Aquaponics is a relatively new system of farming which has received ardent research attention due to its potential for sustainability . However, there is no consensus on comparability between crop yields obtained from aquaponics (AP) and conventional hydroponics (HP). Meta-analysis was used to synthesize the literature for comparability between AP and HP crop yield. Factors responsible for differences were also examined . A literature search was done in five databases with no time restriction in order to capture any publication on AP and HP crop yield comparisons. The search was however, limited to publications in English, Journal, and Conference articles. Study characteristics and outcome measures of food crops were extracted. A natural log response ratio effect size measure was used to transform study outcomes. An unweighted meta-analysis through bootstrapping was used to calculate overall effect size and its confidence interval. Between-Study heterogeneity (I2) was estimated using a random effects model. Sub-group and meta-regression were used assess moderators. The results showed that although crop yield in AP was lower than conventional HP, the difference was not statistically significant. There were differences in effect of aquatic/fish species, HP system type, type of grow media, and crop species on AP crop yield. Nutrient supplementation led to similar or even higher aquaponics crop yield than conventional hydroponics. These findings are vital information source for choosing factors to include in an AP study. These findings also synthesize the current trends in AP crop yields in comparison with conventional HP. However, drawing conclusions on the overall effect size must be done with caution due to the use of unweighted meta-analysis.
Keywords: Aquaponics crop yield, meta-regression, nutrient supplementation, unweighted meta-analysis, subgroup analysis, log response ratio .