Global maps of soil temperature.

Research in global change ecology relies heavily on global climatic grids derived from estimates of air temperature in open areas at around 2 m above the ground. These climatic grids do not reflect conditions below vegetation canopies and near the ground surface, where critical ecosystem functions occur and most terrestrial species reside. Here, we provide global maps of soil temperature and bioclimatic variables at a 1-km <sup>2</sup> resolution for 0-5 and 5-15 cm soil depth. These maps were created by calculating the difference (i.e. offset) between in situ soil temperature measurements, based on time series from over 1200 1-km <sup>2</sup> pixels (summarized from 8519 unique temperature sensors) across all the world's major terrestrial biomes, and coarse-grained air temperature estimates from ERA5-Land (an atmospheric reanalysis by the European Centre for Medium-Range Weather Forecasts). We show that mean annual soil temperature differs markedly from the corresponding gridded air temperature, by up to 10°C (mean = 3.0 ± 2.1°C), with substantial variation across biomes and seasons. Over the year, soils in cold and/or dry biomes are substantially warmer (+3.6 ± 2.3°C) than gridded air temperature, whereas soils in warm and humid environments are on average slightly cooler (-0.7 ± 2.3°C). The observed substantial and biome-specific offsets emphasize that the projected impacts of climate and climate change on near-surface biodiversity and ecosystem functioning are inaccurately assessed when air rather than soil temperature is used, especially in cold environments. The global soil-related bioclimatic variables provided here are an important step forward for any application in ecology and related disciplines. Nevertheless, we highlight the need to fill remaining geographic gaps by collecting more in situ measurements of microclimate conditions to further enhance the spatiotemporal resolution of global soil temperature products for ecological applications

The effcts of biochar application on water relation and soil quality in Vitis vinifera

Soil water status plays an important role on the growth-yield response on Vitis vinifera and on the quality of productions. Moderate water stress periods are in some cases needed to ensure high quality productions, but especially in dry Mediterranean environment, water stress may lead to an unbalance of the sugar/acidity ratio due to berry dehydration. Biochar is a co-product of thermochemical conversion of lignocellulosic biomass and it is well recognized to exert, if incorporated to the soil, an amendant action and an increase of water retention. The scientific literature on soil biochar application show a small overall, but statistically significant, positive effect of the biochar on plant productivity. In this work we investigated the effect of biochar amendments on Vitis vinifera (cv. Merlot) in a acid soil (pH 5.5) in Central Italy for two consecutive seasons. The biochar was applied at two rates 22 and 44 t ha-1 in a strip plot design with 5 replicates During summer 2011 the seasonal course of leaf water potentials, chlorophyll content, and chlorophyll fluorescence were measured as potential indicators of water stress. Detailed soil samples were also made during the entire season to detect the effects of the biochar application on soil parameters and on their dynamic. Preliminary results that will be reported in this presentation are showing that the soil pH increased by about one unit after biochar application and that a substantial reduction of water stress effect of plant treated with biochar has occurre

Compact EDDY: a compact, low consumption eddy covariance logging system

Compact_Eddy is a handheld computer-based logging system developed for eddy covariance installations. It is flexible to support different types of sonic anemometers, it has storing capability on internal memory, and data processing capability. The software is written in the Visual Basic .NET platform, entirely based on standard Windows operating systems thus allowing easy installation and configuration for a wide range of handheld PCs. The software computes half hourly statistics and fluxes with a simplified procedure, stores binary data with efficient memory usage and can be configured to send periodically, to a remote control station, system status information and basic computations using a GSM modem. The use of a handheld computer resulted in an average real conditions power consumption of 2.9 W, very low if compared with other standard logging devices, allowing important savings especially when systems are powered with solar panels in remote areas. Compact_Eddy has been installed and tested in three locations, with very different environmental conditions ranging from eastern European mountain forests to African semi-desertic areas. The field results demonstrated that the system operated reliably, resulting to be a good low-cost alternative to laptop computers and dataloggers. \ua9 2008 Elsevier B.V. All rights reserved

Changes in the pattern of polycyclic aromatic hydrocarbons in soil treated with biochar from a multiyear field experiment

The influence of biochar added to an agricultural soil on polycyclic aromatic hydrocarbon (PAH) levels, PAH diagnostic ratios and soil properties was investigated in a five-year field experiment. The experiment was carried out in an Italian vineyard and included two biochar treatments: 16.5 t ha −1 of biochar applied in 2009 (soil B); 16.5 t ha −1 in 2009 and further 16.5 t ha −1 in 2010 (soil BB). A set of 75 samples that included five replicates and a control soil (untreated) was characterized in terms of organic carbon, pH, cation exchange capacity (CEC), bulk density and concentration of PAHs. Biochar addition to soil caused an increase in organic carbon, pH and CEC, and a decrease of bulk density. After almost two years the first application of biochar, PAH concentrations were higher in soil B (56 ng g −1 ) and BB (153 ng g −1 ) in comparison to control soil (24 ng g −1 ). Thereafter, PAH concentrations decreased significantly, but the original PAHs levels were reached only in soil B after five years. The naphthalene/(naphthalene + phenanthrene) ratios were higher in the treated soils in accordance to the dominance of naphthalene in the original biochar. The cross plots naphthalene/(naphthalene + phenanthrene) vs. fluoranthene/(fluoranthene + pyrene) enabled to trace the signature of biochar PAHs up to five years after its first application. Diagnostic ratios can be a useful tool to study the persistence of PAHs introduced in soil by biochar when the pattern of these contaminants in biochar and original soil are different

Surface albedo following biochar application in durum wheat

The agronomic use of charcoal from biomass pyrolysis (biochar) represents an interesting option for increasing soil fertility and sequestering atmospheric CO2. However, before moving toward large-scale biochar applications, additional research must evaluate all possible land–atmosphere feedbacks. Despite the increasing number of studies investigating the effect of biochar on soil physical, chemical and biological properties, only a few have been done on surface albedo variations on agricultural lands. The present work had the aim of characterizing the annual albedo cycle for a durum wheat crop in Central Italy, by means of a spectroradiometer measurement campaign. Plots treated with biochar, at a rate of 30–60 t ha1, showed a surface albedo decrease of up to 80% (after the application) with respect to the control in bare soil conditions, while this difference tended to decrease during the crop growing season, because of the prevailing effect of canopy development on the radiometer response. After the post-harvesting tillage, the soil treated with biochar again showed a lower surface albedo value (<20–26% than the control), while the measurements taken in the second year after application suggested a clear decrease of biochar influence on soil color. The modeling of the surface energy balance highlighted changes in the partitioning of heat fluxes and in particular a substantial increase of ground heat fluxes on an annual basis

Changes in the pattern of polycyclic aromatic hydrocarbons in soil treated with biochar from a multiyear field experiment

The influence of biochar added to an agricultural soil on polycyclic aromatic hydrocarbon (PAH) levels, PAH diagnostic ratios and soil properties was investigated in a five-year field experiment. The experiment was carried out in an Italian vineyard and included two biochar treatments: 16.5 t ha −1 of biochar applied in 2009 (soil B); 16.5 t ha −1 in 2009 and further 16.5 t ha −1 in 2010 (soil BB). A set of 75 samples that included five replicates and a control soil (untreated) was characterized in terms of organic carbon, pH, cation exchange capacity (CEC), bulk density and concentration of PAHs. Biochar addition to soil caused an increase in organic carbon, pH and CEC, and a decrease of bulk density. After almost two years the first application of biochar, PAH concentrations were higher in soil B (56 ng g −1 ) and BB (153 ng g −1 ) in comparison to control soil (24 ng g −1 ). Thereafter, PAH concentrations decreased significantly, but the original PAHs levels were reached only in soil B after five years. The naphthalene/(naphthalene + phenanthrene) ratios were higher in the treated soils in accordance to the dominance of naphthalene in the original biochar. The cross plots naphthalene/(naphthalene + phenanthrene) vs. fluoranthene/(fluoranthene + pyrene) enabled to trace the signature of biochar PAHs up to five years after its first application. Diagnostic ratios can be a useful tool to study the persistence of PAHs introduced in soil by biochar when the pattern of these contaminants in biochar and original soil are different