Efficient Nutrient Cycling Research Articles

Impact of Bacillus Inoculation on Rhizosphere Bacterial Community Structure: A Review

The rhizosphere is a specialized zone where plant roots interact with the soil microbiome. Among various beneficial microbes, the genus Bacillus stands out due to its diverse functionalities and potential to boost plant growth and resilience. Bacillus is a key genus of plant growth-promoting rhizobacteria (PGPR) known for enhancing nutrient availability, producing phytohormones, and inducing plant resistance to pathogens. Inoculating Bacillus species into the rhizosphere can significantly alter the bacterial community's structure and composition. These alterations are driven by the competitive and cooperative interactions between Bacillus and the native rhizosphere microorganisms. Incorporating soil microorganisms into the host plant's beneficial bacterial community improves soil nutrient cycling and nutrient use efficiency. Using microbial inoculants is an effective strategy to address crop succession challenges, enhance microbial community structure, and improve soil fertility, thereby promoting crop growth. This review thoroughly examines the current understanding of how Bacillus inoculation impacts rhizosphere bacterial community structure.

Nematode community structure suggests perennial grain cropping cultivation as a nature‐based solution for resilient agriculture

AbstractIntroductionConventional agricultural land‐use may negatively impact biodiversity and the environment due to the increased disturbances to the soil ecosystem by tillage, for example. Cultivation of the perennial grain intermediate wheatgrass (Thinopyrum intermedium, IWG, Kernza®) is a nature‐based solution for sustainable agriculture, improving nutrient retention mainly through its extensive root system. Nematodes serve as sensitive bioindicators, detecting early changes in the soil food web, reflecting in changes in their community structure.Materials and MethodsIWG and annual wheat sites in South France, Belgium and South Sweden were investigated in April 2022 for two depths (5–15 cm; 25–35 cm) to evaluate the difference in nematode community structure among the cropping systems.ResultsSites with IWG cultivation held an accumulation of structure indicators (c‐p 3–5 nematodes) compared to sites with annual wheat cultivation. A generalised linear mixed model revealed significantly more root feeders, especially for the subsoil, under IWG as a result of the perennial cultivation. The maturity index, plant‐parasitic index, channel index and structure index were greater for IWG sites. The enrichment index was greater for annual wheat sites due to the dominance of bacterivores and enrichment indicators (c‐p 1 nematodes). The nematode community structure (weighted faunal profile analysis) indicates IWG sites as being a generally undisturbed system with efficient nutrient cycling and balanced distribution of feeding types, as well as higher metabolic footprint values for root feeders (including plant‐parasitic nematodes) and fungivores. Annual wheat sites, on the other hand, held indicators of a disturbed system with increased occurrence of opportunistic species and a more bacterial driven pathway. The topsoil had an increased occurrence of structure indicators in both cropping systems.ConclusionIWG creates favourable conditions for a diverse food web, including improved nutrient cycling and a heterogeneous resource environment, regardless of climatic conditions, establishing it as a stable and resilient agricultural management system.

Arbuscular mycorrhizal fungal diversity and potential association networks among African tropical forest trees.

Tropical forests represent one of the most diverse and productive ecosystems on Earth. High productivity is sustained by efficient and rapid cycling of nutrients, which is in large part made possible by symbiotic associations between plants and mycorrhizal fungi. In these associations, an individual plant typically associates simultaneously with multiple fungi and the fungi associate with multiple plants, creating complex networks among fungi and plants. However, there are few studies that have investigated mycorrhizal fungal composition and diversity in tropical forest trees, particularly in Africa, or that assessed the structure of the network of associations among fungi and trees. In this study, we collected root and soil samples from Ise Forest Reserve (Southwest Nigeria) and used a metabarcoding approach to identify the dominant arbuscular mycorrhizal (AM) fungal taxa in the soil and associating with ten co-occurring tree species to assess variation in AM communities. Network analysis was used to elucidate the architecture of the network of associations between fungi and tree species. A total of 194 Operational Taxonomic Units (OTUs) belonging to six AM fungal families were identified, with 68% of all OTUs belonging to Glomeraceae. While AM fungal diversity did not differ among tree species, AM fungal community composition did. Network analyses showed that the network of associations was not significantly nested and showed a relatively low level of specialization (H2 = 0.43) and modularity (M = 0.44). We conclude that, although there were some differences in AM fungal community composition, the studied tree species associate with a large number of AM fungi. Similarly, most AM fungi had great host breadth and were detected in most tree species, thereby potentially working as interaction network hubs.

Climate change disrupts the seasonal coupling of plant and soil microbial nutrient cycling in an alpine ecosystem.

The seasonal coupling of plant and soil microbial nutrient demands is crucial for efficient ecosystem nutrient cycling and plant production, especially in strongly seasonal alpine ecosystems. Yet, how these seasonal nutrient cycling processes are modified by climate change and what the consequences are for nutrient loss and retention in alpine ecosystems remain unclear. Here, we explored how two pervasive climate change factors, reduced snow cover and shrub expansion, interactively modify the seasonal coupling of plant and soil microbial nitrogen (N) cycling in alpine grasslands, which are warming at double the rate of the global average. We found that the combination of reduced snow cover and shrub expansion disrupted the seasonal coupling of plant and soil N-cycling, with pronounced effects in spring (shortly after snow melt) and autumn (at the onset of plant senescence). In combination, both climate change factors decreased plant organic N-uptake by 70% and 82%, soil microbial biomass N by 19% and 38% and increased soil denitrifier abundances by 253% and 136% in spring and autumn, respectively. Shrub expansion also individually modified the seasonality of soil microbial community composition and stoichiometry towards more N-limited conditions and slower nutrient cycling in spring and autumn. In winter, snow removal markedly reduced the fungal:bacterial biomass ratio, soil N pools and shifted bacterial community composition. Taken together, our findings suggest that interactions between climate change factors can disrupt the temporal coupling of plant and soil microbial N-cycling processes in alpine grasslands. This could diminish the capacity of these globally widespread alpine ecosystems to retain N and support plant productivity under future climate change.

Carbon and nitrogen stock in soils of subtropical urban forests: Isotopic δ13C and δ15N indicators for nature-based solutions in a megacity

Urban forest soils play a pivotal role in enhancing the environmental sustainability of cities, contributing to various natural processes, including plant–microbe interactions, microbial activity, and the decomposition of organic matter. Consequently, urban forest soils emerge as effective NBS, underscoring their potential to mitigate environmental challenges and foster sustainable urban ecosystems. In these sense, this manuscript aimed at evaluating how soil attributes of the urban forests of São Paulo, Brazil, with different adjacent land uses, influence the capacity to store the excess of C and N from anthropogenic emissions, making this ecosystem an important reservoir of urban anthropogenic emissions. Three hundred urban forest soil samples were collected from the surface to a depth of 50 cm. All samples were analyzed for C and N content (and their stable isotopes). In addition, granulometric tests were also carried out to classify the soils. It was found that the most central forest fragment has the highest C and N contents at all analyzed depths, probably due to the association with physical aspects of soil texture. For all layers, the most central fragment soil sample, the only one with a clay soil, presented approximately twice as many elements when compared to the soil samples of the other sites. In general, C and N stocks (and their stable isotopes, δ13C and δ15N, respectively) varied significantly in forests located in the center-periphery direction (%N - F = 24.58, p < 0.05; %C - F = 22.48, p < 0.05; δ15N - F = 4.27, p < 0.05; δ13C - F = 19.8, p < 0.05; C/N - F = 14.56, p < 0.05). This more central forest fragment with higher vehicle emissions showed greater potential to store these atmospheric elements and with greater neutralizing efficiency than the other forest fragments. δ13C and δ15N contents together with the C:N ratio indicated the efficiency of biogeochemical cycling, through decomposition, in different urban forest fragments. More peripheral fragments showed high efficiency in C and N cycling along the analyzed soil profiles, while in the most superficial layer, the most central fragment was highly efficient. These shed light results how integrating NbS principles into strategic urban planning and city-level climate policies can bolster the effectiveness of urban green areas. The integration not only promotes carbon sequestration and efficient nutrient cycling in the soil but also fosters sustainable practices, contributing to a more resilient urban landscape.

Metagenomic assembled genomes indicated the potential application of hypersaline microbiome for plant growth promotion and stress alleviation in salinized soils.

The strategic implementation of metagenomic assembled genomes (MAGs) in exploring the properties and harnessing microorganisms from ecosystems like hypersaline niches has transformative potential in agriculture. This approach promises to redefine our comprehension of microbial diversity and its ecosystem roles. Recovery and decoding of MAGs unlock genetic resources, enabling the development of new solutions for agricultural challenges. Enhanced understanding of these microbial communities can lead to more efficient nutrient cycling, pest control, and soil health maintenance. Consequently, traditional agricultural practices can be improved, resulting in increased yields, reduced environmental impacts, and heightened sustainability. MAGs offer a promising avenue for sustainable agriculture, bridging the gap between cutting-edge genomics and practical field applications.

Dominance of net autotrophy in arid landscape low relief polar lakes, Nunavut, Canada.

The Arctic is the fastest warming biome on the planet, and environmental changes are having striking effects on freshwater ecosystems that may impact the regional carbon cycle. The metabolic state of Arctic lakes is often considered net heterotrophic, due to an assumed supply of allochthonous organic matter that supports ecosystem respiration and carbon mineralization in excess of rates of primary production. However, lake metabolic patterns vary according to regional climatic characteristics, hydrological connectivity, organic matter sources and intrinsic lake properties, and the metabolism of most Arctic lakes is unknown. We sampled 35 waterbodies along a connectivity gradient from headwater to downstream lakes, on southern Victoria Island, Nunavut, in an area characterized by low precipitation, organic-poor soils, and high evaporation rates. We evaluated whether lakes were net autotrophic or heterotrophic during the open water period using an oxygen isotopic mass balance approach. Most of the waterbodies were autotrophic and sites of net organic matter production or close to metabolic equilibrium. Autotrophy was associated with higher benthic primary production, as compared to its pelagic counterpart, due to the high irradiance reaching the bottom and efficient internal carbon and nutrient cycling. Highly connected midstream and downstream lakes showed efficient organic matter cycling, as evidenced by the strong coupling between gross primary production (GPP) and ecosystem respiration, while decoupling was observed in some headwater lakes with significantly higher GPP. The shallow nature of lakes in the flat, arid region of southern Victoria Island supports net autotrophy in most lakes during the open water season. Ongoing climate changes that lengthen the ice-free irradiance period and increase rates of nutrient evapoconcentration may further promote net autotrophy, with uncertain long-term effects for lake functioning.

Tropical forest above‐ground productivity is maintained by nutrients cycled in litter

Abstract Tropical forest productivity represents an important global carbon sink, but many tropical forests grow on infertile soils. Efficient nutrient cycling by litterfall has long been assumed to maintain tropical tree growth, but there is no direct evidence that the nutrients cycled in litterfall are essential for tropical forest productivity. To test whether nutrient cycling by litterfall maintains tropical forest above‐ground productivity, we established large‐scale long‐term litter removal (L−) and litter addition (L+) treatments in a mature lowland tropical forest. We hypothesised that the removal of nutrients in litter would reduce tree growth, survival and litter production in L− plots. By contrast, the addition of nutrients in litter would enhance tree growth, survival and litter production in L+ plots. To test our hypotheses, we recorded tree growth and survival every 2 years, and measured litterfall monthly during 17 years of treatments. Tree growth and litterfall declined over time in L− plots, with consistently lower growth rates compared to controls after 8 years, and lower litter production after 4 years of treatments. By contrast, although litterfall was higher in the L+ plots relative to the controls, there was only a minor transient increase in tree growth immediately after the start of treatments. Tree survival declined over time in all treatments but was not affected by litter manipulation. The long‐term decline in tree growth and litterfall in the L− plots provides the first empirical evidence that nutrient cycling by litterfall plays a key role in maintaining above‐ground productivity in this tropical forest. By contrast, the transient increase in growth in the L+ plots can be attributed to the large inputs of nutrients with the addition of the entire litter standing crop at the start of treatments. The addition of nutrients in litter over the long term was nonetheless sufficient to enhance litter production, possibly by accelerating leaf turnover. Synthesis: Efficient nutrient cycling by litterfall makes an important contribution to the annual nutrient requirements of mature tropical forest trees, compensating for infertile soils. Disturbances that disrupt this finely balanced cycle could therefore reduce biomass carbon sequestration in tropical forests.

Microalgae as Biofertilizers: A Sustainable Way to Improve Soil Fertility and Plant Growth

The intensification of agricultural production in response to the global population increase and the growing demand for food has raised significant concerns regarding environmental impacts over the past few decades. Currently, modern agriculture aims to improve the quantity and quality of crop yield, minimizing the negative effects of treatments on the environment. Recently, microalgae have found extensive application as a valuable biological resource across multiple industries, including the food sector, biofuel production, and the pharmaceutical industry. In agriculture, microalgae have been seen as a promising and sustainable alternative to agrochemicals, offering a range of benefits to improve soil fertility, optimize nutrient management, and reduce reliance on synthetic fertilizers. In general, microalgae have demonstrated efficient nutrient cycling abilities, assimilating and converting essential nutrients, such as nitrogen, phosphorus, and potassium, into forms readily available for plants. Additionally, they produce bioactive substances, including phytohormones, which have a direct impact on the physiological processes of plants and promote their growth. Microalgae can also establish beneficial interactions with other soil microorganisms, supporting the growth of beneficial bacteria and fungi, thus promoting a healthy soil microbiome. On the other hand, as photosynthetic microorganisms, microalgae harness sunlight to convert carbon dioxide (CO2) into organic matter through photosynthesis. This ability allows them to sequester carbon and contribute to sustainable agriculture by reducing greenhouse gas emissions. The present work provides an overview of the potential of microalgae as biofertilizers, highlighting their unique characteristics, benefits, and main limitations for effective implementation in agriculturally sustainable practices.

Physical properties of the litter in successional forests of interfluvial plateau and floodplain in the lower Guamá river, Eastern Amazonia

The forest ecosystems of the Amazonia biome are indispensable for climate regulation and service provision. Among them, the fluvial plains (ESFpf) stand out, due to their role in erosion control and water quality. However, the limited information available on this ecosystem is evident when compared to interfluvial plateaus (ESFpi). Thus, this study aimed to evaluate and compare the litter stock and water storage capacity in successional ecosystems in the Eastern Amazonia. The study ecosystems (ESFpf and ESFpi) are located in the municipality of Belém, Pará, in the region of the lower Guamá River. In each ecosystem, 12 permanent plots (100 m²) were installed, where in the periods of higher and lower rainfall, three subunits of litter samples were randomly collected. Water storage in the rainy season did not differ between ecosystems, while in the less rainy season ESFpf (245.91 ± 73.19%) was higher than ESFpi (182.31 ± 77.25%). For the litter stock, there was no influence of seasonality and in both periods the ESFpi averages were higher. Infer that due to the favorable conditions for the action of the edaphic fauna in the ESFpf, there was a reduction in the contact area of the litter, increasing the water storage capacity. The smaller stock found in the ESFpf allow to infer that there was an efficient cycling of nutrients, since these ecosystems are characterized by high litter deposition. Therefore, the results contribute to the understanding of the functional processes of the Amazon river plains ecosystems.

Efficient anaerobic digestate valorization: Nutrient recovery strategy for enhancing soil fertility in arid agricultural regions

Efficient nutrient cycling in agroecosystems is essential for sustainable agriculture, and the utilization of waste products from various industries can contribute to this process. In this study, we investigated the potential of using anaerobic digestate from food industry waste (sugar beets and food waste) as a nutrient source for fertilizer production. Digestates were sanitized using a mixture of inorganic acids (H2SO4 and H3PO4) or alkaline (KOH), with acidic hydrolysate yielding a higher concentration of amino acids (1981 mg/L) compared to alkaline (186 mg/L). The acidic hydrolysate was centrifuged, and the liquid fraction was used to create a foliar fertilizer. The solid fraction, acidic hydrolysate, sewage sludge incineration ash, and additives (ammonium nitrate, urea with urease inhibitor) were employed to formulate three granular fertilizers. Nitrogen balances were analyzed using Sankey charts for each fertilizer formulation. The highest nitrogen losses (45.90 kg N/1 kg formulation) were recorded in the production of fertilizer containing ammonium nitrate. The fertilizers' effectiveness was evaluated through preliminary wheat germination tests. The highest yields observed for the foliar fertilizer (1% dose) and granular with the addition of urea with a urease inhibitor (20% dose) groups, where fresh sprout mass was approximately 18% and 23% higher than the control, respectively. These findings demonstrate the potential of using anaerobic digestate from food industry waste for nutrient recycling in agroecosystems, contributing to sustainable agriculture.

The microbial landscape in bioturbated mangrove sediment: A resource for promoting nature-based solutions for mangroves.

Globally, soils and sediments are affected by the bioturbation activities of benthic species. The consequences of these activities are particularly impactful in intertidal sediment, which is generally anoxic and nutrient-poor. Mangrove intertidal sediments are of particular interest because, as the most productive forests and one of the most important stores of blue carbon, they provide global-scale ecosystem services. The mangrove sediment microbiome is fundamental for ecosystem functioning, influencing the efficiency of nutrient cycling and the abundance and distribution of key biological elements. Redox reactions in bioturbated sediment can be extremely complex, with one reaction creating a cascade effect on the succession of respiration pathways. This facilitates the overlap of different respiratory metabolisms important in the element cycles of the mangrove sediment, including carbon, nitrogen, sulphur and iron cycles, among others. Considering that all ecological functions and services provided by mangrove environments involve microorganisms, this work reviews the microbial roles in nutrient cycling in relation to bioturbation by animals and plants, the main mangrove ecosystem engineers. We highlight the diversity of bioturbating organisms and explore the diversity, dynamics and functions of the sediment microbiome, considering both the impacts of bioturbation. Finally, we review the growing evidence that bioturbation, through altering the sediment microbiome and environment, determining a 'halo effect', can ameliorate conditions for plant growth, highlighting the potential of the mangrove microbiome as a nature-based solution to sustain mangrove development and support the role of this ecosystem to deliver essential ecological services.

Hydrological and nutrient regulation per occupation unit differ between structurally contrasting native and planted forests in the Northern Andes

Understanding ecohydrological dynamics that result from land-use conversions is fundamental in managing ecosystem services. One common forest transformation in the tropics is the establishment of monospecific plantations with exotic species for timber exploitation, replacing highly diverse natural forests. The impacts of establishing forest plantations in hydrological processes and biogeochemical dynamics have been highly controversial, with functions from structurally homogeneous plantations being sometimes assumed to be comparable to natural forests. To assess the effects of planting exotic conifer species versus natural forests on hydrological and biogeochemical functions, we measured incoming precipitation, throughfall, and stemflow. To compare between forest types, we propose the use of basal area for standardization of hydrochemical fluxes. While net precipitation was similar among forest types, the transmission of water to the forest floor per basal area unit was significantly higher in native forests. Yet, nutrient concentrations were similar among them. However, greater nutrient enrichment per unit basal area was observed for the native species. This more efficient nutrient cycling could be related to native forests being better adapted to oligotrophic soils. The re-establishment of native species rather than with exotic species can result in more efficient hydrochemical regulation, improving the capacity of these ecosystems to produce services.

Interspecific variations in leaf litter decomposition and nutrient release from tropical mangroves

Efficient nutrient cycling through decomposition of leaf litter often regulates the high productivity and subsequent carbon sequestration of mangrove ecosystems along the land-ocean boundary. To understand the characteristics and the potentials of mangrove leaf litter in supplying organic carbon and nutrients to the coastal waters, four major mangrove species (A. officinalis, R. mucronata, H. littoralis and S. apetala) of Bhitarkanika mangrove forest, Odisha, India, were examined in controlled environmental conditions. Half-life time (t0.5), estimated for decomposition of those mangrove leaf litter materials ranged from 18 to 52 days. During the incubation experiment, organic carbon from mangrove leaf litter was released primarily through physical processes and was available for heterotrophic respiration. Among the four species, leaf litter of S. apetala with the lowest initial C/N ratios, released organic carbon with low molecular weight (labile substances) that has a relatively higher potential to support the aquatic food web. On the contrary, leaf litter of R. mucronata released organic material with relatively higher molecular weight (humic substances, higher aromaticity), which revealed its superior non-labile characteristics in this unique environment. The mean total heterotrophic bacterial (THB) population in the incubation was around nine-fold higher than the control. THB population growth and Chromophoric Dissolved Organic Matter (CDOM) spectral data further suggested the rapid release of highly labile and recalcitrant carbon from S. apetala and R. mucronata (between 7th and 21st day of incubation), respectively. The mean litter fall from the Bhitarkanika mangrove forest was estimated to be 11.32 ± 1.57 Mg ha−1 y−1 and its corresponding carbon content was 5.43 ± 0.75 Mg C ha−1. The study revealed the role of leaf litter leachates as an important food source to microbial communities in the adjacent coastal waters, in addition to a potential carbon sequesterer through long-term burial in mangrove soil and export to the deep sea.

THE SIGNIF ICANCE OF HARVEST RESIDUES IN THE SUSTAINABLE MANAGEMENT OF ARABLE LAND. II. HARVEST RESIDUES MANAGEMENT

&amp;lt;p&amp;gt;Harvest residues (HR) are one of the important aspects of sustainable management in agriculture, representing a significant portion of organic matter (OM) that can be retained or removed from agroecosystems. There are several ways to manage plant residues: (i) burning, (ii) incorporation in soil, (iii) leaving plant residues after harvest on the soil surface in form of mulch, (iv) undersowing crops in HR and (v) baling and removing HR from the plot. Burning is the most unreasonable action in agricultural production, which is prohibited by legal regulations in force. The burning means a complete loss of OM &amp;amp;ndash; N and S are irretrievably lost in the air, mineral substances remain in ash, and microorganisms in the soil surface layer are destroyed. Incorporation of HR may be complete or partial, depending on the soil cultivation method applied. This HR management method has a number of soil benefits: increases content of nutrients, OM and humus; increases microbiological activity; improves soil water, air and physical properties; improves soil structure, ultimately contributing to the increase in soil fertility and plant growth. Two practical approaches that were once common, have been neglected. Namely, undersowing and mixed cultivation where various species are simultaneously grown with or between plantings of a main crop. Removal of HR indirectly leads to a decrease of the organic matter in the soil. In essence, there is a need to determine the size of acceptors and the return rates of organic residues of different quality, and to increase the efficiency of nutrient cycling from residues through various land acceptors and crops, with minimal losses from the system.&amp;lt;/p&amp;gt;

Soil Management in Indigenous Agroforestry Systems of Guarana (Paullinia cupana Kunth) of the Sateré-Mawé Ethnic Group, in the Lower Amazon River Region

The Sateré-Mawé Brazilian indigenous people cultivate the guarana liana in biodiverse agroforests that incorporate many species, mainly trees, and produce food, medicines, fuel and income. The objective of this study was to evaluate the soil fertility in nineteen indigenous guarana agroforestry systems (AFSs) compared with areas of adjacent forests in the Andirá–Marau Indigenous Land—an ancestral territory of the Sateré-Mawé people. Soils in both locations showed low natural fertility, with levels of most macronutrients below the minimum agronomic reference levels. Higher C and soil organic matter (SOM) content was observed in the forest soils and may be related to greater vegetation cover and higher litter production. However, the maintenance of the average levels of most nutrients in the soil of the AFSs, at the same level as under the forests, suggests that efficient nutrient cycling is taking place. In these conditions, the management of organic matter seems to be essential to maintain the productivity of guarana AFSs since levels of C, SOM and organic N were not considered as low as those of most of the other soil attributes that were evaluated. The high tree diversity in the guarana agroforests, including N-fixing species, may also contribute to efficient nutrient cycling and maintenance of the soil food web. The results suggest that the addition of limestone, green manure practices and the reincorporation of organic residues from guarana processing, among other sources, can be a low-cost alternative to improve soil fertility and increase guarana production in the AFS under study.

Higher pH is associated with enhanced co-occurrence network complexity, stability and nutrient cycling functions in the rice rhizosphere microbiome.

The rice rhizosphere microbiota is crucial for crop yields and nutrient use efficiency. However, little is known about how co-occurrence patterns, keystone taxa and functional gene assemblages relate to soil pH in the rice rhizosphere soils. Using shotgun metagenome analysis, the rice rhizosphere microbiome was investigated across 28 rice fields in east-central China. At higher pH sites, the taxonomic co-occurrence network of rhizosphere soils was more complex and compact, as defined by higher average degree, graph density and complexity. Network stability was greatest at medium pH (6.5 < pH < 7.5), followed by high pH (7.5 < pH). Keystone taxa were more abundant at higher pH and correlated significantly with key ecosystem functions. Overall functional genes involved in C, N, P and S cycling were at a higher relative abundance in higher pH rhizosphere soils, excepting C degradation genes (e.g. key genes involved in starch, cellulose, chitin and lignin degradation). Our results suggest that the rice rhizosphere soil microbial network is more complex and stable at higher pH, possibly indicating increased efficiency of nutrient cycling. These observations may indicate routes towards more efficient soil management and understanding of the potential effects of soil acidification on the rice rhizosphere system.

Meandering development of tidal creeks splits bacterial communities and functional characteristics: Evidence from a field study in Jiangsu Coast, China

Tidal creeks are common and important geomorphic features in intertidal zones, which provide a broad range of ecosystem services. The meandering development of tidal creeks can cause a discrepancy in sediment properties between the two banks in tidal creek bends, which affects a few geomorphic and biological processes and seems to be another incentive for the ecological effects of tidal creeks. However, how this discrepancy affects the distribution of bacterial communities in tidal creek bends remains unclear. To this end, we collected sediment samples from a typical tidal creek bend in Jiangsu Coast, China. The bacterial communities were characterized by 16S rRNA gene sequencing and the sediment properties were determined. Results showed that bacterial communities and their functions exhibited significant differences between the convex bank (VB) and the concave bank (CB). Bacterial diversity was higher in VB than in CB, mainly attributed to higher nutrients (TOC and TN), moisture, and finer sediment in VB. The oligotrophic (e.g., Chloroflexi), drought-resistant (e.g., Actinobacteria), and mobile (e.g. Nitrospirae) bacteria had higher abundances in CB. In contrast, bacteria with opposite niche preferences (e.g., Proteobacteria and Acidobacteria) tended to inhabit VB. Network analysis revealed that CB bacterial communities had a higher efficiency of nutrient cycling and carbon uptake but were more vulnerable to environmental disturbances. FAPROTAX results showed that bacterial functions associated with carbon cycles were more abundant in CB, whereas those associated with nitrogen and sulfur cycles were more abundant in VB. Overall, these results demonstrate that the meandering development of tidal creeks splits bacterial communities and functional characteristics in tidal creeks bends. These findings are expected to provide useful information for further understanding and predicting the ecological effects of tidal creeks.

A review of agroforestry, precision agriculture, and precision livestock farming—The case for a data-driven agroforestry strategy

Agroforestry can be defined as an agroecosystem whereby soil is used holistically and synergistically by various stakeholders including farmers, livestock, and plants. As such, agroforestry offers numerous benefits that include conservation of biodiversity, regulation of pests and diseases, increased quality of soil, air and water, efficient cycling of nutrients, and resilience to climate change. Review of published studies in agroforestry shows however that research in this area could benefit from increased real-time, spatial and temporal measurements. This situation is to be contrasted with that of precision agriculture in monocultures and precision livestock farming where progress made in sensor systems has attracted considerable research interest. It is advocated in this review article that wireless sensor networks could also significantly impact agroforestry through the monitoring of the local real-time interactions that occur between the various components constituting agroforestry systems. This review article proposes therefore the new field of data-driven agroforestry which lies at the intersection of precision agriculture, precision livestock farming, permaculture, and agroforestry. Data-driven agroforestry has the potential to not only help farmers harness the interactions between the different components of an agroforestry system to their advantage but also shine light on fundamental interactions between soil, plants, trees, and livestock while offering a sustainable agricultural method beneficial to all agroforestry stakeholders.

Adaptive multi-paddock grazing management's influence on soil food web community structure for: increasing pasture forage production, soil organic carbon, and reducing soil respiration rates in southeastern USA ranches.

BackgroundMeasurement of two grazing management’s influence on pasture productivity, soil food web structure, soil organic carbon and soil microbial respiration efficiency was conducted on five southeastern US, across-the-fence ranch pairs to compare adaptive multi-paddock grazing (AMP) management, using short grazing events with planned, adaptive recovery periods, to conventional grazing (CG) management, with continuous grazing at low stock density.MethodologyA point-in-time experimental field analysis was conducted to compare five AMP or CG ranch pairs to better understand the influence of grazing management on (a) standing crop biomass productivity; (b) soil food web community population, structure and functionality; (c) soil organic carbon accrual; and d) soil-C (CO2) respiration kinetics.ResultsAMP grazing systems outperformed CG systems by generating: (a) 92.68 g m−2 more standing crop biomass (SCB), promoting 46% higher pasture photosynthetic capacity (Two sample Mann-Whitney; Z = 6.1836; no DF in MW; p = 6.26 × 10−10; Effect size = 0.35) (b) a strong positive linear relationship of SCB with fungal biomass (R = 0.9915; F(1,3) = 175.35; p = 0.015); fungal to bacterial (F:B) biomass ratio (R = 0.9616; F(1,3) = 36.75; p = 0.009) and a soil food web proxy (R = 0.9616; F(1,3) = 36.75; p = 0.009) and a concurrent very strong inverse relationship with bacteria biomass (R = −0.946; F(1,3) = 25.56; p = 0.015); (c) significant predator/prey interactions with an inverse relationship with bacterial population biomass (R = − 0.946; F(1,3) = 25.56; p = 0.015) and a positive relationship with total protozoa enumeration (R = 0.9826; F(1,3) = 83.68; p = 0.003) when compared to SCB; (d) a 19.52% reduction in soil C (CO2) respiration rates (Two sample t-test; T = −2.3581; DF = 52.3541; p = 0.0221; Effect size = 0.59); and (e) a 20.6% increase in soil organic carbon (SOC) in the top 10 cm of soil profile (Two sample Mann–Whitney; Z = 2.6507; no DF in MW; p = 0.008; Effect size = 0.24). Rancher conversion to AMP grazing strategies would appear to regenerate soil food web population, structure, diversity and biological functionality helping to improve: carbon flow into plant biomass, buildup of soil carbon, predator/prey nutrient cycling and soil microbial respiration efficiency while offering improved climate resilience and a strategy to increase the capture and storage of atmospheric CO2 in soils of the world’s rangeland.