Intercropping system optimization for yield, quality, and weed suppression combining mechanistic and descriptive models

Intercropping leek (Allium porrum L.) with celery (Apium graveolens L.) is an option to reduce growth and reproductive potential of weeds while maintaining productivity. In this study, a combined modeling approach is used to optimize a leek—celery intercropping system with respect to crop yield, product quality, and weed suppression. An ecophysiological model for interplant competition was used to simulate yield and product quality of the crops as well as biomass and seed production of the weed Senecio vulgaris L. for a wide range of crop mixtures and weed infestations. The results of the simulations were summarized using a descriptive hyperbolic yield–density model, which then allowed evaluation of the intercropping system in terms of productivity, product quality, and ability to suppress weeds. In a weed-free mixture, the competitive ability of celery was six times higher than that of leek. With respect to late-emerging S. vulgaris, the relative competitive ability of leek was 5.4 times lower than that of celery. Replacing two leek plants of a leek monoculture by one celery plant resulted in almost 20% biomass reduction of late-emerging S. vulgaris Crop mixtures with a leek density of about 20 plants m−2 and a leek/celery ratio of 2 proved to be the optimum intercropping system, given the current price ratios. Compared with leek monoculture, profitability was maintained, and late-season weed suppression was greatly increased, resulting in reduced weed seed productio