Changes in nutrient solution caused by volcanic cinder media of soilless greenhouse roses in the Canary Islands

摘要

A factorial trial was carried out on growing roses in 3 particle size fractions of basaltic cinder (picon) media and at 3 drip irrigation frequencies using a non-circulating nutrient solution. Physicochemical properties of cinders were determined, and drainage water was periodically analysed during the first year. The cinder media had a low exchange capacity (variable with pH), and a high content of chemically unstable volcanic glass. The main changes detected in the nutrient solution draining fromthe media were a reduction in phosphate and K content, a release of Mn from the media at pH _6, and an increase in Mg and Na content. The origin of these changes, which affect rose growth, are discussed.