Soil organisms are an integral component of ecosystems, but their activities receive little recognition in agricultural management strategies. Here we synthesize the potential of soil organisms to ...enhance ecosystem service delivery and demonstrate that soil biodiversity promotes multiple ecosystem functions simultaneously (i.e., ecosystem multifunctionality). We apply the concept of ecological intensification to soils and we develop strategies for targeted exploitation of soil biological traits. We compile promising approaches to enhance agricultural sustainability through the promotion of soil biodiversity and targeted management of soil community composition. We present soil ecological engineering as a concept to generate human land-use systems, which can serve immediate human needs while minimizing environmental impacts.
Recent evidence showed that soil biodiversity supports several ecosystem functions simultaneously, underpinning its crucial role in ecosystems worldwide.
To enable the proper functioning of ecosystems, soil biodiversity has to be enhanced and maintained.
Our analysis indicates that the sustainability of agricultural ecosystems can be restored by stimulating soil life and internally regulated ecosystem processes.
To face the immense global problems related to a growing human population and deterioration of the global biosphere, targeted manipulations of soil organisms become necessary in addition to promoting soil biodiversity.
Targeted approaches through soil ecological engineering to maximize the contribution of soil biological processes to sustainable ecosystem functioning can help to provide food security while minimizing negative environmental impacts.
Biodiversity loss has become a global concern as evidence accumulates that it will negatively affect ecosystem services on which society depends. So far, most studies have focused on the ecological ...consequences of above-ground biodiversity loss; yet a large part of Earth’s biodiversity is literally hidden below ground. Whether reductions of biodiversity in soil communities below ground have consequences for the overall performance of an ecosystem remains unresolved. It is important to investigate this in view of recent observations that soil biodiversity is declining and that soil communities are changing upon land use intensification. We established soil communities differing in composition and diversity and tested their impact on eight ecosystem functions in model grassland communities. We show that soil biodiversity loss and simplification of soil community composition impair multiple ecosystem functions, including plant diversity, decomposition, nutrient retention, and nutrient cycling. The average response of all measured ecosystem functions (ecosystem multifunctionality) exhibited a strong positive linear relationship to indicators of soil biodiversity, suggesting that soil community composition is a key factor in regulating ecosystem functioning. Our results indicate that changes in soil communities and the loss of soil biodiversity threaten ecosystem multifunctionality and sustainability.
Nutrient loss from terrestrial ecosystems via leaching and gaseous emissions is increasingly threatening global environmental and human health. Although arbuscular mycorrhizal fungi (AMF) have been ...shown to regulate soil N and P losses, a comprehensive quantitative overview of their influences on the losses of these soil nutrients across global scales is currently lacking. This study used a meta-analysis of 322 observations from 36 studies to assess the effect of AMF inoculum on 11 variables related to the loss of soil N and P. We found that the presence of AMF significantly reduced soil N and P losses, with the most pronounced reduction occurring in soil NO3−-N (−32%), followed by total P (−21%), available P (−16%) and N2O (−10%). However, the mitigation effects of AMF on soil N and P loss were dependent on the identity of AMF inoculum, plant type and soil biotic and abiotic factors. Generally, the mitigation effects of AMF increased with increasing AMF root colonization rate, microbial diversity of inoculants, soil organic carbon (SOC) content and experimental duration as well as with decreasing soil sand contents and soil N and P availability. Overall, this meta-analysis highlights the importance of AMF inoculation in mitigating N and P nutrient loss and environmental pollution for terrestrial ecosystem sustainability.
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•The effect of AMF inoculum on soil N and P loss was investigated by meta-analysis.•AMF decreased soil NO3−-N and TP losses by 32% and 21%, respectively.•AMF caused a 10% decrease in soil N2O fluxes.•The mitigation effects of AMF increased with increasing AMF root colonization rate.•The mitigation effects of AMF decreased with increasing soil N and P availability.
Summary
Hotspots of N2O emissions are generated from legume residues during decomposition. Arbuscular mycorrhizal fungi (AMF) from co‐cultivated intercropped plants may proliferate into the ...microsites and interact with soil microbes to reduce N2O emissions. Yet, the mechanisms by which or how mycorrhizal hyphae affect nitrifiers and denitrifiers in the legume residues remain ambiguous. Here, a split‐microcosm experiment was conducted to assess hyphae of Rhizophagus aggregatus from neighbouring maize on overall N2O emissions from stubbles of nodulated or non‐nodulated soybean. Soil microbes from fields intercropped with maize/soybean amended with fertilizer nitrogen (SS‐N1) or unamended (SS‐N0) were added to the soybean chamber only. AMF hyphae consistently reduced N2O emissions by 20.8%–61.5%. Generally, AMF hyphae promoted the abundance of N2O‐consuming (nosZ‐type) denitrifiers and altered their community composition. The effects were partly associated with increasing MBC and DOC. By contrast, AMF reduced the abundance of nirK‐type denitrifiers in the nodulated SS‐N0 treatment only and that of AOB in the non‐nodulated SS‐N1 treatment. Taken together, our results show that AMF reduced N2O emissions from soybean stubbles, mainly through the promotion of N2O‐consuming denitrifiers. This holds promise for mitigating N2O emissions by manipulating the efficacious AMF and their associated microbes in cereal/legume intercropping systems.
Community analyses of arbuscular mycorrhizal fungi (AMF) using ribosomal small subunit (SSU) or internal transcribed spacer (ITS) DNA sequences often suffer from low resolution or coverage. We ...developed a novel sequencing based approach for a highly resolving and specific profiling of AMF communities.
We took advantage of previously established AMF-specific PCR primers that amplify a c. 1.5-kb long fragment covering parts of SSU, ITS and parts of the large ribosomal subunit (LSU), and we sequenced the resulting amplicons with single molecule real-time (SMRT) sequencing.
The method was applicable to soil and root samples, detected all major AMF families and successfully discriminated closely related AMF species, which would not be discernible using SSU sequences. In inoculation tests we could trace the introduced AMF inoculum at the molecular level. One of the introduced strains almost replaced the local strain(s), revealing that AMF inoculation can have a profound impact on the native community.
The methodology presented offers researchers a powerful new tool for AMF community analysis because it unifies improved specificity and enhanced resolution, whereas the drawback of medium sequencing throughput appears of lesser importance for low-diversity groups such as AMF.
Efficient resource use is a key factor for sustainable production and a necessity for meeting future global food demands. However, the factors that control resource use efficiency in agro‐ecosystems ...are only partly understood. We investigated the influence of soil biota on nutrient leaching, nutrient‐use efficiency and plant performance in outdoor, open‐top lysimeters comprising a volume of 230 L. The lysimeters were filled with sterilized soil in two horizons and inoculated with a reduced soil‐life inoculum (soil biota ≤11 μm, microbially dominated) and an enriched soil‐life inoculum soil organisms ≤2 mm, also containing arbuscular mycorrhizal fungi (AMF). A crop rotation was planted, and nutrient leaching losses, plant biomass and nutrient contents were assessed over a period of almost 2 years. In the first year of the experiment, enriched soil life increased crop yield (+22%), N uptake (+29%) and P uptake (+110%) of maize and strongly reduced leaching losses of N (−51%, corresponding to a reduction of 76 kg N ha⁻¹). In the second year, wheat biomass (+17%) and P contents (+80%) were significantly increased by enriched soil life, but the differences were lower than in the first year. Enriched soil life also increased P mobilization from soil (+112%) and significantly reduced relative P leaching losses (−25%), defined as g P leached per kg P plant uptake, as well as relative N leaching losses (−36%), defined as kg N leached per kg N plant uptake, demonstrating that nutrient‐use efficiency was increased in the enriched soil‐life treatment. Synthesis and applications. Soil biota are a key factor determining resource efficiency in agriculture. The results suggest that applying farming practices, which favour a rich and abundant soil life (e.g. reduced tillage, organic farming, crop rotation), can reduce environmental impacts, enhance crop yield and result in a more sustainable agricultural system. However, this needs to be confirmed in field situations. Enhanced nutrient‐use efficiency obtained through farming practices which exert positive effects on soil biota could result in reduced amounts of fertilisers needed for agricultural production and reduced nutrient losses to the environment, providing benefits of such practices beyond positive effects on biodiversity.
Enumerating soil biodiversity Anthony, Mark A; Bender, S Franz; van der Heijden, Marcel G A
Proceedings of the National Academy of Sciences - PNAS,
08/2023, Letnik:
120, Številka:
33
Journal Article
Recenzirano
Odprti dostop
Soil is an immense habitat for diverse organisms across the tree of life, but just how many organisms live in soil is surprisingly unknown. Previous efforts to enumerate soil biodiversity consider ...only certain types of organisms (e.g., animals) or report values for diverse groups without partitioning species that live in soil versus other habitats. Here, we reviewed the biodiversity literature to show that soil is likely home to 59 ± 15% of the species on Earth. We therefore estimate an approximately two times greater soil biodiversity than previous estimates, and we include representatives from the simplest (microbial) to most complex (mammals) organisms. Enchytraeidae have the greatest percentage of species in soil (98.6%), followed by fungi (90%), Plantae (85.5%), and Isoptera (84.2%). Our results demonstrate that soil is the most biodiverse singular habitat. By using this estimate of soil biodiversity, we can more accurately and quantitatively advocate for soil organismal conservation and restoration as a central goal of the Anthropocene.
N2O is a potent greenhouse gas involved in the destruction of the protective ozone layer in the stratosphere and contributing to global warming. The ecological processes regulating its emissions from ...soil are still poorly understood. Here, we show that the presence of arbuscular mycorrhizal fungi (AMF), a dominant group of soil fungi, which form symbiotic associations with the majority of land plants and which influence a range of important ecosystem functions, can induce a reduction in N2O emissions from soil. To test for a functional relationship between AMF and N2O emissions, we manipulated the abundance of AMF in two independent greenhouse experiments using two different approaches (sterilized and re-inoculated soil and non-mycorrhizal tomato mutants) and two different soils. N2O emissions were increased by 42 and 33% in microcosms with reduced AMF abundance compared to microcosms with a well-established AMF community, suggesting that AMF regulate N2O emissions. This could partly be explained by increased N immobilization into microbial or plant biomass, reduced concentrations of mineral soil N as a substrate for N2O emission and altered water relations. Moreover, the abundance of key genes responsible for N2O production (nirK) was negatively and for N2O consumption (nosZ) positively correlated to AMF abundance, indicating that the regulation of N2O emissions is transmitted by AMF-induced changes in the soil microbial community. Our results suggest that the disruption of the AMF symbiosis through intensification of agricultural practices may further contribute to increased N2O emissions.
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