Root litter decomposition in a sub-Sahelian agroforestry parkland dominated by Faidherbia albida

Siegwart, Lorène; Bertrand, Isabelle; Roupsard, Olivier; Duthoit, Maxime; Jourdan, Christophe

doi:10.1016/j.jaridenv.2021.104696

Cited by 8 publications

(14 citation statements)

References 75 publications

(90 reference statements)

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“…Data from isotope profiles down to a depth of 100 cm were used to cover the entire root zone of groundnut (at Site 1) and pasture (at Site 2). It is essential to consider the whole root zone because δ t was weighted with the root‐length density (see Equation ) For groundnut crops, 72.4% of the root system was within the 0–20 cm soil layer depth, while 27.6% was found at 20–50 cm depth (Siegwart et al, 2022). Root‐length density in the pasture at Site 2 was assumed to decrease linearly from its maximum value at the soil surface down to its minimum at the maximum root length (around 40 cm, according to Glendening (1941)).…”

Section: Methodsmentioning

confidence: 99%

“…For groundnut crops, 72.4% of the root system was within the 0-20 cm soil layer depth, while 27.6% was found at 20-50 cm depth (Siegwart et al, 2022). Root-length density in the pasture at Site 2 was assumed to decrease linearly from its maximum value at the soil surface down to its minimum at the maximum root length (around 40 cm, according to Glendening (1941)).…”

Section: Evapotranspiration Partitioningmentioning

confidence: 99%

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Estimating water fluxes in the critical zone using water stable isotope approaches in the Groundnut and Ferlo basins of Senegal

Diongue

Stumpp

Roupsard

et al. 2023

Hydrological Processes

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Sustainable water management in semi-arid agriculture practices requires quantitative knowledge of water fluxes within the soil-vegetation-atmosphere system. Therefore, we used stable-isotope approaches to evaluate evaporation (E a ), transpiration (T a ), and groundwater recharge (R) at sites in Senegal's Groundnut basin and Ferlo Valley pasture region during the pre-monsoon, monsoon, and post-monsoon seasons of 2021. The approaches were based upon (i) the isothermal evaporation model (for quantifying E a ); (ii) water and isotope mass balances (to partition E a and T a for groundnut and pasture); and (iii) the piston displacement method (for estimating R). E a losses derived from the isothermal evaporation model corresponded primarily to Stage II evaporation, and ranged from 0.02 to 0.09 mm d À1 in the Groundnut basin, versus 0.02-0.11 mm d À1 in Ferlo. At the groundnut site, E a rates ranged from 0.01 to 0.69 mm d À1 ; T a was in the range 0.55-2.29 mm d À1 ; and the T a /ET a ratio was 74%-90%. At the pasture site, the ranges were 0.02-0.39 mm d À1 for E a ; 0.9-1.69 mm d À1 for T a ; and 62-90% for T a /ET a . The ET a value derived for the groundnut site via the isotope approach was similar to those from eddy covariance measurements, and also to the results from the previous validated HYDRUS-1D model. However, the HYDRUS-1D model gave a lower T a /ET a ratio (23.2%). The computed groundwater recharge for the groundnut site amounted to less than 2% of the local annual precipitation. Recommendations are made regarding protocols for preventing changes to isotopic compositions of water in samples that are collected in remote arid regions, but must be analysed days later. The article ends with suggestions for studies to follow up on evidence that local aquifers are being recharged via preferential pathways.

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Section: Methodsmentioning

confidence: 99%

Section: Evapotranspiration Partitioningmentioning

confidence: 99%

Estimating water fluxes in the critical zone using water stable isotope approaches in the Groundnut and Ferlo basins of Senegal

Diongue

Stumpp

Roupsard

et al. 2023

Hydrological Processes

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“…Faidherbia-Flux). It is located in the natural agro-silvo-pastoral parkland of Sob (14•29 0 45N, 16•27 0 13W), 135 km East of Dakar, West Senegal [21]. It is classified as an Arenosol [19] with very low level of C and P. All soil samples were collected from three pseudo replicates then mixed and immediately homogenized, sieved through a 2-mm diameter mesh, and stored at 4 ºC until analysis.…”

Section: Soil Samplingmentioning

confidence: 99%

Improved rock phosphate dissolution from organic acids is driven by nitrate assimilation of bacteria isolated from nitrate and CaCO3-rich soil

et al. 2023

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Until now, the solubilization capacities of insoluble mineral P by soil microorganisms have been screened in vitro with media containing NH4+ as a nitrogen source. This presence of NH4+ will lead to an acidification of the medium responsible for the solubilization of the insoluble P. However, besides proton release, the production of organic acids can play a very important role in the release of free P. This physiological mechanism can largely depend on the source of nitrogen (NH4+vs NO3-) assimilated by the bacteria but the influence of the N source on the production of organic acids has yet to be studied. Our aim was to investigate if the N source assimilated by bacteria and the soil characteristics such as the dominant N source (NH4+vs NO3-) and CaCO3 contents might influence the bacterial capacities to solubilize rock phosphate. To fill this objective, we screened the capacity of bacteria isolated from 3 soils to solubilize rock phosphate in vitro in presence of NH4+or NO3-. Then, we selected the most efficient bacterial strains to identify and quantify the release of organic anions into the medium. Among the two hundred and forty-three bacterial strains isolated from the 3 soils, nine and seven isolates were identified with the highest % rock phosphate-solubilization values with NH4+ or NO3- as the sole N-source. Only one strain was able to release free Pi with NH4+ or NO3- as the sole N-source. The most predominant organic acids released by almost all isolates were gluconic acid, lactic acid, glycolic acid, acetic acid, formic acid and pyruvic acid regardless the N-source. However, with NO3- as source of N, the highest concentrations on those acids were found together with the highest release of free Pi into the medium. Molecular analysis of 16S rRNA indicated that almost all strains belonged to Bacillus and Paenibacillus genera. The PCA analysis between soil properties and bacterial capacities to release organic acids and free Pi also revealed that soil factors such as CaCO3 and soil NO3- content positively influenced the release of organic acids by bacteria grown in vitro. Our results concluded that the bacterial rock phosphate-solubilization was intimately related to organic acids production which in turn seemed to be driven by the assimilation of NO3- by bacteria. Therefore, the N-source might be considered a key factor to take into consideration during the screening and selection of suitable strains involved in the P-solubilization.

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“…Spoil heaps strongly disturb the original environment and restructure soils ( Ahirwal and Maiti, 2018 ). Relevant studies have shown that when a soil layer is disturbed, the CO 2 stored in soil pores is released into the atmosphere, which further exacerbates climate change ( Zhang et al., 2019 ; Siegwart et al., 2022 ). Soil organic carbon is segregated into active organic carbon, slow organic carbon, and recalcitrant organic carbon fractions based on the turnover rate of soil carbon, among which active organic carbon includes particulate organic carbon (POC), easily oxidized organic carbon (EOC), microbial biomass carbon (MBC), light fraction organic carbon (LFOC) and soluble organic carbon (DOC) ( Liu et al., 2021 ).…”

Section: Introductionmentioning

confidence: 99%

Characteristics and factors influencing soil organic carbon composition by vegetation type in spoil heaps

Yao,

Dai,

Gao

et al. 2023

Front. Plant Sci.

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IntroductionThe variation of organic carbon content in spoil heaps is closely related to improving soil structure, maintaining soil fertility, and regulating soil carbon cycling balance. Analyzing the soil organic carbon content and related driving factors during the natural vegetation restoration process of spoil heaps is of great significance for promoting the accumulation of soil organic carbon in the spoil heaps.Methodswe selected spoil heaps with the same number of years of restoration to research the variations in soil organic carbon components under different vegetation types (grassland: GL, shrubland: SL, secondary forest: SF) and compared the results with those on bare land (BL).ResultsOur results showed that vegetation type and soil depth significantly affect the content of soil organic carbon components. There was no difference in soil organic carbon components between SF and SL, but both were considerably superior to GL and BL (p<0.05), and the particulate organic carbon (POC) and light fraction organic carbon (LFOC) contents of SL were the highest. A significant positive linear correlation existed between SOC and active organic carbon components. Pearson’s correlation and redundancy analysis showed that the available potassium (AK) and total nitrogen (TN) contents and gravel content (GC) in the BL soil significantly impacted soil organic carbon. When vegetation is present, TN, total phosphorus (TP), and Fine root biomass (FRB) significantly affect soil organic carbon. Structural equation modelling (SEM) shows that AK and soil moisture content (SMC) directly affect the organic carbon composition content of BL, When there is vegetation cover, fine root biomass (FRB) had the largest total effect in the SEM. Soil bulk density (BD) has a negative impact on soil organic carbon, especially in the presence of vegetation.ConclusionThese findings suggest that vegetation restoration can significantly increase soil organic carbon content, FRB, AK, and TN play important roles in enhancing soil organic carbon. Supplementation with nitrogen and potassium should be considered in the bare land stage, and shrubs nitrogen-fixing functions and well-developed roots are more beneficial for the accumulation of soil organic carbon.

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Root litter decomposition in a sub-Sahelian agroforestry parkland dominated by Faidherbia albida

Cited by 8 publications

References 75 publications

Estimating water fluxes in the critical zone using water stable isotope approaches in the Groundnut and Ferlo basins of Senegal

Estimating water fluxes in the critical zone using water stable isotope approaches in the Groundnut and Ferlo basins of Senegal

Improved rock phosphate dissolution from organic acids is driven by nitrate assimilation of bacteria isolated from nitrate and CaCO3-rich soil

Characteristics and factors influencing soil organic carbon composition by vegetation type in spoil heaps

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