Mutualism is the process whereby two or more crops or other kinds of plants provide benefits to one another, and intercropping is one type of mutualism.
Intercropping is the practice of growing different types of crops in the same field. This has many benefits for the crops, including pest control.
Intercropping can be a good alternative to monoculture farming, where only one type of crop is grown in a field. There are many types of intercropping, including row cropping and strip intercropping.
The benefits of intercropping include boosting nutrients for a main crop, increasing profits, and improving weed management. Intercropping also teaches farmers about the concept of mutualism.
Mutualism can appear in many forms, for example, when vining plants climb other plants with strong stems, or when one plant removes toxins from the soil so another plant can benefit.
For more information on the benefits of intercropping, read the Farm Radio International resource The benefits of intercropping: http://scripts.farmradio.fm/radio-resource-packs/108-farm-radio-resource-pack/the-benefits-of-intercropping/ 
For some examples of intercropping, watch these videos from Access Agriculture. You can access the videos by clicking on the blue, underlined text.
- Intercropping maize with pigeon peas 
- Intercropping pineapples 
- Intercropping sorghum and millet with cowpea 
Photo: A Sorghum flower. Credit: Subash BGK.