I found this MSc thesis completely by chance while looking for something else. Although neither permacultural nor organic, it provides a great methodology for studying the effects on yield and insect contol of different intercropping systems. I am posting it here mainly because of the methodology and the literature review which may be useful to others, but if you want a snapshot of the results, the study found maize grows best when intercropped with cluster bean or field bean, both of which have substantial economic benefits. Most of the inter crops clearly reduced insect damage compared to maize alone, with maize/field bean and maize/cluster bean creating the lowest population of insect pests.
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