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Research article1998Peer reviewed

Early Effects of Lime and Hardened and Non-Hardened Ashes on pH and Electrical Conductivity of the Forest Floor, and Relations to Some Ash and Lime Qualities

Eriksson, Hillevi; Nilsson, Torbjörn; Nordin, Annika

Abstract

Wood ash recycling and liming, and combinations of the two, have been suggested as prophylactic measures for maintaining the soil's buffering capacity and preventing under-balanced nutrient budgets in forest ecosystems, particularly in areas where acid deposition is high and/or whole-tree harvest has been practised. To prevent ash additions from negatively impacting the flora and fauna of the soil floor, application of too easily soluble ashes should be avoided. However, the knowledge is scarce on how the early effects of ash additions correlate with the solubility properties of hardened and non-hardened ashes.In this study, a variety of ash types and ash/lime mixtures and a lime were investigated with respect to their effects on the pH and electrical conductivity (EC) of surface layers of a forest soil during the first year after addition. For some ash types, several doses were applied, while other types were divided into fine and coarse material which were applied separately. Levels of exchangeable cations in the soil were determined after 11 months for some of the treatments. The correlations between the effects of the ashes and ash/lime mixtures the on pH and EC, respectively, of the forest soil layers, and the pH and EC, respectively, of the ashes and ash/lime mixtures, as measured after diluting them to various degrees and shaking them for various lengths of time were examined.Within three weeks after application, EC increased most in the upper 8 cm of the soil in all treatments. A hardened ash obtained from burning wood and peat fuels, which had relatively high contents of organic C and S, caused the highest increase in EC. A short-term decrease in pH at 1-8 cm depth was found in cases where large increases in EC were observed. In general, the highest pH values were found after 11 months, also at 0-1 cm soil depth. By that time, the lime and most ash treatments had significantly increased the pH at 0-3 cm soil depth. At all soil depths, the greatest increase in pH was obtained with an untreated, loose wood ash. Ash granules of the same origin as the loose ash only moderately affected EC, and the effect on soil pH was not significant on any of the dates during the first year. A preliminary test to determine an upper limit for the solubility of spreadable ashes is suggested for practice.

Published in

Scandinavian Journal of Forest Research
1998, Volume: Supplement, number: 2, pages: 56-66

      SLU Authors

    • Eriksson, Hillevi

      • Department of Forest Soils, Swedish University of Agricultural Sciences