The benefits and trade-offs of agricultural diversity for food security in low- and middle-income countries: A review of existing knowledge and evidence

Diversity in agricultural systems is often presented as having benefits for multiple purposes like food and nutrition security in low- and middle-income countries. Our review aims to give an overview of the strength and direction of the diversity-food security relationship as presented in research published since 2010, based on a comprehensive search in Web of Science. We present an overview and synthesize results for different spatial scales and units of observation, from individual to global and for the four dimensions of food security: availability, access, stability and utilisation. Eighty-eight of the 924 surveyed publications meet the inclusion criteria and report the direction and magnitude of 314 individual diversity-food security relationships. In almost two thirds of all cases, agricultural diversity had a positive effect on food security. In about one third of the relationships there was no effect of agricultural diversity on food security, or the results were mixed. These numbers hold for the availability, access and utilisation dimensions of food security and at individual, household and farm scales, but the number of studies was too small to draw robust conclusions on the stability dimension and at global scale. Diversity can be an important driver of food security, but the magnitude of the contribution depends on the broader socio-economic and biophysical characteristics of the local farming system. We conclude that diversification can be a potential strategy to improve food and nutrition security. Yet, it is not a necessary characteristic of all agricultural systems at all costs especially in the presence of other strategies that can potentially achieve similar outcomes. We make several recommendations to strengthen future studies that can help identify how strongly related agricultural diversity and food security are.