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
Hm. Eriksson et al., 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, SC J FOR R, 1998, pp. 56-66
Wood ash recycling and liming, and combinations of the two, have been sugge
sted as being prophylactic measures for maintaining the soil's buffering ca
pacity and preventing under-balanced nutrient budgets in forest ecosystems,
particalarly in areas where acid deposition is high and/or whole-tree harv
est has been practised. To prevent ash additions from negatively impacting
the Bora and fauna of the soil floor, application of too easily soluble ash
es should be avoided. However, there is a scarcity of knowledge 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 conduc
tivity (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 applied separately. Levels of e
xchangeable 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 on the pH and EC, respectively, of the forest soil layers, an
d the pH and EC, respectively, of the ashes and ash/lime mixtures, as measu
red after diluting to various degrees and shaking for various lengths of ti
me were examined.
Within three weeks after application, EC increased most in the upper 8 cm o
f the soil in all treatments. A hardened ash obtained from burning wood and
pear 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 ll months, also at 0-1 cm soil depth. By
that time, the lime and most ash treatments had significantly increased th
e pH at 0-3 cm soil depth. At ail soil depths, the greatest increase in pH
was obtained with an untreated, loose wood ash. Ash granules of the same or
igin as the loose ash affected EC only moderately, and the effect on soil p
H was not significant on any of the dates during the first year. A prelimin
ary test to determine an upper limit for the solubility of spreadable ashes
is suggested for practice.