SOLUTION CONCENTRATIONS OF NUTRIENT IONS BELOW THE ROOTING ZONE OF A SUGAR MAPLE STAND - RELATIONS TO SOIL-MOISTURE, TEMPERATURE, AND SEASON

Temporal variations of ion concentrations in soil solution were analyz ed in relation to soil percolate volume, soil water content, soil temp erature, solution chemistry, and season. The study site was an uneven- aged, mature northern tolerant hardwoods dominated by sugar maple (Ace r saccharum Marsh.) within the Turkey Lakes Watershed, Ontario. Six io ns were investigated: nitrate (NO3-), sulfate (SO42-), calcium (Ca2), magnesium (Mg2+), potassium (K+), and ammonium (NH4+). Nitrate concent rations in the soil solution depended on season during the nonfoliage period and responded directly to forest floor percolation, soil water content, and season during the foliage period. Variations of SO42-, Ca 2+, and Mg2+ concentrations were mostly attributable to NO3- concentra tion, and to season to a lesser extent. Concentrations of K+ and NH4correlated only weakly to any of the ''independent'' variables include d in the analysis, reflecting a high affinity between these ions and t he soil colloids.