Intercropping leeks to suppress weeds

Many field vegetables such as leek are weak competitors against weeds, causing high costs for weed management practice. Using celery as a companion cash crop was suggested to improve the weed suppression of leek. Three field experiments were carried out to study the intra- and interspecific competition in a leek:celery intercrop with and without additional weed competition. Results from this experimental work show that intercropping of leek and celery in a row-by-row replacement design considerably shortened the critical period for weed control in the intercrop compared with the leek pure stand. The relative soil cover of weeds that emerged at the end of the critical period was reduced by 41 n the intercrop. In another experiment, the biomass of Senecio vulgaris, which was planted 20 days after crop establishment, was reduced by 58 n the intercrop and the number of seedlings which emerged as offspring was reduced by 98°all reductions compared with the pure stand of leek. The relative yield total of the intercrop exceeded that of the pure stand by 10°probably as a result of an optimized exploitation of the resources. The quality of the leek, however, was reduced. Advantages and bottlenecks of the intercrop system of leek and celery and implications for the weed control are discussed and used to identify future research needs.