Crop rotation

Crop rotation is the practice of growing a series of dissimilar or different types of crops in the same area in sequenced seasons. It is done so that the soil of farms is not used for only one set of nutrients. It helps in reducing soil erosion and increases soil fertility and crop yield.

Growing the same crop in the same place for many years in a row (monocropping) disproportionately depletes the soil of certain nutrients. With rotation, 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. In addition, crop rotation mitigates the buildup of pathogens and pests that often occurs when one species is continuously cropped, and can also improve soil structure and fertility by increasing biomass from varied root structures.

Crop cycle is used in both conventional and organic farming systems.

Crops Kansas AST 20010624
Satellite image of circular crop fields in Kansas in late June 2001. Healthy, growing crops are green. Corn would be growing into leafy stalks by then. Sorghum, which resembles corn, grows more slowly and would be much smaller and therefore, (possibly) paler. Wheat is a brilliant yellow as harvest occurs in June. Fields of brown have been recently harvested and plowed under or lie fallow for the year.
Plodozmian
Effects of crop rotation and monoculture at the Swojec Experimental Farm, Wroclaw University of Environmental and Life Sciences. In the front field, the "Norfolk" crop rotation sequence (potatoes, oats, peas, rye) is being applied; in the back field, rye has been grown for 58 years in a row.

History

Agriculturalists have long recognized that suitable rotations—such as planting spring crops for livestock in place of grains for human consumption—make it possible to restore or to maintain a productive soil. Middle Eastern farmers practiced crop rotation in 6000 BC without understanding the chemistry, alternately planting legumes and cereals[1]. In the Bible, chapter 25 of the Book of Leviticus instructs the Israelites to observe a "Sabbath of the Land". Every seventh year they would not till, prune or even control insects.[2]

Two-field system

Under a two-field rotation, half the land was planted in a year, while the other half lay fallow. Then, in the next year, the two fields were reversed. From the times of Charlemagne (died 814), farmers in Europe transitioned from a two-field crop rotation to a three-field crop rotation.

Three-field system

From the end of the Middle Ages until the 20th century, Europe's farmers practised three-field rotation, dividing available lands into three parts. One section was planted in the autumn with rye or winter wheat, followed by spring oats or barley; the second section grew crops such as peas, lentils, or beans; and the third field was left fallow. The three fields were rotated in this manner so that every three years, a field would rest and be fallow. Under the two-field system, if one has a total of 600 acres (2.4 km2) of fertile land, one would only plant 300 acres. Under the new three-field rotation system, one would plant (and therefore harvest) 400 acres. But the additional crops had a more significant effect than mere quantitative productivity. Since the spring crops were mostly legumes, they increased the overall nutrition of the people of Northern Europe.

Four-field rotation

Farmers in the region of Waasland (in present-day northern Belgium) pioneered a four-field rotation in the early 16th century, and the British agriculturist Charles Townshend (1674–1738) popularised this system in the 18th century. The sequence of four crops (wheat, turnips, barley and clover), included a fodder crop and a grazing crop, allowing livestock to be bred year-round. The four-field crop rotation became a key development in the British Agricultural Revolution. The rotation between arable and ley is sometimes called ley farming.

Modern developments

George Washington Carver (1860s–1943) studied crop-rotation methods in the United States, teaching southern farmers to rotate soil-depleting crops like cotton with soil-enriching crops like peanuts and peas.

In the Green Revolution of the mid-20th century 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 topdressing with fertilizers, adding (for example) ammonium nitrate or urea and restoring soil pH with lime. Such practices aimed to increase yields, to prepare soil for specialist crops, and to reduce waste and inefficiency by simplifying planting and harvesting.

Crop choice

A preliminary assessment of crop interrelationships can be found in how each crop: (1) contributes to soil organic matter (SOM) content, (2) provides for pest management, (3) manages deficient or excess nutrients, and (4) how it contributes to or controls for soil erosion.[3]

Crop choice is often related to the goal the farmer is looking to achieve with the rotation, which could be weed management, increasing available nitrogen in the soil, controlling for erosion, or increasing soil structure and biomass, to name a few.[4] When discussing crop rotations, crops are classified in different ways depending on what quality is being assessed: by family, by nutrient needs/benefits, and/or by profitability (i.e. cash crop versus cover crop).[5] For example, giving adequate attention to plant family is essential to mitigating pests and pathogens. However, many farmers have success managing rotations by planning sequencing and cover crops around desirable cash crops.[6] The following is a simplified classification based on crop quality and purpose.

Row crops

Many crops which are critical for the market, like vegetables, are row crops (that is, grown in tight rows).[5] While often the most profitable for farmers, these crops are more taxing on the soil.[5] Row crops typically have low biomass and shallow roots: this means the plant contributes low residue to the surrounding soil and has limited effects on structure.[7] With much of the soil around the plant exposed to disruption by rainfall and traffic, fields with row crops experience faster break down of organic matter by microbes, leaving fewer nutrients for future plants.[7]

In short, while these crops may be profitable for the farm, they are nutrient depleting. Crop rotation practices exist to strike a balance between short-term profitability and long-term productivity.[6]

Legumes

A great advantage of crop rotation comes from the interrelationship of nitrogen fixing-crops with nitrogen demanding crops. Legumes, like alfalfa and clover, collect available nitrogen from the soil in nodules on their root structure.[8] When the plant is harvested, the biomass of uncollected roots breaks down, making the stored nitrogen available to future crops. Legumes are also a valued green manure: a crop that collects nutrients and fixes them at soil depths accessible to future crops.[9]

In addition, legumes have heavy tap roots that burrow deep into the ground, lifting soil for better tilth and absorption of water.

Grasses and cereals

Cereal and grasses are frequent cover crops because of the many advantages they supply to soil quality and structure. The dense and far-reaching root systems give ample structure to surrounding soil and provide significant biomass for soil organic matter.

Grasses and cereals are key in weed management as they compete with undesired plants for soil space and nutrients.

Green manure

Green manure is a crop that is mixed into the soil. Both nitrogen-fixing legumes and nutrient scavengers, like grasses, can be used as green manure.[8] Green manure of legumes is an excellent source of nitrogen, especially for organic systems, however, legume biomass doesn't contribute to lasting soil organic matter like grasses do.[8]

Planning a rotation

There are numerous factors that must be taken into consideration when planning a crop rotation. Planning an effective rotation requires weighing fixed and fluctuating production circumstances: market, farm size, labor supply, climate, soil type, growing practices, etc.[10] Moreover, a crop rotation must consider in what condition one crop will leave the soil for the succeeding crop and how one crop can be seeded with another crop.[10] For example, a nitrogen-fixing crop, like a legume, should always precede a nitrogen depleting one; similarly, a low residue crop (i.e. a crop with low biomass) should be offset with a high biomass cover crop, like a mixture of grasses and legumes.[3]

There is no limit to the number of crops that can be used in a rotation, or the amount of time a rotation takes to complete.[7] Decisions about rotations are made years prior, seasons prior, or even at the very last minute when an opportunity to increase profits or soil quality presents itself.[6] In short, there is no singular formula for rotation, but many considerations to take into account.

Implementation

Crop rotation systems may be enriched by the influences of other practices such as the addition of livestock and manure,[11] intercropping or multiple cropping, and organic management low in pesticides and synthetic fertilizers.

Incorporation of livestock

Introducing livestock makes the most efficient use of critical sod and cover crops; livestock (through manure) are able to distribute the nutrients in these crops throughout the soil rather than removing nutrients from the farm through the sale of hay.[7]

In Sub-Saharan Africa, as animal husbandry becomes less of a nomadic practice many herders have begun integrating crop production into their practice. This is known as mixed farming, or the practice of crop cultivation with the incorporation of raising cattle, sheep and/or goats by the same economic entity, is increasingly common. This interaction between the animal, the land and the crops are being done on a small scale all across this region. Crop residues provide animal feed, while the animals provide manure for replenishing crop nutrients and draft power. Both processes are extremely important in this region of the world as it is expensive and logistically unfeasible to transport in synthetic fertilizers and large-scale machinery. As an additional benefit, the cattle, sheep and/or goat provide milk and can act as a cash crop in the times of economic hardship.[12]

Organic farming

Crop rotation is a required practice in order for a farm to receive organic certification in the United States.[13] The “Crop Rotation Practice Standard” for the National Organic Program under the U.S. Code of Federal Regulations, section §205.205, states that:

Farmers are required to implement a crop rotation that maintains or builds soil organic matter, works to control pests, manages and conserves nutrients, and protects against erosion. Producers of perennial crops that aren’t rotated may utilize other practices, such as cover crops, to maintain soil health.[7]

In addition to lowering the need for inputs by controlling for pests and weeds and increasing available nutrients, crop rotation helps organic growers increase the amount of biodiversity on their farms.[7] Biodiversity is also a requirement of organic certification, however, there are no rules in place to regulate or reinforce this standard.[7] Increasing the biodiversity of crops has beneficial effects on the surrounding ecosystem and can host a greater diversity of fauna, insects, and beneficial microorganism in the soil.<[7] Some studies point to increased nutrient availability from crop rotation under organic systems compared to conventional practices as organic practices are less likely to inhibit of beneficial microbes in soil organic matter.[14]

While multiple cropping and intercropping benefit from many of the same principals as crop rotation, they do not satisfy the requirement under the NOP.[7]

Intercropping

Multiple cropping systems, such as intercropping or companion planting, offer more diversity and complexity within the same season or rotation, for example the three sisters. An example of companion planting is the inter-planting of corn with pole beans and vining squash or pumpkins. In this system, the beans provide nitrogen; the corn provides support for the beans and a "screen" against squash vine borer; the vining squash provides a weed suppressive canopy and a discouragement for corn-hungry raccoons.[4]

Double-cropping is common where two crops, typically of different species, are grown sequentially in the same growing season, or where one crop (e.g. vegetable) is grown continuously with a cover crop (e.g. wheat).[3] This is advantageous for small farms, who often cannot afford to leave cover crops to replenish the soil for extended periods of time, as larger farms can.[6] When multiple cropping is implemented on small farms, these systems can maximize benefits of crop rotation on available land resources.[6]

Benefits

Agronomists describe the benefits to yield in rotated crops as "The Rotation Effect". There are many found benefits of rotation systems: however, there is no specific scientific basis for the sometimes 10-25% yield increase in a crop grown in rotation versus monoculture. The factors related to the increase are simply described as alleviation of the negative factors of monoculture cropping systems. Explanations due to improved nutrition; pest, pathogen, and weed stress reduction; and improved soil structure have been found in some cases to be correlated, but causation has not been determined for the majority of cropping systems.

Other benefits of rotation cropping systems include production cost advantages. Overall financial risks are more widely distributed over more diverse production of crops and/or livestock. Less reliance is placed on purchased inputs and over time crops can maintain production goals with fewer inputs. This in tandem with greater short and long term yields makes rotation a powerful tool for improving agricultural systems.

Soil organic matter

The use of different species in rotation allows for increased soil organic matter (SOM), greater soil structure, and improvement of the chemical and biological soil environment for crops. With more SOM, water infiltration and retention improves, providing increased drought tolerance and decreased erosion.

Soil organic matter is a mix of decaying material from biomass with active microorganisms. Crop rotation, by nature, increases exposure to biomass from sod, green manure, and a various other plant debris. The reduced need for intensive tillage under crop rotation allows biomass aggregation to lead to greater nutrient retention and utilization, decreasing the need for added nutrients.[5] With tillage, disruption and oxidation of soil creates a less conducive environment for diversity and proliferation of microorganisms in the soil. These microorganisms are what make nutrients available to plants. So, where "active" soil organic matter is a key to productive soil, soil with low microbial activity provides significantly fewer nutrients to plants; this is true even though the quantity of biomass left in the soil may be the same.

Soil microorganisms also decrease pathogen and pest activity through competition. In addition, plants produce root exudates and other chemicals which manipulate their soil environment as well as their weed environment. Thus rotation allows increased yields from nutrient availability but also alleviation of allelopathy and competitive weed environments.

Carbon sequestration

Studies have shown that crop rotations greatly increase soil organic carbon (SOC) content, the main constituent of soil organic matter.[15] Carbon, along with hydrogen and oxygen, is a macronutrient for plants. Highly diverse rotations spanning long periods of time have shown to be even more effective in increasing SOC, while soil disturbances (e.g. from tillage) are responsible for exponential decline in SOC levels.[15] In Brazil, conversion to no-till methods combined with intensive crop rotations has been shown an SOC sequestration rate of 0.41 tonnes per hectare per year.[16]

In addition to enhancing crop productivity, sequestration of atmospheric carbon has great implications in reducing rates of climate change by removing carbon dioxide from the air.

Nitrogen fixing

Rotating crops adds nutrients to the soil. Legumes, plants of the family Fabaceae, for instance, have nodules on their roots which contain nitrogen-fixing bacteria called rhizobia. During a process called nodulation, the rhizobia bacteria use nutrients and water provided by the plant to convert atmospheric nitrogen into ammonia, which is then converted into an organic compound that the plant can use as its nitrogen source.[17] It therefore makes good sense agriculturally to alternate them with cereals (family Poaceae) and other plants that require nitrates. How much nitrogen made available to the plants depends on factors such as the kind of legume, the effectiveness of rhizobia bacteria, soil conditions, and the availability of elements necessary for plant food.[18]

Pathogen and pest control

Crop rotation is also used to control pests and diseases that can become established in the soil over time. The changing of crops in a sequence decreases the population level of pests by (1) interrupting pest life cycles and (2) interrupting pest habitat.[6] Plants within the same taxonomic family tend to have similar pests and pathogens. By regularly changing crops and keeping the soil occupied by cover crops instead of lying fallow, pest cycles can be broken or limited, especially cycles that benefit from overwintering in residue.[19] For example, root-knot nematode 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.

This principle is of particular use in organic farming, where pest control must be achieved without synthetic pesticides.[11]

Weed management

Integrating certain crops, especially cover crops, into crop rotations is of particular value to weed management. These crops crowd out weed through competition. In addition, the sod and compost from cover crops and green manure slows the growth of what weeds are still able to make it through the soil, giving the crops further competitive advantage. By removing slowing the growth and proliferation of weeds while cover crops are cultivated, farmers greatly reduce the presence of weeds for future crops, including shallow rooted and row crops, which are less resistant to weeds. Cover crops are, therefore, considered conservation crops because they protect otherwise fallow land from becoming overrun with weeds.[19]

This system has advantages over other common practices for weeds management, such as tillage. Tillage is meant to inhibit growth of weeds by overturning the soil; however, this has a countering effect of exposing weed seeds that may have gotten buried and burying valuable crop seeds. Under crop rotation, the number of viable seeds in the soil is reduced through the reduction of the weed population.

In addition to their negative impact on crop quality and yield, weeds can slow down the harvesting process. Weeds make farmers less efficient when harvesting, because weeds like bindweeds, and knotgrass, can become tangled in the equipment, resulting in a stop-and-go type of harvest.[20]

Preventing soil erosion

Crop rotation can significantly reduce the amount of soil lost from erosion 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, surface runoff, and soil loss.[21]

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.[22] Soil Erosion and Cill prevent the disruption and detachment of soil aggregates that cause macropores to block, infiltration to decline, and runoff to increase.[23] This significantly improves the resilience of soils when subjected to periods of erosion and stress.

When a forage crop breaks down, binding products are formed that act like an adhesive on the soil, which makes particles stick together, and form aggregates.[24] The formation of soil aggregates is important for erosion control, as they are better able to resist raindrop impact, and water erosion. Soil aggregates also reduce wind erosion, because they are larger particles, and are more resistant to abrasion through tillage practices.[25]

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.[26] 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 sown under optimal conditions, whereas rigid systems are not necessarily sown in the best conditions available.[27]

Crop rotations also affect the timing and length of when a field is subject to fallow.[28] This is very important because depending on a particular region's 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.[26] Such management practices that succeed in retaining suitable soil cover in areas under fallow will ultimately reduce soil loss. In a recent study that lasted a decade, it was found that a common winter cover crop after potato harvest such as fall rye can reduce soil run-off by as much as 43%, and this is typically the most nutritional soil.[29]

Biodiversity

Increasing the biodiversity of crops has beneficial effects on the surrounding ecosystem and can host a greater diversity of fauna, insects, and beneficial microorganisms in the soil.[7] Some studies point to increased nutrient availability from crop rotation under organic systems compared to conventional practices as organic practices are less likely to inhibit of beneficial microbes in soil organic matter, such as arbuscular mycorrhizae, which increase nutrient uptake in plants.[14] Increasing biodiversity also increases the resilience of agro-ecological systems.[5]

Farm productivity

Crop rotation contributes to increased yields through improved soil nutrition. By requiring planting and harvesting of different crops at different times, more land can be farmed with the same amount of machinery and labour.

Risk management

Different crops in the rotation can reduce the risks of adverse weather for the individual farmer.[30][31]

Challenges

While crop rotation requires a great deal of planning, crop choice must respond to a number of fixed conditions (soil type, topography, climate, and irrigation) in addition to conditions that may change dramatically from year to the next (weather, market, labor supply).[6] In this way, it is unwise to plan crops years in advance. Improper implementation of a crop rotation plan may lead to imbalances in the soil nutrient composition or a buildup of pathogens affecting a critical crop.[6] The consequences of faulty rotation may take years to become apparent even to experienced soil scientists and can take just as long to correct.[6]

Many challenges exist within the practices associated with crop rotation. For example, green manure from legumes can lead to an invasion of snails or slugs and the decay from green manure can occasionally suppress the growth of other crops.[9]

See also

Notes

  1. ^ "What Is Crop Rotation?". WorldAtlas. Retrieved 2019-01-25.
  2. ^ "Sabbath of the Land". Retrieved 2016-09-06. It is a well-established agricultural fact that resting the land every seven years is best for the soil and that much-improved crops result from doing so. During this scriptural practice, there was to be no pruning or planting in the sabbath year, nor any attempt to kill the insects, or otherwise interfere with natural processes in the field. The fruit had to remain in the field, except for what passerby[sic], servants, or owners plucked to eat; no real harvesting was permitted, only eating.
  3. ^ a b c Organic Production: Using NRCS Practice Standards to Support Organic Growers (Report). Natural Resources Conservation Service. July 2009. |access-date= requires |url= (help)
  4. ^ a b Dufour, Rex (July 2015). Tipsheet: Crop Rotation in Organic Farming Systems (Report). National Center for Appropriate Technology. Retrieved May 4, 2016.
  5. ^ a b c d e Baldwin, Keith R. (June 2006). Crop Rotations on Organic Farms (PDF) (Report). Center for Environmental Farming Systems. Retrieved May 4, 2016.
  6. ^ a b c d e f g h i Johnson, Sue Ellen; Charles L. Mohler, (2009). Crop Rotation on Organic Farms: A Planning Manual, NRAES 177. Ithica, NY: National Resource, Agriculture, and Engineering Services (NRAES). ISBN 978-1-933395-21-0.
  7. ^ a b c d e f g h i j Coleman, Pamela (November 2012). Guide for Organic Crop Producers (PDF) (Report). National Organic Program. Retrieved May 4, 2016.
  8. ^ a b c Lamb, John; Craig Sheaffer & Kristine Moncada (2010). "Chapter 4 Soil Fertility". Risk Management Guide for Organic Producers (Report). University of Minnesota. |access-date= requires |url= (help)
  9. ^ a b "Green Manures". Royal Horticultural Society. Retrieved May 4, 2016.
  10. ^ a b L. H. Bailey, ed. (1907). "Chapter 5, "Crop Management,"". Cyclopedia of American Agriculture. pp. 85–88.
  11. ^ a b Gegner, Lance; George Kuepper (August 2004). "Organic Crop Production Overview". National Center for Appropriate Technology. Retrieved May 4, 2016.
  12. ^ Powell, J.M.; William, T.O. (1993). "An overview of mixed farming systems in sub-Saharan Africa". Livestock and Sustainable Nutrient Cycling in Mixed Farming Systems of Sub-Saharan Africa: Proceedings of an International Conference, International Livestock Centre for Africa (ILCA). 2: 21–36.
  13. ^ "§205.205 Crop rotation practice standard". CODE OF FEDERAL REGULATIONS. Retrieved May 4, 2016.
  14. ^ a b Mäder, Paul; et al. (2000). "Arbuscular mycorrhizae in a long-term field trial comparing low-input (organic, biological) and high-input (conventional) farming systems in a crop rotation". Biology and Fertility of Soils. 31: 150–156. doi:10.1007/s003740050638.
  15. ^ a b Triberti, Loretta; Anna Nastri & Guido Baldoni (2016). "Long-term effects of crop rotation, manure fertilization on carbon sequestration and soil fertility". European Journal of Agronomy. 74: 47–55. doi:10.1016/j.eja.2015.11.024.
  16. ^ Victoria, Reynaldo (2012). "The Benefits of Soil Carbon". Risk Management Guide for Organic Producers (Report). United Nations Environment Programme. |access-date= requires |url= (help)
  17. ^ Loynachan, Tom (December 1, 2016). "Nitrogen Fixation by Forage Legumes" (PDF). Iowa State University. Department of Agrology. Retrieved December 1, 2016.
  18. ^ Adjei et. al, M. B. (December 1, 2016). "Nitrogen Fixation and Inoculation of Forage Legumes" (PDF). Forage Beef. University of Florida. Retrieved December 1, 2016.
  19. ^ a b Moncada, Kristine; Craig Sheaffer (2010). "Chapter 2 Rotation". Risk Management Guide for Organic Producers (Report). University of Minnesota. |access-date= requires |url= (help)
  20. ^ Davies, Ken (March 2007). "Weed Control in Potatoes" (PDF). British Potato Council. Retrieved December 1, 2016.
  21. ^ Unger PW, McCalla TM (1980). "Conservation Tillage Systems". Advances in Agronomy. 33: 2–53. doi:10.1016/s0065-2113(08)60163-7.
  22. ^ Rose CW, Freebairn DM. "A mathematical model of soil erosion and deposition processes with application to field data".
  23. ^ Loch RJ, Foley JL (1994). "Measurement of Aggregate Breakdown under rain: comparison with tests of water stability and relationships with field measurements of infiltration". Australian Journal of Soil Research. 32: 701–720. doi:10.1071/sr9940701.
  24. ^ "Forages in Rotation" (PDF). Saskatchewan Soil Conservation Association. 2016. Retrieved December 1, 2016.
  25. ^ "Aggregate Stability". Natural Resources Conservation Centre. 2011. Retrieved December 1, 2016.
  26. ^ a b Carroll C, Halpin M, Burger P, Bell K, Sallaway MM, Yule DF (1997). "The effect of crop type, crop rotation, and tillage practice on runoff and soil loss on a Vertisol in central Queensland". Australian Journal of Soil Research. 35: 925–939. doi:10.1071/s96017.
  27. ^ Littleboy M, Silburn DM, Freebairn DM, Woodruff DR, Hammer GL (1989). "PERFECT. A computer simulation model of Productive Erosion Runoff Functions to Evaluate Conservation Techniques". Queensland Department of Primary Industries. Bulletin QB89005.
  28. ^ Huang M, Shao M, Zhang L, Li Y (2003). "Water use efficiency and sustainability of different long-term crop rotation systems in the Loess Plateau of China". Soil & Tillage Research. 72: 95–104. doi:10.1016/s0167-1987(03)00065-5.
  29. ^ Walker, Andy. "Cover crops have major role to play in soil health". peicanada.com. Retrieved 2016-12-01.
  30. ^ [1]
  31. ^ [2]

References

  • Anderson, R.L. 2005. Are some crops synergistic to following crops? Agron. J. 97:7-10
  • Bullock, D.G. 1992. Crop Rotation. Critical Reviews in Plant Sciences, 11:309-326
  • Francis, C.A. 2003. Advances in the design of resource-efficient cropping systems. Journal of Crop Production. 8:15-32
  • Porter et al. 1997. Environment affects the corn and soybean rotation effect. Agron. J. 89:441-448
  • White, L.T. 1962. Medieval Technology and Social Change. Oxford University Press

External links

Agriculture in Chad

In 2006 approximately 80% of Chad's labor force was employed in the agricultural sector. This sector of the economy accounted for almost half of the GDP. With the exception of cotton production, some small-scale sugar cane production, and a portion of the peanut crop, Chad's agriculture consisted of subsistence food production. The types of crops that were grown and the locations of herds were determined by considerable variations in Chad's climate.

Agronomy

Agronomy (from Ancient Greek ἀγρός agrós "field" and νόμος nómos "law") is the science and technology of producing and using plants for food, fuel, fiber, and land reclamation. Agronomy has come to encompass work in the areas of plant genetics, plant physiology, meteorology, and soil science. It is the application of a combination of sciences like biology, chemistry, economics, ecology, earth science, and genetics. Agronomists of today are involved with many issues, including producing food, creating healthier food, managing the environmental impact of agriculture, and extracting energy from plants. Agronomists often specialise in areas such as crop rotation, irrigation and drainage, plant breeding, plant physiology, soil classification, soil fertility, weed control, and insect and pest control.

British Agricultural Revolution

The British Agricultural Revolution, or Second Agricultural Revolution, was the unprecedented increase in agricultural production in Britain due to increases in labour and land productivity between the mid-17th and late 19th centuries. Agricultural output grew faster than the population over the century to 1770, and thereafter productivity remained among the highest in the world. This increase in the food supply contributed to the rapid growth of population in England and Wales, from 5.5 million in 1700 to over 9 million by 1801, though domestic production gave way increasingly to food imports in the nineteenth century as the population more than tripled to over 32 million. The rise in productivity accelerated the decline of the agricultural share of the labour force, adding to the urban workforce on which industrialization depended: the Agricultural Revolution has therefore been cited as a cause of the Industrial Revolution.

However, historians continue to dispute when exactly such a "revolution" took place and of what it consisted. Rather than a single event, G. E. Mingay states that there were a "profusion of agricultural revolutions, one for two centuries before 1750, another emphasising the century after 1650, a third for the period 1750-1880, and a fourth for the middle decades of the nineteenth century". This has led more recent historians to argue that any general statements about "the Agricultural Revolution" are difficult to sustain.One important change in farming methods was the move in crop rotation to turnips and clover in place of fallow. Turnips can be grown in winter and are deep-rooted, allowing them to gather minerals unavailable to shallow-rooted crops. Clover fixes nitrogen from the atmosphere into a form of fertiliser. This permitted the intensive arable cultivation of light soils on enclosed farms and provided fodder to support increased livestock numbers whose manure added further to soil fertility.

Drummond, New Brunswick

Drummond is a Canadian village in Victoria County, New Brunswick. Its population as of the Canada 2006 Census is 839, with roughly 95% of its residents being Francophone

It is located in rolling farmland approximately 5 kilometres southeast of Grand Falls. Drummond's economy is centred on the potato industry, and cereal crops such as wheat, barley and oats are grown mainly through crop rotation. More than 50% of the potatoes grown are sold for processing to McCain Foods Limited, and 45% are grown as seed potatoes for inter-provincial and international export.

Ear (botany)

An ear is the grain-bearing tip part of the stem of a cereal plant, such as wheat or maize. It can also refer to "a prominent lobe in some leaves".The ear is a spike, consisting of a central stem on which tightly packed rows of flowers grow. These develop into fruits containing the edible seeds. In corn, it is protected by leaves called husks.In some species (including wheat), unripe ears contribute significantly to photosynthesis, in addition to the leaves lower down the plant.

A parasite known as Anguina tritici (Ear Cockle) specifically affects the ears on wheat and rye by destroying the tissues and stems during growth. With the exception of North Africa and West Asia, the parasite has been eradicated in all countries by using the

crop rotation system.

Farming systems in India

Farming Systems in India are strategically utilised, according to the locations where they are most suitable. The farming systems that significantly contribute to the agriculture of India are subsistence farming, organic farming, industrial farming. Regions throughout India differ in types of farming they use; some are based on horticulture, ley farming, agroforestry, and many more. Due to India's geographical location, certain parts experience different climates, thus affecting each region's agricultural productivity differently. India is very dependent on its monsoon cycle for large crop yields. India's agriculture has an extensive background which goes back to at least 10 thousand years. Currently the country holds the second position in agricultural production in the world. In 2007, agriculture and other industries made up more than 16% of India's GDP. Despite the steady decline in agriculture's contribution to the country's GDP, agriculture is the biggest industry in the country and plays a key role in the socioeconomic growth of the country. India is the second biggest producer of wheat, rice, cotton, sugarcane, silk, groundnuts, and dozens more. It is also the second biggest harvester of vegetables and fruit, representing 8.6% and 10.9% of overall production, respectively. The major fruits produced by India are mangoes, papayas, sapota, and bananas. India also has the biggest number of livestock in the world, holding 281 million. In 2008, the country housed the second largest number of cattle in the world with 175 million.

Guar

The guar or cluster bean, with the botanical name Cyamopsis tetragonoloba, is an annual legume and the source of guar gum. It is also known as gavar, guwar, or guvar bean.

The origin of Cyamopsis tetragonoloba is unknown, since it has never been found in the wild. It is assumed to have developed from the African species Cyamopsis senegalensis. It was further domesticated in India and Pakistan, where it has been cultivated for centuries.

Guar grows well in semiarid areas, but frequent rainfall is necessary.

This legume is a valuable plant in a crop rotation cycle, as it lives in symbiosis with nitrogen-fixing bacteria.

Agriculturists in semi-arid regions of Rajasthan follow crop-rotation and use guar to replenish the soil with essential fertilizers and nitrogen fixation, before the next crop. Guar has many functions for human and animal nutrition, but the gelling agent in its seeds (guar gum) are the most important use. Demand is rising due to the use of guar gum in hydraulic fracturing (oil shale gas). About 80% of world production occurs in India and Pakistan, but due to strong demand, the plant is being introduced elsewhere.

Heterodera schachtii

Heterodera schachtii (Beet cyst eelworm, Sugarbeet nematode) is a plant pathogenic nematode. It infects more than 200 different plants including economically important crops such as sugar beets, cabbage, broccoli, and radish. H. schachtii is found worldwide. Affected plants are marked by stunted growth, wilting, yellowing, decreased yields, and death. While there are many methods of control, crop rotation with non-susceptible plants is preferred.

Hillbilly tomato

The Hillbilly Tomato, also known as the "hillbilly potato leaf tomato", scientific name Solanum lycopersicum, is an heirloom cultivar originating from West Virginia in the 1800s. This fruit is considered a beefsteak tomato weighing 1-2 pounds. It is round, heavily ribbed and its skin and flesh is orange- yellow with red streaks. The flavor is described "sweet and fruity" and is low in acid. The Hillbilly tomato plant stands anywhere from 52"-84" tall when fully established, needing 85-94 days of growth before it reaches its full maturity. The plant is a low maintenance crop and does not require extra attention as long as it is planted properly, particularly after any season of frost. It requires full sun with a minimum of six hours daily. This plant also requires water but is drought tolerant, and mulching can help to ensure an even supply of moisture to the tomato plant. There are some problems that may occur with the hillbilly tomato plant which include pests and diseases. You can control some of these problems by crop rotation.

Intensive farming

Intensive farming involves various types of agriculture with higher levels of input and output per cubic unit of agricultural land area. It is characterized by a low fallow ratio, higher use of inputs such as capital and labour, and higher crop yields per cubic unit land area. This contrasts with traditional agriculture, in which the inputs per unit land are lower. The term "intensive" involves various meanings, some of which refer to organic farming methods (such as biointensive agriculture and French intensive gardening), and others that refer to nonorganic and industrial methods. Intensive animal farming involves either large numbers of animals raised on limited land, usually concentrated animal feeding operations (CAFOs), often referred to as factory farms, or managed intensive rotational grazing (MIRG), which has both organic and non-organic types. Both increase the yields of food and fiber per acre as compared to traditional animal husbandry. In CAFO, feed is brought to the seldom-moved animals, while in MIRG the animals are repeatedly moved to fresh forage.

Most commercial agriculture is intensive in one or more ways. Forms that rely heavily on industrial methods are often called industrial agriculture, which is characterised by innovations designed to increase yield. Techniques include planting multiple crops per year, reducing the frequency of fallow years, and improving cultivars. It also involves increased use of fertilizers, plant growth regulators, and pesticides and mechanised agriculture, controlled by increased and more detailed analysis of growing conditions, including weather, soil, water, weeds, and pests. This system is supported by ongoing innovation in agricultural machinery and farming methods, genetic technology, techniques for achieving economies of scale, logistics, and data collection and analysis technology. Intensive farms are widespread in developed nations and increasingly prevalent worldwide. Most of the meat, dairy, eggs, fruits, and vegetables available in supermarkets are produced by such farms.

Smaller intensive farms usually include higher inputs of labor and more often use sustainable intensive methods. The farming practices commonly found on such farms are referred to as appropriate technology. These farms are less widespread in both developed countries and worldwide, but are growing more rapidly. Most of the food available in specialty markets such as farmers markets is produced by these small holder farms.

Islandmagee

Islandmagee (from Irish: Oileán Mhic Aodha, meaning "Magee’s island/peninsula") is a peninsula and civil parish on the east coast of County Antrim, Northern Ireland, located between the towns of Larne and Whitehead. It is part of the Mid and East Antrim Borough Council area and is a sparsely populated rural community with a long history since the mesolithic period. In the early medieval period it was known as Semne, a petty-kingdom within Ulaid.

As part of an agricultural crop rotation programme of old, beans were grown to supply nitrogen to the soil. "Bean Eaters" became a nickname for the people of Islandmagee.

.

It is the site of Northern Ireland's main power station Ballylumford and the endpoint of the Scotland-Northern Ireland gas pipeline.

Legume

A legume () is a plant in the family Fabaceae (or Leguminosae), or the seed of such a plant (also called pulse). Legumes are grown agriculturally, primarily for human consumption, for livestock forage and silage, and as soil-enhancing green manure. Well-known legumes include alfalfa, clover, peas, chickpeas, lentils, lupin bean, mesquite, carob, soybeans, peanuts and tamarind.

A legume fruit is a simple dry fruit that develops from a simple carpel and usually dehisces (opens along a seam) on two sides. A common name for this type of fruit is a pod, although the term "pod" is also applied to a number of other fruit types, such as that of vanilla (a capsule) and of the radish (a silique).

Legumes are notable in that most of them have symbiotic nitrogen-fixing bacteria in structures called root nodules. For that reason, they play a key role in crop rotation.

Monoculture

Monoculture is the agricultural practice of producing or growing a single crop, plant, or livestock species, variety, or breed in a field or farming system at a time. Polyculture, where more than one crop is grown in the same space at the same time, is the alternative to monoculture. Monoculture is widely used in both industrial farming and organic farming and has allowed increased efficiency in planting and harvest.

Continuous monoculture, or monocropping, where the same species is grown year after year, can lead to the quicker buildup of pests and diseases, and then rapid spread where a uniform crop is susceptible to a pathogen. The practice has been criticized for its environmental effects and for putting the food supply chain at risk. Diversity can be added both in time, as with a crop rotation or sequence, or in space, with a polyculture.

Oligoculture has been suggested to describe a crop rotation of just a few crops, as is practiced by several regions of the world.The term monoculture is frequently applied for other uses to describe any group dominated by a single variety, e.g. social monoculturalism, or in the field of musicology to describe the dominance of the American and British music-industries in Western pop music, or in the field of computer science to describe a group of computers all running identical software.

Row crop

A row crop is a crop that can be planted in rows wide enough to allow it to be tilled or otherwise cultivated by agricultural machinery, machinery tailored for the seasonal activities of row crops. Such crops are sown by drilling rather than broadcasting.

The distinction is significant in crop rotation strategies, where land is planted with row crops, commodity food grains, and sod-forming crops in a sequence meant to protect the quality of the soil while maximizing the soil's annual productivity.Row crops are generally grown on irrigated land, and some, such as cotton, can be grown only under irrigation. During the growing season, the interrow spaces are hoed two to four times and the rows are weeded to conserve moisture and improve aeration. As a result, the soil’s microbiological activity increases and mobilization of nutrients is intensified. Row crops are valuable precursors of spring grain crops, flax, and hemp. The beneficial effect of row crops extends to the second crop.

Examples of row crops include

sunflower,

potato,

canola,

dry bean,

field pea,

flax,

safflower,

buckwheat,

cotton,

maize,

soybeans, and

sugar beets.

Soil conservation

Soil conservation is the preventing of soil loss from erosion or reduced fertility caused by over usage, acidification, salinization or other chemical soil contamination.

Slash-and-burn and other unsustainable methods of subsistence farming are practiced in some lesser developed areas. A sequel to the deforestation is typically large scale erosion, loss of soil nutrients and sometimes total desertification. Techniques for improved soil conservation include crop rotation, cover crops, conservation tillage and planted windbreaks and affect both erosion and fertility. When plants, especially trees, die, they decay and become part of the soil. Code 330 defines standard methods recommended by the U.S. Natural Resources Conservation Service.

Farmers have practiced soil conservation for millennia. In Europe, policies such as the Common Agricultural Policy are targeting the application of best management practices such as reduced tillage, winter cover crops, plant residues and grass margins in order to better address the soil conservation.Political and economic action is further required to solve the erosion problem. A simple governance hurdle concerns how we name and value the land and what we call it and this can be changed by cultural adaptation.

Strip farming

Strip cropping is a method of farming which involves cultivating a field partitioned into long, narrow strips which are alternated in a crop rotation system. It is used when a slope is too steep or when there is no alternative method of preventing soil erosion. The most common crop choices for strip cropping are closely sown crops such as hay, wheat, or other forages which are alternated with strips of row crops, such as corn, soybeans, cotton, or sugar beets. The forages serve primarily as cover crops. In certain systems, strips in particularly eroded areas are used to grow permanent protective vegetation; in most systems, however, all strips are alternated on an annual basis.

Three-field system

The three-field system is a regime of crop rotation that was used in medieval and early-modern Europe. Crop rotation is the practice of growing a series of different types of crops in the same area in sequential seasons.

The three field system let farmers plant more crops and therefore increase production. Under this system, the arable land of an estate or village was divided into three large fields: one was planted in the autumn with winter wheat or rye; the second field was planted with other crops such as peas, lentils, or beans; and the third was left fallow (unplanted). Cereal crops deplete the ground of nitrogen, but legumes can fix nitrogen and so fertilize the soil. The fallow fields were soon overgrown with weeds and used for grazing farm animals. Their excrement fertilized that field's soil to regain its nutrients. Crop assignments were rotated every year, so each field segment would be planted for two out of every three years.

Previously a "two field system" had been in place, with half the land being left fallow. With more crops available to sell and agriculture dominating the economy at the time, the three-field system created a significant surplus and increased economic prosperity.The three field system needed more plowing of land and its introduction coincided with the adoption of the moldboard plow. These parallel developments complemented each other and increased agricultural productivity. The legume crop needed summer rain to succeed, and so the three-field system was less successful around the Mediterranean. Oats for horse food could also be planted in the spring, which, combined with the adoption of horse collars and horseshoes, led to replacement of oxen by horses for many farming tasks, with an associated increase in agricultural productivity and the nutrition available to the population.One of the first Germans to question this system, and new ways of expanding beyond this medieval system was Johann Friedrich Mayer, in his 1769 work Lehre vom Gyps als vorzueglich guten Dung zu allen Erd-Gewaechsen auf Aeckern und Wiesen, Hopfen- und Weinbergen.

Waasland

The Waasland is a Belgian region. It is part of the Belgian provinces of East Flanders and Antwerp. The other borders of the Land van Waas are with the Scheldt and Durme rivers. The (informal) capital and major city of the region is Sint-Niklaas.

It is also called the Land van Waas (Land of Waas); Waas most likely refers to the soggy soil of the region although the exact etymology is unknown. One possibility is a connection to the English word "wasteland". The swamps that characterized it have long been drained although many fields are still noticeably convex; the result of many years of plowing the topsoil towards the center to improve drainage.

Historically, on account of its waterlogged, poor soils the region was thinly populated in comparison to the rest of Belgium and agriculture was by necessity based on holder farms using innovative techniques not usually applied elsewhere even if the farmers had ready markets nearby in the cities of Ghent and Antwerp. Charles Townshend, one of the proponents of the early agricultural revolution was an explicit advocate of agricultural practices first developed here in Belgium, such as the use of turnips in crop rotation, and the region for some time attracted study trips by early agriculturists in his wake.

The epic tale of the fox Reynard is set in the region.

The surname "Waas" and variants thereof is quite common in Belgium and refers to this region.

Weed control

Weed control is the botanical component of pest control, which attempts to stop weeds, especially noxious or injurious weeds, from competing with desired flora and fauna, this includes domesticated plants and livestock, and in natural settings, it includes stopping non local species competing with native, local, species, especially so in reserves and heritage areas.

Weed control is important in agriculture. Many strategies have been developed in order to contain these plants. Methods include hand cultivation with hoes, powered cultivation with cultivators, smothering with mulch, lethal wilting with high heat, burning, and chemical attack with herbicides (weed killers).

A plant is often termed a "weed" when it has one or more of the following characteristics:

Little or no recognized value (as in medicinal, material, nutritional or energy)

Rapid growth and/or ease of germination

Competitive with crops for space, light, water and nutrientsThe definition of a weed is completely context-dependent. To one person, one plant may be a weed, and to another person it may be a desirable plant. In one place, a plant may be viewed as a weed, whereas in another place, the same plant may be desirable.

This page is based on a Wikipedia article written by authors (here).
Text is available under the CC BY-SA 3.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.