Lavkulich, L. M. and Arocena, J. M. 2011. Luvisols of Canada: Genesis, distribution, and classification. Can. J. Soil Sci. 91: 781–806. Luvisols link the soil continuum on the Quaternary landscapes. These soils are developed from parent materials rich in Ca and Mg in a relatively humid climate. An acidic eluvial horizon overlying a phyllosilicate-enriched illuvial Bt horizon is the common horizon sequence in Luvisolic soils. Lessivage or the translocation of clays with minimal chemical alteration is the characteristic soil-forming process and results to the diagnostic Bt horizon with well-developed, oriented clay skins or cutans. These soils commonly form intergrades with Chernozems, Podzols and Vertisols. With time, the eluvial horizons experience increased chemical weathering and further release of sequioxides to form Brunisolic and Podzolic sequences within the eluvial Ae in biseqeual soils. Lessivage significantly influences several ecosystem functions of soils. The high amounts of phyllosilicates in the Bt horizon serve as one of the most active sorption sites in soils for metals and organic materials including soil carbon. Sorption of cations takes place through cation exchange reactions and determines the availability of cations to plant roots as well as in the “colloid facilitated transport” of strongly sorbing metals and organic pollutants. Clays in Bt can be restrictive to water and air movement as well as to root growth and distribution. Agricultural and forestry practices such as tillage can compact the structure of Luvisols and may decrease soil productivity.

Thomas, E. C. and Lavkulich, L. M. 2015. Community considerations for quinoa production in the urban environment. Can. J. Plant Sci. 95: 397Á404. Production of food crops in urban settings is an increasingly consumer-accepted means of contributing to local food security and access to fresh produce. Many urban gardens are located on former industrial sites (brownfields) that may be contaminated by heavy metals. Growing crops in trace metal contaminated soil can pose human health concerns. Little has been documented on the uptake of metals from urban sites by crops, and especially the partitioning of metals between roots, shoots and seeds. Human health impacts are of particular concern when locally grown produce constitutes a major proportion of the local diet. The results of this study show that quinoa grown on brownfield sites in Vancouver, Canada may contain elevated levels of metals such as Cd, Cu and Pb.Key words: Quinoa, brownfield, urban agriculture, trace metals Thomas, E. C. et Lavkulich, L. M. 2015. Aspects communautaires de la culture du quinoa en zone urbaine. Can. J. Plant Sci. 95: 397Á404. La production de cultures vivrie`res en milieu urbain est une fac¸on de plus en plus accepte´e par les consommateurs de concourir a`la se´curite´alimentaire locale et d'acce´der a`des fruits et le´gumes frais. Beaucoup de jardins urbains sont ame´nage´s sur d'anciens sites industriels (friches industrielles) qui peuvent eˆtre contamine´s par des me´taux lourds. Les cultures poussant sur un sol pollue´par des oligoe´le´ments peuvent entraıˆner des proble`mes de sante´. On posse`de peu de documentation sur l'absorption des me´taux pre´sents dans les sites urbains par les cultures, plus pre´cise´ment sur la distribution des me´taux dans les racines, les pousses et les graines. L'impact sur la sante´humaine est un souci particulier quand les fruits et les le´gumes produits localement constituent une part importante du re´gime. Les re´sultats de cette e´tude indiquent que le quinoa cultive´sur les friches industrielles a`Vancouver, au Canada, pourrait renfermer une concentration e´leve´e de me´taux comme le cadmium, le cuivre et le plomb.

Baugé, S. M. Y., Lavkulich, L. M. and Schreier, H. E. 2013. Serpentine affected soils and the formation of magnesium phosphates (struvite). Can. J. Soil Sci. 93: 161–172. The Sumas River watershed, located in the intensive agricultural region of the Lower Fraser Valley of British Columbia (Canada), contains serpentine asbestos from a natural landslide. Serpentinic soils have a high Mg to Ca ratio that can affect soil fertility, including soil-solution P relations. The objectives of the study were: (i) to evaluate some common methods of estimating plant available phosphorus in the surface horizons of the serpentine-affected soils and those receiving large quantities of livestock manure, and (ii) to determine if there is evidence for the formation of soluble Mg phosphates, e.g., struvite, a meta-stable P phase in these soils. Seven soil nutrient extractants were used to determine major and minor elemental concentrations. Acid ammonium oxalate, 1 M HCl and Bray P1 extractions were most effective for measuring available phosphorus in these soils. Manure and fertilizer applications appear to favor the formation of Mg-phosphates, and are considered to be more soluble in terms of phosphorus than either calcium-phosphates or aluminum/iron-phosphates. X-ray diffraction, scanning electron microscopy and nuclear magnetic resonance examinations gave positive evidence for the presence of struvite in the soils.

Baugé, S. M. Y., Lavkulich, L. M. and Schreier, H. E. 2013. Phosphorus and trace metals in serpentine-affected soils of the Sumas Basin, British Columbia. Can. J. Soil Sci. 93: 359–367. Soils of the Sumas watershed in the Lower Fraser Valley of British Columbia have contrasting P, Mg and trace elements contents arising from two major sources, periodic deposition of serpentine-rich sediments and intensive agricultural activities. Four study sites were examined for soil P by several extractants commonly used for P availability assessments. The results were compared with aqua regia to determine best estimates of extractable P. In addition, these extractants were evaluated as indices of associated trace metal amounts. Aqua regia, acid ammonium oxalate and 1 M HCl extracted similar amounts of P and trace metals. Acid ammonium oxalate was found to be closely related to the estimates of total P and recoverable elements, followed by 1 M HCl. There was clear separation of the sites by both P values and trace elements associated with serpentine (Cr and Ni) and those from agricultural activities (Cu and Zn). Results suggest that a single extraction, 1 M HCl, can be an effective measure of both available P and trace elements in serpentinitic soils.

Baugé, S. M. Y., Lavkulich, L. M., Wilson, J. E. and Schreier, H. E. 2014. Comparison of surface properties of synthetic and soil struvite. Can. J. Soil Sci. 94: 169–176. X-ray, Raman and nuclear magnetic resonance (NMR) analyses of intensively managed agricultural soils in southwestern British Columbia reported the presence of the Mg-phosphate mineral, struvite. Soils are heterogeneous, thus analytical techniques based on single minerals require calibration in order to provide reliable results. A synthetic struvite was used to compare the properties of the soil phosphate with struvite. The results confirmed the presence of struvite and possibly additional species of Mg. Time of flight–secondary ion mass spectroscopy (TOF-SIMS) revealed that the surface of struvite, to 2nm depth, is dominated by Mg with other cations, notably Fe and NH4 that were measured in minor amounts and were associated with the Mg rich surface layer. The results suggest that P is located within the struvite structure. Chemical reactions of struvite and phosphorus chemistry in these soils appear to be governed by the Mg surface layer.