What is Intercropping and how does it work?

Intercropping is a sustainable agricultural technique that involves the intermixed planting of different crops in very close proximity. It is an all encompassing term that can be performed in a variety of ways, such as by growing crops that utilize different regions of space within a single row (Ex: a root crop interplanted with an above-ground fruiting crop in a single row), or by planting a second crop in the space between the rows of the first crop’s bed. The goal of intercropping is to have multiple crops within close enough proximity that the plants can interact with one another (Mohler & Stoner, n.d.), thus mimicking what happens in natural ecosystems.

When plants are allowed to interact with each other, they create diverse, biological systems that not only benefits the plants involved, but also the soil and biota (microbes, insects, pollinators, wildlife, etc.) that live within the system.

Intercropping improves the sustainable system in a variety of ways:

Use of resources

When multiple crops are interplanted in close proximity, they may be able to use the surrounding resources more effectively than if only a single crop was planted (Mohler & Stoner, n.d.). For example, intercropping lettuce within a bed of poorly germinated carrots allows you to make better use of the space, an all-important resource in farming. The carrots utilize the underground space and the lettuce uses the above ground space, thus competition between crops is eliminated. Plus, the non-germinated portions of the carrot bed are now being efficiently utilized instead of wasted, which increased the overall income this bed produces. Intercropping can also permit resources such as sunlight, water and soil nutrients to be utilized more efficiently through careful planning of the intercrop pairings.  

Lower pest density

Intercropping is a useful pest management technique. When multiple plant types are grown together in polyculture, the diversity confuses insect pests – especially those that feed on a single specific crop. Additionally, if the crop pairing is well planned the companion plants can be used to repel certain pests or attract beneficial predatory insects – who in turn help reduce the pest load (Mohler & Stoner, n.d.).

Improves soil structure

Intercropping improves soil structure in that your soil is held together by a diversity of different roots (Engels, 2016). A tap-rooted plant will help break up compaction and aerate the soil, and a fibrous rooted plant will prevent erosion and help absorb excess water after heavy rainfalls.  When these two root types work together, they improve soil structure and quality while occupying different regions of space, therefore avoiding resource competition.

More Financial Stability:

Intercropping, because it naturally incorporates more diversity, also provides the farmer with a more diverse product line. Instead of growing one crop type in a certain area, multiple are grown. If a crop fails, the farmer can rely on sales of the second crop rather than losing an entire season’s worth of income.  

Challenges associated with intercropping

Crop rotation is an essential aspect of sustainable farming and it is made much more difficult when intercropping is used. When plants of different families are grown in close proximity, you must plan your rotation so that neither of those families are repeated in the same block for at least 3 years (Mohler & Stoner, n.d.). This becomes very complicated when each field block contains more than one plant family. Thoroughly planning your crop rotation in advance is essential when using the intercropping technique.

Intercropping also requires very careful planning so that the crops do not negatively harm the system through competition of root space, aboveground space or nutrients (Engels, 2016). Poor plant pairings may also inhibit the growth of the intercrops, so a thorough understanding of companion planting is a must. Additionally, a plant pairing that worked in the past may not necessarily work in the future if the environmental conditions change and one plant becomes either favoured or hindered, throwing off the system’s delicate balance (Mohler & Stoner, n.d.).

Finally, intercropping requires precise timing for planting as the crops used will likely grow at different rates (Mohler & Stoner, n.d.). You must be able to balance the growth of both crops through timed planting so that the quicker crop doesn’t overgrow or cast shade and ultimately hinder the growth of the slower crop.

Examples of Intercropping:

The most well known example of intercropping is the Three Sisters Garden. This traditional indigenous intercropping technique utilises the growing habits of corn, beans and squash to grow a large volume of food, sustainably, in a small space. The corn has very shallow, fibrous roots which holds the soil together, preventing erosion and helping improve soil stability. It grows tall and becomes a support for the beans, whose roots fix nitrogen, adding to the soil nutrition. Finally, squash, a deep-rooted plant feeds from water and nutrients below the reach of the corn and bean roots, minimizing competition. It also grows very large and leafy, blocking out weeds and keeping pests such as racoons away from the corn and beans. All three of these plants interact and support each other. In fact, they grow better when intercropped together than when grown individually (Kimmerer, 2013).

Another example of intercropping is planting lettuce around the base of tomato plants. As the tomatoes grow, they vine up and away from the soil. Lettuce remains close to the soil even when fully mature and acts as weed suppression, blocking out weeds that may impact the tomato growth. This intercropping allows you to maximize the profitability and space within your bed AND minimizes the amount of weeding required to keep the row tidy.

Real World Statistics:

According to a study put on by the University of Manitoba, the technique of intercropping produced a Land Equivalency Ration (LER) of above 1, meaning the crops produced higher yields when intercropped than when grown in monoculture for the same area of land use, for all types of intercrops studied (University of Manitoba, 2014).  This study also found that the more intercropping occurred, the lower the pest and weed pressure; so they recommend growing as many different companion plants together as feasibly possible (University of Manitoba, 2014). Finally, on a conventional scale, intercropping produces overyield in about 75% of cases and is highly feasible (University of Manitoba, 2014).

According to a study performed in Australia by Lithourgidis, Dordas, Damalas, and Vlachostergios, “Various types of intercropping were known and presumably employed in ancient Greece about 300 B.C” (Lithourgidis, Dordas, Damalas & Vlachostergios, 2011), so this method of agriculture has truly withstood the test of time.  Additionally, intercrop systems are currently being used for an estimated 15-20% of the world’s food supply, primarily in Indigenous and global south communities (Lithourgidis, Dordas, Damalas & Vlachostergios, 2011).

Conclusion:

Often misunderstood, the role of farmers is to feed their community, not the world. If farmers worldwide switch to diverse, small-scale, intercropped agricultural systems, a lot of the problems that persist in agriculture today will improve. They will be able to provide their local communities with a diverse offering of highly nutritious fruits, vegetables and animal products while regenerating the health of the ecosystem, rather than draining it. Not only does intercropping increase yield, it promotes an improved use of resources, reduced pest and weed pressure, healthier soils and more financial stability. Overall, the use of intercropping is an extremely beneficial sustainable farming technique that should be employed by farmers, replacing conventional systems.  We use intercropping at Laughing Radish Eco Farm because it allows us to maximize our farm’s efficiency while promoting the health of our overall system. It might take more planning than a traditional market garden, but the extra planning is worth it. We are rewarded with a beautiful, healthy, holistic ECO farm.

References:

Engels, J. (August 12, 2016). Intercropping: What it is, What it isn’t, and Why we do it. Permaculture Research Institute. Retrieved from https://www.permaculturenews.org/2016/08/12/intercropping-what-it-is-what-it-isnt-and-why-we-do-it/

Kimmerer, R.W. (2013). Braiding Sweetgrass. Minneapolis, MN. Milkweed Editions

Lithourgidis, A.S., Dordas, C.A., Damalas, C.A., Vlachostergios, D.N. (2011). Annual Intercrops: An alternative pathway for sustainable agriculture. Australian Journal of Crop Science. Retrieved from https://www.researchgate.net/publication/224934832_Annual_intercrops_An_alternative_pathway_for_sustainable_agriculture

Mohler C.L. & Stoner K.A. (n.d.) Guidelines for Intercropping. Sustainable Agriculture Research and Education. Retrieved from https://www.sare.org/Learning-Center/Books/Crop-Rotation-on-Organic-Farms/Text-Version/Guidelines-for-Intercropping

University of Manitoba. (2014). Agronomic Benefits of Intercropping in Manitoba. University of Manitoba Natural Systems Agriculture. Retrieved from http://www.umanitoba.ca/outreach/naturalagriculture/articles/intercrop.html