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Abstract. SoilGrids produces maps of soil properties for the entire globe at medium spatial resolution (250 m cell size) using state-of-the-art machine learning methods to generate the necessary models. It takes as inputs soil observations from about 240 000 locations worldwide and over 400 global environmental covariates describing vegetation, terrain morphology, climate, geology and hydrology. The aim of this work was the production of global maps of soil properties, with cross-validation, hyper-parameter selection and quantification of spatially explicit uncertainty, as implemented in the SoilGrids version 2.0 product incorporating state-of-the-art practices and adapting them for global digital soil mapping with legacy data. The paper presents the evaluation of the global predictions produced for soil organic carbon content, total nitrogen, coarse fragments, pH (water), cation exchange capacity, bulk density and texture fractions at six standard depths (up to 200 cm). The quantitative evaluation showed metrics in line with previous global, continental and large-region studies. The qualitative evaluation showed that coarse-scale patterns are well reproduced. The spatial uncertainty at global scale highlighted the need for more soil observations, especially in high-latitude regions.

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Background, Aims, and Scope. Historically, built areas were ignored in soil mapping and in studies of soil formation and behaviour. It is now recognized that these areas, and therefore their soils, are of prime importance to human populations. Another trend is the large increase in reclaimed lands and new uses for old industrial areas. In several countries there are active projects to map such areas, either with locally-developed classification systems or ad-hoc names. Soil classification gives unique and reproducible names to soil individuals, thereby facilitating correlation of soil studies; this should be possible also for urban soils. The World Reference Base for Soil Resources (WRB) is the soil classification system endorsed by the International Union of Soil Science (IUSS). The 2006 edition has important enhancements which allow urban and industrial soils to be described and mapped, most notably a new reference group, the Technosols.Main Features. Urban soils are first defined, followed by the philosophical basis of soil classification in general and the WRB in particular. WRB 2006 added a new Technosols reference soil group for soils whose properties and function are dominated by technical human activity as evidenced by either a substantial presence of artefacts, or an impermeable constructed geomembrane, or technic hard rock. Technosols are one of Ekranic, Linic, Urbic, Spolic or Garbic; further qualifiers are added to show intergrades to other groups as well as specific soil properties. Soils from fill are recognized as Transportic Regosols or Arenosols. Toxic soils are specifically recognized by a qualifier.Discussion. The limit between Technosols and other groups may be difficult to determine, because of the requirement that the technic nature dominate any subsequent pedogenesis. Recommendations and Perspectives.The WRB should certainly be used in all urban soil studies to facilitate communication and correlation of results. In the period leading up to the next revision in 2010, the quantitative results from urban soil studies should be used to refine class definitions.

The potential economic and agronomic impacts of gradual climate warming are examined at the farm level. Three models of the relevant climatic, agronomic, and economic processes are developed and linked to address climate change impacts and agricultural adaptability. Several climate warming scenarios are analyzed, which vary in severity. The results indicate that grain farmers in southern Minnesota can effectively adapt to a gradually changing climate (warmer and either wetter or drier) by adopting later maturing cultivars, changing crop mix, and altering the timing of field operations to take advantage of a longer growing season resulting from climate warming.