scholarly journals Using Diffuse Reflectance Spectroscopy as a High Throughput Method for Quantifying Soil C and N and Their Distribution in Particulate and Mineral-Associated Organic Matter Fractions

2021 ◽  
Vol 9 ◽  
Author(s):  
Paulina B. Ramírez ◽  
Francisco J. Calderón ◽  
Michelle Haddix ◽  
Emanuele Lugato ◽  
M. Francesca Cotrufo
Keyword(s):  
Land Use ◽  
Organic Matter ◽  
High Throughput ◽  
Diffuse Reflectance ◽  
N Content ◽  
Soil C ◽  
Mir Spectroscopy ◽  
C Pools ◽  
Soil C And N ◽  
C And N

Large-scale quantification of soil organic carbon (C) and nitrogen (N) stocks and their distribution between particulate (POM) and mineral-associated (MAOM) organic matter is deemed necessary to develop land management strategies to mitigate climate change and sustain food production. To this end, diffuse reflectance mid-infrared spectroscopy (MIR) coupled with partial least square (PLS) analysis has been proposed as a promising method because of its low labor and cost, high throughput and the potential to estimate multiple soil attributes. In this paper, we applied MIR spectroscopy to predict C and N content in bulk soils, and in POM and MAOM, as well as soil properties influencing soil C storage. A heterogeneous dataset including 349 topsoil samples were collected under different soil types, land use and climate conditions across the European Union and the United Kingdom. The samples were analyzed for various soil properties to determine the feasibility of developing MIR-based predictive calibrations. We obtained accurate predictions for total soil C and N content, MAOM C and N content, pH, clay, and sand (R2> 0.7; RPD>1.8). In contrast, POM C and N content were predicted with lower accuracies due to non-linear dependencies, suggesting the need for additional calibration across similar soils. Furthermore, the information provided by MIR spectroscopy was able to differentiate spectral bands and patterns across different C pools. The strength of the correlation between C pools, minerals, and C functional groups was land use-dependent, suggesting that the use of this approach for long-term soil C monitoring programs should use land-use specific calibrations.

Soil aggregate stability and soil organic matter fractions under agropastoral systems established in native savanna

Soil Research ◽  
1996 ◽  
Vol 34 (6) ◽  
pp. 891 ◽  
Author(s):  
AJ Gijsman
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Aggregate Stability ◽  
Aggregate Size ◽  
Soil Disturbance ◽  
N Content ◽  
Soil C ◽  
Size Classes ◽  
Soil C And N ◽  
C And N

An area of native savanna on an Oxisol in the Eastern Plains of Colombia was opened and sown to various rotations of grass or grass-legume pasture with rice. After 4.5 years, the soil was sampled for studying the effect of land conversion on soil aggregation and on the distribution of total and particulate soil organic matter across the aggregate size classes. The size distribution of undisturbed aggregates did not vary among treatments. Five different methods were used to measure wet aggregate stability (WAS). The choice of method affected the WAS average across treatments as well as the differences among treatments. The only consistent observation was the lower WAS under monocropped rice compared with the other treatments. Inclusion of a legume in a pasture hardly affected aggregate stability. In contrast to the WAS measurements, which were carried out with soil aggregates of 1-2 mm, wet sieving of whole-soil samples revealed additional differences among treatments: large macroaggregates (>2 mm) proved less stable under those treatments that involved soil disturbance through ploughing and harvesting. Total soil C and N content did not vary among treatments, despite considerable differences in plant production levels. The C concentration, but not the N concentration, declined with decreasing aggregate size. The distribution of whole-soil C and N content across aggregate size classes depended more on the amount of soil in a certain size class than on the size class's C or N concentration. Those treatments that involved frequent soil disturbance had a smaller fraction of large macroaggregates (>2 mm) and, as a consequence, less C and N in the large macroaggregate fraction. The particulate organic matter (POM) fraction accounted for only 6.2-8.5% of total soil carbon. The small size of this pool makes it unlikely that POM can serve in these Oxisols for estimating the amount of soil organic matter with medium turnover rate, as suggested by others.

Decoupled Soil Labile Carbon and Nitrogen Dynamics Triggered by Urban Vegetation

2021 ◽  
Author(s):  
Xiaolin Dou ◽  
Meng Lu ◽  
Liding Chen
Keyword(s):  
Land Use ◽  
Urban Forest ◽  
Urban Ecosystems ◽  
Isotopic Analysis ◽  
C Sequestration ◽  
Bare Soil ◽  
N Dynamics ◽  
Soil C ◽  
Soil C And N ◽  
C And N

Abstract Purpose Studies about soil carbon (C) and nitrogen (N) dynamics with land use change are urgently needed for urban ecosystems. We used fractionation of soils combined with stable isotopic analysis to examine soil C and N cycles after decadal forest and lawn planting in the Pearl River Delta, China. Methods Soil samples from bare soil (CK) and four land use treatments (55 and 20 years of forest plantation, F-55 and F-20; 55 and 20 years of lawn plantation, L-55 and L-20) were split into different chemical fractions. Then we analyzed the C and N contents, C/N ratio, δ13C and δ15N, C and N recalcitrant indices (RIC, RIN), and a C pool management index (CPMI).Results Forest vegetation substantially enhanced soil organic carbon (SOC) caused by the recalcitrant (RC) and labile C (LC) pools, while the larger soil organic nitrogen (SON) was ascribed to the increased recalcitrant N (RN). Enhanced LC but minor changes in labile N (LN) suggested a decoupled C and N in labile fractions of the forest soils. In contrast, the larger LN, and the enhanced decomposition of SOC, indicated that the lawns may have inhibited N mineralization of labile pools, also suggesting a decoupled C and N turnover and leading to low RIN values. Conclusions Urban forest and lawn plantations significantly changed the soil C and N dynamics, and emphasized the inconsistency between C and N processes, especially in labile pools, which would eventually lead to minor changes in N and limit the ecosystem C sequestration.

scholarly journals Land-Use Change on Soil C and N Stocks in the Humid Savannah Agro-Ecological Zone of Ghana

2022 ◽  
Vol 13 (01) ◽  
pp. 32-68
Author(s):  
Johnny Kofi Awoonor ◽  
Fowzia Adiyah ◽  
Bright Fafali Dogbey
Keyword(s):  
Land Use ◽  
Land Use Change ◽  
Ecological Zone ◽  
Soil C ◽  
Soil C And N ◽  
C And N

Mineralisation of organic matter in intact versus sieved/refilled soil cores

Soil Research ◽  
2002 ◽  
Vol 40 (1) ◽  
pp. 149 ◽  
Author(s):  
R. Stenger ◽  
G. F. Barkle ◽  
C. P. Burgess
Keyword(s):  
Organic Matter ◽  
N Mineralisation ◽  
Soil Cores ◽  
Nitrogen Mineralisation ◽  
Soil C ◽  
Soil Microbial ◽  
Conditioning Period ◽  
Incubation Study ◽  
Soil C And N ◽  
C And N

In a 6-month laboratory incubation study, we compared the net C and N mineralisation of the soil organic matter (SOM) of 3 pasture soils and the mineralisation of glucose-C in intact versus sieved/refilled soil cores. The main questions were whether the net C and N mineralisation differed between intact and sieved/refilled soil cores after a conditioning period of 4 weeks, and how much the C and N mineralisation of SOM differed among the similarly managed pasture soils. Apart from the net nitrogen mineralisation in one soil, there were no significant differences in cumulated mineralisation of C or N from SOM between the core types. In a fine-textured soil, net mineralisation of glucose-C differed significantly between core types, which was attributed to the different distribution of the amended glucose in intact and sieved/refilled cores. Net C and N mineralisation of SOM were closely correlated in the sieved/refilled cores, whereas no significant correlation was found in the intact cores. Expressing net C and N mineralisation as percentages of total soil C and N showed a more than 2-fold maximum difference between the soils in spite of similar long-term organic matter input. Subsequent studies should be done using more replicates and wider diameter, better controllable cores on ceramic plates. CO2, net nitrogen mineralisation (NNM), soil microbial biomass.

Soil C and N Content Under Evolving Landscapes in an Arid Inland River Basin of Northwest China

2004 ◽  
Vol 19 (6) ◽  
pp. 621-629 ◽  
Author(s):  
Wang Genxu ◽  
Yao Jinzhong ◽  
Luo Lin ◽  
Qian Ju
Keyword(s):  
River Basin ◽  
Northwest China ◽  
N Content ◽  
Soil C ◽  
Inland River ◽  
Inland River Basin ◽  
Soil C And N ◽  
C And N
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