Reading tea leaves worldwide: Decoupled drivers of initial litter decomposition mass-loss rate and stabilization.

The breakdown of plant material fuels soil functioning and biodiversity. Currently, process understanding of global decomposition patterns and the drivers of such patterns are hampered by the lack of coherent large-scale datasets. We buried 36,000 individual litterbags (tea bags) worldwide and found an overall negative correlation between initial mass-loss rates and stabilization factors of plant-derived carbon, using the Tea Bag Index (TBI). The stabilization factor quantifies the degree to which easy-to-degrade components accumulate during early-stage decomposition (e.g. by environmental limitations). However, agriculture and an interaction between moisture and temperature led to a decoupling between initial mass-loss rates and stabilization, notably in colder locations. Using TBI improved mass-loss estimates of natural litter compared to models that ignored stabilization. Ignoring the transformation of dead plant material to more recalcitrant substances during early-stage decomposition, and the environmental control of this transformation, could overestimate carbon losses during early decomposition in carbon cycle models.

Effect of long-term organic and mineral fertilization strategies on rhizosphere microbiota assemblage and performance of lettuce.

Long-term agricultural fertilization strategies gradually change soil properties including the associated microbial communities. Cultivated crops recruit beneficial microbes from the surrounding soil environment via root exudates. In this study, we aimed to investigate the effects of long-term fertilization strategies across field sites on the rhizosphere prokaryotic (Bacteria and Archaea) community composition and plant performance. We conducted growth chamber experiments with lettuce (Lactuca sativa L.) cultivated in soils from two long-term field experiments, each of which compared organic versus mineral fertilization strategies. 16S rRNA gene amplicon sequencing revealed the assemblage of a rhizosphere core microbiota shared in all lettuce plants across soils, going beyond differences in community composition depending on field site and fertilization strategies. The enhanced expression of several plant genes with roles in oxidative and biotic stress signalling pathways in lettuce grown in soils with organic indicates an induced physiological status in plants. Lettuce plants grown in soils with different fertilization histories were visibly free of stress symptoms and achieved comparable biomass. This suggests a positive aboveground plant response to belowground plant-microbe interactions in the rhizosphere. Besides effects of fertilization strategy and field site, our results demonstrate the crucial role of the plant in driving rhizosphere microbiota assemblage.

Enhanced top soil carbon stocks under organic farming.

It has been suggested that conversion to organic farming contributes to soil carbon sequestration, but until now a comprehensive quantitative assessment has been lacking. Therefore, datasets from 74 studies from pairwise comparisons of organic vs. nonorganic farming systems were subjected to metaanalysis to identify differences in soil organic carbon (SOC). We found significant differences and higher values for organically farmed soils of 0.18 ± 0.06% points (mean ± 95% confidence interval) for SOC concentrations, 3.50 ± 1.08 Mg C ha(-1) for stocks, and 0.45 ± 0.21 Mg C ha(-1) y(-1) for sequestration rates compared with nonorganic management. Metaregression did not deliver clear results on drivers, but differences in external C inputs and crop rotations seemed important. Restricting the analysis to zero net input organic systems and retaining only the datasets with highest data quality (measured soil bulk densities and external C and N inputs), the mean difference in SOC stocks between the farming systems was still significant (1.98 ± 1.50 Mg C ha(-1)), whereas the difference in sequestration rates became insignificant (0.07 ± 0.08 Mg C ha(-1) y(-1)). Analyzing zero net input systems for all data without this quality requirement revealed significant, positive differences in SOC concentrations and stocks (0.13 ± 0.09% points and 2.16 ± 1.65 Mg C ha(-1), respectively) and insignificant differences for sequestration rates (0.27 ± 0.37 Mg C ha(-1) y(-1)). The data mainly cover top soil and temperate zones, whereas only few data from tropical regions and subsoil horizons exist. Summarizing, this study shows that organic farming has the potential to accumulate soil carbon.

Selected conservation management strategies enhance maize yield stability in the sub-humid tropical agro-ecozone of Upper Eastern Kenya.

Conservation management strategies have been recommended to enhance soil fertility, moisture retention, crop yield, and yield stability in rainfed agriculture. However, there is limited research on yield stability. We evaluated the effect of integrating soil inputs in conservation tillage on yield and yield stability in Meru South, Upper Eastern Kenya, for eleven consecutive cropping seasons. The trial treatments included conservation tillage without soil inputs (Mt), conservation tillage with soil inputs: sole inorganic fertilizer (F), residue + inorganic fertilizer (RF), residue + inorganic fertilizer + manure (RFM), residue + manure + legume Dolichos Lablab L. (RML), residue + Tithonia + manure (RTM), residue + Tithonia + phosphate rock (RTP) and conventional tillage (Control). Conservation tillage with RFM was the best-fit strategy for enhancing yields. There was heterogeneity in yield residual variance. A larger residual variance implied lesser yield stability. Mt treatment had the least yield residual variance of 0.12 Mg ha-2, followed by Ct and RML, 0.15 Mg ha-2, while RTM had the highest yield residual variance of 0.62 Mg ha-2. Contrarily, the most stable treatments had the least average yields. The study indicated a positive influence of incorporating soil inputs in conservation tillage on yield and suggests longer-term research for yield stability.

Influence of soil fertility management technologies on phosphorus fractions, sorption characteristics, and use efficiency in humic Nitisols of Upper Eastern Kenya.

Fractions of phosphorus (P) and its sorption characteristics are affected by different soil fertility (FM) technologies which ultimately affect crop growth and productivity. However, the response of P fractions and sorption characteristics to soil fertility technologies that integrate diverse amendments is still poorly understood in acidic Nitisols. A randomized complete block design was layout in an acidic Nitisol to determine fractions of P, its sorption characteristics and use efficiencies in acidic Nitisols under various FM technologies in field conditions. The use of minimum tillage + maize residue + inorganic fertilizer + goat manure (MTCrGF) had the highest impact on and significantly increased resin-Pi, NaHCO3-Pi, and maximum P sorption (Smax) by 182, 76, and 52 mg P kg-1. Moreover, NaOH-Pi and Smax concentrations were higher under conventional tillage + maize residue + inorganic fertilizer + goat manure (CTCrGF) by 216 mg P kg-1 and 49 mg P kg-1 than the control. MTCrGF and CTCrGF also had the lowest P bonding energy (0.04 L mg-1). CTCrGF had the highest P partial productivity factor (0.093 and 0.140 kg biomass kg-1 P) and P agronomic efficiency (0.080 and 0.073 kg biomass kg-1 P) during the two cropping seasons. The results demonstrate the positive influence of combining multiple P sources on soil P fractions, sorption characteristics, and use efficiencies. Notably, combining either conventional or minimum tillage with maize straw and applying integrated manure and inorganic fertilizer (MTCrGF or CTCrGF) can increase the labile P concentrations and reduce the potential depletion of the non-renewable rock phosphate and the use of inorganic phosphatic fertilizers for agricultural production.

Data on the response of Zea Mays L. and soil moisture content to tillage and soil amendments in the sub-humid tropics.

The datasets presented were collected from Chuka and Kandara on-station trials sites in Kenya, conducted for two consecutive years. The main aim of the data collection was to evaluate the soil amendments and tillage influence on Zea Mays L. (maize) crop performance and soil moisture content, as reported by Kiboi et al. [1]. Rainfall data were collected using a manual rain gauge installed within the trial site. A non-destructive sampling of four maize plants next to each other on the centre row in each plot was conducted at the 6th and 10th leaf phase to determine crop growth dynamics. Maize grain and stover were harvested at maturity from net plots of 21 m2 in Chuka and 15 m2 in Kandara. The net plot was derived by excluding the first, the last (guard) rows, and the first and last maize plants in each plot. The net plot approach aimed to minimize the edge effect. For soil moisture content determination, a Polyvinyl Chloride access tube was installed at the centre of each plot. Crop phenology was observed and recorded at 50 and 100% stages per treatment. The datasets presented are supplementary materials to the research article by Kiboi et al. [1]. For statistical analysis, the data were subjected to analysis of variance (ANOVA). The datasets under consideration include daily rainfall, relative chlorophyll content- SPAD values and plant heights, grain yields and stover yields, and periodic soil moisture content.

Corrigendum to "Data on the response of Zea Mays L. and soil moisture content to tillage and soil amendments in the sub-humid tropics" Data in Brief 43 (2022) 108381.

[This corrects the article DOI: 10.1016/j.dib.2022.108381.].

Trophic niche but not abundance of Collembola and Oribatida changes with drought and farming system.

Higher frequencies of summer droughts are predicted to change soil conditions in the future affecting soil fauna communities and their biotic interactions. In agroecosystems drought effects on soil biota may be modulated by different management practices that alter the availability of different food resources. Recent studies on the effect of drought on soil microarthropods focused on measures of abundance and diversity. We here additionally investigated shifts in trophic niches of Collembola and Oribatida as indicated by stable isotope analysis (13C and 15N). We simulated short-term summer drought by excluding 65% of the ambient precipitation in conventionally and organically managed winter wheat fields on the DOK trial in Switzerland. Stable isotope values suggest that plant litter and root exudates were the most important resources for Collembola (Isotoma caerulea, Isotomurus maculatus and Orchesella villosa) and older plant material and microorganisms for Oribatida (Scheloribates laevigatus and Tectocepheus sarekensis). Drought treatment and farming systems did not affect abundances of the studied species. However, isotope values of some species increased in organically managed fields indicating a higher proportion of microorganisms in their diet. Trophic niche size, a measure of both isotope values combined, decreased with drought and under organic farming in some species presumably due to favored use of plants as basal resource instead of algae and microorganisms. Overall, our results suggest that the flexible usage of resources may buffer effects of drought and management practices on the abundance of microarthropods in agricultural systems.

Soil microarthropods respond differently to simulated drought in organic and conventional farming systems.

In Central Europe, summer droughts are increasing in frequency which threatens production and biodiversity in agroecosystems. The potential of different farming systems to mitigate detrimental drought effects on soil animals is largely unknown. We investigated the effects of simulated drought on the abundance and community composition of soil microarthropods (Collembola and Oribatida and Meso-, Pro-, and Astigmata) in winter wheat fields under long-term conventional and organic farming in the DOK trial, Switzerland. We simulated drought by excluding 65% of the ambient precipitation during the wheat-growing season from March to June 2017. The abundance of Collembola and Oribatida declined more consistently in conventionally managed fields compared to organically managed fields under simulated drought. The abundance of Collembola as well as Meso-, Pro- and Astigmata, but not the abundance of Oribatida, increased in deeper soil layers due to simulated drought, suggesting vertical migration as a drought avoidance strategy. The species composition of Oribatida communities, but not of Collembola communities, differed significantly between drought treatments and between farming systems. Soil carbon content was a major factor structuring Oribatida communities. Our results suggest that organic farming buffers negative effects of drought on soil microarthropods, presumably due to higher soil carbon content and associated higher soil moisture and improved soil structure. This potential of organic farming systems to mitigate consequences of future droughts on soil biodiversity is promising and needs further exploration across larger climatic and spatial scales and should be extended to other groups of soil biota.

Conventional agriculture and not drought alters relationships between soil biota and functions.

Soil biodiversity constitutes the biological pillars of ecosystem services provided by soils worldwide. Soil life is threatened by intense agricultural management and shifts in climatic conditions as two important global change drivers which are not often jointly studied under field conditions. We addressed the effects of experimental short-term drought over the wheat growing season on soil organisms and ecosystem functions under organic and conventional farming in a Swiss long term trial. Our results suggest that activity and community metrics are suitable indicators for drought stress while microbial communities primarily responded to agricultural practices. Importantly, we found a significant loss of multiple pairwise positive and negative relationships between soil biota and process-related variables in response to conventional farming, but not in response to experimental drought. These results suggest a considerable weakening of the contribution of soil biota to ecosystem functions under long-term conventional agriculture. Independent of the farming system, experimental and seasonal (ambient) drought conditions directly affected soil biota and activity. A higher soil water content during early and intermediate stages of the growing season and a high number of significant relationships between soil biota to ecosystem functions suggest that organic farming provides a buffer against drought effects.

Estimation by PLFA of microbial community structure associated with the rhizosphere of Lygeum spartum and Piptatherum miliaceum growing in semiarid mine tailings.

The objective of this study was to compare the microbial community composition and biomass associated with the rhizosphere of a perennial gramineous species (Lygeum spartum L.) with that of an annual (Piptatherum miliaceum L.), both growing in semiarid mine tailings. We also established their relationship with the contents of potentially toxic metals as well as with indicators of soil quality. The total phospholipid fatty acid (PLFA) amount was significantly higher in the rhizosphere soil of the annual species than in the rhizosphere soil of the perennial species. The fungal/bacterial PLFA ratio was significantly greater in the perennial species compared to the annual species. The fatty acid 16:1ω5c, the fungal/bacterial PLFA ratio and monounsaturated/saturated PLFA ratio were correlated negatively with the soluble contents of toxic metals. The cyc/prec (cy17:0 + cy19:0/16:1ω7 + 18:1ω7) ratio was correlated positively with the soluble contents of Pb, Zn, Al, Ni, Cd, and Cu. The results of the PLFA analysis for profiling microbial communities and their stress status of both the plant species indicate that perennial and annual gramineous species appear equally suitable for use in programmes of revegetation of semiarid mine tailings.

Effects of simulated drought on biological soil quality, microbial diversity and yields under long-term conventional and organic agriculture.

Drought and agricultural management influence soil microorganisms with unknown consequences for the functioning of agroecosystems. We simulated drought periods in organic (biodynamic) and conventional wheat fields and monitored effects on soil water content, microorganisms and crops. Above the wilting point, water content and microbial respiration were higher under biodynamic than conventional farming. Highest bacterial and fungal abundances were found in biodynamically managed soils, and distinct microbial communities characterised the farming systems. Most biological soil quality parameters and crop yields were only marginally affected by the experimental drought, except for arbuscular mycorrhizal fungi (AMF), which increased in abundance under the experimental drought in both farming systems. AMF were further strongly promoted by biodynamic farming resulting in almost three times higher AMF abundance under experimental drought in the biodynamic compared with the conventional farming system. Our data suggest an improved water storage capacity under biodynamic farming and confirms positive effects of biodynamic farming on biological soil quality. The interactive effects of the farming system and drought may further be investigated under more substantial droughts. Given the importance of AMF for the plant's water supply, more in-depth studies on AMF may help to clarify their role for yields under conditions predicted by future climate scenarios.

Diversity and structure of prokaryotic communities within organic and conventional farming systems in central highlands of Kenya.

Management practices such as tillage, crop rotation, irrigation, organic and inorganic inputs application are known to influence diversity and function of soil microbial populations. In this study, we investigated the effect of conventional versus organic farming systems at low and high input levels on structure and diversity of prokaryotic microbial communities. Soil samples were collected from the ongoing long-term farming system comparison trials established in 2007 at Chuka and Thika in Kenya. Physicochemical parameters for each sample were analyzed. Total DNA and RNA amplicons of variable region (V4-V7) of the 16S rRNA gene were generated on an Illumina platform using the manufacturer's instructions. Diversity indices and statistical analysis were done using QIIME2 and R packages, respectively. A total of 29,778,886 high quality reads were obtained and assigned to 16,176 OTUs at 97% genetic distance across both 16S rDNA and 16S rRNA cDNA datasets. The results pointed out a histrionic difference in OTUs based on 16S rDNA and 16S rRNA cDNA. Precisely, while 16S rDNA clustered by site, 16S rRNA cDNA clustered by farming systems. In both sites and systems, dominant phylotypes were affiliated to phylum Actinobacteria, Proteobacteria and Acidobacteria. Conventional farming systems showed a higher species richness and diversity compared to organic farming systems, whilst 16S rRNA cDNA datasets were similar. Physiochemical factors were associated differently depending on rRNA and rDNA. Soil pH, electrical conductivity, organic carbon, nitrogen, potassium, aluminium, zinc, iron, boron and micro-aggregates showed a significant influence on the observed microbial diversity. The observed higher species diversity in the conventional farming systems can be attributed to the integration of synthetic and organic agricultural inputs. These results show that the type of inputs used in a farming system not only affect the soil chemistry but also the microbial population dynamics and eventually the functional roles of these microbes.

Site-Specific Conditions Change the Response of Bacterial Producers of Soil Structure-Stabilizing Agents Such as Exopolysaccharides and Lipopolysaccharides to Tillage Intensity.

Agro-ecosystems experience huge losses of land every year due to soil erosion induced by poor agricultural practices such as intensive tillage. Erosion can be minimized by the presence of stable soil aggregates, the formation of which can be promoted by bacteria. Some of these microorganisms have the ability to produce exopolysaccharides and lipopolysaccharides that "glue" soil particles together. However, little is known about the influence of tillage intensity on the bacterial potential to produce these polysaccharides, even though more stable soil aggregates are usually observed under less intense tillage. As the effects of tillage intensity on soil aggregate stability may vary between sites, we hypothesized that the response of polysaccharide-producing bacteria to tillage intensity is also determined by site-specific conditions. To investigate this, we performed a high-throughput shotgun sequencing of DNA extracted from conventionally and reduced tilled soils from three tillage system field trials characterized by different soil parameters. While we confirmed that the impact of tillage intensity on soil aggregates is site-specific, we could connect improved aggregate stability with increased absolute abundance of genes involved in the production of exopolysaccharides and lipopolysaccharides. The potential to produce polysaccharides was generally promoted under reduced tillage due to the increased microbial biomass. We also found that the response of most potential producers of polysaccharides to tillage was site-specific, e.g., Oxalobacteraceae had higher potential to produce polysaccharides under reduced tillage at one site, and showed the opposite response at another site. However, the response of some potential producers of polysaccharides to tillage did not depend on site characteristics, but rather on their taxonomic affiliation, i.e., all members of Actinobacteria that responded to tillage intensity had higher potential for exopolysaccharide and lipopolysaccharide production specifically under reduced tillage. This could be especially crucial for aggregate stability, as polysaccharides produced by different taxa have different "gluing" efficiency. Overall, our data indicate that tillage intensity could affect aggregate stability by both influencing the absolute abundance of genes involved in the production of exopolysaccharides and lipopolysaccharides, as well as by inducing shifts in the community of potential polysaccharide producers. The effects of tillage intensity depend mostly on site-specific conditions.

Soil amendment with Pseudomonas fluorescens CHA0: lasting effects on soil biological properties in soils low in microbial biomass and activity.

Pseudomonas fluorescens strains are used in agriculture as plant growth-promoting rhizobacteria (PGPR). Nontarget effects of released organisms should be analyzed prior to their large-scale use, and methods should be available to sensitively detect possible changes in the environments the organism is released to. According to ecological theory, microbial communities with a greater diversity should be less susceptible to disturbance by invading organisms. Based on this principle, we laid out a pot experiment with field-derived soils different in their microbial biomass and activity due to long-term management on similar parent geological material (loess). We investigated the survival of P. fluorescens CHA0 that carried a resistance toward rifampicin and the duration of potential changes of the soil microflora caused by the inoculation with the bacterium at the sowing date of spring wheat. Soil microbial biomass (C(mic), N(mic)) basal soil respiration (BR), qCO(2), dehydrogenase activity (DHA), bacterial plate counts, mycorrhiza root colonization, and community level substrate utilization were analyzed after 18 and 60 days. At the initial stage, soils were clearly different with respect to most of the parameters measured, and a time-dependent effect between the first and the second set point were attributable to wheat growth and the influence of roots. The effect of the inoculum was small and merely transient, though significant long-term changes were found in soils with a relatively low level of microbial biomass. Community level substrate utilization as an indicator of changes in microbial community structure was mainly changed by the growth of wheat, while other experimental factors were negligible. The sensitivity of the applied methods to distinguish the experimental soils was in decreasing order N(mic), DHA, C(mic), and qCO(2). Besides the selective enumeration of P. fluorescens CHA0 rif(+), which was only found in amended soils, methods to distinguish the inoculum effect were DHA, C(mic), and the ratio of C(mic) to N(mic). The sampling time was most sensitively indicated by N(mic), DHA, C(mic), and qCO(2). Our data support the hypothesis-based on ecosystem theory-that a rich microflora is buffering changes due to invading species. In other words, a soil-derived bacterium was more effective in a relatively poor soil than in soils that are rich in microorganisms.

A long-term field experiment demonstrates the influence of tillage on the bacterial potential to produce soil structure-stabilizing agents such as exopolysaccharides and lipopolysaccharides.

BACKGROUND: Stable soil aggregates are essential for optimal crop growth and preventing soil erosion. However, tillage is often used in agriculture to loosen the soil, which disrupts the integrity of these aggregates. Soil aggregation can be enhanced by bacteria through their ability to produce exopolysaccharides and lipopolysaccharides. These compounds stabilize soil aggregates by "gluing" soil particles together. However, it has yet to be shown how tillage influences the bacterial potential to produce aggregate-stabilizing agents. Therefore, we sampled conventional and reduced tillage treatments at 0-10 cm, 10-20 cm and 20-50 cm from a long-term field trial in Frick, Switzerland. We compared the stable aggregate fraction of the soil and the bacterial potential to produce exopolysaccharides (EPS) and lipopolysaccharides (LPS) under different tillage regimes by employing a shotgun metagenomic approach. We established a method which combines hidden Markov model searches with blasts against sequences derived from the Kyoto Encyclopedia of Genes and Genomes database to analyze genes specific for the biosynthesis of these compounds. RESULTS: Our data revealed that the stable aggregate fraction as well as the bacterial potential to produce EPS and LPS were comparable under both tillage regimes. The highest potential to produce these compounds was found in the upper soil layer, which was disturbed by tillage, but had higher content of organic carbon compared to the layer below the tillage horizon. Additionally, key players of EPS and LPS production differed at different sampling depths. Some families with high potential to produce EPS and LPS, such as Chitinophagaceae and Bradyrhizobiaceae, were more abundant in the upper soil layers, while others, e.g. Nitrospiraceae and Planctomycetaceae, preferred the lowest sampled soil depth. Each family had the potential to form a limited number of different aggregate-stabilizing agents. CONCLUSIONS: Our results indicate that conventional tillage and reduced tillage equally promote the bacterial potential to produce EPS and LPS in the tillage horizon. However, as major bacterial groups triggering EPS and LPS formation were not the same, it is likely that gene expression pattern differ in the different treatments due to various pathways of gene induction and transcription in different bacterial species.

Direct and indirect effects of urban gardening on aboveground and belowground diversity influencing soil multifunctionality.

Urban gardens are popular green spaces that have the potential to provide essential ecosystem services, support human well-being, and at the same time foster biodiversity in cities. We investigated the impact of gardening activities on five soil functions and the relationship between plant (600 spp.) and soil fauna (earthworms: 18 spp., springtails: 39 spp.) in 85 urban gardens (170 sites) across the city of Zurich (Switzerland). Our results suggest that high plant diversity in gardens had a positive effect on soil fauna and soil multifunctionality, and that garden management intensity decreased plant diversity. Indices of biological activity in soil, such as organic and microbial carbon and bacterial abundance, showed a direct positive effect on soil multifunctionality. Soil moisture and disturbance, driven by watering and tilling, were the driving forces structuring plant and soil fauna communities. Plant indicator values proved useful to assess soil fauna community structure, even in anthropogenic plant assemblages. We conclude that to enhance soil functions, gardeners should increase plant diversity, and lower management intensity. Soil protective management practices, such as applying compost, mulch or avoiding soil tilling, should be included in urban green space planning to improve urban biodiversity and nature's contribution to people.

Litter decomposition driven by soil fauna, plant diversity and soil management in urban gardens.

In the face of growing urban densification, green spaces in cities, such as gardens, are increasingly important for biodiversity and ecosystem services. However, the influences of urban green space management on biodiversity and ecosystem functioning (BEF) relationships is poorly understood. We investigated the relationship between soil fauna and litter decomposition in 170 urban garden sites along a gradient of urbanisation intensity in the city of Zurich, CH. We used litter bags of 1 and 4 mm mesh size to evaluate the contribution of soil meso- and macrofauna on litter decomposition. By using multilevel structural equation models (SEM), we investigated direct and indirect environmental effects and management practices on litter decomposition and litter residue quality. We evaluated the role of taxonomic, functional and phylogenetic diversity of soil fauna species on litter decomposition, based on a sample of 120 species (81,007 individuals; 39 collembola, 18 earthworm, 16 isopod, 47 gastropod species). We found highest litter decomposition rates using 4 mm mesh size litter bags, highlighting the importance of soil macrofauna. Urban warming, a proxy for urbanisation intensity, covaried positively, whereas soil disturbances, such as intensive soil and crop management, were negatively correlated with decomposition rates. Interestingly, soil fauna species richness decreased, with the exception of gastropods, and soil fauna abundance increased with urban warming. Our data also show that plant species richness positively affected litter decomposition by increasing soil fauna species richness and microbial activity. A multivariate analysis of organic compounds in litter residues confirmed the importance of soil fauna species richness and garden management on litter decomposition processes. Overall, we showed, that also in intensively managed urban green spaces, such as gardens, biodiversity of plants and soil fauna drives key ecosystem processes. Urban planning strategies that integrate soil protecting management practices may help to maintain important ecosystem services in this heavily used urban environment.

Response of soil microbial biomass and community structures to conventional and organic farming systems under identical crop rotations.

In this study the influence of different farming systems on microbial community structure was analyzed using soil samples from the DOK long-term field experiment in Switzerland, which comprises organic (BIODYN and BIOORG) and conventional (CONFYM and CONMIN) farming systems as well as an unfertilized control (NOFERT). We examined microbial communities in winter wheat plots at two different points in the crop rotation (after potatoes and after maize). Employing extended polar lipid analysis up to 244 different phospholipid fatty acids (PLFA) and phospholipid ether lipids (PLEL) were detected. Higher concentrations of PLFA and PLEL in BIODYN and BIOORG indicated a significant influence of organic agriculture on microbial biomass. Farmyard manure (FYM) application consistently revealed the strongest, and the preceding crop the weakest, influence on domain-specific biomass, diversity indices and microbial community structures. Esterlinked PLFA from slowly growing bacteria (k-strategists) showed the strongest responses to long-term organic fertilization. Although the highest fungal biomass was found in the two organic systems of the DOK field trial, their contribution to the differentiation of community structures according to the management regime was relatively low. Prokaryotic communities responded most strongly to either conventional or organic farming management.