scholarly journals Hot or not? connecting rhizosphere hotspots to total soil respiration

2021 ◽  
Author(s):  
Joscha N. Becker ◽  
Maire Holz
Keyword(s):  
Enzyme Activity ◽  
Soil Respiration ◽  
Root Biomass ◽  
Root Exudation ◽  
Bulk Soil ◽  
Small Scale ◽  
Individual Plant ◽  
Imaging Data ◽  
Total Soil ◽  
Total Soil Respiration

Abstract Aims Soil organic carbon (C) efflux is tightly linked to the rhizosphere, where soil microorganisms rapidly decompose organic compounds released from roots. Recently, imaging approaches have greatly improved our understanding of small-scale C-turnover heterogeneity and promoted the term ‘rhizosphere hotspots’ for highly active areas. However, despite often assumed, the effect of these hotspots on total soil C balances is still unknown. We aim to bridge this gap by correlating rhizosphere imaging data to soil respiration on individual plant scale. Methods We grew 17 maize (Zea mays L.) plants in rhizoboxes filled with sandy arable soil. After four weeks, the plants were labelled with 14CO2 and root exudation was visualized and quantified by 14C-imaging one day after labeling. The evolved CO2 was trapped in NaOH and 14CO2 as well as total CO2 was quantified before and after labelling. Enzyme activity (β-glucosidase) was quantified by soil zymography. Results Bulk soil β-glucosidase activitiy negatively correlated to total CO2 efflux, and was the most important predictor (R2 = 0.55). Total and rhizosphere specific 14C-activity were solely correlated to 14CO2 efflux (r = 0.51, r = 0.58). A combination of bulk soil β-glucosidase activity, rhizosphere-14C activity and root biomass, explained about 75% of variance in CO2 efflux. Conclusions This indicates that root exudation and enzyme-activity hotspots are suitable predictors for total soil respiration, particularly when combined with root biomass to account for three-dimensional variation, and that hotspots on the rhizosphere scale are directly linked to larger scale C balances.

Relationships between denitrification rate and determinant soil properties under barley

1993 ◽  
Vol 73 (4) ◽  
pp. 567-578 ◽  
Author(s):  
D. W. Bergstrom ◽  
E. G. Beauchamp
Keyword(s):  
Enzyme Activity ◽  
Moisture Content ◽  
Soil Properties ◽  
Respiration Rate ◽  
Denitrification Rate ◽  
Bulk Soil ◽  
Small Scale ◽  
Mean Values ◽  
Acetylene Blockage ◽  
A Site

To better understand environmental regulation of denitrification, we examined relationships between denitrification rate and six determinant soil properties: moisture content, air-filled porosity, NO3− content, respiration rate, mineralizable-C concentration and denitrifying enzyme activity (DEA). Soil cores were collected on 27 sampling dates over a growing season at a site seeded to barley (Hordeum vulgare). Denitrification rate was measured using a static core technique and acetylene blockage. Moisture content and air-filled porosity and, to a lesser extent, mineralizable-C concentration and respiration rate were more strongly related to denitrification rate than was DEA. Denitrification rate was unrelated to NO3− content. On most sampling dates, mean denitrification rate increased substantially only below an air-filled porosity of 0.3. Moreover, the distribution of individual measurements of denitrification rate was less skewed at lower air-filled porosities. Approximately 60% of variation in mean values of denitrification rate for each sampling date could be accounted for by measurements of bulk soil properties, of which moisture content and air-filled porosity were most important. Measurements of bulk soil properties did not account for nil values of denitrification rate at low air-filled porosities or for small-scale spatial variability. Such measurements were better indicators of temporal variation — that is, when denitrification occurred — than of actual rates. Key words: Denitrification, air-filled porosity, denitrifying enzyme activity

Variability of total soil respiration in a Mediterranean vineyard

Soil Research ◽  
2015 ◽  
Vol 53 (5) ◽  
pp. 531 ◽  
Author(s):  
Egidio Lardo ◽  
Assunta Maria Palese ◽  
Vitale Nuzzo ◽  
Cristos Xiloyannis ◽  
Giuseppe Celano
Keyword(s):  
Soil Respiration ◽  
Spatial Variability ◽  
Co2 Emissions ◽  
Temporal Dynamics ◽  
Non Invasive ◽  
Total Soil ◽  
Greenhouse Gas Flux ◽  
Flux Measurements ◽  
Total Soil Respiration

Total soil respiration (TSR) is the major component of the CO2 global flux. The knowledge of the temporal-spatial variability of TSR allows for a better interpretation of a critical component of global greenhouse gas flux measurements. The objective of the research was to evaluate the TSR dynamic over a long measurement period in a vineyard in the South of Italy. A static home-made automatic system was used to measure TSR for a three year period. A portable gas analyser (Li-Cor 6400-09) was used to study TSR spatial variability. A non-invasive geophysical technique (Electromagnetic Induction – EMI) was applied to search for a significant relationship between apparent soil electrical conductivity (ECa), the EMI signal and TSR. Long-term measurements of TSR enabled to study its temporal dynamics. CO2 rates ranged from 0.78 to 43.7 g CO2 m–2 day–1. TSR increased during spring and decreased by 45–50% during the mid-summer. The daily trend of TSR showed differences between the seasons studied reporting a clearly variation among TSR measured on row and inter-row positions. The supplemental irrigation significantly affected (P < 0.001) CO2 soil effluxes which showed a weekly mean increase of 300%. Significant inverse relationships were found by interpolating TSR values and ECa (coefficient of correlation ranging from –0.43 to –0.83 at P < 0.001). The spatialisation of TSR at field scale was performed using the linear regression between TSR values and EMI signals. TSR spatialisation gave a more detailed view of CO2 emissions distribution within the vineyard. EMI technique could be a useful tool to compute accurately the global CO2 emissions which are a complex and hard to measure component of the agrosystem carbon balance.

scholarly journals Contribution of root respiration to total soil respiration during non-growing season in mine reclaimed soil with different covering soil thicknesses

2020 ◽  
Author(s):  
Min Chen ◽  
Xiaoyang Chen ◽  
Zhiyong Hu ◽  
Tingyu Fan ◽  
Shiwen Zhang ◽  
...  
Keyword(s):  
Soil Respiration ◽  
Soil Temperature ◽  
Root Respiration ◽  
Growing Season ◽  
Growth Season ◽  
Soil Thickness ◽  
Total Soil ◽  
Reclaimed Soil ◽  
Total Soil Respiration ◽  
Monthly Variations

Abstract An accurate assessment of root respiration in mine reclaimed soil is important for effectively evaluating mining area ecosystem. This study investigated dynamic changes in root respiration and contribution of root respiration to total soil respiration (Rr/Rt ratio) during the non-growth season in mine reclaimed soil with different covering soil thicknesses. According to covering soil thicknesses, the study area was divided into four sites: 10-25 cm (site A), 25-45 cm (site B), 45-55 cm (site C) and 55-65 cm (site D). From November 2017 to April 2018 (except February in 2018), the soil respiration, root respiration, temperature at 5 cm, water content and root biomass were measured. The results showed that soil temperature and root respiration exhibited similar diurnal and monthly variations. The root respiration was strongly influenced by soil temperature during the non-growing season, which showed an exponential and positive relationship with soil temperature (P<0.001). The root respiration varied with the covering soil thickness and was the greatest with the covering soil thickness at 25–45 cm. The Rr/Rt ratio also exhibited monthly variations. During the non-growth season, the mean value of the Rr/Rt ratio were 51.15% in mine reclaimed soil. The study indicated that root respiration was the primary source of soil respiration and important to estimate the potential of emission of soil CO 2 at regional scale in mine reclaimed soil.

scholarly journals Contribution of root respiration to total soil respiration during non-growing season in mine reclaimed soil with different covering soil thicknesses

2020 ◽  
Author(s):  
Min Chen ◽  
Xiaoyang Chen ◽  
Zhiyong Hu ◽  
Tingyu Fan ◽  
Shiwen Zhang ◽  
...  
Keyword(s):  
Soil Respiration ◽  
Soil Temperature ◽  
Root Respiration ◽  
Regional Scale ◽  
Growing Season ◽  
Soil Thickness ◽  
Total Soil ◽  
Reclaimed Soil ◽  
Total Soil Respiration ◽  
Monthly Variations

Abstract An accurate assessment of root respiration in mine reclaimed soil is important for effectively evaluating mining area ecosystem. This study investigated dynamic changes in root respiration and contribution of root respiration to total soil respiration (Rr/Rt ratio) during the non-growing season in mine reclaimed soil with different covering soil thicknesses. According to covering soil thicknesses, the study area was divided into four sites: 10-25 cm (site A), 25-45 cm (site B), 45-55 cm (site C) and 55-65 cm (site D). From November 2017 to April 2018 (except February in 2018), the soil respiration, root respiration, temperature at 5 cm, water content and root biomass were measured. The results showed that soil temperature and root respiration exhibited similar diurnal and monthly variations. The root respiration was strongly influenced by soil temperature during the non-growing season, which showed an exponential and positive relationship with soil temperature (P<0.001). The root respiration varied with the covering soil thickness and was the greatest with the covering soil thickness at 25–45 cm. The Rr/Rt ratio also exhibited monthly variations. During the non-growing season, the mean value of the Rr/Rt ratio was 51.15% in mine reclaimed soil. The study indicated that root respiration was the primary source of soil respiration and important to estimate the potential emission of soil CO2 at regional scale in mine reclaimed soil.

Partitioning of total soil respiration into root, rhizosphere and basal-soil CO2 fluxes in contrasting rice production systems

Soil Research ◽  
2020 ◽  
Vol 58 (6) ◽  
pp. 592
Author(s):  
S. Neogi ◽  
P. K. Dash ◽  
P. Bhattacharyya ◽  
S. R. Padhy ◽  
K. S. Roy ◽  
...  
Keyword(s):  
Soil Respiration ◽  
Dehydrogenase Activity ◽  
Root Respiration ◽  
Production Systems ◽  
Rice Production ◽  
Carbon Pools ◽  
Labile Carbon ◽  
Basal Soil Respiration ◽  
Total Soil ◽  
Total Soil Respiration

Soil respiration contributes significantly to ecosystem respiration and is vital in the context of climate change research. In a season-long experiment we studied total soil respiration (TSR) and its partitioning into root respiration, rhizospheric respiration (RhR) and basal-soil respiration in four contrasting rice production systems: irrigated lowland (IL) (cv. Gayatri); organic nutrient managed irrigated lowland (OIL) (cv. Geetanjali); system of rice intensification (SRI) (cv. Swarna); and aerobic rice system (Aerobic) (cv. APO). We considered TSR to be the sum of root respiration, RhR and basal-soil respiration. Irrespective of the rice production system, TSR was higher at panicle initiation stage. Considering all four systems, the RhR contributed the most (59–83%) and basal-soil respiration the least (10–19%) to the TSR. Mean RhR showed the trend of Aerobic &gt; SRI &gt; IL &gt; OIL across the growing seasons and indicated higher rhizosphere activities in the aerobic system. Mean root respiration showed a trend of IL &gt; OIL &gt; SRI &gt; Aerobic and mean basal-soil respiration had SRI &gt; IL &gt; OIL &gt; Aerobic. Soil labile carbon pools and heterotrophic populations were higher in OIL and dehydrogenase activity was higher in SRI. Microbial biomass carbon, readily mineralisable carbon, dehydrogenase activity and the heterotroph population showed positive correlations with RhR. Hence, regulation of RhR is crucial and can be achieved through rhizosphere modifications linked with labile carbon pools and soil enzymatic activities by plant physiological modification or through soil carbon stabilisation.

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