EFFECTS OF GYPSUM ON GROWTH AND MINERAL-CONTENT OF BRUSSELS-SPROUTS, AND SOIL PROPERTIES OF ORTHIC PODZOLS

Studies of crop response to Ca fertilizers are generally few as well as information concerning the Ca nutrition of Brussels sprouts (Brassica oleracea var. gemmifera). Six field studies were conducted, over three years, to determine yield response of Brussels sprouts to soil applied gypsum (CaSO4.2H2O), lime (calcite), and elemental S on sandy loam to loamy sand Orthic Podzols in Prince Edward Island. Relative yield of marketable (0-32mm) Brussels sprouts were related to soil ammonium acetate extractable Ca (r = 0.71). The highest yields (11 to 13 t ha-1) were associated with an extractable Ca of above 400 μg g-1 soil, while a Ca level below 400 μg reduced yield by 20%. Highest marketable yields were associated with a Ca level in the leaf tissue (in upper mature leaves at sprout formation) of above 2.2% (w/w) (r = 0.55), this in turn was associated (r = 0.87) with an extractable soil Ca above 400 μg g-1 soil. Calcite and elemental S did not influence yield or mineral content. Gypsum, as expected increased leaf S content, but leaf tissue S levels were not related to marketable yield. Slight decreases in soil pH due to increasing gypsum rate (0.5-4.3 t ha-1) were associated with changing accumulations of B, Mn, Fe, Ca, and Zn in the leaf tissue. Gypsum had little effect on soil porosity and structure indices, but changing pH (in both gypsum and lime treatments) significantly influenced soil microbial biomass. © 1990 Kluwer Academic Publishers.