scholarly journals Seasonal drought in Mediterranean soils mainly changes microbial C and N contents whereas chronic drought mainly impairs the capacity of microbes to retain P

2022 ◽  
Vol 165 ◽  
pp. 108515
Author(s):  
S. Marañón-Jiménez ◽  
D. Asensio ◽  
J. Sardans ◽  
P. Zuccarini ◽  
R. Ogaya ◽  
...  
Keyword(s):  
Seasonal Drought ◽  
C And N ◽  
Microbial C ◽  
Mediterranean Soils

scholarly journals Perennial herbaceous legumes as live soil mulches and their effects on C, N and P of the microbial biomass

2003 ◽  
Vol 60 (1) ◽  
pp. 139-147 ◽  
Author(s):  
Gustavo Pereira Duda ◽  
José Guilherme Marinho Guerra ◽  
Marcela Teixeira Monteiro ◽  
Helvécio De-Polli ◽  
Marcelo Grandi Teixeira
Keyword(s):  
Microbial Biomass ◽  
Soil Depth ◽  
Vegetation Management ◽  
Pueraria Phaseoloides ◽  
Organic C ◽  
Arachis Pintoi ◽  
Factorial Combination ◽  
C And N ◽  
Microbial C ◽  
Macroptilium Atropurpureum

The use of living mulch with legumes is increasing but the impact of this management technique on the soil microbial pool is not well known. In this work, the effect of different live mulches was evaluated in relation to the C, N and P pools of the microbial biomass, in a Typic Alfisol of Seropédica, RJ, Brazil. The field experiment was divided in two parts: the first, consisted of treatments set in a 2 x 2 x 4 factorial combination of the following factors: live mulch species (Arachis pintoi and Macroptilium atropurpureum), vegetation management after cutting (leaving residue as a mulch or residue remotion from the plots) and four soil depths. The second part had treatments set in a 4 x 2 x 2 factorial combination of the following factors: absence of live mulch, A. pintoi, Pueraria phaseoloides, and M. atropurpureum, P levels (0 and 88 kg ha-1) and vegetation management after cutting. Variation of microbial C was not observed in relation to soil depth. However, the amount of microbial P and N, water soluble C, available C, and mineralizable C decreased with soil depth. Among the tested legumes, Arachis pintoi promoted an increase of microbial C and available C content of the soil, when compared to the other legume species (Pueraria phaseoloides and Macroptilium atropurpureum). Keeping the shoot as a mulch promoted an increase on soil content of microbial C and N, total organic C and N, and organic C fractions, indicating the importance of this practice to improve soil fertility.

Release of ninhydrin-reactive compounds during fumigation of soil to estimate microbial C and N

1993 ◽  
Vol 25 (12) ◽  
pp. 1803-1805 ◽  
Author(s):  
G.P. Sparlig ◽  
V.V.S.R. Gupta ◽  
Chunya Zhu
Keyword(s):  
C And N ◽  
Microbial C

Changes in extractable and microbial C, N, and P in a Western Australian wheatbelt soil following simulated summer rainfall

Soil Research ◽  
1998 ◽  
Vol 36 (5) ◽  
pp. 841 ◽  
Author(s):  
A. M. McNeill ◽  
G. P. Sparling ◽  
D. V. Murphy ◽  
P. Braunberger ◽  
I. R. P. Fillery
Keyword(s):  
Organic N ◽  
Land Uses ◽  
Simulated Rainfall ◽  
Soil Extracts ◽  
Rainfall Events ◽  
Olsen P ◽  
Significant Difference ◽  
C And N ◽  
Microbial C ◽  
Western Australian

The effects of simulated rainfall events during the summer fallow period on extractable and microbial carbon (C), nitrogen (N), and phosphorus (P) in soils under either continuous wheat or the second-year pasture phase of a 2-pasture-1-wheat rotation in the Western Australian wheatbelt were investigated. A ‘single wetting’ treatment (45 mm rainfall on Day 0) was compared with a 55 mm ‘multiple wetting’ treatment (45 mm at Day 0, 5 mm at Day 3, and 5 mm at Day 8). Soil samples from 0{10 cm depth were taken prior to, and at regular intervals up to 14 days following, the inital wetting event. Soil extracts were assayed for total soluble N (TSN), total oxidisable C (TOC), Olsen-P, and ninhydrin-positive compounds (NPC). Prior to the simulated rainfall events, extractable TSN and TOC in the air-dry fallow soils were significantly higher (P < 0·01), and Olsen-P significantly lower, for the pasture land use compared with the continuous wheat. However, subsequent to wetting there were no significant differences between the 2 land uses, or single and multiple wetting treatments, for extractable TSN, TOC, Olsen P, or NPC. Extractable soluble organic N (SON), calculated by subtracting measured inorganic N from TSN, decreased within 48 h of each wetting event to a minimal value but, after the first 2 wetting events, subsequently increased to at least the prewet value. Microbial C, N, and P were estimated from the difference in TOC, TSN, and Olsen-P of extracts from fumigated and unfumigated soils (microbial ‘flush’) and microbial C and N were also estimated from the NPC ‘flush’. There was generally good agreement between the 2 estimates of microbial N (NPC and TSN, R2 = 0·50), but less so for the 2 estimates of microbial C (NPC and TOC, R2 = 0 ·31). There was no significant difference in microbial C, N, or P between the 2 land uses, but there was a highly significant response of the microbial biomass to wetting events and also significant differences in temporal patterns between the single and multiple wetting treatments. Microbial C and N increased in the period following initial wetting, more rapidly in the wheat than the pasture, reaching a peak at Day 2 for wheat and Day 3 for pasture. Subsequently, for the single wet treatment, there was a steady linear decline in microbial C and N until Day 10, whereas over the same period (Days 4-10) in the multiple wet treatment there were 2 highly significant quadratic responses to time, manifest as a linear increase in microbial C and N following each re-wetting event, to a peak value 24 h after the event, and a subsequent decline to the pre-wet value after a further 24 h.

scholarly journals Preferential protein depolymerization as a preservation mechanism for vascular litter decomposing in <i>Sphagnum</i> peat

2019 ◽  
Author(s):  
Hendrik Reuter ◽  
Julia Gensel ◽  
Marcus Elvert ◽  
Dominik Zak
Keyword(s):  
Protein Content ◽  
Litter Breakdown ◽  
N Dynamics ◽  
N Content ◽  
Sphagnum Peat ◽  
Elemental Analyses ◽  
Microbial Carbon ◽  
C And N ◽  
Microbial C ◽  
Microbial N

Abstract. Nitrogen (N) dynamics in Phragmites australis litter due to anaerobic decomposition in three anoxic wetland substrates were analyzed by elemental analyses and infrared spectroscopy (FTIR). After 75 days of decomposition, a relative accumulation of bulk N was detected in most litters, but N accumulated less when decomposition took place in a more N-poor environment. FTIR was used to quantify the relative content of proteins in litter tissue and revealed a highly linear relationship between bulk N content and protein content. Changes in bulk N content thus paralleled and probably were governed by changes in litter protein content. Such changes are the result of two competing processes within decomposing litter: enzymatic protein depolymerization as a part of the litter breakdown process and microbial protein synthesis as a part of microbial biomass growth within the litter. Assuming microbial homeostasis, DNA signals in FTIR spectra were used to calculate the amount of microbial N in decomposed litter which ranged from 14 to 42 % of the total litter N for all leaf samples. Microbial carbon (C) content and resultant calculated carbon-use efficiencies (CUEs) indicate that microbial N in litter accumulated according to predictions of the stoichiometric decomposition theory. Subtracting microbial C- and N-contributions from litter, however, revealed decomposition site dependent variations in the percentual amount of remaining, still unprocessed plant N compared to remaining plant C, an indicator for preferential protein depolymerization. For all leaf litters, the coefficient of preferential protein depolymerization (α), which relates N-compound depolymerization to C-compound depolymerization, ranged from 0.74–0.88 in a nutrient-rich detritus mud to 1.38–1.82 in Sphagnum peat, the most nutrient-poor substrate in this experiment. Preferential protein depolymerization leads to a gradual N depletion of decomposing litter which we propose as a preservation mechanism for vascular litter decomposing in Sphagnum peat.

Dynamics of microbial-C, N-flush and ATP, and enzyme activities of gradually dried soils from a climosequence

Soil Research ◽  
1988 ◽  
Vol 26 (3) ◽  
pp. 519 ◽  
Author(s):  
AW West ◽  
GP Sparling ◽  
TW Speir ◽  
JM Wood
Keyword(s):  
Annual Rainfall ◽  
Silt Loam ◽  
Strongly Correlated ◽  
Total Change ◽  
Moisture Regimes ◽  
Substrate Induced Respiration ◽  
C And N ◽  
Microbial C ◽  
Soil Phosphatase ◽  
Microbial N

Three silt loam soils from a climosequence (1000-2700 mm annual rainfall) were gradually dried from field moisture content to air-dryness at 25�C in the laboratory. Microbial C measured by substrate-induced respiration (SIR), fumigation-incubation (FI) or fumigation-extraction (FE), microbial N-flush measured by FI and FE, microbial ATP content and soil phosphatase and sulfatase activities were monitored throughout the drying period (approx. 60 h). All indices declined as the gravimetric soil water content (W) decreased until reaching air-dryness. Significant declines in the biomass sometimes occurred only following a large decrease in W, dependent on the soil. In general, when microbial C and N-flush declined, the rates of decline were linearly correlated with W. However, ATP and soil phosphatase were exponentially related to W. When expressed as a ratio of the total change in microbial indices against the total change in W for the whole drying period, the ratios were consistent between the soils. Agreement between the SIR and FE estimates of microbial C, whilst significant (r = 0 58***), was poor, especially for the low rainfall soil, although the FE C- and N-flushes correlated well (r = 0-76***). In contrast, the FI C- and N-flushes correlated very poorly (r = 0.30**) and were not significantly correlated with W or the other indices. ATP and soil phosphatase activity were strongly correlated (r = 0.89***). The reliability of the methods and the influence of soil moisture regimes on microbial survival are discussed.

The influence of roots on flushes of microbial C and N following fumigation-incubation of a pasture soil

1990 ◽  
Vol 22 (7) ◽  
pp. 1001-1002 ◽  
Author(s):  
F.A. Robertson ◽  
P.G. Saffigna ◽  
R.J.K. Myers
Keyword(s):  
Pasture Soil ◽  
C And N ◽  
Microbial C
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