EFFECTS OF GYPSUM ON YIELD AND NUTRIENT STATUS OF NATIVE LOWBUSH BLUEBERRY

Information is required on the response of native lowbush blueberry (V accinium angustifolium Ait.) to soil-applied calcium amendments. Field experiments were carried out in Prince Edward Island to determine the effects of applied gypsum, as a Ca source, on yield and leaf nutrient content of native lowbush blueberry at six sites, two locations per y ear. Sites were studied over several cropping cycles. Gypsum applied a t 2, 4, 6, and 8 t ha(-1) in the spring of the sprout year increased m arketable yield (from 3.2 to 4.7 t ha(-1)) at three of six sites in th e first crop year following application of gypsum. Averaged over these three sites, marketable yield was increased 47% by the application of gypsum at 4.0 t ha(-1). Yield was not affected in the second and thir d cropping cycles. Mean berry weight and plant growth were not affecte d by gypsum application. Concentration of leaf Ca was increased but no t consistently significant, while leaf S was significantly increased a t all sites in the first cropping cycle. Soil pH was significantly red uced by gypsum in the first cropping cycle. A yield increase of 225 kg ha(-1) would be sufficient to recover the costs of the applied gypsum .