The Effect of Nitrogen and Phosphorous Fertilization on the Cation Exchange Capacity of Arctic Soils and Plant Nutrient Content

Jeremy Sinaikin

The organic horizon of three arctic soils across a pH gradient were compared to determine whether there was a relationship between soil pH and the quantity of base cations in both the organic horizon and the plant material. In addition, all three sites were fertilized with nitrogen (NH4NO3), phosphate (P2O5) and both nitrogen and phosphate to observe the affect of nutrient addition on the soil pH and the base cation levels of both the soils and the plants.

At the site, the organic horizon had a pH value of 3.4, 5.3 and 6.4. Sites with a lower initial pH also had lower levels of base cations. Nitrogen addition led to an acidification of the soil and a reduction in the number of base cations. Phosphorous addition was found to increase the pH and the cation concentrations of the soil. Nitrogen plus phosphorous addition led to both increases and decreases in both the soil pH and cation concentration. Both calcium and magnesium concentrations within the soil were significantly correlated with the soil pH.

The soil pH affected the calcium concentration within the three plants species sampled Eriophorum vaginatum, Cassiope tetragona and Betula nana, but did significantly affect magnesium, potassium and sodium concentration. Calcium had a significant positive correlation with both soil pH and soil calcium concentration and was very susceptible to changes in the pH of the soil.