SYSTEM DEVELOPMENT FOR OUTDOOR SOILLESS PRODUCTION OF LEEK (ALLIUM PORRUM)

Abstract

Current open field vegetable production systems in The Netherlands do not meet market and society demands. Among the most important demands are: (1) the EU Water Framework Directive, requesting strong reductions in emissions of nutrients and pesticides to surface- and groundwater; (2) continuous delivery of uniform, high quality products by retailers. These demands could not be fulfilled by adapting current production systems, new production systems have to be developed and tested for a number of field grown crops. This paper emphasizes the development of soilless growing systems for leek. Important current product requirements for leek are a white part of the stem of at least 14 cm, a minimal thickness of 2.5 cm and a straight, firm stem. Important system requirements for outdoor cultivation are handling of rainfall, wind and frost. Opportunities for soilless systems for leek are a clean product without soil contamination and a strong reduction in labor need for preparing it for the market. Finally, the developed system needs to be economically viable, acceptable by growers and give sufficient reduction in emissions. From 2008 aspects of plant raising (traditional method with stone wool and coir plugs) were investigated together with demands to get a firm straight stem. Covering of the plants to achieve a long white part was investigated comparing several smart solutions. The use of substrate, NFT and deep flow were also compared. Results show a fast growing crop, where 4 crops per year with at least 80 plants per m2 and a total yield up to 300 t/ha are possible. It can achieve the minimal market weight in a much shorter period (40-60 days in summer) compared to growing in the soil. However, the production of long white stems requires special measures. With a good system design there are hardly any problems with rain and frost.