Earth is an “electrical” planet in nature. All the processes in biosphere occur in ever-changing electrical fields, which arise due to changes in solar activity, magnetic field of earth, and electrical processes in atmosphere. These global and local fluctuations in electrical fields create electro-tropism at all levels of biosphere, including the Soil-Plant system. Electro-tropism in Soil-Plant system is a combination of the natural electrical potential differences on the interfaces inside soil (between soil horizons or peds), on the interfaces inside growing plant (between different plant tissues), as well as between soil and plant. The largest electrical potential differences were observed inside soils. The natural electrical potentials (stationary and fluctuating) in soils were studied by our group for last 10 years and the results were summarized and presented on 17th World Congress of Soil Science in 2002. Recently, we advanced to the measurements and research of the natural electrical potentials between soil and growing plants. Natural electrical potentials between soils of major genetic types and more than 100 species of native and cultural plants of Ukraine, Russia, and Philippines in different growing conditions have been studied in 2003-2005. We used LandMapper ERM-03 and our patented non-polarizing electrodes made from standard AgCl-electrodes cupped with solidified agar solution of 1% KCl. The reference electrode was always placed in the topsoil near a growing plant and the measuring electrode was firmly contacted to the surface of the tissues of the plant (flowers, stems, or leaves). The electrical potential difference between soil and a plant was always negative. This difference is relatively stable for particular plant specie and varies from -20 mV to -120 mV for different plant species. For the plants in temperate climate, electrical potential between plant and soil is highest during spring and for young plants in summer, and decreases in fall when plants in Ukraine and Russia are ready for dormancy. Tropical plants showed higher potential differences than plants of temperate climate. The potentials for all plants decreased in a row flower-leaf-stem. Electrical potential of herbaceous plants is directly related with the leaf area, the highest potentials were observed for burdock, cow-parsnip, and young banana palms. Plant's electro-tropism in relation to soil is, probably, sort of “information” channel for a plant in search for soil water and nutrients. Favorable electro-tropism was created in artificial growing media by burying different metal stakes (Zn/Cu) at different depth of the media to facilitate plant growth. The research is underway for evaluating relationship between natural electrical potentials in plants and plant's water stress.