17 Soil Water Chemistry
Nuria Melia, Juan Bellot and V. Ramon Vallejo
17.1 Introduction
Soil solution is the medium in which most terrestrial biogeochemical processes occur. Its chemical composition results from the dynamic equilibria
between the solid, liquid and gas phases of the soil (Wolt 1994). Soil solution
chemistry provides valuable information on the dynamics of nutrient cycling
and availability to plants, .mineral stability, weathering trends, and pollutant
mobility within the soil' proflle. Moreover, the effects of environmental
changes induced by anthropogenic disturbances on the ecosystem may be
promptly reflected in the soil solution composition. However, the range of
variability found in soil solution may mask the extent of these effects.
Many authors have reported spatial and temporal patterns of variation in
soil solution chemistry (Zabowski and Ugolini 1990; Giesler and Lundstrom
1993; Manderscheid and Matzner 1995). Various soil properties, e.g. CEC, pH,
organic matter and clay content, may lead to differences in processes at each
soil horizon and, therefore, to spatial (both vertical and lateral) differences in
the chemical composition of the soil solution (Tokuchi et al. 1993). Thus,
water that moves down through the soil proflle carries solutes from the forest
floor and the topsoil, where nutrient concentrations are high and organic
matter decomposition is the major process, to the deeper horizons, which
have lower nutrient concentrations and where plant uptake and exchange
processes predominate. Temporal changes in soil solution may be attributed
to the effect of seasonal patterns on soil temperature, moisture and biological
activity in these soil horizons.
This chapter summarizes the main characteristics of soil water chemistry
in the holm oak forests of Montseny and Prades. Chapter 16 dealt with nitrate leaching in gravitational soil water. In the present chapter vertical
changes within the soil proflle and their seasonal pattern are described for
all major ions both in free-flowing soil water (gravitational water) and in soil
water held at higher tensions (soil solution). Comparison of these soil water
fractions between both sites and the relationship with the main processes occurring in these soils are emphasized.
Ecological Studies, Vol. 137
Ferran Roda et al. (eds) Ecology of Mediterranean
Evergreen Oak Forests
© Springer-Verlag, Berlin Heidelberg 1999
Nuria Melia, Juan Bellot and V. Ramon Vallejo
17.1 Introduction
Soil solution is the medium in which most terrestrial biogeochemical processes occur. Its chemical composition results from the dynamic equilibria
between the solid, liquid and gas phases of the soil (Wolt 1994). Soil solution
chemistry provides valuable information on the dynamics of nutrient cycling
and availability to plants, .mineral stability, weathering trends, and pollutant
mobility within the soil' proflle. Moreover, the effects of environmental
changes induced by anthropogenic disturbances on the ecosystem may be
promptly reflected in the soil solution composition. However, the range of
variability found in soil solution may mask the extent of these effects.
Many authors have reported spatial and temporal patterns of variation in
soil solution chemistry (Zabowski and Ugolini 1990; Giesler and Lundstrom
1993; Manderscheid and Matzner 1995). Various soil properties, e.g. CEC, pH,
organic matter and clay content, may lead to differences in processes at each
soil horizon and, therefore, to spatial (both vertical and lateral) differences in
the chemical composition of the soil solution (Tokuchi et al. 1993). Thus,
water that moves down through the soil proflle carries solutes from the forest
floor and the topsoil, where nutrient concentrations are high and organic
matter decomposition is the major process, to the deeper horizons, which
have lower nutrient concentrations and where plant uptake and exchange
processes predominate. Temporal changes in soil solution may be attributed
to the effect of seasonal patterns on soil temperature, moisture and biological
activity in these soil horizons.
This chapter summarizes the main characteristics of soil water chemistry
in the holm oak forests of Montseny and Prades. Chapter 16 dealt with nitrate leaching in gravitational soil water. In the present chapter vertical
changes within the soil proflle and their seasonal pattern are described for
all major ions both in free-flowing soil water (gravitational water) and in soil
water held at higher tensions (soil solution). Comparison of these soil water
fractions between both sites and the relationship with the main processes occurring in these soils are emphasized.
Ecological Studies, Vol. 137
Ferran Roda et al. (eds) Ecology of Mediterranean
Evergreen Oak Forests
© Springer-Verlag, Berlin Heidelberg 1999