scholarly journals Effects of long-term mowing on the fractions and chemical composition of soil organic matter in a semiarid grassland

2016 ◽  
Author(s):  
Jiang-Ye Li ◽  
Qi-Chun Zhang ◽  
Yong Li ◽  
Hong-Jie Di
Keyword(s):  
Organic Matter ◽  
Chemical Composition ◽  
Soil Organic Matter ◽  
Functional Groups ◽  
Soil Microbial Activity ◽  
Net N Mineralization ◽  
Organic C ◽  
Semiarid Grassland ◽  
Soil Microbial ◽  
The Stability

Abstract. Grassland is the second largest carbon pool following forest. Intensive mowing is common to meet the need of increased livestock. However, little information on the quality and quantity of soil organic matter (SOM) under different mowing managements was documented. In this work, the fractions and chemical composition of SOM under different mowing managements were studied using traditional fractionation method and spectroscopy technology (13C-NMR and FTIR) based on a 13-year mowing trial with four treatments: control (CK, unmown), mowing once every second year (M1/2), mowing once a year (M1) and mowing twice a year (M2). The results showed that M1/2 and M1 significantly enhanced the SOM accumulation while M2 did not significantly impacted SOM content but it significantly limited the SOM humification and degradation. Substituted alkyl carbon (C) was the major organic C type as it made up over 40 % of the total C. M1/2 and M1 significantly increased stable C functional groups (alkyl C and aromatic C) by degrading labile C functional group (O-alkyl C) and forming calcium humic acid while M2 had opposite effects. The increase of NMR indices (HB/HI, Al/Ar, A/OA and CC/MC) in M1/2 and M1 further suggested that M1/2 and M1 increased the stability of SOM. Significant correlations between net N mineralization or MBC and C functional groups indicated that the shifts of SOM fractions and chemical composition were closely related to soil microbial activity. Meanwhile, M1 significantly increased soil MBC while M2 worked oppositely. Therefore, M1 are the most recommended mowing management while M2 should be avoided in the semiarid grassland.

scholarly journals Effects of long-term mowing on the fractions and chemical composition of soil organic matter in a semiarid grassland

2017 ◽  
Vol 14 (10) ◽  
pp. 2685-2696 ◽  
Author(s):  
Jiangye Li ◽  
Qichun Zhang ◽  
Yong Li ◽  
Yimeng Liu ◽  
Jianming Xu ◽  
...  
Keyword(s):  
Organic Matter ◽  
Chemical Composition ◽  
Soil Organic Matter ◽  
Microbial Biomass ◽  
Functional Groups ◽  
13C Nmr ◽  
Magic Angle ◽  
Grassland Ecosystem ◽  
Semiarid Grassland ◽  
The Stability

Abstract. The grassland ecosystem is a significantly important terrestrial carbon pool. Intensive mowing is common to meet the need of increased livestock. However, little information on the quality and quantity of soil organic matter (SOM) under different mowing managements has been documented. In this work, in order to evaluate the impacts of different mowing managements on the quality and quantity of SOM, the fractions and chemical composition of SOM under different mowing managements were determined using traditional fractionation methods and spectroscopy technologies, including advanced nuclear magnetic resonance (NMR) (e.g. cross-polarization magic angle spinning 13C-NMR, CPMAS 13C-NMR) and Fourier-transform infrared (FTIR) based on a 13-year field mowing trial with four treatments: unmown (M0), mowing once every second year (M1/2), mowing once a year (M1) and mowing twice a year (M2). The results showed that compared with M0, M1/2 and M1 significantly enhanced the SOM accumulation and increased the stability of SOM by enhancing humification, while M2 limited SOM accumulation and microbial biomass. Substituted alkyl carbon (C) was the major organic C type in the grassland ecosystem, and it made up over 40 % of the total C. M1/2 and M1 significantly increased stable C functional groups (alkyl C and aromatic C) by degrading labile C functional groups (O-alkyl and carbonyl C) and forming recalcitrant humus, while M2 had opposite effects. The consistent increase in the values of NMR indices reflecting the degradation degree, hydrophobicity and aromaticity of SOM in M1 reflected the fact that M1 had the largest contribution to increasing the stability of SOM, while these values in M2 were similar to those in M0. Significant correlations between different SOM fractions and nitrogen (N) mineralization, and between the contents of different C functional groups and net soil organic nitrogen mineralization or microbial biomass C, indicated that the shifts in SOM fractions and chemical composition were closely related to soil microbial biomass and activity. Therefore, in view of the quality and quantity of SOM and the sustainable development of grassland ecosystems, M1 was the optimal mowing management, while M2 should be avoided in the semiarid grassland.

scholarly journals Effect of compaction on microbial activity and carbon and nitrogen transformations in two oxisols with different mineralogy

2011 ◽  
Vol 35 (4) ◽  
pp. 1141-1149 ◽  
Author(s):  
Sérgio Ricardo Silva ◽  
Ivo Ribeiro da Silva ◽  
Nairam Félix de Barros ◽  
Eduardo de Sá Mendonça
Keyword(s):  
Organic Matter ◽  
Microbial Activity ◽  
Soil Compaction ◽  
N Mineralization ◽  
Organic N ◽  
Net N Mineralization ◽  
Mineral N ◽  
Organic C ◽  
Soil Microbial ◽  
Controlled Conditions

The use of machinery in agricultural and forest management activities frequently increases soil compaction, resulting in greater soil density and microporosity, which in turn reduces hydraulic conductivity and O2 and CO2 diffusion rates, among other negative effects. Thus, soil compaction has the potential to affect soil microbial activity and the processes involved in organic matter decomposition and nutrient cycling. This study was carried out under controlled conditions to evaluate the effect of soil compaction on microbial activity and carbon (C) and nitrogen (N) mineralization. Two Oxisols with different mineralogy were utilized: a clayey oxidic-gibbsitic Typic Acrustox and a clayey kaolinitic Xantic Haplustox (Latossolo Vermelho-Amarelo ácrico - LVA, and Latossolo Amarelo distrófico - LA, respectively, in the Brazil Soil Classification System). Eight treatments (compaction levels) were assessed for each soil type in a complete block design, with six repetitions. The experimental unit consisted of PVC rings (height 6 cm, internal diameter 4.55 cm, volume 97.6 cm³). The PVC rings were filled with enough soil mass to reach a final density of 1.05 and 1.10 kg dm-3, respectively, in the LVA and LA. Then the soil samples were wetted (0.20 kg kg-1 = 80 % of field capacity) and compacted by a hydraulic press at pressures of 0, 60, 120, 240, 360, 540, 720 and 900 kPa. After soil compression the new bulk density was calculated according to the new volume occupied by the soil. Subsequently each PVC ring was placed within a 1 L plastic pot which was then tightly closed. The soils were incubated under aerobic conditions for 35 days and the basal respiration rate (CO2-C production) was estimated in the last two weeks. After the incubation period, the following soil chemical and microbiological properties were detremined: soil microbial biomass C (C MIC), total soil organic C (TOC), total N, and mineral N (NH4+-N and NO3--N). After that, mineral N, organic N and the rate of net N mineralization was calculated. Soil compaction increased NH4+-N and net N mineralization in both, LVA and LA, and NO3--N in the LVA; diminished the rate of TOC loss in both soils and the concentration of NO3--N in the LA and CO2-C in the LVA. It also decreased the C MIC at higher compaction levels in the LA. Thus, soil compaction decreases the TOC turnover probably due to increased physical protection of soil organic matter and lower aerobic microbial activity. Therefore, it is possible to conclude that under controlled conditions, the oxidic-gibbsitic Oxisol (LVA) was more susceptible to the effects of high compaction than the kaolinitic (LA) as far as organic matter cycling is concerned; and compaction pressures above 540 kPa reduced the total and organic nitrogen in the kaolinitic soil (LA), which was attributed to gaseous N losses.

scholarly journals The Relationship between Winter Temperature Rise and Soil Fertility properties

2012 ◽  
Vol 5 ◽  
pp. ASWR.S8599 ◽  
Author(s):  
Xiao Guoju ◽  
Zhang Qiang ◽  
Bi Jiangtao ◽  
Zhang Fengju ◽  
Luo Chengke
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Microbial Activity ◽  
Soil Ph ◽  
Salt Content ◽  
Soil Microbial Activity ◽  
Winter Temperature ◽  
Available Phosphorus ◽  
Available Nitrogen ◽  
Soil Microbial

The effects of winter temperature rises on soil microbial activity, nutrient and salinity in Ningxia Plain were studied in a field experiment using an infrared radiator to raise temperatures. Winter temperature rises led to increases in soil organic matter, available phosphorus, soil pH and total salt content, but decreased the available nitrogen in soil and the activities of soil catalase, urease and phosphatase. With a winter temperature of 0.5 °C-2.0 °C, the activities of soil catalase, urease and phosphatase were respectively decreased by 0.08-1.20 mL g-1, 0.004-0.019 mg g-1, and 0.10-0.25 mg kg-1; soil organic matter was increased by 0.01-0.62 g kg-1, available nitrogen decreased by 2.45-4.66 g kg-1, available phosphorus increased by 2.92-5.74 g kg-1; soil pH increased by 0.42-0.67, and total salt increased by 0.39-0.50 g kg-1. Winter temperature rises decreased soil microbial activity, accelerated the decomposition of soil nutrients, and intensified soil salinization.

scholarly journals Erosion Induced Heterogeneity of Soil Organic Matter in Catenae from the Baltic Sea Catchment

Soil Systems ◽  
2019 ◽  
Vol 3 (2) ◽  
pp. 42 ◽  
Author(s):  
Gerald Jandl ◽  
Christel Baum ◽  
Goswin Heckrath ◽  
Mogens H. Greve ◽  
Arno Kanal ◽  
...  
Keyword(s):  
Organic Matter ◽  
Chemical Composition ◽  
Soil Organic Matter ◽  
Baltic Sea ◽  
The Baltic Sea ◽  
Microbial Decomposition ◽  
Organic C ◽  
C Stocks ◽  
Arable Fields ◽  
The Baltic

Soil organic matter (SOM) is unevenly distributed in arable fields in undulated landscapes, but the chemical composition resulting from their turnover, transport and deposition processes is insufficiently known. Therefore, we aimed at disclosing the molecular-chemical composition of SOM in four different catenae at shoulderslope, backslope and footslope positions in arable fields in the Baltic Sea catchment, Europe. The backslope positions always had the lowest organic C-contents (Corg) (1.6…11.8 g·kg−1) and C-stocks (3.8…8.5 kg·m−2) compared to the shoulderslopes and footslopes (1.7…17.7 g·Corg·kg−1, 5.4…15 kg·Corg·m−2). In the SOM-poor backslope positions, the organic matter was characterized by relatively high proportions of carbohydrates, phenols + lignin monomers, alkylaromatic compounds, N-compounds and amides, indicating intensive microbial decomposition. By contrast, the footslopes had the largest Corg-contents (9.3…16.5 g·kg−1) and C-stocks (8.9…15 kg·m−2) in the catenae and particular enrichments in lipids, lignin dimers, sterols and free fatty acids. These relatively stabile SOM compound classes are interpreted as leftovers from erosive downslope transport and concurrent microbial decomposition, e.g., they are pronounced at backslope positions, followed by restricted microbial decomposition. This heterogeneous SOM distribution calls for an adapted soil management that reduces erosion and places amendments to field areas, such as the shoulderslope and backslope.

How vegetation drives initial soil development together with soil organic matter accrual in maritime Antarctica

2020 ◽  
Author(s):  
Isabel Prater ◽  
Filip Hrbacek ◽  
Lars Arne Meier ◽  
Christina Braun ◽  
Daniel Nyvlt ◽  
...  
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Soil Microbial Activity ◽  
Soil Development ◽  
Cold Climate ◽  
South Shetland Islands ◽  
Maritime Antarctica ◽  
Soil Microbial ◽  
James Ross Island ◽  
Land Surfaces

<p>Antarctica with its unique conditions for soil development offers the opportunity to disclose basic soil biogeochemical processes in an environment with a low degree of ecosystem interactions. The region’s climate is divided by the mountain ridge of the Antarctic Peninsula: on the South Shetland Islands (King George Island (KGI)) in the west a maritime cold climate prevails, while James Ross Island (JRI) in the east faces the continental cold climate of a polar desert with less precipitation and distinctly more pronounced temperature variations throughout the year. In addition, the autochthonous vegetation differs; while it solely consists of cryptogams on JRI, on KGI two vascular plants (Dechampsia antarctica, Colobanthus quitensis) are endemic. This scarce vegetation patterns together with land surfaces ice-free for several millenia allows studying the complex interaction between soil organic matter (SOM) sequestration and soil structure development with respect to the varying presence and growth of vegetation.  </p><p>The main aim of our study is to decode the mechanisms determining the fate of SOM in maritime Antarctica and to understand how the scarce vegetation drives the chemical composition and distribution of SOM within specific physical SOM fractions. Therefore, we sampled transects ranging from vegetated patches to plant-free soil surfaces. The distance to these vegetation patches was reflected in clear variations in the distribution of carbon and nitrogen and in a decrease in labile SOM constituents as revealed by <sup>13</sup>C-CPMAS NMR spectroscopy, while clay-sized mineral-associated SOM dominated the carbon storage throughout all sites. The ongoing climate change is assumed to significantly alter the vegetation distribution and thus drive the storage and composition of SOM. In the future, this will also strongly affect soil microbial activity and land-ocean transitions in Antarctica.</p>

Soil microbial biomass and carbon dioxide flux under wheat as influenced by tillage and crop rotation

1999 ◽  
Vol 79 (2) ◽  
pp. 273-280 ◽  
Author(s):  
N. Z. Lupwayi ◽  
W. A. Rice ◽  
G. W. Clayton
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Microbial Biomass ◽  
Soil Microbial Biomass ◽  
Conventional Tillage ◽  
Zero Tillage ◽  
Organic C ◽  
Soil Microbial ◽  
Total Soil ◽  
Northern Alberta

Soil organic matter is important both from an agronomic and an environmental perspective because it affects the capacity of the soil to sustain crop growth, and it is a source and sink of atmospheric CO2-C. Soil microbial biomass comprises a small proportion of total soil organic matter, but it is more dynamic than total soil organic matter. Therefore, measurements of soil microbial biomass may show the effects of soil management on potential changes in soil organic matter before such effects can be detected by measuring total soil organic matter. The effects of tillage and crop rotation on soil microbial biomass and activity were studied in 1995–1997 in the wheat phase of different cropping rotations that had been established in 1992 under zero tillage or conventional tillage in northern Alberta. Soil microbial biomass was often significantly (P < 0.05) higher, but never significantly lower, under zero tillage than under conventional tillage. However, CO2 evolution (basal respiration) was usually higher under conventional tillage than under zero tillage, resulting in higher specific respiration (qCO2) under conventional tillage than under zero tillage. The higher additions but lower losses of labile C under zero tillage mean that more C is sequestered in the soil in the zero-tillage system. Thus, this system contributes less to atmospheric CO2 than conventional tillage, and that soil organic matter accumulates more under zero tillage. Plots preceded by summerfallow, especially under conventional tillage, usually had the lowest microbial biomass and CO2 evolution, and plots preceded by legume crops had higher microbial biomass and lower qCO2 than other treatments. Tillage and rotation had little effect on total soil organic matter 5 yr after the treatments had been imposed, probably because of the cold climate of northern Alberta, but the results confirm that the labile forms of soil C are more sensitive indicators of soil organic C trends than total soil organic C. These effects of tillage and rotation on soil microbial biomass were similar to those on microbial diversity reported previously. These results confirm that zero tillage and legume-based crop rotations are more sustainable crop management systems than conventional tillage and fallowing in the Gray Luvisolic soils of northern Alberta. Key words: Carbon sequestration, carbon mineralization, microbial activity, soil organic matter

scholarly journals Effect of Plant Growth Regulators on Protease Activity in Forest Floor of Norway Spruce Stand

Forests ◽  
2021 ◽  
Vol 12 (6) ◽  
pp. 665
Author(s):  
Ladislav Holik ◽  
Jiří Volánek ◽  
Valerie Vranová
Keyword(s):  
Organic Matter ◽  
Proteolytic Activity ◽  
Protease Activity ◽  
Forest Floor ◽  
Soil Microbial Activity ◽  
Inhibitory Effects ◽  
Chlorocholine Chloride ◽  
Soil Microbial ◽  
Native Soil ◽  
Transformation Processes

Soil proteases are involved in organic matter transformation processes and, thus, influence ecosystem nutrient turnovers. Phytohormones, similarly to proteases, are synthesized and secreted into soil by fungi and microorganisms, and regulate plant rhizosphere activity. The aim of this study was to determine the effect of auxins, cytokinins, ethephon, and chlorocholine chloride on spruce forest floor protease activity. It was concluded that the presence of auxins stimulated native proteolytic activity, specifically synthetic auxin 2-naphthoxyacetic acid (16% increase at added quantity of 5 μg) and naturally occurring indole-3-acetic acid (18%, 5 μg). On the contrary, cytokinins, ethephon and chlorocholine chloride inhibited native soil protease activity, where ethephon (36% decrease at 50 μg) and chlorocholine chloride (34%, 100 μg) showed the highest inhibitory effects. It was concluded that negative phytohormonal effects on native proteolytic activity may slow down organic matter decomposition rates and hence complicate plant nutrition. The study enhances the understanding of rhizosphere exudate effects on soil microbial activity and soil nitrogen cycle.

Chemical composition of cover crops and soil organic matter pools in no‐tillage systems in the Cerrado

2021 ◽  
Author(s):  
Arminda Moreira de Carvalho ◽  
Luana Ramos Passos Ribeiro ◽  
Robélio Leandro Marchão ◽  
Alexsandra Duarte de Oliveira ◽  
Karina Pulrolnik ◽  
...  
Keyword(s):  
Organic Matter ◽  
Chemical Composition ◽  
Soil Organic Matter ◽  
Cover Crops ◽  
No Tillage ◽  
Tillage Systems
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