Soil and lodgepole pine foliar responses to two fertilizer sulphur forms in the sub-boreal spruce zone, central interior British Columbia

Sulphur (S) fractions, total nitrogen (N) concentrations, and cumulative net S mineralization of forest floors and surface mineral soils (0-20 cm) were measured 13 years after an S-deficient lodgepole pine (Pinus contorta var. latifolia Engelm.) stand was fertilized (100 kg S·ha^-1 + 400 kg N·ha^-1) in 1990. Fertilizer treatments compared two S sources: elemental S (S⁰) and ammonium sulphate (AS). Total S and ester sulphate-S (SO₄-S) concentrations and cumulative net S mineralization in forest floors were significantly higher in the S⁰ treatment than in the control and AS treatment. Except for a slight elevation of extractable SO₄-S, such differences were absent in the mineral soils. Total S and SO₄-S concentrations in current-year (2002) pine foliage from the S⁰ treatment were significantly higher than in foliage from the control and AS treatment, while foliar N concentrations indicated that all treatments had caused a return to N-deficiency. These results indicate that prolonged amelioration of S deficiencies in lodgepole pine stands in central interior British Columbia may be possible with single applications of S⁰.