Ion availabilities in two forest soils amended with alkaline-treated biosolids, agricultural lime, and wood fly ash over a 10-week period

Abstract

Two forest soil B-horizons were amended with alkaline-treated biosolids (ATB), powdered agricultural lime, and wood fly ash under controlled conditions to compare initial ion availabilities over a 10-week period. ATB was most effective in supplying available Ca2+ but least effective in supplying available Mg2+, for which lime was most effective. Availability of K+ and SO42–-S was greatest in fly ash amended soils because of high K and S loading rates and the high electrical conductivity of this amendment. Mineral N (NO3–-N + NH4+-N) availability increased in ATB amended soils, stayed the same in lime amended soils, and decreased in fly ash amended soils. Availability of PO43–-P was low in all soils but slightly enhanced in ATB amended soils. Fluxes of Cu2+, Pb2+, Zn2+, and Mn2+ in amended soils generally decreased over time in association with increased soil pH. Fluxes of Cd2+ were not affected by any treatment. Results suggest that ATB is equally as effective as or more effective than lime and fly ash at immediately supplying Ca2+, but less effective at supplying Mg2+ because of low inputs and cation competition. This suggests that ATB amendments could be an alternative means of quickly adding available Ca2+ to Ca-depleted forest soils as long as potential impacts on other nutrient base cations are considered.