Intercropping systems between broccoli and fava bean can enhance overall crop production and improve soil fertility

Abstract

Legumes can be regarded as a good alternative in intercropping systems to increase soil fertility and biodiversity whilst enhancing crop production and reducing fertilizer use. The aims of this study were to: i) assess whether crop yield, crop quality and soil physicochemical properties can be improved using different intercropping patterns between broccoli (Brassica oleracea var italica) and fava bean (Vicia faba) compared with their respective monocrops, all grown under organic management; and ii) assess if fava bean grown as an intercrop can partially replace fertilizer use without negative effects on crop production. We compared, for three crop cycles, monocrops with three different broccoli-fava intercropping patterns: mixed intercropping, row intercropping 1:1 (broccoli:fava), and row intercropping 2:1 (broccoli:fava). Fertilization was reduced by 30% in the diversified plots. After three crop cycles, the results showed that the intercropping systems, regardless of the pattern, kept soil organic C levels, while they significantly decreased in broccoli monoculture. Intercropping also significantly increased soil total N, available P and exchangeable K (0.13%, 39 mg·kg−1 and 364 mg·kg−1, respectively), compared to the broccoli monocrop (0.11%, 11 mg·kg−1 and 277 mg·kg−1). Total production was significantly higher under the diversified systems, which doubled the overall yield of the monocrops every crop cycle, with land equivalent ratios > 1. Hence, the introduction of fava bean associated to broccoli could be considered a feasible strategy for sustainable agriculture, with environmental gains and economic savings for fertilizers and water.