This invention relates to a preparation and a method for reducing the consumption of water in agriculture and other activities in which plants are cultivated, and which at the same time helps to reduce the seepage of nutrient-rich, fertilizer-saturated water into the ground water. More particularly, the invention relates to an electronegative, antioxidizing powder mixture which, upon application to an upper layer of soil, is capable of forming a biologically degradable membrane in the upper layer of soil, preferably comprising the surface of the soil and a biologically active zone for root and plant formation, wherein the membrane has a combined effect in that it increases the retention time of water and nutrients in the root zone, has an antioxidizing effect on the environment in order to combat ozone and other free radical induced damage to the vegetation, and regulates the albedo of the top soil layer so that the temperature in the root zone is held within the temperature at which the plants thrive. This is obtained by a powder mixture comprising a water-soluble, dried and ground organic raw material from marine brown algae with at least one added pigment, and that the powder mixture is exposed to an E-field of negative polarity so that the material at least is saturated with electrons.
