A sustainable use of croplands should utilize beneficial services provided by their resident soil microbiome. To identify potentially adverse environmental effects on soil microbiomes in the future, a better understanding of their natural variability is fundamental. Here, we characterized the abundance and diversity of soil microbial communities over 2 years at two-week intervals on three neighboring fields at an operational farm in Northern Germany. Field soils differed in texture (clay, loam) and tillage (soil conservation vs. conventional). PCRamplicon analyses of soil DNA revealed distinct temporal variations of bacteria, archaea, fungi, and protists (Cercozoa and Endomyxa). Annual differences and seasonal effects on all microbial groups were detected. In addition to soil pH, prokaryotic communities varied with total soil C and N, but fungi with temperature and precipitation. The C/N ratio had contrasting effects on prokaryotic phyla and protistan classes, but all fungal phyla responded positively. Irrespective of the sampling date, prokaryotic and fungal but not protistan community compositions from the three soils were distinct. Compositional turnover rates were higher for fungi and protists than for prokaryotes and, for all, lower in clay. Conventional tillage had the strongest effect on protist diversity. In co-occurrence networks, most nodes were provided by prokaryotes, but highly connected nodes by predatory protists in the first, and by saprotrophic fungi in the second year. The temporal variation established here can provide insights of what is natural and thus below the limits of concern in detecting adverse effects on the soil microbiome.

In the context of sustainable building development, Compressed Earth Blocks (CEBs) have garnered increasing attention in recent years owing to their minimal environmental and economic impact. However, owing to the inherent diversity of raw soil and the production process's reliance on expertise, the properties of these blocks are subjected to multifaceted influences. Among these, the significance of soil particle size variation often remains overlooked, leaving its impact ambiguous. This study endeavours to address this gap in existing research by delving into this aspect. Two distinct batches of CEBs were produced by adjusting the grain size curve of a single type of sieved soil with different maximum mesh openings: 2 mm for R1 CEBs and 12.5 mm for R2 CEBs. Experimental results reveal significant differences in thermophysical characteristics: on average, R1 blocks show superior thermal performance, boasting a 23% reduction in thermal conductivity compared to R2 blocks, and are lighter, with an 8% decrease in dry bulk density. Although no significant changes in mechanical parameters were observed, finer-structured R1 blocks showed a 25% greater tendency to absorb water due to changes in their porous structure. This study sheds light on the sensitivity of thermal parameters to changes in soil particle size and shows that blocks with finer particles exhibit poorer heat conduction and heat diffusion. Besides providing new insights into the literature, this research also provides a strategic approach to optimise the thermophysical properties of CEBs. By understanding the influence of particle size, researchers and practitioners can now develop strategies to enhance these properties and improve the overall performance of CEBs.

Important agricultural pests in the Canadian Prairies, wireworms are the soil-living larvae of click beetles. Several notable species are found within the Prairies, with Hypnoidus bicolor being the most ubiquitous in most parts of the region. Despite their prevalence, H. bicolor is often disregarded as a significant pest species due to their comparatively small larval sizes. However, few studies have directly assessed the capacity of wireworms to cause damage to particular crop(s), and thus far no such studies have been undertaken for H. bicolor. We therefore carried out laboratory experiments under controlled environmental conditions, with soil and wireworms transplanted from the field, to determine the capability of H. bicolor to damage soybean. As expected, wireworm damage was strongly associated with larval densities, with more severe soybean injury occurring in the presence of greater numbers of H. bicolor. Further, feeding damage to soybean by H. bicolor was greater at lower temperatures (10 degrees C and 20 degrees C) than at higher temperatures (30 degrees C). In terms of soil texture, soybean grown in loam and silt soils were the most susceptible to wireworm damage and those grown in clay soil were the least affected. Although the larvae are not capable of damaging soybean to the same extent as other Prairie pest species, Limonius californicus and Hypnoidus abbreviatus, in high enough densities and under ideal environmental conditions H. bicolor can significantly impact soybean growth. Overall, our study suggests that soybean is susceptible to considerable wireworm damage and H. bicolor is an under recognized pest species of this legume.

Permafrost degradation can stimulate the decomposition of organic soil matter and cause a large amount of greenhouse gas emissions into the atmosphere. The light fraction organic matter (LFOM) is a labile substrate for microbial decomposition and probably plays an important role in future permafrost carbon cycles. However, little is known about the distribution of LFOM and its relationship with permafrost and environmental factors. Here, we investigated the light fraction carbon (LFC) and nitrogen (LFN) contents and stocks under meadows and wet meadows with different permafrost conditions on the southern Qinghai-Tibetan Plateau. Our results showed that LFC and LFN were mainly distributed in the upper 30 cm of soils, and the sites with permafrost had significantly higher contents of LFC and LFN than those from the sites without existing permafrost. The LFC and LFN decreased sharplywith depth, suggesting that the soil organicmatter (SOM) in this areawas highly decomposed in deep soils. Soil moisture and bulk density explained approximately 50% of the variances in LFC and LFN for all the sampling sites, while soil moisture explained approximately 30% of the variance in permafrost sites. Both the C:N ratios and LFC: LFN ratios in the sites with permafrost were higher than those in the sites without permafrost. The results suggested that the permafrost and land cover types are the main factors controlling LFOM content and stock, and that permafrost degradation would lead to a decrease of LFOM and soil C: N ratios, thus accelerating the decomposition of SOM. (C) 2017 Elsevier B.V. All rights reserved.

Climatic warming is presumed to cause topsoil drought by increasing evapotranspiration and water infiltration, and by progressively inducing land degradation in alpine meadows of the Qinghai-Tibetan Plateau. However, how soil moisture and temperature patterns of degraded alpine meadows respond to climate warming remains unclear. A 6-year continuous warming experiment was carried out in both degraded and undegraded alpine meadows in the source region of the Yangtze River. The goal was to identify the effects of climatic warming and land degradation on soil moisture (), soil surface temperature (T-sfc), and soil temperature (T-s). In the present study, land degradation significantly reduced by 45-61% at a depth of 0-100cm (p<0001) and increased the annual mean T-sfc by 08 degrees C. Warming with an infrared heater (radiation output of 150Wm(-2)) significantly increased the annual mean T-sfc by 25 degrees C (p<0001) and significantly increased by 47% at a depth of 40-60cm. Experimental warming in degraded land reversed the positive effects of the infrared heater and caused the yearly average to decrease significantly by 37-81% at a depth of 0-100cm. Our research reveals that land degradation caused a significant water deficit near the soil surface. Experimental warming aggravated topsoil drought caused by land degradation, intensified the magnitude of degradation, and caused a positive feedback in the degraded alpine meadow ecosystem. Therefore, an immediate need exists to restore degraded alpine meadow grasslands in the Qinghai-Tibetan Plateau in anticipation of a warmer future. Copyright (c) 2017 John Wiley & Sons, Ltd.

We investigated the main parameters [e.g. mean annual air temperature , mean annual soil temperature, mean annual precipitation, soil moisture (SM), soil chemistry, and physics] influencing soil organic carbon (C-org), soil total nitrogen (N-t) as well as plant available nitrogen (N-min) at 47 sites along a 1200 km transect across the high-altitude and low-latitude permafrost region of the central-eastern Tibetan Plateau. This large-scale survey allows testing the hypothesis that beside commonly used ecological variables, diversity of pedogenesis is another major component for assessing carbon (C) and nitrogen (N) cycling. The aim of the presented research was to evaluate consequences of permafrost degradation for C and N stocks and hence nutrient supply for plants, as the transect covers all types of permafrost including heavily degraded areas and regions without permafrost. Our results show that SM is the dominant parameter explaining 64% of C-org and 60% of N variation. The extent of the effect of SM is determined by permafrost, current aeolian sedimentation occurring mostly on degraded sites, and pedogenesis. Thus, the explanatory power for C and N concentrations is significantly improved by adding CaCO3 content (P=0.012 for C-org; P=0.006 for N-t) and soil texture (P=0.077 for C-org; P=0.015 for N-t) to the model. For soil temperature, no correlations were detected indicating that in high-altitude grassland ecosystems influenced by permafrost, SM overrides soil temperature as the main driving parameter at landscape scale. It was concluded from the current study that degradation of permafrost and corresponding changes in soil hydrology combined with a shift from mature stages of pedogenesis to initial stages, have severe impact on soil C and plant available N. This may alter biodiversity patterns as well as the development and functioning of the ecosystems on the Tibetan Plateau.