Effects of soil limestone and foliar manganese and zinc applications on field cauliflower growth and element contents

Abstract

A trial was conducted in a field where a previous study suggested that a deficiency of manganese (Mn) or zinc (Zn) was created by the application of limestone, with the objective to confirm whether lime-induced deficiency is a potential problem in coastal British Columbia acidic soils. The trial involved the application and incorporation of limestone at two rates (9 and 19 Mg ha-1) in addition to a control with no limestone, and five foliar applications of Mn and Zn. The foliar applications included a control, Mn at two rates (2.3 and 4.5 kg ha-1), Zn at one rate (2.3 kg ha-1) and a combination of Mn and Zn, both at 2.3 kg ha-1. The trial was conducted at the same location over seven growing seasons (1979-1985), with the cauliflower grown in five of those years. The plot was fallowed in 1981 and 1983. The limestone treatments were applied in the spring of 1979, and again in the summer of 1981, while the foliar applications were applied to the plant each cropped season. Limestone increased plant dry matter yield in three years, decreased it in one, and had no effect in the other. The micronutrient applications did not affect dry matter yield in any of the years. Chemical analyses on the plants showed that limestone increased Ca and decreased Mn and Zn concentrations. The foliar applications increased plant Mn and Zn concentrations. Limestone, but not the micronutrient, applications influenced other element concentrations, with decreased concentrations of potassium, magnesium, sodium, strontium and rubidium. Iron and copper concentrations were not influenced by limestone applications. The decreased concentrations of nutrients could not account for the yield reduction by limestone applications in the one year, since concentrations of the nutrients measured in that year were not significantly different to concentrations in years when yields were increased. Further, basal applications of nutrients (nitrogen, phosphorus, potassium, magnesium and boron) had been applied to ensure that non-treatment nutrients were not deficient. Although monthly weather conditions were similar for one year of increased yield and one year of decreased yield, the influence of weather on the variable response by the crop could not be discounted as there could have been adverse weather conditions at critical stages of plant growth. Strontium and rubidium tended to respond to limestone similar to calcium and potassium, showing that their measurements have potential to further evaluate nutrient dynamics since they have characteristics similar to calcium and potassium, respectively. This field trial showed that limestone applications had many and variable effects on the availability of numerous nutrients and associated elements on cauliflower in addition to Mn and Zn. This showed the high degree of complexity of limestone applications on acidic soils.Key words: Liming, soil pH, Ca, nutrient elements, nutrient analogs