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The spatial variability in soil physical and hydraulic properties for a managed podzol was assessed using soil apparent electrical conductivity (ECa). Two EMI sensors, the multi-coil (MC) and multi-frequency (MF), were adopted for measurement of ECa on a silage- corn experimental plot in western Newfoundland, Canada. Results demonstrated a significant relationship between the ECa mean relative differences (MRD) and the soil moisture content MRD (R2 = 0.33 to 0.70) for both MC and MF sensors. The difference in depth sensitivity between MC and MF sensors accounted for the variation (0.015 to 0.09) in ECa standard deviation of the relative differences. A significant linear relationship was found between the ECa MRD and sand (R2 = 0.35 and 0.53) or silt (R2 = 0.43), but not with clay (R2 = 0.06 and 0.16). The spatial variability of the ECa-based predictions (CV = 3.26 to 27.61) of soil properties was lower than the measured values (CV = 5.56 to 41.77). These results inferred that the temporal stability of ECa might be a suitable proxy to understand the spatial variability of soil physical and hydraulic properties in agricultural podzols. [ABSTRACT FROM AUTHOR]

Plant clusters govern soil microbiology in desert systems. Female Acanthosicyos horridus plants in the Namib Desert are preferentially accessed by grazers, especially during fruit availability. We hypothesized that this differential grazing affects the taxonomic diversity of soil bacterial populations. Sampling was carried out at three locations on a northwest-to-southeast transect starting at the Kuiseb Delta, near the shores of the Atlantic in the western Namib Desert, and extending inland over a distance of 140 km. Analyses of the soil samples showed that proximity to the sea had a strong impact on soil salinity. Soil pH and organic matter content were generally not significantly correlated with the presence or absence of plants and varied little and non-uniformly along the transect. A. horridus presence led to distinct under-canopy bacterial-community diversity in contrast with the non-vegetated spaces between shrubs. However, plant gender has only a marginal, statistically insignificant impact on the bacterial-diversity properties, thus not supporting our hypothesis. Therefore, the taxonomic diversity of the bacterial community in Namib Desert soils vegetated with A. horridus is primarily governed by the presence or absence of plants and by proximity to the ocean. [ABSTRACT FROM AUTHOR]

Microbial function, composition, and distribution play a fundamental role in ecosystem ecology. The interaction between desert plants and their associated microbes is expected to greatly affect their response to changes in this harsh environment. Using comparative analyses, we studied the impact of three desert shrubs, Atriplex halimus (A), Artemisia herba-alba (AHA), and Hammada scoparia (HS), on soil- and leaf-associated microbial communities. DNA extracted from the leaf surface and soil samples collected beneath the shrubs were used to study associated microbial diversity using a sequencing survey of variable regions of bacterial 16S rRNA and fungal ribosomal internal transcribed spacer (ITS1). We found that the composition of bacterial and fungal orders is plant-type-specific, indicating that each plant type provides a suitable and unique microenvironment. The different adaptive ecophysiological properties of the three plant species and the differential effect on their associated microbial composition point to the role of adaptation in the shaping of microbial diversity. Overall, our findings suggest a link between plant ecophysiological adaptation as a 'temporary host' and the biotic-community parameters in extreme xeric environments. [ABSTRACT FROM AUTHOR]

Quantitative viral risk assessments for wastewaters are notoriously difficult. The often considered quantitative reverse transcriptase PCR reflects poorly on virus infectivity rates leading to inaccurate risk interpretations. Various techniques focused on the degradation of the nucleic acids of non-infective viruses were previously employed. We comparatively assessed the effectiveness of such enzymatic treatments for MS2 bacteriophage in treated wastewaters. The single use of RNase A at an appropriate concentration may be as effective as the combination of RNase followed by Proteinase K and more rapid. While all tested enzymatic treatments minimized recovery of RNA (>95 %) in the absence of infective MS2, none completely eliminated the signal recovery. Selection of any enzymatic protocol for minimizing recovery of RNA from degraded, non-infective viruses should balance the methods efficacy with its expediency. [ABSTRACT FROM AUTHOR]

Water and nutrient availability are the major limiting factors of biological activity in arid and semiarid ecosystems. Therefore, perennial plants have developed different ecophysiological adaptations to cope with harsh conditions. The chemical profile of the root exudates varies among plant species and this can induce variability in associated microbial populations. We examined the influence of two shrubs species, Artemisia sieberi and Noaea mucronata, on soil microbial diversity. Soil samples were collected monthly, from December 2006 to November 2007, near canopies of both shrubs (0-10-cm depth). Samples were used for abiotic tests and determination of soil bacterial diversity. No significant differences were found in the abiotic variables (soil moisture, total organic matter, and total soluble nitrogen (TSN)) between soil samples collected from under the two shrubs during the study period. No obvious differences in the Shannon-Weaver index, evenness values, or total phylogenetic distances were found for the soil microbial communities. However, detailed denaturing gradient gel electrophoresis (DGGE) clustering as well as taxonomic diversity analyses indicated clear shifts in the soil microbial community composition. These shifts were governed by seasonal variability in water availability and, significantly, by plant species type. [ABSTRACT FROM AUTHOR]

Under food security concerns and accelerated global warming, northern regions are becoming new agricultural frontiers. While diverse regional, national, and local policies support northern agricultural intensification and expansion through land use conversion, the scope and environmental consequences of northern agriculture are yet to be fully understood. As northern agriculture is poised to increase its role in both the local and global food production, its sustainable growth depends on a comprehensive understanding of opportunities and challenges. To evaluate the current perception of the status of northern agricultural research and the extent to which there is a need for a coordinated approach to its growth, we developed a targeted survey delivered online. Questions are aimed at revealing similarities and discrepancies in the awareness of northern agriculture and obtaining feedback on the need for a global synchronization of research and development. Out of 309 respondents, a curated dataset of 238 respondents was employed for analysis. This included respondents with knowledge and expertise in boreal and/or Arctic agriculture (41%), of temperate and/or alpine agriculture (37%), and other respondents (22%). Most are involved in agricultural (60%) or applied environmental (23.5%) sciences. Results revealed that scientists working in the northern regions are cautiously optimistic about climate change–driven expansion of northern agriculture while also realistic about the need for environmentally sustainable agricultural systems. Respondents with limited exposure to northern agriculture were more pessimistic about its expansion. Surprisingly, there was a limited and inconsistent knowledge of extant networks and research entities focusing on northern agriculture research. Nevertheless, there was a strong consensus that a concerted approach among multiple disciplines and across global regions would benefit northern agriculture and its ongoing growth. The survey's results illuminate for the very first time the need for better coordination and a greater emphasis on northern agriculture under climate change. [ABSTRACT FROM AUTHOR]