Vagabond: The Trans-Species Ecologies of Plant/Human Encounters

[First paragraph] The opening scene of the acclaimed documentary King Corn (2007) shows Ian Cheney and Curtis Ellis, main protagonists, learning that corn constitutes one of the main carbon molecules of their hair. Segue to introduce the crop’s omnipresence in North American processed foods, principally used as sweetener, starch and animal feeds, the almost banal scientific fact presented in this scene is mesmerizing, providing a somewhat embodied support to the popular environmentalist saying “you are what you eat,” or to Donna Haraway’s poetic understanding of bodies and species as “full of their own others, full of messmates, of companions” (Haraway 2008, 165). Corn has indeed subtly made its way into our body, bite after bite, making it hard not to share Ian and Curtis’ awe while watching the film’s opening scene as it suggests that we, eaters of North American food, unknowingly became corn. Well established as the darling crop of nutritional technoscience, the introduction of genetically engineered corn in the late nineties juxtaposed to its wide presence in processed foods has spawned important political resistance, especially within Indigenous communities in Mexico. From street protest, field-testing to heirloom seeds international distribution, what is it exactly these activists were so desperately trying to protect

Advances in characterization of the soil clay mineralogy using X-ray diffraction: from decomposition to profile fitting

International audienceStructural characterization of soil clay minerals often remains limited despite their key influence on soil properties. In soils, complex clay parageneses result from the coexistence of clay species with contrasting particle sizes and crystal-chemistry and from the profusion of mixed layers with variable compositions. The present study aimed at characterizing the mineralogy and crystal chemistry of the < 2 μm fraction along a profile typical of soils from Western Europe and North America (Neo Luvisol). X-ray diffraction (XRD) patterns were nterpreted using i) the combination of XRD pattern decomposition and indirect identification from peak positions commonly applied in soil science and ii) the multi-specimen method. This latter approach implies direct XRD profile fitting and has recently led to significant improvements in the structural characterization of clay minerals in diagenetic and hydrothermal environments. In contrast to the usual approach, the multi-specimen method allowed the complete structural characterization of complex clay parageneses encountered in soils together with the quantitative analysis of their mineralogy. Throughout the profile, the clay paragenesis of the studied Neo Luvisol systematically includes discrete smectite, illite and kaolinite in addition to randomly interstratified illite-smectite and chlorite-smectite. Structural characteristics of the different clay minerals, including the composition of mixed layers, did not vary significantly with depth and are thus indicative of the parent material. The relative proportion of the < 2 μm fraction increased with increasing depth simultaneously with smectite relative proportion. These results are consistent with the leaching process described for Luvisols in the literature