Influence of Soil Moisture on Soil Solution Chemistry and Concentrations of Minerals in the Calcicoles Phleum phleoides and Veronica spicata Grown on a Limestone Soil

Abstract

Veronica spicata and Phleum phleoides are calcicole plants, mainly occurring on neutral or alkaline soil. An experiment of 16 weeks duration was performed in a glasshouse with the objective of elucidating the influence of soil moisture level on soil solution chemistry, and biomass concentrations and uptake of mineral nutrients by the plants. Seven levels of moisture, corresponding to 35–85% of the water holding capacity (WHC) of the soil, were tested. Soil solution HCO3, P and Mn concentrations, and pH, increased, whereas Ca, Mg and Zn concentrations decreased, with increasing soil moisture. Concentrations of K were highest at 50–70% WHC. Concentrations and amounts of P, Zn and Mn in the two species were usually related to soil solution concentrations; these are elements with low solubility and availability in calcareous soils. Concentrations of nutrients in biomass were more influenced by soil moisture in V. spicata than inP. phleoides . This indicates that P. phleoides is more capable of controlling its uptake of mineral nutrients, whereas V. spicata is sensitive to variations in soil moisture. It is concluded that variation in soil moisture regime may greatly influence concentrations of mineral nutrients in calcareous soil solutions and their uptake by plants. Species able to utilize these solubility fluctuations may have an advantage in competition for nutrients. Variation in soil moisture content might even be a prerequisite for adequate acquisition of mineral nutrients and growth of plants on limestone soils, thereby influencing the field distribution of native plants among habitats.