Organic agriculture and companion planting
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Organic agriculture and companion planting |
Key words, tags- Organic Agriculture, Companion planting, organic essential oilsCompiled by Gurpreet Singh at earthyflavorance.bizAbstractCompanion planting is based on the idea that certain plants can benefit others when planted in near proximity. Thus, its implication for ORGANIC AGRICULTURE needs to be well understood for its incorporation.My last blog detailed the salient features of ORGANIC CERTIFICATION.Companion planting can be described as the establishment of two or more plant species in close proximity so that some cultural benefit (pest control, higher yield, etc.) is derived. The concept embraces a number of strategies that increase the biodiversity of agro-ecosystems, on the theory that they assist each other in nutrient uptake, pest control, pollination, and other factors necessary to increasing crop productivity.Companion planting is used by farmers and gardeners in both industrialized and developing countries for many reasons. Many of the modern principles of companion planting were present many centuries ago in cottage gardens in England and Home gardens in Asia.Companion planting is considered to be a form of polyculture.Companion planting has applications to commercial horticultural and agronomic crops, specially, organic agriculture systems, where-in, there is a restriction on use of chemicals insecticides.HistoryIn China, the mosquito fern has been used for at least one thousand years, as a companion plant for rice crops. It hosts a special cyanobacteria that fixes nitrogen from the atmosphere, and also blocks out light from getting to any competing plants, aside from the rice, which is planted when tall enough to stick out of the water above the azolla layer.Companion planting was practiced in various forms by Native Americans prior to the arrival of Europeans. One common system was the planting of corn (maize) and pole beans together. The cornstalk would serve as a trellis for the beans to climb while the beans would fix nitrogen for the corn. The inclusion of squash with these two plants completes the Three Sisters technique, pioneered by Native American peoples.Companion planting was widely touted in the 1970s as part of the organic gardening movement[citation needed]. It was encouraged for pragmatic reasons, such as natural trellising, but mainly with the idea that different species of plant may thrive more when close together[citation needed]. It is also a technique frequently used in permaculture, together with mulching, polyculture, and changing of crops.While companion planting has a long history, the mechanisms of beneficial plant interaction have not always been well understood. some of the recommendations for companion planting, made around the middle of this century, were based on the results of sensitive crystallization tests.Originally developed by Dr. Ehrenfried Pfeiffer, sensitive crystallization testing entails the mixing of plant extracts with select salt reagents like sodium sulfate or copper chloride. The resulting solution is placed in a controlled environment chamber and allowed to evaporate slowly. The process results in a precipitate that often takes on beautiful geometric forms and patterns. The characteristics of the pattern are studied and interpreted to establish whether the plants are likely to interact well with each other (1). Sensitive crystallization appeals to practitioners of Biodynamics™ (BD) and others who take a more metaphysical approach to nature. Conventional science is much more skeptical of this process as a means to evaluate plant associations.Host-finding disruptionRecent studies on host-plant finding have shown that flying pests are far less successful if their host-plants are surrounded by any other plant or even "decoy-plants" made of green plastic, cardboard, or any other green material.The host-plant finding process occurs in phases: * The first phase is stimulation by odours characteristic to the host-plant. This induces the insect to try to land on the plant it seeks. But insects avoid landing on brown (bare) soil. So if only the host-plant is present, the insects will quasi-systematically find it by simply landing on the only green thing around. This is called (from the point of view of the insect) "appropriate landing." When it does an "inappropriate landing," it flies off to any other nearby patch of green. It eventually leaves the area if there are too many 'inappropriate' landings.
* The second phase of host-plant finding is for the insect to make short flights from leaf to leaf to assess the plant's overall suitability. The number of leaf-to-leaf flights varies according to the insect species and to the host-plant stimulus received from each leaf. The insect must accumulate sufficient stimuli from the host-plant to lay eggs; so it must make a certain number of consecutive 'appropriate' landings. Hence if it makes an 'inappropriate landing', the assessment of that plant is negative, and the insect must start the process anew.Thus it was shown that clover used as a ground cover had the same disruptive effect on eight pest species from four different insect orders. An experiment showed that 36% of cabbage root flies laid eggs beside cabbages growing in bare soil (which resulted in no crop), compared to only 7% beside cabbages growing in clover (which allowed a good crop). Simple decoys made of green cardboard also disrupted appropriate landings just as well as did the live ground cover.The Scientific Foundations for Companion PlantingWhile conventional agriculturalists and BD practitioners may disagree over the validity of sensitive crystallization research, there is general agreement today on the validity of several mechanisms that create beneficial plant associations
Trap CroppingSometimes, a neighboring crop may be selected because it is more attractive to pests and serves to distract them from the main crop. An excellent example of this is the use of collards to draw the diamond back moth away from cabbage (2).
Symbiotic Nitrogen FixationLegumes—such as peas, beans, and clover—have the ability to fix atmospheric nitrogen for their own use and for the benefit of neighboring plants via symbiotic relationship with Rhizobium bacteria. Forage legumes, for example, are commonly seeded with grasses to reduce the need for nitrogen fertilizer. Likewise, beans are sometimes inter-planted with corn.Biochemical Pest SuppressionSome plants exude chemicals from roots or aerial parts that suppress or repel pests and protect neighboring plants. The African marigold, for example, releases thiopene—a nematode repellent—making it a good companion for a number of garden crops. The manufacture and release of certain biochemicals is also a factor in plant antagonism. Allelochemicals such as juglone—found in black walnut—suppress the growth of a wide range of other plants, which often creates a problem in home horticulture. A positive use of plant allelopathy is the use of mow-killed grain rye as a mulch. The allelochemicals that leach from rye residue prevent weed germination but do not harm transplanted tomatoes, broccoli, or many other vegetables.Physical Spatial InteractionsFor example, tall-growing, sun-loving plants may share space with lower-growing, shade-tolerant species, resulting in higher total yields from the land. Spatial interaction can also yield pest control benefits. The diverse canopy resulting when corn is companion-planted with squash or pumpkins is believed to disorient the adult squash vine borer and protect the vining crop from this damaging pest. In turn, the presence of the prickly vines is said to discourage raccoons from ravaging the sweet corn.Nurse CroppingTall or dense-canopied plants may protect more vulnerable species through shading or by providing a windbreak. Nurse crops such as oats have long been used to help establish alfalfa and other forages by supplanting the more competitive weeds that would otherwise grow in their place. In many instances, nurse cropping is simply another form of physical-spatial interaction.Beneficial HabitatsBeneficial habitats—sometimes called refugia—are another type of companion plant interaction that has drawn considerable attention in recent years. The benefit is derived when companion plants provide a desirable environment for beneficial insects and other arthropods—especially those predatory and parasitic species which help to keep pest populations in check. Predators include ladybird beetles, lacewings, hover flies, mantids, robber flies, and non-insects such as spiders and predatory mites. Parasites include a wide range of fly and wasp species including tachinid flies, and Trichogramma and ichneumonid wasps. Agroecologists believe that by developing systems to include habitats that draw and sustain beneficial insects, the twin objectives of reducing both pest damage and pesticide use can be attained.Security Through DiversityA more general mixing of various crops and varieties provides a degree of security to the grower. If pests or adverse conditions reduce or destroy a single crop or cultivar, others remain to produce some level of yield. Furthermore, the simple mixing of cultivars, at times can reduce pest infestation.Options For System DesignAgronomists use the term "intercropping" to describe the spatial arrangements of companion planting systems. Intercropping systems range from mixed intercropping to large-scale strip intercropping. Mixed intercropping is commonly seen in traditional gardens where two or more crops are grown together without a distinct row formation. Strip intercropping is designed with two or more crops grown together in distinct rows to allow for mechanical crop production. No-till planting or transplanting into standing cover crops can be considered another form of intercroppingOther Miscellaneous BenefitsFlavor enhancement — some plants, especially herbs, seem to subtly change the flavor of other plants around them.Hedged investment — multiple plants in the same space increase the odds of some yield being given, even if one category encounters catastrophic issues.Increased level interaction — plants that grow on different levels in the same space, perhaps providing ground cover or working as a trellis for another plantPollinator and predator recruitment — The use of plants that produce copious nectar and protein-rich pollen in a vegetable garden (insectary plants) is a good way to recruit higher populations of beneficial insects that control pests. Some insects in the adult form are nectar or pollen feeders, while in the larval form they are voracious predators of pest insects.Positive hosting — attracts or is inhabited by beneficial insects or other organisms which benefit plants, as with ladybugs or some "good nematodes"Protective shelter — one type of plant may serve as a wind break or shade for anotherPattern disruption — in a monoculture, pest spread from one plant to the next, is interrupted by companion plantsTechnorati Tags: organic agriculture,companion planting,earthyflavorance.biz
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* The second phase of host-plant finding is for the insect to make short flights from leaf to leaf to assess the plant's overall suitability. The number of leaf-to-leaf flights varies according to the insect species and to the host-plant stimulus received from each leaf. The insect must accumulate sufficient stimuli from the host-plant to lay eggs; so it must make a certain number of consecutive 'appropriate' landings. Hence if it makes an 'inappropriate landing', the assessment of that plant is negative, and the insect must start the process anew.Thus it was shown that clover used as a ground cover had the same disruptive effect on eight pest species from four different insect orders. An experiment showed that 36% of cabbage root flies laid eggs beside cabbages growing in bare soil (which resulted in no crop), compared to only 7% beside cabbages growing in clover (which allowed a good crop). Simple decoys made of green cardboard also disrupted appropriate landings just as well as did the live ground cover.The Scientific Foundations for Companion PlantingWhile conventional agriculturalists and BD practitioners may disagree over the validity of sensitive crystallization research, there is general agreement today on the validity of several mechanisms that create beneficial plant associations
Trap CroppingSometimes, a neighboring crop may be selected because it is more attractive to pests and serves to distract them from the main crop. An excellent example of this is the use of collards to draw the diamond back moth away from cabbage (2).
Symbiotic Nitrogen FixationLegumes—such as peas, beans, and clover—have the ability to fix atmospheric nitrogen for their own use and for the benefit of neighboring plants via symbiotic relationship with Rhizobium bacteria. Forage legumes, for example, are commonly seeded with grasses to reduce the need for nitrogen fertilizer. Likewise, beans are sometimes inter-planted with corn.Biochemical Pest SuppressionSome plants exude chemicals from roots or aerial parts that suppress or repel pests and protect neighboring plants. The African marigold, for example, releases thiopene—a nematode repellent—making it a good companion for a number of garden crops. The manufacture and release of certain biochemicals is also a factor in plant antagonism. Allelochemicals such as juglone—found in black walnut—suppress the growth of a wide range of other plants, which often creates a problem in home horticulture. A positive use of plant allelopathy is the use of mow-killed grain rye as a mulch. The allelochemicals that leach from rye residue prevent weed germination but do not harm transplanted tomatoes, broccoli, or many other vegetables.Physical Spatial InteractionsFor example, tall-growing, sun-loving plants may share space with lower-growing, shade-tolerant species, resulting in higher total yields from the land. Spatial interaction can also yield pest control benefits. The diverse canopy resulting when corn is companion-planted with squash or pumpkins is believed to disorient the adult squash vine borer and protect the vining crop from this damaging pest. In turn, the presence of the prickly vines is said to discourage raccoons from ravaging the sweet corn.Nurse CroppingTall or dense-canopied plants may protect more vulnerable species through shading or by providing a windbreak. Nurse crops such as oats have long been used to help establish alfalfa and other forages by supplanting the more competitive weeds that would otherwise grow in their place. In many instances, nurse cropping is simply another form of physical-spatial interaction.Beneficial HabitatsBeneficial habitats—sometimes called refugia—are another type of companion plant interaction that has drawn considerable attention in recent years. The benefit is derived when companion plants provide a desirable environment for beneficial insects and other arthropods—especially those predatory and parasitic species which help to keep pest populations in check. Predators include ladybird beetles, lacewings, hover flies, mantids, robber flies, and non-insects such as spiders and predatory mites. Parasites include a wide range of fly and wasp species including tachinid flies, and Trichogramma and ichneumonid wasps. Agroecologists believe that by developing systems to include habitats that draw and sustain beneficial insects, the twin objectives of reducing both pest damage and pesticide use can be attained.Security Through DiversityA more general mixing of various crops and varieties provides a degree of security to the grower. If pests or adverse conditions reduce or destroy a single crop or cultivar, others remain to produce some level of yield. Furthermore, the simple mixing of cultivars, at times can reduce pest infestation.Options For System DesignAgronomists use the term "intercropping" to describe the spatial arrangements of companion planting systems. Intercropping systems range from mixed intercropping to large-scale strip intercropping. Mixed intercropping is commonly seen in traditional gardens where two or more crops are grown together without a distinct row formation. Strip intercropping is designed with two or more crops grown together in distinct rows to allow for mechanical crop production. No-till planting or transplanting into standing cover crops can be considered another form of intercroppingOther Miscellaneous BenefitsFlavor enhancement — some plants, especially herbs, seem to subtly change the flavor of other plants around them.Hedged investment — multiple plants in the same space increase the odds of some yield being given, even if one category encounters catastrophic issues.Increased level interaction — plants that grow on different levels in the same space, perhaps providing ground cover or working as a trellis for another plantPollinator and predator recruitment — The use of plants that produce copious nectar and protein-rich pollen in a vegetable garden (insectary plants) is a good way to recruit higher populations of beneficial insects that control pests. Some insects in the adult form are nectar or pollen feeders, while in the larval form they are voracious predators of pest insects.Positive hosting — attracts or is inhabited by beneficial insects or other organisms which benefit plants, as with ladybugs or some "good nematodes"Protective shelter — one type of plant may serve as a wind break or shade for anotherPattern disruption — in a monoculture, pest spread from one plant to the next, is interrupted by companion plantsTechnorati Tags: organic agriculture,companion planting,earthyflavorance.biz