Chemical and microbiological properties of alpine forest soils: Effects of pelletized ashes in a short-term trial

Weekly measurements of pH and electrical conductivity (EC) from the soil leachates were performed. A higher pH, relative to Ct, was found in treatment A for Podsol. Additionally, treatments B and C led to a pH rise in Leptosol. Electrical conductivity, total C and N, and inorganic N forms were not significantly affected by the pelletized treatments regardless the soil type. A similar trend was recorded for pH and EC levels from the leachate samples. A lower metabolic quotient (qCO2), relative to Ct, was recorded in Podsol following treatment A. However, when pellet ashes were applied in combination with digestate, a higher qCO2 than that in Ct was found for this type of soil, which might indicate a lower microbial C utilization efficiency and/or microbial stress. This latter treatment also resulted in a lower dehydrogenase activity in Podsol, whilst soil protease activity and N mineralization were not affected in any of the studied soils. We conclude that ash amendment in pellets form on certain soils improves their acidity levels without causing extreme effects.