Advances in Using Soft X-Ray Spectroscopy for Measurement of Soil Biogeochemical Processes

Gillespie, Adam; Phillips, Courtney L.; Dynes, James J.; Chevrier, D.; Regier, T. Z.; Peak, Derek

doi:10.1016/bs.agron.2015.05.003

Cited by 39 publications

(36 citation statements)

References 40 publications

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“…The highest %OC replicate for each treatment was selected for XANES measurement to maximize the signal. Data was collected using slew scanning mode to minimize radiation damage to the sample (Gillespie et al 2015). An average of 60 scans were taken per sample at a new spot on the sample for each scan.…”

Section: Soil Chemical Analysesmentioning

confidence: 99%

“…Normalization to incident flux (I 0 ) was carried out by recording the scattering intensity from a freshly sputtered (carbon free) Au surface across the C -Kedge (Gillespie et al 2015). The N K-edge data was calibrated to the t = 0 vibration of interstitial N 2 gas (at 400.8 eV) in solid-state ammonium sulfate (Gillespie et al 2008).…”

Section: Soil Chemical Analysesmentioning

confidence: 99%

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Long term effects of reduced fertilizer rates on millet yields and soil properties in the West-African Sahel

Adams

Gillespie

Kar

et al. 2016

Nutr Cycl Agroecosyst

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Microdosing, the point-source application of a reduced fertilizer rate within 10 days of sowing, has increased short-term crop yields across the Sahel and is being actively scaled up as an agronomic practice. However, there is no information on the longterm effects of the technique upon soil fertility. To rectify this, this study used soil samples from the International Crop Research Institute for the SemiArid Tropics in Sadore, Niger, to assess the effects of 16 years of a reduced fertilizer rate of 15 kg N and 4.4 kg P ha -1 compared to unfertilized soil and a recommended rate of 30 kg N and 13.2 kg P ha -1 upon millet yield trend, soil chemical properties, and soil organic matter quality. The interaction of fertilizer with crop residue and manure amendments at 300, 900, and 2700 kg ha -1 was also assessed. Compared to unfertilized soil, the reduced fertilizer rate improved yield by 116 % but did not increase total N or available P. The recommended rate doubled available P and increased total N by 27 %, but resulted in slightly lower pH compared to the reduced rate. Yield trends were negative for both fertilizer treatments, indicating mineral fertilizer alone is not sustainable at Sadore. Crop residue or manure addition at 2700 kg ha -1 with fertilizer did not improve SOC but buffered pH by 0.3 units, provided nutrients beyond N and P, and changed the forms C and N functional groups in soil organic matter.

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Section: Soil Chemical Analysesmentioning

confidence: 99%

Section: Soil Chemical Analysesmentioning

confidence: 99%

Long term effects of reduced fertilizer rates on millet yields and soil properties in the West-African Sahel

Adams

Gillespie

Kar

et al. 2016

Nutr Cycl Agroecosyst

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“…Infrared spectroscopy yields information about the chemical groups in soil OM and provides a fingerprint of the composition of the OM (Bouskill et al 2016). Synchrotron-based near-edge Xray absorption fine structure (NEXAFS) spectroscopy is used to determine the chemical environment of C and N in the soil samples (Solomon et al 2012;Leinweber et al 2013;Gillespie et al 2015). In comparison with other techniques such as infrared or nuclear magnetic resonance (NMR) spectroscopies, NEXAFS spectroscopy is very sensitive to element speciation and has been applied to soil samples in order to elucidate chemical changes in C and N of soil OM due to effects of land management (Solomon et al 2005), N fertilization (Gillespie et al 2013) or climate change (Purton et al 2015).…”

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confidence: 99%

Chemical changes in organic matter after fungal colonization in a nitrogen fertilized and unfertilized Norway spruce forest

et al. 2017

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Background and aims Decomposition and transformation of organic matter (OM) in forest soils are conducted by the concomitant action of saprotrophic and mycorrhizal fungi. Here, we examine chemical changes in OM after fungal colonization in nitrogen fertilized and unfertilized soils from a Norway spruce forest. Methods Sand-filled bags amended with composted maize leaves were placed in the forest soil and harvested after 17 months. Infrared and near edge X-ray absorption fine structure spectroscopies were used to study the chemical changes in the OM. Fungal community composition of the bags was also evaluated. Results The proportion of ectomycorrhizal fungi declined in the fertilized plots, but the overall fungal community composition was similar between N treatments. Decomposition of the OM was, independently of the N level or soil horizon, accompanied by an increase of C/N ratio of the mesh-bag content. Moreover, the proportions of carboxylic compounds in the incubated OM increased in the mineral horizon, while heterocyclic-N compounds decreased, especially in unfertilized plots with higher N demand from the trees. Conclusions Our results indicate that more oxidized organic C and less heterocyclic-N proportions in the OM remain after fungal colonization in the mineral layers, and suggest that ectomycorrhizal fungi transfer less heterocyclic-N from the mesh bags to the host trees under high N levels.

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“…The spot size on the beamline was 1000 μm × 100 μm. Data was collected using silicon drift detectors (SDD) and a titanium filter to reject higher order harmonics (Gillespie et al, 2015). The entrance and exit slit gaps were set to 249.9 μm and 25 μm.…”

Section: Release Kinetics Of Aromatic Carbonmentioning

confidence: 99%

“…Normalization of the data involved collecting an I 0 by measuring the scatter of the incident beam from a freshly Aucoated Si wafer using an SDD. The scatter in the sample data was removed by adjusting the pre-edge baseline to near zero before normalizing with the I 0 (Gillespie et al, 2015).…”

Section: Release Kinetics Of Aromatic Carbonmentioning

confidence: 99%

Asynchronous reductive release of iron and organic carbon from hematite–humic acid complexes

et al. 2016

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Solid-phase iron (Fe) plays an important role in the accumulation and stabilization of soil organic matter (SOM). However, ferric minerals are subject to redox reactions, which can compromise the stability of Fe-bound SOM. To date, there is limited information available concerning the fate of Fe-bound SOM during redox reactions at Fe mineral surfaces. In this study, we investigated the release kinetics of hematite-bound organic carbon (OC) during the abiotic reduction of hematite-humic acid (HA) complexes by dithionite, to elucidate important processes governing the stability and fate of organic matter during the redox processes. Our results indicate that the reductive release of Fe obeyed first-order kinetics with release rate constants of 6.67-13.0 × 10 −3 min −1 . The Febound OC was released rapidly during the initial stage with release rate constants of 0.011-1.49 min −1 , and then became stable with residual fractions of 4.6-58.2% between 120 and 240 min. The release rate of aromatic OC was much faster than for the non-aromatic fraction of HA, and 90% of aromatic OC was released within the first hour for most samples. Our findings show that in the reductive reaction the mobilization of Fe-bound OC was asynchronous with the reduction of Fe, and aromatic OC was released more readily than other components of SOM. This study highlights the importance of evaluating the release of SOM bound with Fe during the redox reactions, especially the influence of the physicochemical properties of SOM.

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Advances in Using Soft X-Ray Spectroscopy for Measurement of Soil Biogeochemical Processes

Cited by 39 publications

References 40 publications

Long term effects of reduced fertilizer rates on millet yields and soil properties in the West-African Sahel

Long term effects of reduced fertilizer rates on millet yields and soil properties in the West-African Sahel

Chemical changes in organic matter after fungal colonization in a nitrogen fertilized and unfertilized Norway spruce forest

Asynchronous reductive release of iron and organic carbon from hematite–humic acid complexes

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