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1.
Identifying the impact of plant material inputs on soil amino sugar synthesis may advance our knowledge of microbial transformation
processes in soils. In a 12-week laboratory microcosm incubation, 1, 2, 4, and 6% (w/w) soybean leaf or maize stalk were initially
added to soil, respectively, whereas soil without plant addition was used as a control. The results showed that adding organic
materials to the soil led to a net accumulation of amino sugars, because of greater microbial synthesis. The ratios of glucosamine
to galactosamine and of glucosamine to muramic acid, two indicators differentiating the relative contribution to soil organic
matter of fungi and bacteria, showed substantial variance across the gradient of substrate addition. Our results suggest that
the amount of nutrients in a given substrate is the primary attribute determining microbial net accumulation of soil amino
sugars, especially in the relatively short term, whereas the composition of nutrients might be more important in the relatively
long term when nutrients are not sufficient. The use of the two ratios (glucosamine to galactosamine and glucosamine to muramic
acid) reflects different dynamics of galactosamine and muramic acid during the decomposition of organic substrates in soils.
Muramic acid, compared with galactosamine, is more likely to accumulate in the soil active organic fraction under abundant
nutrient conditions, whereas it would be decomposed along with active organic matter when the nutrients are scarce and remain
in minor quantities in the clay fraction without being attacked by microbes. 相似文献
2.
Dynamics of soil amino sugar pools during decomposition processes of corn residues as affected by inorganic N addition 总被引:1,自引:0,他引:1
Purpose
Identifying the impact of inorganic-nitrogen (N) availability on soil amino sugar dynamics during corn (Zea mays L.) residue decomposition may advance our knowledge of microbial carbon (C) and N transformations and the factors controlling these processes in soils. Amino sugars are routinely used as microbial biomarkers to investigate C and N sequestration in microbial residues, and they are also involved in microbial-mediated soil organic matter (SOM) turnover. We conducted a 38-week incubation study using a Mollisol which was amended with corn residues and four levels of inorganic N (i.e., 0, 60.3, 167.2, and 701.9 mg N kg−1 soil). The objective of this study was to examine the effects of inorganic-N availability on fungal and bacterial formation and stabilization of heterogeneous amino sugars during the corn residue decomposition in soil. 相似文献3.
《Soil biology & biochemistry》2004,36(3):399-407
Characterizing functional and phylogenetic microbial community structure in soil is important for understanding the fate of microbially-derived compounds during the decomposition and turn-over of soil organic matter. This study was conducted to test whether amino sugars and muramic acid are suitable biomarkers to trace bacterial, fungal, and actinomycetal residues in soil. For this aim, we investigated the pattern, amounts, and dynamics of three amino sugars (glucosamine, mannosamine and galactosamine) and muramic acid in the total microbial biomass and selectively cultivated bacteria, fungi, and actinomycetes of five different soils amended with and without glucose. Our results revealed that total amino sugar and muramic acid concentrations in microbial biomass, extracted from soil after chloroform fumigation varied between 1 and 27 mg kg−1 soil. In all soils investigated, glucose addition resulted in a 50-360% increase of these values. In reference to soil microbial biomass-C, the total amino sugar- and muramic acid-C concentrations ranged from 1-71 g C kg−1 biomass-C. After an initial lag phase, the cultivated microbes revealed similar amino sugar concentrations of about 35, 27 and 17 g glucosamine-C kg−1 TOC in bacteria, fungi, and actinomycetes, respectively. Mannosamine and galactosamine concentrations were lower than those for glucosamine. Mannosamine was not found in actinomycete cultures. The highest muramic acid concentrations were found in bacteria, but small amounts were also found in actinomycete cultures. The concentrations of the three amino sugars studied and muramic acid differed significantly between bacteria and the other phylogenetic microbial groups under investigation (fungi and actinomycetes). Comparison between the amino sugar and muramic acid concentrations in soil microbial biomass, extracted after chloroform fumigation, and total concentrations in the soil showed that living microbial biomass contributed negligible amounts to total amino sugar contents in the soil, being at least two orders of magnitude greater in the soils than in the soil inherent microbial biomass. Thus, amino sugars are significantly stabilized in soil. 相似文献
4.
Land use effects on amino sugar signature of chromic Luvisol in the semi-arid part of northern Tanzania 总被引:3,自引:0,他引:3
Characterizing amino sugar signature in particle size separates of tropical soils is important for further understanding
the fate of microbial-derived compounds during the decomposition of soil organic matter (SOM) in tropical agroecosystems.
We investigated the impact of land-use changes on the nature, amount and dynamics of amino sugars in soil of the semi-arid
northern Tanzania. Samples were collected from the uppermost 10 cm of native woodland, degraded woodland, fields cultivated
for 3 and 15 years and homestead fields fertilized with animal manure. The amount of glucosamine, galactosamine, mannosamine
and muramic acid were determined in bulk soil and size separates. Compared to the native woodland, a 68% and 72% reduction
in total amino sugar contents were found in the 3- and 15-year cultivated fields, respectively. Moreover, 39% of the total
amino sugar was lost from the degraded woodland. This may be attributed to accelerated decomposition of amino sugars and/or
decreasing microbial biomass input under the semi-arid environment following clear-cutting and cultivation. In contrast, only
a 20% decline was found from the fields where animal manure had been applied. Most of the amino sugar depletion occurred from
the coarse and fine sand-associated SOM. The decline from the silt and clay-bound amino sugar was relatively small, indicating
the importance of organo-mineral associations in the stabilization of microbial-derived sugars in this tropical soil. After
15 years of continuous cultivation, the ratio of glucosamine:galactosamine increased from 1.44 to 2.23, while the ratio of
glucosamine:muramic acid increased from 14.5 to 26.5 (P<0.05). These results suggest that cultivation may have led to preferential depletion of bacterial-derived amino sugars (muramic
acid and galactosamine) compared with fungal-derived glucosamine.
Received: 22 June 2000 相似文献
5.
Organic matter, microbial biomass and enzyme activity of soils under different crop rotations in the tropics 总被引:8,自引:0,他引:8
Soil organic matter level, soil microbial biomass C, ninhydrin-N, C mineralization, and dehydrogenase and alkaline phosphatase
activity were studied in soils under different crop rotations for 6 years. Inclusion of a green manure crop of Sesbania aculeata in the rotation improved soil organic matter status and led to an increase in soil microbial biomass, soil enzyme activity
and soil respiratory activity. Microbial biomass C increased from 192 mg kg–1 soil in a pearl millet-wheat-fallow rotation to 256 mg kg–1 soil in a pearl millet-wheat-green manure rotation. Inclusion of an oilseed crop such as sunflower or mustard led to a decrease
in soil microbial biomass, C mineralization and soil enzyme activity. There was a good correlation between microbial biomass
C, ninhydrin-N and dehydrogenase activity. The alkaline phosphatase activity of the soil under different crop rotations was
little affected. The results indicate the green manuring improved the organic matter status of the soil and soil microbial
activity vital for the nutrient turnover and long-term productivity of the soil.
Received: 7 January 1996 相似文献
6.
Transformations and recovery of residue and fertilizer nitrogen-15 in a sandy Lixisol of West Africa
The fate of 15N-labeled plant residues from different cover-cropping systems and labeled inorganic N fertilizer in the organic, soil mineral,
microbial biomass and soil organic matter (SOM) particle-size fractions was investigated in a sandy Lixisol. Plant residues
were from mucuna (legume), lablab (legume), imperata (grass), maize (cereal) and mixtures of mucuna or lablab with imperata
or maize, applied as a surface mulch. Inorganic N fertilizer was applied as 15N-(NH4)2SO4 at two rates (21 and 42 mg N kg–1 soil). Total N release from mucuna or lablab residues was 2–3 times higher than from the other residues, whereas imperata
immobilized N throughout the study period. In contrast, 15N was mineralized from all the plant residues irrespective of the mineralization–immobilization pattern observed for total
N. After 168 days, 69% of soil mineral N in mucuna- or lablab-mulched soils was derived from the added residues, representing
4–8% of residue N, whereas 9–30% of inorganic N was derived from imperata, maize and the mixed residues. At the end of the
study, 4–19% of microbial biomass N was derived from the added residue/fertilizer-N, accounting for 1–3% of added residue-N.
Averaged across treatments, particulate SOM fractions accounted for less than 1% of the total soil by weight but contained
20% of total soil C and 8% of soil N. Soils amended with mucuna or lablab incorporated more N in the 250–2000 μm SOM pool,
whereas soil amended with imperata or the mixed residues incorporated similar proportions of labeled N in the 250–2000 μm
and 53–250 μm fractions. In contrast, in soils receiving the maize or inorganic fertilizer-N treatments, higher proportions
of labeled N were incorporated into the 53–250 μm than the 250–2000 μm fractions. The relationship between these differences
in residue/fertilizer-N partitioning into different SOM particle-size fractions and soil productivity is discussed.
Received: 12 March 1999 相似文献
7.
Effects of increasing periods under intensive arable vegetable production on biological, chemical and physical indices of soil quality 总被引:6,自引:0,他引:6
The effects on soil condition of increasing periods under intensive cultivation for vegetable production on a Typic Haplohumult
were compared with those of pastoral management using soil biological, physical and chemical indices of soil quality. The
majority of the soils studied had reasonably high pH, exchangeable cation and extractable P levels reflecting the high fertilizer
rates applied to dairy pasture and more particularly vegetable-producing soils. Soil organic C (Corg) content under long-term pasture (>60 years) was in the range of 55 g C kg–1 to 65 g C kg–1. With increasing periods under vegetable production soil organic matter declined until a new equilibrium level was attained
at about 15–20 g C kg–1 after 60–80 years. The loss of soil organic matter resulted in a linear decline in microbial biomass C (Cmic) and basal respiratory rate. The microbial quotient (Cmic/Corg) decreased from 2.3% to 1.1% as soil organic matter content declined from 65 g C kg–1 to 15 g C kg–1 but the microbial metabolic quotient (basal respiration/Cmic ratio) remained unaffected. With decreasing soil organic matter content, the decline in arginine ammonification rate, fluorescein
diacetate hydrolytic activity, earthworm numbers, soil aggregate stability and total clod porosity was curvilinear and little
affected until soil organic C content fell below about 45 g C kg–1. Soils with an organic C content above 45 g C kg–1 had been under pasture for at least 30 years. At the same Corg content, soil biological activity and soil physical conditions were markedly improved when soils were under grass rather
than vegetables. It was concluded that for soils under continuous vegetable production, practices that add organic residues
to the soil should be promoted and that extending routine soil testing procedures to include key physical and biological properties
will be an important future step in promoting sustainable management practices in the area.
Received: 18 November 1997 相似文献
8.
Effects of long-term waste water irrigation on soil organic matter, soil microbial biomass and its activities in central Mexico 总被引:4,自引:0,他引:4
The effect of long-term waste water irrigation (up to 80 years) on soil organic matter, soil microbial biomass and its activities
was studied in two agricultural soils (Vertisols and Leptosols) irrigated for 25, 65 and 80 years respectively at Irrigation
District 03 in the Valley of Mezquital near Mexico City. In the Vertisols, where larger amounts of water have been applied
than in the Leptosols, total organic C (TOC) contents increased 2.5-fold after 80 years of irrigation. In the Leptosols, however,
the degradability of the organic matter tended to increase with irrigation time. It appears that soil organic matter accumulation
was not due to pollutants nor did microbial biomass:TOC ratios and qCO2 values indicate a pollutant effect. Increases in soil microbial biomass C and activities were presumably due to the larger
application of organic matter. However, changes in soil microbial communities occurred, as denitrification capacities increased
greatly and adenylate energy charge (AEC) ratios were reduced after long-term irrigation. These changes were supposed to be
due to the addition of surfactants, especially alkylbenzene sulfonates (effect on denitrification capacity) and the addition
of sodium and salts (effect on AEC) through waste water irrigation. Heavy metals contained in the sewage do not appear to
be affecting soil processes yet, due to their low availability. Detrimental effects on soil microbial communities can be expected,
however, from further increases in pollutant concentrations due to prolonged application of untreated waste water or an increase
in mobility due to higher mineralization rates.
Received: 28 April 1999 相似文献
9.
M. A. Sánchez-Monedero C. Mondini M. L. Cayuela A. Roig M. Contin M. De Nobili 《Biology and Fertility of Soils》2008,44(6):885-890
The hydrolysis of the fluorescein diacetate (FDA), related to several soil hydrolases, has been utilised to estimate the potential
microbial activity of soil freshly amended with a wide range of organic amendments and compared to the size and activity of
soil microflora, measured by the microbial biomass C (B
C) and CO2 evolution, respectively. Three different composting mixtures at different phases of the composting process were added to
a semi-arid soil and incubated for 2 months under laboratory conditions. The addition of the organic amendment immediately
increased B
C and both measures of microbial activity (FDA and CO2 evolution). Highly significant correlations were found between FDA hydrolysis and B
C for soil amended with the three composting mixtures (r = 0.81–0.96; P < 0.01), regardless of the origin, composition and degree of stability of the organic amendments. FDA hydrolysis, conversely
to CO2 evolution, was unaffected by the disturbance caused by the soil amendment, indicating that the two parameters probably reflect
different aspects of soil microbial activity. FDA hydrolysis could serve as an alternative estimation of the microbial biomass
in freshly amended soils, despite the disturbance caused by the exogenous organic matter. 相似文献
10.
This study examines the effects of atrazine on both microbial biomass C and C mineralization dynamics in two contrasting agricultural
soils (organic C, texture, and atrazine application history) located at Galicia (NW Spain). Atrazine was added to soils, a
Humic Cambisol (H) and a Gleyic Cambisol (G), at a recommended agronomic dose and C mineralization (CO2 evolved), and microbial biomass measurements were made in non-treated and atrazine-treated samples at different time intervals
during a 12-week aerobic incubation. The cumulative curves of CO2–C evolved over time fit the simple first-order kinetic model [Ct = Co (1 − e
−kt
)], whose kinetic parameters were quantified. Differences in these parameters were observed between the two soils studied;
the G soil, with a higher content in organic matter and microbial biomass C and lower atrazine application history, exhibited
higher values of the total C mineralization and the potentially mineralizable labile C pool than those for the H soil. The
addition of atrazine modified the kinetic parameters and increased notably the C mineralized; by the end of the incubation
the cumulative CO2–C values were 33–41% higher than those in the corresponding non-added soils. In contrast, a variable effect or even no effect
was observed on the soil microbial biomass following atrazine addition. The data clearly showed that atrazine application
at normal agricultural rates may have important implications in the C cycling of these two contrasting acid soils. 相似文献