Impact of microbial activity on the mobility of metallic elements (Fe, Al and Hg) in tropical soils

Geoderma ◽  
2019 ◽  
Vol 334 ◽  
pp. 146-154 ◽  
Author(s):  
C. Balland-Bolou-Bi ◽  
E.B. Bolou-Bi ◽  
V. Alphonse ◽  
S. Giusti-Miller ◽  
M.D. Jusselme ◽  
...  
Keyword(s):  
Microbial Activity ◽  
Tropical Soils ◽  
Metallic Elements

Investigating nutrient controls over microbial activity in tropical soils

2021 ◽  
Author(s):  
Lucia Fuchslueger
Keyword(s):  
Organic Matter ◽  
Microbial Biomass ◽  
Microbial Communities ◽  
Microbial Activity ◽  
Microbial Growth ◽  
Tropical Soils ◽  
Phosphorus Availability ◽  
Soil P ◽  
Soil Microbial ◽  
Low Phosphorus

<p>The Amazon rainforest is an important sink for atmospheric CO<sub>2</sub> counteracting increased emissions from anthropogenic fossil fuel combustion and land use change storing large amounts of carbon in plant biomass and soils. However, large parts of the Amazon Basin are characterized by highly weathered soils (ultisols and oxisols) with low availability of rock-derived phosphorus (and cations), which are mostly occluded in soil or bound in organic matter. Such low phosphorus availability is thought to be (co-)limiting plant productivity. However, much less is known whether low phosphorus availability influences the activity of heterotrophic microbial communities controlling litter and soil organic matter decomposition and thereby long-term carbon sequestration in tropical soils.</p><p>In tropical soils high temperature and humid conditions allow overall high microbial activity. Over a larger soil phosphorus fertility gradient across several Amazonian rainforest sites, at low P sites almost 40 % of total P was stored in microbial biomass, highlighting the competitive strength of microorganisms and their importance as P reservoir. Across all sites soil microbial biomass was a significant predictor for soil microbial respiration, but mass-specific respiration rates (normalized by microbial biomass C) rather decreased at higher soil P. Using the incorporation of <sup>18</sup>O from labelled water into DNA (i.e., a substrate-independent method) to determine microbial growth, we found significantly lower microbial growth rates per unit of microbial biomass at higher soil P. This resulted in a lower microbial carbon use efficiency, at a narrower C:P stoichiometry in soils with higher P levels, and pointed towards a microbial co-limitation of phosphorus and carbon at low soil P levels. Furthermore, data from a multi-year nutrient manipulation experiment in French Guiana and from short-term lab incubations suggest that microbial communities thriving at low P levels are highly efficient in taking up and storing added P, but do not necessarily respond with increased growth.</p><p>Soil microbial communities play a crucial role in soil carbon and phosphorus cycling in tropical soils as potent competitors for available P. They also play an important role in storing and buffering P losses from highly weathered tropical soils. The potential non-homoeostatic stoichiometric behavior of microbial communities in P cycling is important to consider in soil and ecosystem models based on stoichiometric relationships.</p>

scholarly journals Aerobic microbial activity in four tropical earthworm-soil systems. A mesocosm experiment

Soil Research ◽  
2014 ◽  
Vol 52 (6) ◽  
pp. 584 ◽  
Author(s):  
J. Sierra ◽  
G. Loranger-Merciris ◽  
L. Desfontaines ◽  
M. Boval
Keyword(s):  
Microbial Activity ◽  
Tropical Soils ◽  
Mesocosm Experiment ◽  
P Availability ◽  
N Mineralisation ◽  
Organic C ◽  
Aerobic Activity ◽  
Aerobic Processes ◽  
C Mineralisation ◽  
Earthworm Activity

Soil organic matter (SOM) quality and carbon (C) availability may be major features influencing the effect of earthworms on the aerobic processes in clayey tropical soils. In this study, we assessed the effect of an anecic (Polypheretima elongata), an endogeic (Pontoscolex corethrurus) and an epigeic (Eudrilus eugeniae) earthworm on the aerobic microbial activity of two tropical soils, a calcic Vertisol and an acid Ferralsol, with clay content >70% and very different organic C content and SOM stability. The soil–earthworm interaction was studied in a 6-month mesocosm experiment in a greenhouse using soils with and without (control soil) earthworm addition. Potential C mineralisation, actual net nitrogen (N) mineralisation and dehydrogenase activity (DHA), as indicators of the aerobic activity of the soils, and phosphorus (P) availability were determined during the trial. DHA was used as an indicator of the global aerobic activity. Earthworms had little effect on potential C mineralisation but significantly increased actual net N mineralisation. The increase in N mineralisation in the Vertisol was twice as great as, and longer (6 v. 3 months) than for the Ferralsol. Differences between soils for N mineralisation were associated with a less recalcitrant SOM in the Vertisol. Available P increased 10% in the earthworm treatments. Earthworm activity improved N and P availability. DHA was 15 times higher for the Vertisol than for the Ferralsol, but the positive effect of earthworms on DHA was greater for the Ferralsol. This effect was greater for E. eugeniae, probably because of surface burrows generated by this epigeic earthworm, which favoured oxygen entry into the soil. Differences between the two soils were greater for DHA than for C and N mineralisation, and this was observed for the control soils as well as for the earthworm treatments. This indicates that earthworm activity modified the rate of the aerobic processes but it did not affect the intrinsic biological properties of these tropical soils, which were controlled mainly by SOM quality and C availability.

Compressive response of some agricultural soils influenced by the mineralogy and moisture

2013 ◽  
Vol 27 (3) ◽  
pp. 239-246 ◽  
Author(s):  
A.E. Ajayi ◽  
M.S. Dias Junior ◽  
N. Curi ◽  
I. Oladipo
Keyword(s):  
Agricultural Soils ◽  
Tropical Soils ◽  
Homogeneity Test ◽  
Confined Compression ◽  
Moisture Retention ◽  
Soil Mineralogy ◽  
Undisturbed Soil ◽  
Statistical Homogeneity ◽  
Compressive Response ◽  
Fine Clay

Abstract This study aimed to investigate the mineralogy, moisture retention, and the compressive response of two agricultural soils from South West Nigeria. Undisturbed soil cores at the A and B horizons were collected and used in chemical and hydrophysical characterization and confined compression test. X-ray diffractograms of oriented fine clay fractions were also obtained. Our results indicate the prevalence of kaolinite minerals relating to the weathering process in these tropical soils. Moisture retention by the core samples was typically low with pre-compression stress values ranging from50 to 300 kPa at both sites. Analyses of the shape of the compression curves highlight the influence of soil moisture in shifts from the bi-linear to S-shaped models. Statistical homogeneity test of the load bearing capacity parameters showed that the soil mineralogy influences the response to loading by these soils. These observations provide a physical basis for the previous classification series of the soils in the studied area. We showed that the internal strength attributes of the soil could be inferred from the mineralogical properties and stress history. This could assist in decisions on sustainable mechanization in a datapoor environment.

Effects of Meat Meal on Steer Performance and Rumen Microbial Activity

1958 ◽  
Vol 17 (2) ◽  
pp. 391-397 ◽  
Author(s):  
I. A. Dyer ◽  
D. W. Fletcher
Keyword(s):  
Microbial Activity ◽  
Meat Meal

Effect of Sodium Bicarbonate on Microbial Activity in the Rumen

1963 ◽  
Vol 22 (2) ◽  
pp. 335-340 ◽  
Author(s):  
J. W. Lassiter ◽  
M. K. Hamdy ◽  
Prasob Buranamanas
Keyword(s):  
Sodium Bicarbonate ◽  
Microbial Activity
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