Agroecosystem Functioning Research Articles

Soil microbial biodiversity supports the delivery of multiple ecosystem functions under elevated CO2 and warming

The contribution of the soil microbes to agroecosystem multifunctionality under global change remains poorly understood. Here, based on data from a field experiment involving elevated carbon dioxide (CO2) and warming in a rice-wheat agroecosystem, we found that soil microbes influence the impact of climate change on agroecosystem functions. The stability of food production during the rice season increased under elevated CO2 but decreased under warming, with no significant changes in the wheat season. The interactive influences of elevated CO2 and warming on agroecosystem multifunctionality were found to be minimal. The abundance of soil fungi and nematode was associated with agroecosystem stability during the rice and wheat seasons, respectively. Soil archaeal diversity and bacterial abundance were linked to agroecosystem multifunctionality in the rice and wheat seasons, respectively. Our work proves the positive effects of soil microbes on agroecosystem functions and highlights the implications of maintaining microbial diversity for agroecosystem health under climate change.

Microbial rrn copy number is associated with soil C: N ratio and pH under long-term fertilization

Soil microbial life-history strategies, as indicated by rRNA operon (rrn) copy numbers, strongly influence agro-ecosystem functioning. Long-term N fertilization causes strong and lasting changes in soil properties, yet its impact on microbial strategies remains largely unexplored. Using long-term field experiments across three agro-ecosystems, we consistently found that N fertilization strongly decreased soil C: N ratio and pH, further increasing the community-level rrn copy number, including both average rrn copy number and total 16S rRNA copy number. Soil C: N stoichiometry balanced by N supplement favored the growth of N-dependent copiotrophic species containing high rrn copy numbers (an average of 2.5) and increased their network connections, predominantly contributing to community-level rrn copy number increase. Decreased soil pH caused by N fertilization also favored the growth of some species whose abundances negatively correlated with pH, partially contributing to the community-level rrn copy number increase. By examining the genomes of two dominant species, we found that microorganisms with a higher rrn copy number (6), e.g., Streptomyces scabiei, possessed more genes related to C and N transport and metabolism. In contrast, the Mycobacterium simiae with a lower rrn copy number (1) has more genes associated with secondary metabolite biosynthesis and lipid transport and metabolism. Our finding challenges the concept of microbial life-strategy regulation solely by nutrient availability, highlighting the important contributions of soil stoichiometric balance and pH to microbial strategies in agro-ecosystems under long-term N inputs.

Regenerative soil management practices no‐till and sheep grazing induce significant but contrasting short‐term changes in the vineyard soil microbiome

Societal Impact StatementWinegrape production is an essential cultural heritage and economic engine of many regions of the world. Regenerative management, which is gaining traction with industry and consumers alike, relies on soil biodiversity for agroecosystem function, reducing external inputs and increasing ecosystem resilience to climate change. We evaluated the effects of no‐till and sheep integration on vineyard soil biodiversity and soil ecosystem function. No‐till had stronger effects on microbial diversity, while sheep grazing stimulated microbial functioning. By providing a better understanding of the practices, we provide fundamental information for growers that want to embrace regenerative principles, ultimately contributing to the sustainability and resilience of the winegrape industry.Summary Regenerative management aims to optimize soil microbial function and diversity for enhanced agroecosystem functionality. Understanding the effects of management practices on soil microorganisms is crucial in the context of growing societal interest in this type of management. This study evaluated the short‐term effects of two soil conservation practices: sheep grazing and no‐till, on abundance, diversity, activity, and network complexity of prokaryotes and fungi in a vineyard soil. Four treatments were applied for 3 years: (1) grazed and tilled, (2) grazed and non‐tilled, (3) non‐grazed and tilled, and (4) non‐grazed and non‐tilled. We hypothesized that stacking of conservation practices (grazing and no‐till) would increase microbial diversity, function, and network complexity. Grazing had strong effects on microbial function, increasing the α‐glucosidase, β‐glucosidase, cellulase, phosphatase, and β‐xylosidase enzymatic activity by 82%, 48%, 61%, 39%, and 55%, respectively, compared to non‐grazed soils, while not causing significant changes in soil microbial diversity. Tillage had strong effects on soil prokaryotic and fungal diversity. For prokaryotes, significant interactions in alpha diversity were found between tillage and grazing, and between tillage and sampling location (tractor row and under vine). Fungal Shannon diversity index was higher in the subsoil (15–30 cm) while a significant interaction between depth, location, tillage, and grazing was found for the Chao‐1 index. Microbial network properties were only significantly affected by sampling depth. This study shows that the lack of disturbance in non‐tilled and non‐grazed soils resulted in a more diverse soil community, while grazing stimulated microbial function, thus showing a decoupling between diversity and function in vineyard soil ecosystems.

Improving Beneficial Traits in Bacillus cabrialesii subsp. cabrialesii TE3T through UV-Induced Genomic Changes.

It is essential to hunt for new technologies that promote sustainable practices for agroecosystems; thus, the bioprospecting of beneficial microorganisms complementing with mutation induction techniques to improve their genomic, metabolic, and functional traits is a promising strategy for the development of sustainable microbial inoculants. Bacillus cabrialesii subsp. cabrialesii strain TE3T, a previously recognized plant growth-promoting and biological control agent, was subjected to UV mutation induction to improve these agro-biotechnological traits. Dilutions were made which were spread on Petri dishes and placed under a 20 W UV lamp at 10-min intervals for 60 min. After the UV-induced mutation of this strain, 27 bacterial colonies showed morphological differences compared to the wild-type strain; however, only a strain named TE3T-UV25 showed an improvement in 53.6% of the biocontrol against Bipolaris sorokiniana vs. the wild-type strain, by competition of nutrient and space (only detected in the mutant strain), as well as diffusible metabolites. Furthermore, the ability to promote wheat growth was evaluated by carrying out experiments under specific greenhouse conditions, considering un-inoculated, strain TE3T, and strain TE3T-UV25 treatments. Thus, after 120 days, biometric traits in seedlings were quantified and statistical analyses were performed, which showed that strain TE3T-UV25 maintained its ability to promote wheat growth in comparison with the wild-type strain. On the other hand, using bioinformatics tools such as ANI, GGDC, and TYGS, the Overall Genome Relatedness Index (OGRI) and phylogenomic relationship of mutant strain TE3T-UV25 were performed, confirming that it changed its taxonomic affiliation from B. cabrialesii subsp. cabrialesii to Bacillus subtilis. In addition, genome analysis showed that the mutant, wild-type, and B. subtilis strains shared 3654 orthologous genes; however, a higher number of shared genes (3954) was found between the TE3T-UV25 mutant strain and B. subtilis 168, while the mutant strain shared 3703 genes with the wild-type strain. Genome mining was carried out using the AntiSMASH v7.0 web server and showed that mutant and wild-type strains shared six biosynthetic gene clusters associated with biocontrol but additionally, pulcherriminic acid cluster only was detected in the genome of the mutant strain and Rhizocticin A was exclusively detected in the genome of the wild-type strain. Finally, using the PlaBase tool, differences in the number of genes (17) associated with beneficial functions in agroecosystems were detected in the genome of the mutant vs. wild-type strain, such as biofertilization, bioremediation, colonizing plant system, competitive exclusion, phytohormone, plant immune response stimulation, putative functions, stress control, and biocontrol. Thus, the UV-induced mutation was a successful strategy to improve the bioactivity of B. cabrialesii subsp. cabrialesii TE3T related to the agro-biotecnology applications. The obtained mutant strain, B. subtilis TE3T-UV25, is a promising strain to be further studied as an active ingredient for the bioformulation of bacterial inoculants to migrate sustainable agriculture.

Consistency of landscape compositional effects on microclimate, arthropods and plant performance across different years and regions

ContextReinforcement of agrobiodiversity in peri-urban areas requires a landscape lens. Relationships between land use composition and indicators of ecosystem services can depend on weather conditions and differ between regions.ObjectivesIn this study we present new empirical data on relationships between landscape composition and indicators of regulating and provisioning agroecosystem services. Furthermore, we check if these data are consistent between two different ecoregions and different years.MethodsWe apply an innovative methodology in a research landscape in the province of Antwerp (Flanders, Belgium) in 2021 with 1 m²-garden as phytometers along a landscape compositional gradient. Landscape composition at different scales is used as explanatory variable for microclimate variation, arthropod activity, leaf herbivory and crop yield in the 1 m²-gardens. Results are compared to an identical experiment in another ecoregion in East Flanders in 2018, 2019.ResultsWe found that the proportion of built-up areas is negatively related to local agroecosystem functioning. High-value herbaceous vegetation (e.g. extensive grasslands) promotes the activity of predators and high green vegetation buffers soil moisture and temperature variation, during dry and warm periods. Comparison between cases indicates that there is more consistency in the response of predatory invertebrates to the landscape composition than in the response of pollinators. The buffering effect of high green vegetation in the landscape increases when temperature and drought extremes occur.ConclusionsThe extent of high green vegetation can be enhanced at landscape level to maximise their ability to buffer extreme weather conditions. In peri-urban areas we should avoid further urban sprawl into the rural matrix and promote high-value herbaceous vegetation.

Crop functional structure predicts the provision of Nature´s material Contribution to People in diversified agroforestry

Applying concepts from natural ecosystem ecology, particularly through diversified cropping systems that integrate woody crops with other crops, can enhance agrobiodiversity and significantly contribute to multifunctional agriculture. The ecological and, more recently, the agronomic literature have indicated that functional trait aspects of diversity offer a more comprehensive explanation for ecosystem functions compared to species richness alone. In this study, we apply the trait-based approach during experimental agroforest succession in subtropical Southern Brazil to investigate the main factors of crop functional structure, differentiating the effects of functional diversity (FD) from functional identity (CWM - community weighted mean), on Nature's Contributions to People (NCP). The experiment was designed varying crop FD, based on leaf nitrogen concentration, while maintaining crop species richness constant across all treatments. To assess FD and CWM, we measured six crop traits; maximum plant height, leaf area, specific leaf area, leaf nitrogen content, leaf dry-matter content, and stem-specific density. Additionally, we evaluated four material NCP (green manure, forage, germplasm, and food) based on data collected during the initial four years of the experiment (2017–2020). To analyze the data, we employed principal component analysis to reduce the number of variables and subsequently fitted linear mixed-effect models. Our findings provide support for the hypothesis that crop functional structure, particularly in relation to leaf traits (leaf area and leaf nitrogen content) and vegetative height, significantly influences material outputs and predicts above-ground biomass production that can be utilized as green manure and animal feed in agroforestry and silvopastoral systems. Both FD and CWM were important drivers of NCPs, showing that both niche complementarity and selection effects contribute to explain agroecosystem functioning. By utilizing functional traits, we reached valuable insights for generating agronomical recommendations and enhancing cropping system diversification through effective trait-based management.

Changes in root and nutrient uptake of chickpea affected by organic fertilizers and inoculation with arbuscular mycorrhizal fungi and Rhizobium

AbstractAlthough humans have studied biological nitrogen (N) fixation for nearly two centuries, our understanding of how legumes–microbiome interactions impact agroecosystem function is still evolving. To understand the effects of organic fertilizers and dual inoculation with Rhizobium and arbuscular mycorrhizal fungi (AMF) on root activity, N fixation and nutrient uptake of chickpea (Cicer arietinum), a two‐year greenhouse study was conducted in 2020–2021 at the research station of Ferdowsi University of Mashhad, Iran. The experiment design was a randomized complete blocks in the factorial arrangement with three replications. The first factor consisted of two seedbeds including S1 (field soil) and S2 (soil + humic acid + 40 ton ha−1 cattle manure). The second factor included inoculation with Rhizobium alone, mycorrhiza alone, both Rhizobium and mycorrhiza and non‐inoculated treatment. The results showed that the application of organic fertilizers increased the number of nodules, nodule weight, AMF colonization, leaf N content, leaf P content, root volume, root biomass and N uptake of chickpea, significantly. Also, the effect of seed inoculation was significant on all studied parameters where the highest root biomass (2 g), root volume (3.6 cm3) and leaf phosphorus (0.54%) were obtained in co‐inoculated treatments. There was no significant difference between the effect of single inoculation of Rhizobium and dual inoculation of mycorrhiza and Rhizobium on nodule number, nodule weight, leaf N and N uptake of chickpea. Generally, rhizobia and AMF can benefit nutrient uptake and root activity of chickpea, potentially leading to higher crop production.

Comparative microbiome diversity in root-nodules of three Desmodium species used in push-pull cropping system.

Desmodium species used as intercrops in push-pull cropping systems are known to repel insect-pests, suppress Striga species weeds, and shift soil microbiome. However, the mechanisms through which Desmodium species impact the soil microbiome, either through its root exudates, changes in soil nutrition, or shading microbes from its nodules into the rhizosphere, are less understood. Here, we investigated the diversity of root-nodule microbial communities of three Desmodium species- Desmodium uncinatum (SLD), Desmodium intortum (GLD), and Desmodium incanum (AID) which are currently used in smallholder maize push-pull technology (PPT). Desmodium species root-nodule samples were collected from selected smallholder farms in western Kenya, and genomic DNA was extracted from the root-nodules. The amplicons underwent paired-end Illumina sequencing to assess bacterial and fungal populations. We found no significant differences in composition and relative abundance of bacterial and fungal species within the root-nodules of the three Desmodium species. While a more pronounced shift was observed for fungal community compositions compared to bacteria, no significant differences were observed in the general diversity (evenness and richness) of fungal and bacterial populations among the three Desmodium species. Similarly, beta diversity was not significantly different among the three Desmodium species. The root-nodule microbiome of the three Desmodium species was dominated by Bradyrhizobium and Fusarium species. Nevertheless, there were significant differences in the proportion of marker gene sequences responsible for energy and amino acid biosynthesis among the three Desmodium species, with higher sequence proportions observed in SLD. There is no significant difference in the microbial community of the three Desmodium species used in PPT. However, root-nodule microbiome of SLD had significantly higher marker gene sequences responsible for energy and amino acid biosynthesis. Therefore, it is likely that the root-nodules of the three Desmodium species host similar microbiomes and influence soil health, consequently impacting plant growth and agroecosystem functioning.

Potential of undersown species identity versus diversity to manage disease in crops

Abstract In the absence of chemical control with its negative side effects, fungal pathogens can cause large yield losses, requiring us to develop agroecosystems that are inherently disease resistant. Grassland biodiversity experiments often find plant species diversity to reduce pathogen pressure, but whether incorporating high biodiversity levels in agricultural fields have similar effects remains largely unknown. We tested if undersown plant species diversity could reduce barley disease, and whether the effect was mediated through above‐ or below‐ground mechanisms, by combining an agricultural field trial with a soil transplant experiment. As predicted, barley disease decreased in the presence of undersown plants. Undersown species richness had no effect, but their abundance led to early season disease reduction. Above‐ground mechanisms underpinned this disease reduction. Barley yield slightly decreased with increasing undersown species richness, and undersown species varied in their impact on yield. We identified two undersown species, Trifolium repens and T. hybridum, that contributed most to disease reduction and had the potential to increase barley yield. Furthermore, our results indicate that above‐ground mechanisms caused this. We show that agroecosystem functioning can be improved without trade‐offs on yield by targeted selection of undersown species. Read the free Plain Language Summary for this article on the Journal blog.

Comprehensive Assessment of the Effect of Multi-Cropping on Agroecosystems.

Multi-cropping is becoming an increasingly popular technique in agriculture to tackle major and complex agroecosystem problems such as biodiversity and soil fertility loss, erosion and degradation, increased greenhouse gas emissions, etc. Comprehensively assessing the impact of multi-cropping intensity on agroecosystems is a new and still under-researched approach that can provide a better understanding of the impact of individual indicators on the overall functioning of biodiverse agroecosystems. Data from a stationary field experiment using multi-cropping at the Vytautas Magnus University Experimental Station between 2020 and 2022 were used to carry out this study. The study included maize, hemp, and faba bean as single, binary, and ternary crops. A complex assessment approach (CEI value) was used to determine the impact of these crops on the agroecosystem, the interrelationships between the main indicators, and the strength of their effects. It was found that the ternary maize-hemp-faba bean crop had the most positive effect on the agroecosystem. The effectiveness of other crops was 2 to 35% less. The lowest value was calculated for the maize-faba bean crop.

Quantifying farm sustainability through the lens of ecological theory.

The achievements of the Green Revolution in meeting the nutritional needs of a growing global population have been won at the expense of unintended consequences for the environment. Some of these negative impacts are now threatening the sustainability of food production through the loss of pollinators and natural enemies of crop pests, the evolution of pesticide resistance, declining soil health and vulnerability to climate change. In the search for farming systems that are sustainable both agronomically and environmentally, alternative approaches have been proposed variously called 'agroecological', 'conservation agriculture', 'regenerative' and 'sustainable intensification'. While the widespread recognition of the need for more sustainable farming is to be welcomed, this has created etymological confusion that has the potential to become a barrier to transformation. There is a need, therefore, for objective criteria to evaluate alternative farming systems and to quantify farm sustainability against multiple outcomes. To help meet this challenge, we reviewed the ecological theories that explain variance in regulating and supporting ecosystem services delivered by biological communities in farmland to identify guiding principles for management change. For each theory, we identified associated system metrics that could be used as proxies for agroecosystem function. We identified five principles derived from ecological theory: (i) provide key habitats for ecosystem service providers; (ii) increase crop and non-crop habitat diversity; (iii) increase edge density: (iv) increase nutrient-use efficiency; and (v) avoid extremes of disturbance. By making published knowledge the foundation of the choice of associated metrics, our aim was to establish a broad consensus for their use in sustainability assessment frameworks. Further analysis of their association with farm-scale data on biological communities and/or ecosystem service delivery would provide additional validation for their selection and support for the underpinning theories.

Comparative analysis of the effects of microplastics and nitrogen on maize and wheat: Growth, redox homeostasis, photosynthesis, and AsA-GSH cycle

Microplastics (MPs) pose a significant threat to the function of agro-ecosystems. At present, research on MPs has mainly focused on the effects of different concentrations or types of MPs on a crop, while ignoring other environmental factors. In agricultural production, the application of nitrogen (N) fertilizer is an important means to maintain the high yield of crops. The effects of MPs and N on growth parameters, photosynthetic system, active oxygen metabolism, nutrient content, and ascorbate-glutathione (AsA-GSH) cycle of maize and wheat were studied in order to explicit whether N addition could effectively alleviate the effects of MPs on maize and wheat. The results showed that MPs inhibited the plant height of both maize and wheat, and MPs effects on physiological traits of maize were more severe than those of wheat, reflecting in reactive oxygen metabolism and restriction of photosynthetic capacity. Under the condition of N supply, AsA-GSH cycle of two plants has different response strategies to MPs: Maize promoted enzyme activity and co-accumulation of AsA and GSH, while wheat tended to consume AsA and accumulate GSH. N application induced slight oxidative stress on maize, which was manifested as an increase in hydrogen peroxide and malonaldehyde contents, and activities of polyphenol oxidase and peroxidase. The antioxidant capacity of maize treated with the combination of MPs + N was better than that treated with N or MPs alone. N could effectively alleviate the adverse effects of MPs on wheat by improving the antioxidant capacity.

Ageing influences the toxicity of two innovative nanofertilizers to the soil invertebrates Enchytraeus crypticus and Folsomia candida

The increasing global food demand is threatening the sustainability of agrifood production systems. The intensification of agricultural practices, with inadequate use of pesticides and fertilizers, poses major challenges to the good functioning of agroecosystems and drastically degrades the soil quality. Nanotechnology is expected to optimize the current farming practices and mitigate some associated impacts. Layered double hydroxides (LDHs) are a class of nanomaterials with high potential for use in agricultural productions, mostly due to their sustained release of nutrients. Considering its novelty and lack of studies on the terrestrial ecosystem, it is essential to assess potential long-term harmful consequences to non-target organisms. Our study aimed to evaluate the effect of Zn–Al–NO3 LDH and Mg–Al–NO3 LDH ageing on the survival and reproduction of two soil invertebrate species Enchytraeus crypticus and Folsomia candida. We postulated that the toxicity of nanomaterials to soil invertebrates would change with time, such that the ageing of soil amendments would mediate their impacts on both species. Our results showed that the toxicity of LDHs was species-dependent, with Zn–Al–NO3 LDH being more toxic to E. crypticus, while Mg–Al–NO3 LDH affected more F. candida, especially in the last ageing period, where reproduction was the most sensitive biological parameter. The toxicity of both nanomaterials increased with ageing time, as shown by the decrease of the EC50 values over time. The influence of LDH dissolution and availability of Zn and Mg in the soil pore water was the main factor related to the toxicity, although we cannot rule out the influence of other structural constituents of LDHs (e.g., nitrates and aluminium). This study supports the importance of incorporating ageing in the ecotoxicity testing of nanomaterials, considering their slow release, as effects on soil organisms can change and lead to more severe impacts on the ecosystem functioning.

Tree lines influence soil temperatures, sward growth dynamics and litter decomposition in permanent grassland

Climate change is likely to have a negative impact on soil functions in agro-ecosystems in the future. Alley cropping combines trees and agricultural crops or grassland on the same agricultural area. It has recently been discussed as more sustainable and resilient than comparable systems without trees for the temperate zone. So far, the influence of tree lines on biomass growth and decomposition of aboveground litter in the adjacent grassland is not fully clear. We measured the effect of tree lines on soil temperatures of an adjacent grass sward at five positions differing in distance and orientation (facing the tree line in the East or West) in a temperate alley-cropping system. Growth dynamics (sward height and soil cover) as well as litter half-life times for two cutting frequencies (four vs. two annual cuts) were monitored during two experimental years. The botanical composition at the transect positions was evaluated using the dry weight rank method. We found lower soil temperatures close to the trees, even though the proportion of soil cover was slightly lower close to the trees. The sward heights did not show a consistent pattern with respect to distance to the trees. Annual biomass accumulation was greatest at 6 m distance to the trees. An intermediate distance to the trees had a beneficial effect on productivity compared to the position with the lowest tree effect (25 m). Litter half-life times decreased with increasing sward height without a consistently positive/negative influence of the tree line over the examined growth periods. Lower litter half-life times in taller grass swards indicate that the sward height is the main factor driving litter decomposition while the influence of the trees is of minor importance.

Intercropping Chickpea with Durum Wheat Enhances Nutrient Uptake and Grain Yield Under Low Phosphorus Availability

ABSTRACT Intercropping is a traditional farming system that increases crop diversity to strengthen agroecosystem functions while decreasing chemical inputs and minimizing negative environmental effects of crop production. However, the effect of intercropping legume-cereal in enhancing nutrient uptake and use efficiency under low phosphorus (P) soils is poorly understood. Growth, nodulation, P uptake and use efficiency, and changes in inorganic P availability in the rhizosphere of intercropped species were thus investigated in a field experiment with durum wheat and chickpea either grown alone or intercropped. The results showed that both plant biomass and grain yield, and consequently, the amount of P uptake by intercropped durum wheat increased significantly (30%, 12%, and 46%, respectively) compared with sole cropping during the two seasons. P availability increased in the rhizosphere of the two species, either grown as sole crops or as intercrops, and was enhanced by intercropping. Moreover, total biomass, grain yield, and P uptake were significantly improved, as indicated by higher land equivalent ratio (LER > 1) in intercropping over sole cropping treatments. The increased biomass and grain yield for intercropped durum wheat were associated with the stimulation of P absorption and use efficiency. Furthermore, intercropped wheat was more competitive than their respective chickpea over two growing seasons. The results of this study suggest that changes in the intercropped chickpea rhizosphere may enhance plant growth, P uptake, and use efficiency of the intercropped wheat under low-P soils.

Effect of crop rotation on nitrogen leaching with the lysimetric waters in vulnerable areas

Abstract. Climate change is known to subject the functioning of agroecosystems to high levels of biotic and abiotic stress and has a significant impact on agricultural production worldwide. Crop rotation is believed to be one way of adapting agriculture to climate change compared to monoculture This study aimed to examine the maize-wheat rotation impact on soil nitrogen dynamics and leaching losses. A study has been carried out on the experimental field of Tsalapitsa, Plovdiv region on Fluvisol. In this maize-wheat rotation experiment, we compared three fertilization treatments with increasing nitrogen and phosphorus rates to a control with no fertilization. In 2020, grain maize (Zea mays L.) FAO group 310, was grown with fertilizer rates (T0N0P0; T1N120P80; T2N160P120; T3N200P160). In the period 2020/2021, wheat, (Triticum aestivum L.), was grown with the following fertilizer variants – (Т0 N0P0; Т1N100P60; Т2 N140P100; Т3 N180P140). The field plots were equipped with modification of Ebermayer type of lysimeters, which collect water from 100 cm depth of soil profile. The volume of lysimetric waters was calculated, the nitrogen content and its leaching were analyzed. The study found that the lysimetric water volume after maize cultivation was 75.95 liters per square meter, approximately 2.5 to 3 times higher than that observed after wheat cultivation. Nitrogen content varied with fertilization rates, ranging from 10.8 to 37.5 mg/L for maize and 8.73 to 23.58 mg/L for wheat. The losses of the element with drainage runoff with the first crop were – 5.6-28.5 kg.ha-1, and with wheat – 1.2-6.3 kg.ha-1, respectively. It was established that when cereal crops were grown the losses of nitrate nitrogen out of the root zone were significantly reduced.

Decreased microbial phylogenetic diversity and community stability due to less bioavailable carbon and greater oxygen supply in Mollisols along a cultivation chronosequence

Soil microorganisms support multiple agroecosystem functions, but responses of the microbiome to prolonged agricultural land-use and underlying mechanisms remain poorly understood. In this study, upland soils in the Mollisol region of Northeast China were selected along a 100-year cultivation chronosequence to examine the effects of intensive agriculture on the diversity, composition and co-occurrence network of bacterial and fungal communities. To elucidate the determinants driving the dynamics and interactions of microbial communities, the researchers quantified the functional groups and bioavailable fractions of soil organic carbon, and estimated the microenvironments including soil texture and oxygen availability. Our findings revealed that fungal diversity and community stability decreased over cultivation time, while that of bacteria showed a less significant decline. The increased oxygen availability and decreased soil carbon supply, particularly polyphenols, jointly drove the dynamics in the composition and stability of the microbial communities. Crucially, these microbial responses were significantly regulated by interspecific associations. Phylotypes showing stronger responses to changes in oxygen availability and carbon supply demonstrated a higher level of connectivity within co-occurrence networks, signifying their potential role as pivotal “hubs” in transmitting the environmental influences across the entire community via interspecific associations. Moreover, the decline in fungal diversity over longer cultivation periods could liberate more survival niches for bacterial species through fungi-bacteria associations, thereby bolstering the stability of the bacterial community. Overall, this study accentuates the pivotal role of trophic associations in facilitating the oxygen and carbon-induced succession of belowground microbiota in long-term cultivated Mollisols. In view of the agricultural intensification propelled by the increasing demand for crop production, these findings suggest strategies integrating improvements in soil structure and carbon with microbial processes to ensure the sustainability of agroecosystem functions.

Biochar and organic fertilizer applications enhance soil functional microbial abundance and agroecosystem multifunctionality

Biochar and organic fertilizer are widely supported to maintain crop production and sustainable development of agroecosystems. However, it is unclear how biochar and organic fertilizer alone or in combination regulate soil functional microbiomes and their relationships to ecosystem multifunctionality (EMF). Herein, a long-term (started in 2013) field experiment, containing five fertilization treatments, was employed to explore the effects of biochar and organic fertilizer applications on the EMF (based on 18 functional indicators of crop productivity, soil nutrient supply, element cycling, and microbial biomass) and the functional microbiomes of bulk soil and rhizosphere soil [normalizing the abundances of 64 genes related to carbon (C), nitrogen (N), phosphorus (P), and sulphur (S) cycles]. Compared with single-chemical fertilization, biochar and organic fertilizer inputs significantly enhanced most ecosystem-single functions and, in particular, the EMF significantly increased by 18.7–30.1%; biochar and organic fertilizer applications significantly increased the abundances of soil microbial functional taxa related to C-N-P-S cycles to varying degree. The combined application of biochar and organic fertilizer showed a better improvement in these indicators compared to using them individually. Most functional microbial populations in the soil, especially the taxa involved in C degradation, nitrification, nitrate-reduction, organic P mineralization, and S cycling showed significantly positive associations with the EMF at different threshold levels, which ultimately was regulated by soil pH and nutrient availability. These results highlight the strong links between soil microbiomes and agroecosystem functions, as well as providing scientific support for inclusion of biochar in agricultural production and services with organic amendments.Graphical

Three years of cover crops management increased soil organic matter and labile carbon pools in a subtropical vegetable agroecosystem

AbstractCover crops have been widely adopted to improve soil functions in agroecosystems, including providing carbon (C) inputs that can contribute to soil C sequestration. However, soil C changes may be slow after introducing cover crops in unfavorable environments for soil organic matter (SOM) accumulation, like the Southeast United States subtropical region characterized by a warm humid climate, and coarse‐textured soils. We examined labile C pools as potential early indicators of SOM changes after cover crop introduction in a sandy subtropical vegetable production system. We compared the effects of four cover crop monocultures namely two grasses [sorghum sudangrass, Sorghum bicolor × S bicolor var. Sudanese and pearl millet, Pennisetum glaucum (L.) R. Br.], two legumes (sunn hemp, Crotalaria juncea L., and cowpea, Vigna unguiculata Walp.), and one four‐species mixture on soil organic carbon pools for 3 years. Soil samples were collected at a 15‐cm depth before cover crop planting and post cover crop incorporation to assess changes in SOM, permanganate‐oxidizable carbon (POX‐C), mineralizable carbon (Cmin), and water extractable organic carbon (WEOC). The incorporation of cover crops increased concentrations of SOM, POX‐C, and Cmin in year 3 relative to their baseline values in year 1. Concentration of SOM increased by 0.24 ± 0.05% (mean ± standard error) after 3 years of cover crop management. However, concentrations of WEOC significantly decreased in years 2 and 3 relative to the baseline. Monocultures and the mixture had similar effects on measured C pools, likely due to comparable aboveground biomass production. Our findings highlight the potential of POX‐C and Cmin as early indicators of SOM accumulation driven by cover crops use, as well as the capacity of cover crops to build SOM in similar subtropical systems and coarser textured soils.

2016–2021年海南文昌菜地土壤微生物数据集

With the rapid development of tropical-specific and efficient agriculture coupled with changes in planting structures, the uncertainty regarding the implications of new farming management patterns on vegetable ecosystems has heightened. As important indicators for assessing soil quality, soil microorganisms play a crucial role in maintaining soil function. Therefore, monitoring microbial community composition and function and metabolism under the cropping system in tropical region is particularly important for investigating microbial community successions and their driving factors and unraveling intricate processes like nutrient cycling and other microscopic mechanisms.. Based on soil microbial DNA/RNA molecular biology techniques, this dataset was integrated with high-throughput sequencing data of soil bacteria and fungi under three fertilization patterns: chemical fertilizer alone, straw return, and chemical fertilizer + straw return in vegetable fields in Wenchang City, Hainan Province during 2016-2021. The processes of site setting, observation and maintenance, sample collection, sample preparation and preservation, data filling and quality control are strictly implemented in accordance with the unified standards of China Ecological Research Network (CERN). The dataset is of great significance for studying the nutrient cycling of vegetable ecosystems in tropical regions, analyzing the interaction mechanism between environmental elements and production systems, adjusting crop cultivation management methods and nutrient inputs, and improving the service functions of tropical agroecosystems.