SEEDLING GROWTH AND MINERAL NUTRITION OF SCOTS PINE UNDER ACIDIC TO CALCAREOUS SOIL CONDITIONS

Abstract

We investigated the growth and mineral nutrition of Scots pine (Pinus sylvestris L.) seedlings under a shift from an acidic to a calcareous soil chemical environment using a Chernozemic (Typic Boroll) soil. The study consisted of a greenhouse experiment to evaluate the response of Scots pine to changes in soil chemistry, specifically increasing soil pH, soluble ions, and CaCO3. As the soil pH increased from 5.5-6.2, seedling weight and height decreased 15 and 37%, respectively. Further growth decreases were related to soil EC and soluble Ca levels in excess of 2 dS .cntdot. m-1 and 11-19 meq .cntdot. L-1, respectively. In addition, "active" CaCo3 and NO3-N were also factors in conifer growth. Plant analysis indicated that increasing cation uptake, especially Ca, was associated with organic anion accumulation and a decrease in P uptake. The decrease in seedling weight was also related (r2 = 0.90) to organic anion accumulation. The Ca to P ratio in the seedlings increased from 2.6 to 9.9 as the soil pH increased from 5.5 to 7.9, respectively. Expressing nutrient content in proportions relative to N indicated an imbalance of Ca and K to P as soil acidity decreased. Mean proportions of nutrient content (N:P:K:Ca:Mg) were 100:5:48:14:7 and 100:3:61:33:7 at a soil pH of 5.5 and 7.9, respectively. Scots pine on high base-saturated Chenozemic soils, with neutral pH and acceptable EC and soluble Ca levels, will show a slight but significant reduction in growth rate compared with acidic soil conditions.