Effect of Ash from Salix viminalis on the Biomass and Heating Value of Zea mays and on the Biochemical and Physicochemical Properties of Soils

Wood ash is sometimes used as an alternative to mineral fertilizers; however, there is still a paucity of reliable data concerning its effect on plants—and on biological properties of soil. The present study aimed to determine the possible extent of soil pollution with ash from Salix viminalis that does not disturb the growth of Zea mays L., intended for energetic purposes, in order to identify how the increasing ash doses affect biochemical and physicochemical properties of soil and to finally to establish the neutralizing effects of soil additives, i.e., compost and HumiAgra preparation, on this soil pollutant. The study demonstrated that the heating value of Zea mays L. was stable and not modified by the excess content of ash from Salix viminalis in the soil. This finding points to the feasibility of Zea mays L. cultivation on soils contaminated with ash from Salix viminalis and its use in bio-power engineering. The biomass of the aboveground parts of Zea mays L. was significantly reduced after soil contamination with Salix viminalis ash dose of 20 g kg−1 d.m. soil, whereas the smaller ash doses tested (5–10 g kg−1 d.m. soil) did not impair either the growth or the development of Zea mays L. The ash inhibited activities of all analyzed soil enzymes but increased soil pH and sorption capacity. Fertilization with compost proved more effective in neutralizing the adverse effect of ash on enzymatic activity of the soil.