Growth of jack pine forest on an acid brunisol treated with lime

Abstract

The 17‐year growth response of a 45‐year‐old jack pine (Pinus bariksiana Lamb.) forest on an acid brunisolic soil to applications of 224 and 448 kg Ca ha^‐1 (560 and 1120 kg ha^‐1 of CaCO₃) in 1970 was examined. Increases in the level of exchangeable Ca and pH and decreases in exchangeable acidity, in relation to untreated soil, suggest that liming had a modest long‐lasting effect on base saturation of the forest humus. Liming produced significant increases in the amount of ammonium contained and mineralized in humus layers and the Bm₁ horizon after 15 years, but no changes in the bulk of the mineral soil N were detected. Liming had a negligible effect on nitrification in the soil. It had no effect on pine growth nor did the treatment significantly influence the N concentration in foliage collected prior to the growing season of 1987. The results suggest that in N‐limited jack pine forests, lime‐stimulated N turnover is not sufficient to produce a growth response to N by the trees.

Key words:

• Nitrogen
• soil acidity
• tree nutrition
• forest fertilization
• Pinus bariksiana