The influence of variations in soil copper on the yield and nutrition of spinach grown in microplots on two organic soils

Abstract

Abstract Spinach (Spinacia oleracea L. cv. Symphony) was grown in spring 1982 in field microplots of an organic soil (site I a mucky peat) containing 81 to 1063 μg Cu.g‐1 soil, and cv. America of the same crop taken in summer 1982 on a peaty organic soil (site II) varying in Cu content from 13 to 1659 μg.g‐1. The variations in soil Cu were mainly due to three rates of Cu applications in 1978 at site II and in 1979 at site I. At site I, the diversity in soil‐Cu had no effect on yield or foliar‐Cu levels in the crop. At site II soil‐Cu was positively correlated with yield and foliar Cu; and negatively with leaf Fe due to a dilution effect. Neither soil Cu nor foliar Cu had any significant effect on Mo in leaves at both sites, except that the increase in yield due to the highest level of Cu at site II was accompanied by an increased plant uptake of Mo. Also, foliar Cu was positively correlated with P, Mg and Mn levels in leaves at site I; and foliar Ca, Mg and Mn at site II. Residual soil Cu up to 1063 μg.g‐...