed or otherwise and used for agricultural purposes such as:* Cultivating crop ...
under continuous production, without the need to let them lie fallow, and reducing the need for artificial fertilizer

Fertilizer

Fertilizers are chemical compounds given to plants to promote growth; they are usually applied either through the soil, for uptake by plant roots, or by foliar feeding, for uptake through leaves....
s, both of which can be expensive. Rotating crops adds nutrients to the soil.

Legumes, plants of the family Fabaceae

Fabaceae

Fabaceae or Leguminosae is a large and economically important family of flowering plants, which is commonly known as the legume family, pea family, bean family or pulse family....
, for instance, have nodules on their root

Root

In vascular plants, the root is the organ of a plant body that typically lies below the surface of the soil. This is not always the case, however, since a root can also be aerial root or aerating ....
s which contain nitrogen-fixing

Nitrogen fixation

Nitrogen fixation is the process by which nitrogen is taken from its relatively inert molecular form in the Earth's atmosphere and converted into nitrogen compounds ....
bacteria. It therefore makes good sense agriculturally to alternate them with cereals (family Poaceae

Poaceae

Poaceae or Gramineae is a family in the Class Liliopsida of the Magnoliophyta. Plants of this family are usually called grasses; the shrub- or tree-like plants in this family are called bamboo ....
) and other plants that require nitrates. A common modern crop rotation is alternating soybean

Soybean

The soybean or soya bean is a species of legume native to East Asia. The plant is classed as an oilseed rather than a Pulse . It is an annual plant that has been used in China for 5,000 years as a food and a component of drugs....
s and maize

Maize

Maize , known as corn in some countries, is a cereal domesticated in Mesoamerica and subsequently spread throughout the American continents....
(corn). In subsistence farming

Subsistence agriculture

Subsistence agriculture is self-sufficiency farming in which farmers grow only enough food to feed their family and pay taxes. The typical subsistence farm has a range of crops and animals needed by the family to eat during the year....
, it also makes good nutritional sense to grow beans and grain at the same time in different fields.

Crop rotation is a type of cultural control that is also used to control pests and diseases that can become established in the soil over time. The changing of crops in a sequence tends to decrease the population level of pests. Plants within the same taxonomic family

Family (biology)

In biological classification, family is a taxonomic rank. Exact details of formal nomenclature depend on the Nomenclature Codes which applies....
tend to have similar pests and pathogens. By regularly changing the planting location, the pest cycles can be broken or limited. For example, root-knot nematode

Root-knot nematode

Root-knot nematodes are plant-parasitism nematodes from the genus Meloidogyne. They exist in soil in areas with hot climates or short winters....
is a serious problem for some plants in warm climates and sandy soils, where it slowly builds up to high levels in the soil, and can severely damage plant productivity by cutting off circulation from the plant roots. Growing a crop that is not a host for root-knot nematode for one season greatly reduces the level of the nematode in the soil, thus making it possible to grow a susceptible crop the following season without needing soil fumigation

Fumigation

File:Tent_fumigation.jpgFumigation is a method of pest control that completely fills an area with gaseous pesticides - or fumigants - to suffocate or poison the pests within....
.

It is also difficult to control weed

WEED

WEED is a radio station broadcasting a Gospel format. Licensed to Rocky Mount, North Carolina, USA, it serves the area. The station is currently owned by Northstar Broadcasting Corporation....
s similar to the crop which may contaminate the final produce. For instance, ergot

Ergot

Ergot refers to a group of fungus of the genus Claviceps . The most prominent member of this group is Claviceps purpurea. This fungus grows on rye and related plants, and can cause ergotism in humans and other mammals consuming seeds contaminated with the fruiting structure of this fungus, called an ergot sclerotium....
in weed grasses is difficult to separate from harvested grain. A different crop allows the weeds to be eliminated, breaking the ergot cycle

Cycle

Cycle or Cyclic may refer to:* Motorcycle* Bicycle* Cycling, the act of riding a bicycle or tricycle* Tricycle...
.

This principle is of particular use in organic farming

Organic farming

Organic farming is a form of agriculture that relies on crop rotation, green manure, compost, biological pest control, and mechanical cultivation to maintain soil productivity and control pest s, excluding or strictly limiting the use of synthetic fertilizers and synthetic pesticides, plant growth regulators, livestock feed additives, and gen...
, where pest control

Biological pest control

Biological control of pests in agriculture is a method of pest control that relies on predation, parasitism, herbivory, or other natural mechanisms....
may be achieved without synthetic pesticides.

A general effect of crop rotation is that there is a geographic mixing of crops, which can slow the spread of pests and diseases during the growing season. The different crops can also reduce the effects of adverse weather for the individual farmer and, by requiring planting and harvest at different times, allow more land to be farmed with the same amount of machinery and labor.

The choice and sequence of rotation crops depends on the nature of the soil

Soil

Climate

Climate encompasses the temperatures, humidity, atmospheric pressure, winds, rainfall, atmospheric particle count and numerous other Meteorology elements in a given region over long periods of time, as opposed to the term weather, which refers to current activity of these same elements....
, and precipitation

Precipitation (meteorology)

File:MeanMonthlyP.gifIn meteorology, precipitation is any product of the condensation of Atmosphere water vapor that is deposited on the earth's surface....
which together determine the type of plants that may be cultivated. Other important aspects of farming such as crop marketing and economic variables must also be considered when choosing a crop rotation.

History

Old crop rotation methods were mentioned in Roman

Roman Empire

The Roman Empire was the Roman Republic phase of the Ancient Rome, characterised by an autocracy form of government and large territorial holdings in Europe and around the Mediterranean....
literature, and referred to by several civilizations in Asia

Asia

Asia is the world's largest and most populous continent. It covers 8.6% of the Earth's total surface area and, with over 4 billion people, it contains more than 60% of the world's current human population....
and Africa

Africa

Africa is the world's second-largest and second most-populous continent, after Asia. At about 30.2 million km? including adjacent islands, it covers 6% of the Earth's total surface area and 20.4% of the total land area....
. During the Muslim Agricultural Revolution

Muslim Agricultural Revolution

The Islamic Golden Age from the 8th century to the 13th century witnessed a fundamental transformation in agriculture known as the Arab Agricultural Revolution, Medieval Green Revolution, or Muslim Agricultural Revolution....
of the Islamic Golden Age

Islamic Golden Age

The Islamic Golden Age, also sometimes known as the Islamic Renaissance, was traditionally dated from the 700 A.D. to 1200 A.D.Common Era, but has been extended to the 15th and 16th centuries by some scholars....
, Muslim engineers and farmers introduced a new modern rotation system where land was cropped four times or more in a two-year period. Winter crops were followed by summer ones, and in some cases there was a crop in between. In areas where plants of shorter growing season were used, ie.spinach

Spinach

Spinach is a flowering plant in the family of Amaranthaceae. It is native to central and southwestern Asia. It is an annual plant , which grows to a height of up to 30 cm....
and eggplants, the land could be cropped three or more times a year. According to some sources, in parts of Yemen

Yemen

Yemen , officially the Republic of Yemen is an Arab country located on the Arabian Peninsula in Southwest Asia. Yemen has an estimated population of more than 23 million people and is bordered by Saudi Arabia to the North, the Red Sea to the West, the Arabian Sea and Gulf of Aden to the South, and Oman to the east....
wheat yielded two harvests a year on the same land, as did rice in Iraq. Scholars such as Andrew Watson

Andrew Watson

Andrew Watson is widely considered to be the world's first black people association football player to play at international level. He was Cap three times Scotland national football team between 1881 and 1882....
have written of a Muslim agricultural revolution as the Islamic world made significant progress in developing a more "scientific" approach based on three major elements: sophisticated systems of crop rotation, highly developed irrigation techniques and the introduction of a large variety of crops which were studied and catalogued according to the season, type of land and amount of water they require. Numerous farming encyclopaedias, with surprisingly great precision and details, were produced.

From the end of the Middle Ages

Middle Ages

File:Karl 1 mit papst gelasius gregor1 sacramentar v karl d kahlen.jpgThe Middle Ages of European history are a period in history which lasted for roughly a millennium, commonly dated from the fall of the Roman Empire in the 5th century to the beginning of the Early Modern Period in the 16th century, marked by the division of Western Christi...
until the 20th century, the three-year rotation was practiced by farmers in Europe with a rotation of rye

Rye

Rye is a Poaceae grown extensively as a grain and forage crop. It is a member of the wheat tribe and is closely related to barley and wheat. Rye grain is used for flour, rye bread, rye beer, some rye whiskey, some vodkas, and animal fodder....
or winter wheat

Wheat

Wheat , is a worldwide cultivated Poaceae from the Levant region of the Middle East. Globally, after maize, wheat is the second most-produced food among the cereal just above rice....
, followed by spring oat

Oat

The common oat is a species of Cereal Agriculture for its seed, which is known by the same name . While oats are suitable for human consumption as oatmeal and rolled oats, one of the most common uses is as livestock feed....
s or barley

Barley

Barley is an annual plant cereal grain derived from the grass Hordeum vulgare. It serves as a major animal feed crop, with smaller amounts used for malting and in health food, as well as the making of alcoholic beverages beer and whisky....
, then letting the soil rest (leaving it fallow) during the third stage. The fact that suitable rotations made it possible to restore or to maintain a productive soil has long been recognized by planting spring crops for livestock in place of grains for human consumption.

A four-field rotation was pioneered by farmers, namely in the region Waasland

Waasland

The Waasland is a region in Flanders, Belgium, although without any administrative functions. It is also called the Land van Waas , Waas refers to the soggy soil of the region....
in the early 16th century and popularised by the British

United Kingdom

The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom , the UK or Britain,is a sovereign state located off the northwestern coast of continental Europe....
agriculturist Charles Townshend

Charles Townshend, 2nd Viscount Townshend

Charles Townshend, 2nd Viscount Townshend , was a British British Whig Party statesman. He served for a decade as Secretary of State, directing British foreign policy....
in the 18th century. The system (wheat, turnip

Turnip

The turnip is a root vegetable commonly grown in temperate climates worldwide for its white, bulbous taproot. Small, tender, varieties are grown for human consumption, while larger varieties are grown as fodder for livestock....
s, barley and clover

Clover

Clover , or trefoil, is a genus of about 300 species of plants in the pea family Fabaceae. The genus has a cosmopolitan distribution; the highest diversity is found in the temperate Northern Hemisphere, but many species also occur in South America and Africa, including at high altitudes on mountains in the tropics....
), opened up a fodder crop and grazing crop allowing livestock

Livestock

Livestock is the term used to refer to a domesticated animal intentionally reared in an agricultural setting to produce things such as food or fibre, or for its labour....
to be bred year-round. The four-field crop rotation was a key development in the British Agricultural Revolution

British Agricultural Revolution

The British Agricultural Revolution describes a period of development in Britain between the 17th century and the end of the 19th century, which saw a massive increase in agricultural productivity and net output....
.

George Washington Carver

George Washington Carver

George Washington Carver , was an United States scientist, botanist, educator, and inventor whose studies and teaching revolutionized agriculture in the Southern United States....
pioneered crop rotation methods in the United States

United States

The United States of America is a Federal government constitutional republic comprising U.S. state and a federal district. The country is situated mostly in central North America, where its Contiguous United States and Washington, D.C., the Capital districts and territories, lie between the Pacific Ocean and Atlantic Oceans, Borders of the U...
by teaching southern farmers to rotate soil depleting crops like cotton with soil enriching crops like peanut

Peanut

The peanut, or groundnut , is a species in the legume Fabaceae native to South America, Mexico and Central America. It is an annual plant herbaceous plant growing to 30 to 50 cm tall....
s and pea

Pea

A pea is most commonly the small spherical seed or the seed-pod of the legume Pisum sativum. Each pod contains several peas. Although treated as a vegetable in cooking, it is botanically a fruit....
s.

In the Green revolution

Green Revolution

Green Revolution usually refers to the transformation of agriculture that began in 1945. One significant factor came at the request of the Mexican government to establish an agricultural research station to develop more varieties of wheat that could be used to feed the rapidly growing population of the country....
, the traditional practice of crop rotation gave way in some parts of the world to the practice of supplementing the chemical inputs to the soil through top dressing with fertilizers, e.g., adding ammonium nitrate

Ammonium nitrate

The chemical compound ammonium nitrate, the nitrate of ammonia with the chemical formula NitrogenHydrogen4NitrogenOxygen3, is a white powder at room temperature and standard pressure....
or urea

Urea

Urea is an organic compound with the chemical formula 2carbonoxygen.Urea is also known by the International Nonproprietary Name carbamide, as established by the World Health Organization....
and restoring soil pH

pH is a measure of the Acid or Base of a solution. It is defined as the cologarithm of the Activity of dissolved hydrogen ions . Hydrogen ion activity coefficients cannot be measured experimentally, so they are based on theoretical calculations....
with lime

Lime (mineral)

Lime is a general term for calcium-containing inorganic materials, in which carbonates, oxides and hydroxides predominate. Strictly speaking, lime is calcium oxide or calcium hydroxide....
in the search for increased yields, preparing soil for specialist crops, and seeking to reduce waste and inefficiency by simplifying planting and harvesting. Some disadvantages of this type of monoculture

Monoculture

Monoculture is the agricultural practice of producing or growing one single crop over a wide area. The term is also applied in several fields. It is usually developed by extensive growing farmers....
have since become apparent, notably from the perspective of sustainable agriculture

Sustainable agriculture

Sustainable agriculture integrates three main goals: natural environment stewardship, farm profitability, and prosperous farming community. These goals have been defined by a variety of List of academic disciplines and may be looked at from the vantage point of the farmer or the consumer....
and the risk of catastrophic crop failure.

Effects on soil erosion

Crop rotation can greatly affect the amount of soil lost from erosion

Erosion

For morphological image processing operations, see Erosion 'For use of in dermatopathology, see Erosion Erosion is the removal of solids in the natural environment....
by water. In areas that are highly susceptible to erosion, farm management practices such as zero and reduced tillage can be supplemented with specific crop rotation methods to reduce raindrop impact, sediment detachment, sediment transport

Sediment transport

Sediment transport is the movement of solid particles due to the movement of the fluid in which they are entrained. This is typically studied in natural systems, where the particles are clastic rocks , mud, or clay, and the fluid is air, water, or ice....
, surface runoff

Surface runoff

Surface runoff is the water flow which occurs when soil is infiltrated to full capacity and excess water, from rain, snowmelt, or other sources flows over the land....
, and soil loss .

Protection against soil loss is maximized with rotation methods that leave the greatest mass of crop stubble (plant residue left after harvest) on top of the soil. Stubble cover in contact with the soil minimizes erosion from water by reducing overland flow velocity, stream power, and thus the ability of the water to detach and transport sediment . For example, wheat stubble consistently leaves a significant mass of plant residue after harvest. Wheat production supplemented with no till or reduced till management systems can typically yield 90% post-harvest soil cover with up to 15 months of stubble retention .

The amount of stubble mass retained over time governs whether a crop will be successful in controlling erosion. Crops with little stubble mass retained over time should not be planted following a plant production system with similar characteristics. Sunflowers for example typically produce less than 40% soil cover after harvest with very little stubble remaining after cultivation . This leaves a significant percentage of the soil susceptible to erosion. However, when sunflower crops are rotated with wheat crops in production, the soils are less prone to erosion because the high-stubble producing wheat crops are followed by the low-stubble producing sunflower crop . A corn – soybean crop rotation in a no till system works similarly. Corn plants leave substantial residue mass after harvest. Soybeans, a relatively low-residue producing plant, following corn will have sufficient cover from the previous crops corn residue to limit soil losses. It is important to avoid mono-cropping low-stubble producing plants when attempting to reduce soil loss.

The additional crop residue added by rotation with crops with substantial biomass will also enhance soil structure. Stubble cover will prevent the disruption and detachment of soil aggregates that cause macrospores to block, infiltration to decline, and runoff to increase . This significantly improves the resilience of soils when subjected to periods of erosion and stress.

The effect of crop rotation on erosion control varies by climate. In regions under relatively consistent climate conditions, where annual rainfall and temperature levels are assumed, rigid crop rotations can produce sufficient plant growth and soil cover. In regions where climate conditions are less predictable, and unexpected periods of rain and drought may occur, a more flexible approach for soil cover by crop rotation is necessary. An opportunity cropping system promotes adequate soil cover under these erratic climate conditions . In an opportunity cropping system, crops are grown when soil water is adequate and there is a reliable sowing window. This form of cropping system is likely to produce better soil cover than a rigid crop rotation because crops are only sewn optimal conditions, whereas rigid systems are sown in the best conditions available .

Crop rotations also affect the timing and length of when a field is subject to fallow . This is very important because depending on a particular regions climate, a field could be the most vulnerable to erosion when it is under fallow. Efficient fallow management is an essential part of reducing erosion in a crop rotation system. Zero tillage is a fundamental management practice that promotes crop stubble retention under longer unplanned fallows when crops cannot be planted . Such management practices that succeed in retaining suitable soil cover in areas under fallow will ultimately reduce soil loss.

External links

ed. by L. H. Bailey (1911), Vol. II--Crops, Chapter V "Crop Management," primarily the history and theory of crop rotation.

Crop rotation

Method and purpose

History

Effects on soil erosion

See also

External links