Consistent efficiency of horticultural intercropping: a quantitative synthesis

Agroecosystem diversification through intercropping is a strategy to mitigate biodiversity loss and enhance ecosystem services while maintaining or improving productivity, resource-use efficiency, and pest regulation. Although field crop intercropping has been well studied, horticultural intercropping remains less explored, despite its relevance for food security. Our study aims to address this gap by assessing the overall efficiency of horticultural intercropping through a quantitative synthesis of global experimental data. In addition, we examine how system design, management practices, and species characteristics influence land-use advantage. Our primary finding is that horticultural intercropping is advantageous compared with monocultures, providing the first large-scale, global quantitative evidence of a land-use advantage in horticultural systems. Overall, the mean Land Equivalent Ratio was 1.41, indicating that monocultures would require 41% more land than intercropping to achieve the same yield, with values exceeding 1 in over 90% of the experimental observations. Additive intercropping and species combinations that include trees or nitrogen-fixing species were particularly efficient, a pattern consistent with ecological interactions such as niche complementarity and facilitation. Notably, the benefits of intercropping decreased with insecticide use, suggesting that this input may suppress indirect positive effects of plant associations, corroborating the recommendation of intercropping for low-input agriculture. In this context, intercropping research holds potential to address some of the persistent challenges in diversification, such as optimizing systems without relying on chemical inputs. To realize this potential, we suggest a deeper investigation into the underlying ecological mechanisms and the use of complementary indices for productivity assessments. The consistent land-use advantage of horticultural intercropping across varied contexts, as identified in this study, supports the productive viability of agroecosystem diversification.