Effects of two types of Ca fertilizer on sugar maple nutrition, vigor and growth after 7 years

Abstract

Sugar maple (Acer saccharum Marsh., hereafter SM) dieback has been of concern in many stands of northeastern North America for decades. In acidic, base-poor forest soils, this phenomenon has often been attributed to calcium (Ca) deficiency. Corrective measures such as dolomitic lime addition (CaMg(CO3)2) have been tested to restore SM vitality in these ecosystems. However, few studies have evaluated the effect of Ca addition alone on SM. Furthermore, liming experiments have showed that the Mg content of lime could induce a nutritional antagonism which hinders potassium (K) uptake. This may have limited the response of SM to dolomitic lime application. To address these issues, two calcium fertilizers with negligible Mg content (CaCO3 and CaSO4·2H2O) were applied at rates of 1, 2 and 4tCaha−1 on SM trees. After 7years, foliar Ca nutrient concentrations of treated trees increased in both Ca treatments, reaching published concentration ranges for healthy SM trees. These increases were greater than those observed after a similar period in two nearby experiments in which CaMg(CO3)2 and CaCO3 were used at comparable or lower doses. Also, no nutrient antagonism was detected in the present study. Tree crown vigor and basal area growth were improved by the Ca treatments, but the magnitude of the growth response for trees treated with the CaCO3 fertilizer was far less than in the other nearby experiment where CaCO3 was also used. This strongly suggests that Mg nutrition is not a limiting factor in this ecosystem. The comparatively lower growth response of trees to Ca treatments in this study is unclear, but better growth conditions at the studied site, compared to the two other nearby experiments, may have played a role in this phenomenon. Long-term monitoring of these experiments seems warranted to clarify these issues.