Companion planting /intercropping

Companion Planting Mechanisms” diagram by Chiswick Chap, CC BY-SA 4.0, via Wikimedia Commons.

Companion planting is a method of planting groups of different plants together in a mutually beneficial way. These plantings can contain both annual and perennial crops, and can be used in various forms of agriculture, including home gardens, market gardening, agroforestry, orchards, and food-forests. The most well-known example is the “three sisters” (corn, beans, and squash) with origins in Indigenous Mesoamerica (Klopotek et al., 2023). In the three sisters, corn provides a structure, beans provide nitrogen fixation to increase soil fertility, and squash provides a ground cover layer that shades the soil, retaining moisture.

In a companion planted garden there can be multiple interactions between plants, the soil, microorganisms, and their environment (Reddy, 2017). These are often complex, but essentially constitute a planted ecosystem in which all the components are supporting the health and vitality of one another.

Companion planting is an umbrella term that encompasses several different methodologies. These include:

  • Annual companion planting: Planting two or more annual plants (usually herbs and vegetable crops) together in the same space for mutual benefits.
  • Intercropping: Planting a row or bed of a companion species between the main crop.
  • Trap cropping: Planting a crop attractive to pests, for the benefit of the main crop. The concentration of pests can then be managed accordingly (such as physical removal of the trap crop and pest).
  • Push-pull strategies: Push-pull plantings include a pest repelling (push) plant and a pest attracting trap (pull) plant.
  • Alley cropping: Planting a diverse system of trees, shrubs, herbs, and annual plants together in long rows.
  • Agroforestry: Planting a main tree crop or crops together with a productive or supporting understory layer of perennial and annual crops, shrubs, and herbs. A planting which is modelled from a natural forest system.
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Name of NbS

Polyculture and Companion Planting

Type of NbS

Created or constructed living ecosystems

Location

  • Urban
  • Peri-urban
  • Rural

Companion planting can occur in any context, with examples in Te Moananui Oceania of practices similar to companion planting occurring in urban and peri-urban farms and gardens, as well as rural areas (Clarke et al., 1993; Fotsing et al., 2023; Suiyanata, 2002; Thaman et al., 2006). Companion planting strategies can be employed at any garden size, from a home garden scale to commercial scale agriculture. In Te Moananui Oceania gardening predominantly takes place in the surroundings of a town or village, especially in regions where a subsistence lifestyle still prevails.

Case study:

OMG (Organic Market Garden) Urban Farm

Companion planting” showing zucchini, planted with calendula and other companion plants. By Brian Pettinger, CC BY-NC-SA 2.0 via flickr.

Relationship to Indigenous knowledge

Companion planting as an agriculture practice has existed for thousands of years, with examples of the practice in many cultures around the world. Companion planting experienced a resurgence of popularity with the increase in interest in organic gardening since the 1970s. Companion planting advice is often found in garden guides and almanacs and based on common annual crops. Although it is not often described specifically, there are examples of the practice in Te Moananui Oceania. Some Moananui Oceanic people practice agroforestry, a practice with many similarities to companion planting. Quintus et al. (2019) gives an example in Tikopia, a ‘Polynesian outlier’ under the jurisdiction of Solomon Islands, where a number of tree crops (notably breadfruit and coconut) are grown in permanent multi-story gardens with an understory of banana, taro and yam, mimicking the islands natural forest. Gardening practices in which plants are arranged in a mutually beneficial way do appear to be component of Indigenous gardening knowledge in some parts of Te Moananui Oceania (Clarke et al., 1993), even if it is not explicitly described as “companion planting”.

Climate change benefits
  • Biomass cover loss
  • Changes in rainfall
  • Freshwater flooding (Misty creek)
  • Increased incidence / distribution of disease
  • Increased pests or spread of weeds
  • Loss of food production
  • Reduced soil quality
  • Wind damage

Companion planting discourages biomass cover loss by encouraging diverse systems which mimic natural ecosystems. Revitalisation of traditional gardening practices in combination with more modern sustainable agriculture practices like companion planting is part of a movement away from the extractive resource and food production practice experienced in many places since the 1800s and the arrival of Europeans in Te Moananui Oceania (Quintus et al., 2019).

Companion planting employs the natural properties of plants to repel, attract or confuse pests. Companion planting systems also promote diversity, and can create more desirable conditions for target plants, reducing the likelihood of disease or spread of disease. Spread of weeds can also be managed by companion planting by ensuring that soil is covered with desirable plants, and that the desirable plants are supported by one another. If soil is occupied by plant roots, and shaded, and if desirable plants are healthy, fewer weeds establish (Reddy, 2017). 

Companion planting can mitigate the adverse effects of changes in rainfall by regulating soil shading and moisture. Maintaining healthy, living soil protects the moisture holding capacity and structure of the topsoil layer. Improved soil structure and the stability that comes with many roots in the soil also means less erosion occurs in high winds or flood events (Reddy, 2017). Diverse plantings are less susceptible overall to wind and flood damage, because of the structural support that multiple species generate (i.e. one plant climbing or being held up by another).
Companion planting can reduce loss of food production by providing a secondary harvest in the case that the main crop fails. Companion planting’s additional benefits of reduction of pest and disease pressure, and increased adaptability to environmental events, like those induced by climate change, means overall, food production is supported.

Companion planting can improve soil physically and chemically. Some plants such as legumes (including beans, peas) fix atmospheric nitrogen into the soil in a process facilitated by a plant symbiotic soil bacteria (Wagner, 2011). Roots can physically improve soil quality by breaking up or tying together soils particles, and if left to biodegrade in the ground, introducing organic matter to the soil (Reddy, 2017). Plants also release exudates from their roots which promote soil microbiology and tie together soil aggregates, which are hallmarks of healthy soil

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Societal / socio-cultural benefits
  • Climate change adaption
  • Food security and quality

Companion planting supports climate change adaptation by encouraging nature-based solutions to numerous challenges that climate change introduces to horticulture. It is a cultural method, meaning that it fundamentally requires a change of thinking and practice, but the principles of companion planting work mostly with complex biological and chemical processes which occur between plants, soil, insects, and other organisms (both beneficial and disease causing), and the environment (Reddy, 2017). By mitigating many climate change related challenges, and working in a manner that recognizes and implements natural interactions and a relationship the natural processes, food security and quality are improved.

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Ecological and biodiversity benefits
  • Aesthetic value
  • Biological control
  • Climate regulation
  • Disturbance prevention
  • Food production (for humans)
  • Genetic resources (diversity)
  • Habitat provision
  • Nutrient cycling
  • Soil building

Companion planting incorporates plants of varying textures, colours and flowering periods increasing aesthetic value to people and beneficial insects like butterflies and bees. Various plants work as biological control agents, repelling, attracting or confusing insect pests. Climate regulation can occur in companion planted agriculture, in which layered plantings are employed (Reddy, 2017). Taller plants create a shaded environment for a lower growing species below, which in turn acts as a living mulch to lower soil temperature and maintain soil moisture. Companion planted gardens are more diverse than monocultures (plantings of a single crop) and can provide multiple harvests from the same area. They also allow people to maintain and cultivate more plant species and varieties, and to maintain open pollinated seed types which contribute to the maintenance of locally adapted and genetically diverse heritage plant types. Equally, a diverse agricultural system supports a greater diversity of insects and other organisms. Habitat can be provisioned by a companion planting system, such as planting of umbelliferous plants for butterflies and pollinating insects. Nutrient cycling is provided by companion plants which fix nitrogen, those which take up alternative soil nutrients, or which can be mulched or dug into the soil after harvesting (Reddy, 2017). These methodologies build soil by introducing organic matter from the natural properties of companion species.

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Agroforestry – Tonga” showing Tannia and Taro planted under a fabaceous (nitrogen fixing) tree. By Vilimaka Foliaki, CC BY-SA 2.0 via flickr.
Companion planting” showing Scarlet Runner Beans growing supported by a flowering corn stalk. By Lynne Hand, CC BY-NC-ND 2.0 via flickr.

Technical requirements

and therefore requires careful planning and scheduling. Plants can have different growth rates and habits and must be propagated and planted in specific time frames. The effects of companion planting can vary in differing conditions, so developing companion planting techniques for a specific locality will take some time and repeated observation. Additional labour may also be required to establish and maintain companion planted gardens. More research is needed on companion planting and related practices to understand the mechanisms involved (Kuepper & Dodson, 2001)

Issues and Barriers

There are limited examples of explicit companion planting in Te Moananui Oceania, although layered gardening methods have existed in many parts of the Te Moananui Oceania for generations (Sherzad, 2018), and systems of agroforestry that exist in the area referred to as Polynesia have parallels (Thaman et al., 2006). Annual cropping can be more difficult in tropical regions due to the lack of distinct seasons, and long periods of high humidity encouraging fungal disease. Soil quality in much of Te Moananui Oceania is a limiting factor, there is often limited access to fresh water for agricultural use (SOURCE), and salinity of soil and ground water is increasing in many places (SOURCE).

The increasing incidence of destructive climate change related events (Lefale, 2010) means any agriculture is increasingly susceptible to damage from weather and hostile climate.

As Oceanic communities urbanise and imported products becomes more readily available, subsistence lifestyles including farming begin to be substituted by a reliance on imported foods (Fotsing et al., 2023).

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Opportunities

Companion planting offers generally better agricultural outcomes, with greater pest and disease resistance, improved resilience to weather and climate, and potentially lower maintenance cost (Reddy, 2017). Diverse yields are also provided from the same land area. Companion planting might mean more valuable crops are able to be grown, or overall yields are increased, increasing both food security and economic outcomes (Borron, 2006). Companion planted agriculture lowers or replaces the need for fertilisers, pesticides, or other industrial products (Reddy, 2017). Overall, companion planting can promote a more environmentally friendly, and economically sustainable agricultural sector.

Financial case

Companion planting systems like agroforestry can improve productivity (Feintrenie et al., 2015), this is particularly important for subsistence farmers and developing economies in Te Moananui Oceania. Agroforestry is also widely considered more sustainable in Te Moananui Oceania, requiring less labour, more diversified crops, and obtain greater yields (Clarke et al., 1993). Equally, agroforestry and other companion planting practices may require higher initial financial investment and time cost for the establishment of a system.

References
  • Borron, S. (2006). Building resilience for an unpredictable future: How organic agriculture can help farmers adapt to climate change. Food and Agriculture Organization of the United Nations. https://www.fao.org/documents/card/en?details=d736bbbe-d445-5f32-bfb0-1f7dec3d5530%2f
  • Clarke, W. C., Thaman, R. R., Manner, H. I., Decker, B. G., & Ali, I. (1993). Agroforestry in the Pacific islands: Systems for sustainability. United Nations University Press. http://hdl.handle.net/1885/114665
  • Feintrenie, L., Enjalric, F., & Ollivier, J. (2015). Coconut- and cocoa-based agroforestry systems in Vanuatu: A diversification atrategy in tune with the farmers’ life cycle. In Economics and Ecology of Diversification (pp. 283–295). Springer Netherlands. https://doi.org/10.1007/978-94-017-7294-5_14
  • Fotsing, J.-M., Mweleul, A., Rogers-Nilwo, F., Le Roux, P.-Y., Wattelez, G., & Galy, O. (2023). Urban agriculture, traditional food and health in Melanesia, a multidisciplinary approach in Port Vila, Vanuatu. In P. Brown & N. Gaertner-Mazouni (Eds.), Small Islands, Big Issues: Pacific Perspectives on the Ecosystem of Knowledge (1st ed., pp. 61–84). Peter Lang Ltd. International Academic Publishers.
  • Klopotek, B., Claybrook, T., & Scott, J. (2023). Indigenous companion planting in the great churn: Three sisters in Kalapuya ilihi. Environment and Planning E: Nature and Space, 6(3), 1889–1904. https://doi.org/10.1177/25148486221126618
  • Kuepper, G., & Dodson, M. (2001). Companion planting & botanical pesticides: Concepts & resources. In ATTRA Sustainable Agriculture. NCAT. https://attra.ncat.org/publication/companion-planting-resources/
  • Lefale, P. F. (2010). Ua ‘afa le aso stormy weather today: Traditional ecological knowledge of weather and climate. The Samoa experience. Climatic Change, 100(2), 317–335. https://doi.org/10.1007/s10584-009-9722-z
  • Quintus, S., Huebert, J., Kirch, P. V., Lincoln, N. K., & Maxwell, J. (2019). Qualities and contributions of agroforestry practices and novel forests in pre-European Polynesia and the Polynesian outliers. Human Ecology, 47(6), 811–825. https://doi.org/10.1007/s10745-019-00110-x
  • Reddy, P. P. (2017). Agro-ecological Approaches to pest management for sustainable agriculture. Springer Singapore. https://doi.org/10.1007/978-981-10-4325-3
  • Sherzad, S. (2018). Family farming in the Pacific islands countries. FAO. http://www.fao.org/3/ca0305en/CA0305EN.pdf
  • Suiyanata, K. (2002). Diversified agriculture, land use, and agrofood networks in Hawaii. Economic Geography, 78(1), 71. https://doi.org/10.2307/4140824
  • Thaman, R. R., Elevitch, C. R., & Kennedy, J. (2006). Urban and homegarden agroforestry in the Pacific islands: Current status and future prospects. In Tropical Homegardens (Vol. 3, pp. 25–41). Springer Dordrecht. https://doi.org/10.1007/978-1-4020-4948-4_3
  • Wagner, S. C. (2011). Biological nitrogen fixation. Nature Education Knowledge, 3(10), 15. https://www.nature.com/scitable/knowledge/library/biological-nitrogen-fixation-23570419/