AUTHOR=Baier Clara , Gross Arthur , Thevs Niels , Glaser Bruno 

TITLE=Effects of agroforestry on grain yield of maize (Zea mays L.)—A global meta-analysis

JOURNAL=Frontiers in Sustainable Food Systems

VOLUME=Volume 7 - 2023

YEAR=2023

URL=https://www.frontiersin.org/journals/sustainable-food-systems/articles/10.3389/fsufs.2023.1167686

DOI=10.3389/fsufs.2023.1167686

ISSN=2571-581X

ABSTRACT=Maize cropping systems, the world's most important cropping systems in terms of production volume, are responsible for many environmental problems. This calls for sustainable practices that enable environment-friendly production while generating sufficient output, as farmers and consumers worldwide depend on adequate yields. Agroforestry can offer solutions to both these pressing concerns – food insecurity and adverse environmental impacts of intensive maize cultivation. This meta-analysis investigated the effects of agroforestry on maize (Zea mays L.) grain yield under different environmental and management regimes on a global scale. It is based on 1,215 pairwise data entries from 95 peer-reviewed studies. Overall, agroforestry was able to increase median maize yields by 0.24 Mg ha-1 (7%). In subtropical and tropical regions, the median yield increment under agroforestry was 0.30 Mg ha-1 (16%), and the best results were achieved using broadleaved trees (+0.42 Mg ha-1, +53%), especially N-fixing tree species (+0.56 Mg ha-1, +60%). Maize yields responded very well to tree pruning (+0.54 Mg ha-1, +62%), particularly if the pruned material was added to the soil of the maize crop (+0.48 Mg ha-1, +24%). Rotating maize with other crops was beneficial if the intermediate crop is able to fix atmospheric N (+0.28 Mg ha-1, +13%). We found that tree planting densities of at least 5,000 trees ha-1 are required for the positive impacts of agroforestry on maize yields to take effect, and these effects increased with both tree age (+1.17 Mg ha-1, +48% under trees 11-15 years of age) and time under agroforestry (+0.85 Mg ha-1, 81% in response to >15 continuous maize seasons under agroforestry). In addition, they were particularly pronounced on sandy soils (+0.46 Mg ha-1, +23%), moderately acidic soils of pH 5-6 (+0.67 Mg ha-1, +35%), soils with <0.5 g kg-1 N (+1.19 Mg ha-1, +81%), soils with a plant-available water holding capacity <10 mm dm-1 (+1.10 Mg ha-1, +44%), and hyper arid conditions (+0.60 Mg ha-1, +35%). These findings prove that if designed with due regard for local conditions and crop/tree species characteristics, agroforestry can be a powerful tool to increase food security and the sustainability of our food production systems.