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Back to Fall 2013 PNN Articles

‘Three Sisters’ Inspire Modern Crop Rotation

The practice of planting corn, beans and squash close together in the same soil has its roots in Native American agriculture. The legend behind the technique varies from region to region, but the principle is always the same; corn, beans and squash (dubbed the “Three Sisters”) grow stronger when they are together. Here’s how it works:

  • Tall, thin corn acts as a perfect climbing pole for beans
  • To return the favour, beans hold the corn stalks stable in high winds
  • Beans also improve the quality of the soil by pulling nitrogen from the air and depositing it in the earth
  • Well-fed squash plants are happy to lay their flat leaves at the base of both corn & beans -- thus helping to discourage weeds and keeping precious moisture from escaping

This traditional practice of companion planting, sometimes called interplanting, produces higher quality crops, with minimal environmental impact, and works quite well on a small scale.

As large-scale farming operations rely heavily on machines to plant and harvest their crops, growing crops together in the same field is less feasible. Machines do not have the ability to discern individual crop types and treat and harvest each plant accordingly. But lessons learned from the “Three Sisters” have evolved into a practice that does work on a large-scale.

Today, Canadian farmers practice crop rotation, where different crops are grown after each other, year after year. Common crop rotations in Canada include corn, beans (soy or dry beans) and wheat in Ontario and Québec, and canola, wheat and pulses in the Prairie Provinces. Crop rotation has many of the same benefits as growing crops together, where every crop is important and provides specific benefits in terms of managing pests, utilizing nutrients and water, and boosting yield while reducing the need for inputs like fertilizer and pesticides.

Pulse crops like peas, beans, lentils and chickpeas provide a unique boost to crop rotations, helping Canadian farmers grow more with less. As nitrogen fixing crops, pulses require little to no nitrogen fertilizer. Pulse crops also benefit other crops in rotation by improving the soil, and leaving nitrogen behind for the next crop in the form of their straw. All of this means that pulses also improve the environmental footprint of Canadian agriculture, reducing non-renewable energy use and greenhouse gas emissions.

The idea of combining pulses with other crops is not only good for crop quality and the environment, there are dietary advantages to eating pulses together with other plant-based foods like cereals. Pulses contain high amounts of protein however most plant protein sources do not contain all the amino acids important for growth. The good news is that the essential amino acids lacking in pulses are actually present in cereals and vice versa, so including both foods in the diet ensures a more balanced protein intake.

Of the 20 million hectares of cropland in Western Canada, pulses are grown in crop rotations on roughly 40% of the land. As this number continues to grow, the health of Canada’s environment improves as well!

WATCH THE VIDEO: See how Canadian farmers are using pulse crops likes peas, beans, lentils and chickpeas in Cropping Rotation Systems to help other crops prosper: