'Effective Micro-organisms' (EM): An Effective Plant Strengthening Agent for Tomatoes in Protected Cultivation

The effect of treating organically grown tomato plants with Effective Micro-organisms (EM) combined with a stone dust-suspension (EM treatment) was tested in a pot experiment in a foliar tunnel at the University of Natural Resources and Life Sciences Vienna. In the EM treatment, the irrigation water was amended with EMa (R) and plants were treated with EM-stone dust-suspension. In the control treatment, tap water was used instead. In the EM treatment, bokashi, wheat bran fermented with EMa (R), was additionally added to the planting substrate in both years. Only in 2007, the equivalent amount of wheat bran, composted without EMa (R) addition, was added to the substrate in the control as well. Inorganic N contents of the substrate were lower in the control in 2006, but increased when wheat bran compost was added in 2007. N mineralization at later stages of the experiment was higher in the EM treatment in 2007. Microbial biomass in the substrate was enhanced in both years. Total yield was higher and the number of fruits damaged by blossom-end rot was reduced in the EM-treated plants in 2007. The percentage of fruits in the best quality class was significantly higher in the EM treatment in both years. N, P and K contents in tomato leaves of the EM treatment were reduced, whereas the Fe content was higher. A more even N supply to the plants in the EM treatment, combined with the effect of a direct stone dust-application onto the plants, clearly increased plant yield and fostered plant health.