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Kowalenko, C. G. and Ihnat, M. 2010. Effects of soil limestone and foliar manganese and zinc applications on field cauliflower growth and element contents. Can. J. Soil Sci. 90: 177Á188. 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 ) 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 (1979Á1985), 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.

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Well-characterized reference materials are needed by laboratories in the food testing and nutrition communities to facilitate compliance with nutritional labeling laws, to provide traceability for food exports needed for acceptance in many foreign markets, and to improve the accuracy of nutrition information that is provided to assist consumers in making sound dietary choices. As a result of the enactment of the Nutrition Labeling and Education Act of 1990 and the Infant Formula Act of 1980, the National Institute of Standards and Technology (NIST) has developed a suite of food-matrix Standard Reference Materials (SRMs) characterized for nutrient concentrations. These include SRM 1544 Fatty Acids and Cholesterol in a Frozen Diet Composite, SRM 1546 Meat Homogenate, SRM 1548a Typical Diet, SRM 1566b Oyster Tissue, SRM 1846 Infant Formula, SRM 1946 Lake Superior Fish Tissue, SRM 2383 Baby Food Composite, SRM 2384 Baking Chocolate, SRM 2385 Spinach, and SRM 2387 Peanut Butter. Many of these materials were developed at the request of the food industry to populate a nine-sectored fat-protein-carbohydrate triangle developed by AOAC International. With the completion of SRM 2387, SRMs representing each sector of the triangle are now available. These food-matrix reference materials are intended primarily for validation of analytical methods for the measurement of proximates, fatty acids, vitamins, minerals, and so on in foods of similar composition. They may also be used as "primary control materials" in the value-assignment of in-house, secondary, control materials to confirm accuracy as well as to establish traceability to NIST.

A fluorometric method using 2,3-diaminonaphthalene for estimating selenium has been evaluated with regard to its applicability to food samples. Charring of the sample during digestion appeared to result in losses of native and added selenium from some samples, so a modified wet digestion procedure was introduced. Digestion first in nitric acid followed by a mixture of nitric-perchloric-sulfuric acids substantially reduced the incidence of sample charring for a variety of foods. The mean apparent recovery of selenium added as selenite or selenate at 100 and 500 ng levels to 0.1 and 1.0 g corn cereal, skim milk powder, and meat and 0.1 g fish was 101.0%; the actual recovery of the same levels of selenium from standard solutions was 96.6%. For a variety of samples containing 5—750 ng native or added selenium, the standard deviation as 4.7 + 1.95 X 10-2W ng, where W = ng selenium in the sample taken for analysis. The relative standard deviation (RSD) as a function of selenium weight (ng) was 50% (10), 6.7% (100), 4.3% (200), 3.1% (400), 2.7% (600), and 2.5% (800). The detection limit (weight of selenium at which RSD = 50%) was 10 ng at a mean blank level of 25 ng.