scholarly journals Soil organic carbon fractionation and metagenomics pipeline to link carbon content and stability with microbial composition - First results investigating fungal endophytes

2021 ◽  
Author(s):  
Wolfram Buss ◽  
Raghvendra Sharma ◽  
Scott Ferguson ◽  
Justin O Borevitz

Society needs to capture gigatons of carbon dioxide from the atmosphere annually and then store it long-term to limit and ultimately reverse the effects of climate change. Bringing lost carbon back into agricultural soils should be a priority as it brings the added benefit of improving soil properties. Linking soil organic carbon (SOC) fractions of different stability with soil microbial composition can help understand and subsequently manage SOC storage. Here we develop a pipeline for evaluating the effects of microbial management on SOC content using rapid and low-cost SOC fractionation and metagenomics approaches. We tested the methods in a wheat pot trial inoculated with 17 individual endophytic fungal isolates. Two fungi increased total SOC in the area under the plant stem by ~15%. The fractionation assay showed that the medium stability soil aggregate carbon fraction (AggC) was increased by one of these fungi (+21%) and the chemically recalcitrant proportion (bleach oxidation) of AggC by the other (+35%). Both fungi increased mineral-associated organic carbon (MAOC), the long-term SOC storage, by ~10%. We used rapid, portable, low-cost, whole metagenome long read sequencing to detect a shift in the microbial composition for one of the fungi-inoculated treatments. This treatment showed a more diverse microbial community and a higher quantity of DNA in soil. The results emphasise the link between composition and abundance of soil microorganisms with soil carbon formation. Our dual carbon fractional and metagenomic analysis pipeline can be used to further test the effects of microbial management and ultimately to model the soil factors that influence SOC storage, such as nutrient and water availability, starting SOC content, soil texture and aggregation.

Forests ◽  
2019 ◽  
Vol 10 (9) ◽  
pp. 797 ◽  
Author(s):  
Tan ◽  
Kan ◽  
Su ◽  
Liu ◽  
Zhang

Soil microbes are of great significance to driving the biogeochemical cycles and are affected by multiple factors, including urbanization. However, the response of soil microbes to urbanization remains unclear. Therefore, we designed an urban-to-rural gradient experiment to investigate the response of soil microbial composition and diversity to urbanization. Here, we used a high-throughput sequencing method to analyze the biotic and abiotic effects on soil microbial composition and diversity along the urban-to-rural gradient. Our results showed that soil bacterial diversity was the highest in urban areas, followed by suburban areas, and was the lowest in exurbs; however, fungal diversity did not vary significantly among the three areas. Plant traits, i.e., tree richness, shrub richness, the number of tree stems, diameter at breast height of trees, and soil properties, i.e., pH, soil organic carbon, soil exchangeable calcium and magnesium, and soil water content, were only significantly influenced bacterial diversity, but not fungal diversity. The effect of trees and shrubs was higher than that of herbs on microbial composition. Soil organic carbon, pH, soil available nitrogen, soil exchangeable calcium, and magnesium were the major soil factors influencing the soil bacterial and fungal composition. Soil properties had a greater influence on bacterial than on fungal composition at genus level, while plant traits contributed more to fungal than to bacterial composition at genus level. Our study suggests that the urban-to-rural gradient affect the composition and diversity of bacterial community as well as the fungal composition, but not the fungal diversity.


Soil Research ◽  
2010 ◽  
Vol 48 (5) ◽  
pp. 413 ◽  
Author(s):  
Subhadip Ghosh ◽  
Brian R. Wilson ◽  
Biswapati Mandal ◽  
Subrata K. Ghoshal ◽  
Ivor Growns

Soil organic carbon (SOC) constitutes a significant proportion of the terrestrial carbon (C) store and has a pivotal role in several physical, chemical, and biological soil processes that contribute to soil productivity and sustainability. Applications of inorganic and organic materials are management options that have the potential to increase SOC in agricultural systems. A study was conducted in 3 long-term fertility experiments (Barrackpur, Mohanpur, and Cuttack) on agricultural soils in the eastern cereal belt of India, to examine the effect of cultivation and the application of inorganic and organic amendments on total soil organic carbon (TOC) and on the proportions of soil C fractions at these sites. A supplementary aim of this study was to determine the suitability of the loss-on-ignition (LOI) method to routinely estimate SOC (Walkley and Black, WB) in this region by determining relationships and conversion factors between the WB and LOI techniques. Soil was sampled at 3 depths (0–0.15, 0.15–0.30, and 0.30–0.45 m) from 4 treatments (conventional cultivation, NPK, NPK+FYM, and fallow) of the experimental sites and analysed for TOC and various soil C pools. There were differences in the magnitude of TOC values among the sites. Conventional cultivation had the lowest TOC contents (148 t/ha) and NPK+FYM amended soils the largest (207 t/ha), with intermediate values in the other treatments. The non-labile or residual SOC fraction (Cfrac4) constituted the largest percentage of SOC under all treatments and varied from 35–49%. A higher proportion of the labile Cfrac1 fraction was observed under the fallow, whereas the proportion of Cfrac4 was significantly larger under NPK+FYM. There was a significant decrease in SOC with increasing soil depth. SOC decreased up to 17% at 0.15–0.30 m and declined a further 21% at 0.30–0.45 m. The more labile C fractions (Cfrac1, Cfrac2, Cfrac3) dominated in the near surface soil layers, but decreased significantly in the deeper layers to be dominated by Cfrac4 at 0.30–0.45 m depth. We also observed a strong correlation between the WB and LOI methods (calibrated for each soil) irrespective of soil depths and conclude that this might be a suitable method to estimate SOC where other techniques are not available. We conclude that fertiliser application and especially manure application have the potential to significantly increase SOC in agricultural soils.


2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Arthur Gross ◽  
Bruno Glaser

AbstractManure application to agricultural soils is widely considered as a source of nutrients and a method of maintaining levels of soil organic carbon (SOC) to mitigate climate change. At present, it is still unclear which factors are responsible for the SOC stock dynamics. Therefore, we analyzed the relationship between SOC stock changes and site characteristics, soil properties, experiment characteristics and manure characteristics. Overall, we included 101 studies with a total of 592 treatments. On average, the application of manure on agricultural soils increased SOC stocks by 35.4%, corresponding to 10.7 Mg ha−1. Manure applications in conventional tillage systems led to higher SOC stocks (+ 2.2 Mg ha−1) than applications under reduced tillage. Soil organic carbon increase upon manure application was higher in soils under non-tropical climate conditions (+ 2.7 Mg ha−1) compared to soils under sub-tropical climate. Larger SOC increases after manure application were achieved in intermediate and shallow topsoils (in 0–15 cm by 9.5 Mg ha−1 and in 16–20 cm by 13.6 Mg ha−1), but SOC stocks were also increased in deeper soils (> 20 cm 4.6 Mg ha−1), regardless of the tillage intensity. The highest relative SOC increase (+ 48%) was achieved if the initial SOC was below 1% but the absolute SOC increased with increasing initial SOC. Clay soils showed higher SOC increase rates compared to sandy soils (+ 3.1 Mg ha−1). Acidic soils showed comparable relative effects but a higher stock difference than neutral (+ 5.1 Mg ha−1) and alkaline soils (+ 5.1 Mg ha−1). The application of farmyard-, cattle- and pig manure showed the highest SOC increases (50%, 32% and 41%, respectively), while green manure and straw showed only minor effects. If manure applications were combined with additional mineral fertilizer, the SOC increases were higher (+ 1.7 Mg ha−1) compared to manure alone. Higher applied amounts generally led to higher SOC stocks. However the annually applied amount is only important under conventional tillage, non-tropical climate conditions, and pH-neutral as well as SOC-rich or SOC-depleted soils and if no additional mineral fertilization is applied. Further studies should focus on the SOC dynamics under tropical climate conditions and factors influencing a potential carbon saturation. In both cases, the number of data was too small. For this reason, additional field studies should be conducted primarily in the tropics. On the other hand, long-term field trials should be re-assessed or newly established to specifically investigate potential saturation effects and long-term (> 20 years) fertilizer effects and carbon sequestration.


Land ◽  
2020 ◽  
Vol 9 (11) ◽  
pp. 455
Author(s):  
Rebecca M. Swab ◽  
Nicola Lorenz ◽  
Nathan R. Lee ◽  
Steven W. Culman ◽  
Richard P. Dick

After strip mining, soils typically suffer from compaction, low nutrient availability, loss of soil organic carbon, and a compromised soil microbial community. Prairie restorations can improve ecosystem services on former agricultural lands, but prairie restorations on mine lands are relatively under-studied. This study investigated the impact of prairie restoration on mine lands, focusing on the plant community and soil properties. In southeast Ohio, 305 ha within a ~2000 ha area of former mine land was converted to native prairie through herbicide and planting between 1999–2016. Soil and vegetation sampling occurred from 2016–2018. Plant community composition shifted with prairie age, with highest native cover in the oldest prairie areas. Prairie plants were more abundant in older prairies. The oldest prairies had significantly more soil fungal biomass and higher soil microbial biomass. However, many soil properties (e.g., soil nutrients, β-glucosoidase activity, and soil organic carbon), as well as plant species diversity and richness trended higher in prairies, but were not significantly different from baseline cool-season grasslands. Overall, restoration with prairie plant communities slowly shifted soil properties, but mining disturbance was still the most significant driver in controlling soil properties. Prairie restoration on reclaimed mine land was effective in establishing a native plant community, with the associated ecosystem benefits.


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