Effects of base cation fertilization on soil and foliage nutrient concentrations, and litter-fall and throughfall nutrient fluxes in a sugar maple forest

Abstract

Application of base cation fertilizers is widely used to ameliorate decline symptoms in hardwood forests in southern Quebec, but little is known about the effects of fertilization on nutrient cycling. Control and fertilized plots in a sugar maple (Acersaccharum Marsh.) dominated stand were monitored over a 4-year period to determine the effects of fertilization on exchangeable soil base cations in soil, foliar nutrient concentrations, and fluxes of N, K, Ca, and Mg in litter fall and throughfall. Fertilization had a large, immediate effect on exchangeable K, whereas effects on Ca and Mg were delayed and restricted to the organic forest floor, presumably because of the lower solubility of the limestone-based Ca and Mg components of the fertilizer. Fertilization raised pH in the organic forest floor the second and third years after application but had no effect in the B horizon. Foliar K, Ca, and Mg were elevated in the year of fertilization, but foliar concentrations of Ca and Mg did not differ from, or were lower than, controls in following years. Litter-fall K flux was increased by fertilization, but litter-fall Ca and Mg fluxes and all through-fall base cation fluxes were unaffected. In control plots, nutrient concentrations in soil remained relatively constant throughout the study, but foliar concentrations and, in particular, litter-fall fluxes varied widely from year to year. This natural variation caused control plots to shift from a state of deficiency in N, Ca, and Mg to a nutrient-sufficient state between the first and second years of study. Fertilization effects are superimposed on a naturally variable nutrient cycling system, and controls on this variability must be understood if fertilizer response is to be accurately predicted.