Liming influences growth and nutrient balances in sugar maple (Acer saccharum) seedlings on an acidic forest soil

Forests in the northeastern US have been limed to mitigate soil acidification and the acidity of surface waters and to improve soil base cation status. Much of the area considered for liming is within the range of sugar maple (Acer saccharum), but there is a poor understanding of how liming influences growth and nutrient balance of this species on sites that are not deficient in Ca. Of particular concern is the balance of K, a nutrient deficient in parts of the range of sugar maple and a deficiency linked with sugar maple decline in vigor. This buried pot study used soil that was low in K availability to test the influence of liming an acidic forest soil on biomass production and nutrient balance in 2-year-old sugar maple seedlings. The influence of surface applied lime and lime incorporated into the soil were compared with a control. Seedlings were planted on May 9 and were harvested on August 30. Plant parts were freeze-dried, weighed and analyzed for N, P, K, Ca, Mg, Al and Fe. In addition to concentrations, nutrient ratios and the diagnosis and recommendation integrated system (DRIS) were used to estimate nutrient balances. Although seedlings were similar in mass and dimensions at the start of the experiment, harvested seedlings were 37”/;, larger in the incorporated treatment and 9’s smaller in the surface limed treatment compared to control. Only fine roots showed no difference in mass among treatments. Seedlings from the incorporated treatment had greater foliar Ca (P = 0.002), K (P = 0.004) and P (P =‘0.004) than the other treatments. There were no significant differences in foliar Mg, N, Fe or Al concentrations. At the end of the experiment, seedlings from the surface limed treatment contained 11% less K and 3% less P than control seedlings, while seedlings in the incorporated treatment contained 23% more K and 86% more P than in the control. Of the 14 nutrient ratios analyzed, four became more balanced and three became more imbalanced in the incorporated treatment and 10 nutrient ratios became more imbalanced and one ratio improved in the surface limed treatment compared to control. The DRIS indices showed that N was the most closely balanced nutrient relative to other nutrients and K was the most imbalanced nutrient in all treatments. Also, P was quite deficient while Ca, Mg and Fe were overabundant and Al was highly overabundant in all treatments. Surface liming exacerbated K, P and Al imbalances and nutrients remained similarly balanced in seedlings from the control and incorporated seedlings. This study suggested that liming acidic forest soils could intensify nutrient deficiencies, but that over the long term, the availability of highly deficient nutrients could improve.