scholarly journals Competitive Capacity and Rhizosphere Mineralization of Organic Matter During Weed-Soil Microbiota Interactions

2019 ◽  
Vol 37 ◽  
Author(s):  
C.C. MATOS ◽  
M.D. COSTA ◽  
I.R. SILVA ◽  
A.A. SILVA
Keyword(s):  
Organic Matter ◽  
Soil Microorganisms ◽  
Natural Ecosystems ◽  
Soil Microbiota ◽  
Productivity Losses ◽  
Promising Tool ◽  
Elemental Stoichiometry ◽  
Mineralization Of Organic Matter ◽  
Competitive Success ◽  
Main Factors

ABSTRACT: The competition between weeds and crops is one of the main factors responsible for productivity losses in agricultural fields. This review aimed at presenting and discussing how the interactions between weeds and microorganisms can affect the competitive capacity of weeds and soil physicochemical properties. We also discuss how changes in the elemental stoichiometry of weeds can reflect their competitive and adaptative capacity. Although weeds are more dependent on associations with soil microorganisms than crops for growth, few studies have assessed the contribution of the soil microbiota to their competitive success in agroecosystems. When in competition, plants can change the elemental stoichiometry of their tissues in environments with varied nutrient availability. Elemental stoichiometry of plants has been particularly well studied using ecological approaches on the dynamics of weed populations in natural ecosystems, being a promising tool for understanding weed capacity to adapt to different agricultural managements. Plants control the biogeochemical cycles of carbon (C) and nitrogen (N) in the rhizosphere through a phenomenon known as the rhizosphere priming effect (RPE). Although this review has found some information in the literature that provides strong indications that the coexistence of weeds and crops may increase soil organic matter mineralization, we are not aware of studies investigating the effects of competition among these plants on RPE.

Microbial necromass as a source for soil organic matter formation - implications for soil processes

2020 ◽  
Author(s):  
Anja Miltner ◽  
Tiantian Zheng ◽  
Chao Liang ◽  
Matthias Kästner
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Microbial Biomass ◽  
Surface Properties ◽  
Soil Microorganisms ◽  
Plant Litter ◽  
Plant Residues ◽  
Elemental Stoichiometry ◽  
Stress Changes ◽  
Cell Envelopes

<p>The vital role of soil microorganisms as catalysts for soil organic matter (SOM) formation has long been recognised. Plant residues are now considered to be transformed by soil microorganisms who use the plant litter as a carbon source for microbial biomass formation. How much carbon is retained as microbial biomass during transformation of plant material, critically depends on substrate availability, carbon use efficiency of the microorganisms, and maximum microbial growth. In addition, microorganisms presumably recycle biomass building blocks from plant or microbial material to avoid energy expenditure for biomass synthesis. After cell death, a part of the microbial necromass is cycling through the microbial food web; the other part is stabilised in soil (Miltner et al., 2012). Potential stabilisation mechanisms are similar to those for SOM in general, with organo-mineral interactions, in particular encapsulation and physical isolation, being important mechanisms. Independent of which pathway the plant-derived carbon goes, SOM constitutes a continuum of plant and microbial necromass at various stages of decay. The contribution of microbial necromass to the topsoil organic matter pool has recently been estimated to range from 30 to 60% (Liang et al., 2019). Such high contributions of microbial necromass have a number of important implications for understanding SOM transformation and sequestration processes. Most obviously, the chemical identity of the organic material changes. For example, while retaining a substantial part of the carbon, the elemental stoichiometry changes substantially. Some microbial necromass materials are rather long-lasting in soil. In general, cell envelope residues have a higher stability than bulk biomass carbon. Proteins have also been shown to be rather persistent in soil, presumably due to conformational changes and the spatial arrangement of microbial necromass material, e.g. fragments of cell envelopes presumably pile up in multiple layers and the material forms clusters of macromolecular size. Residual electron-shuttle biomolecules (e.g. oxidoreductases, Fe-S-cluster, quinoid complexes of respiratory chains) may persist and retain some activity and thus contribute to redox reactions in soil. In addition, the necromass is expected to cover soil particle surfaces and thus determine the surface properties of these particles. In particular, these materials contribute to the water storage potential. They affect water retention and nutrient diffusion as well as microbial motility. Adaption of microbes to water stress changes their cell surface properties and molecular composition and thus may determine overall soil wettability. Knowledge on the contribution of microbial necromass to SOM would thus be essential for modelling SOM formation and optimising soil management practices for maintaining soil functions.</p><p> </p><p>References:</p><p>Miltner A, Bombach P, Schmidt-Brücken B, Kästner M (2012) SOM genesis: Microbial biomass as a significant source. Biogeochemistry 111: 41-55.</p><p>Liang C, Amelung W, Lehmann J, Kästner M (2019) Quantitative assessment of microbial necromass contribution to soil organic matter. Global Change Biology 25: 3578-3590.</p>

scholarly journals Humic substances: a valuable agronomic tool for improving crop adaptation to saline water irrigation

2019 ◽  
Vol 19 (6) ◽  
pp. 1735-1740 ◽  
Author(s):  
D. De Hita ◽  
M. Fuentes ◽  
A. C. García ◽  
M. Olaetxea ◽  
R. Baigorri ◽  
...  
Keyword(s):  
Organic Matter ◽  
Humic Substances ◽  
Saline Water ◽  
Water Sources ◽  
Natural Ecosystems ◽  
Crop Adaptation ◽  
Promising Tool ◽  
Fresh Organic Matter ◽  
Main Components ◽  
As Stress

Abstract Availability of fresh water for crop irrigation is becoming scarce and rather expensive. In this context, the research about the potential reutilization of non-conventional water sources becomes highly relevant, principally in arid and semi-arid areas. On many occasions, these new water resources involve water with a moderate concentration of salt, making it necessary to improve plant growth under moderate saline conditions. Besides plant breeding techniques, the use of molecules able to improve plant adaptation to saline conditions has great interest. Between these molecules, humic substances (HS) have proven to be efficient as stress-protectors under specific conditions of stress intensity and moment of application. The HS are main components of the soil organic matter and dissolved organic matter resulting from the biotic and abiotic transformation of fresh organic matter in natural ecosystems. Although knowledge about their structure is still under open debate, HS contain aromatic and aliphatic domains presenting O-, N- and S- containing functional groups with high biological and chemical activities. The aim of this presentation is to summarize the main effects of humic acids (HA) applied either on the root or on the shoot, on the metabolism and hormonal balance of plants cultivated under normal and stressing conditions, from studies carried out for our group and collaborations during the last years. Summarizing, all these results show HA as a promising tool for improving crop adaptation to irrigation using moderate saline water sources.

The effect of aggregate disruption on the activity of microorganisms in the soil

1957 ◽  
Vol 8 (6) ◽  
pp. 659 ◽  
Author(s):  
AD Rovira ◽  
EL Greacen
Keyword(s):  
Organic Matter ◽  
Oxygen Uptake ◽  
Microbial Activity ◽  
Soil Microorganisms ◽  
Arable Land ◽  
Drying And Rewetting ◽  
Mineralization Of Organic Matter ◽  
Tillage Treatment

Laboratory tillage of soils causes an increase in the oxygen uptake of soil microorganisms. The effect is closely related to the extent of aggregate disruption caused by the tillage treatment and is attributed largely to exposure of organic matter that was previously inaccessible. In some soils drying and rewetting after tillage causes a further increase in microbial activity, but this is not accounted for by disaggregation. As drying and rewetting commonly follow tillage in the field the resultant higher microbial activity could contribute to the faster mineralization of organic matter in arable land.

A four-year mass balance for a natural wetland system receiving domestic wastewater

1994 ◽  
Vol 30 (8) ◽  
pp. 235-244 ◽  
Author(s):  
M. Hosomi ◽  
A. Murakami ◽  
R. Sudo
Keyword(s):  
Organic Matter ◽  
Removal Rate ◽  
Domestic Wastewater ◽  
Residential Area ◽  
Flowing Water ◽  
Natural Wetland ◽  
N Release ◽  
Main Factors ◽  
Wetland System ◽  
Natural Purification

In order to clarify the natural purification potential of a natural wetland having free-flowing water, we performed a four-year study on such a wetland system which had been receiving for 12 years the domestic wastewater discharged from a residential area comprised of 45 households. The wetland's removal rate of organic matter throughout the four years ranged from 80% for COD to 95% for BOD, whereas the corresponding nitrogen removal rate was comparatively lower. Results indicate that NH4-N release from the bottom sediment and repression of nitrification are the main factors responsible for the wetland's low removal rate of nitrogen during winter. The wetland purification performance even in winter was determined as follows (g m−2 d−1): 2.2 BOD, 0.81 COD, 1.1 TOC, 0.10 T-N, and 0.023 T-P.

scholarly journals New perspectives in ecosystem services science as instruments to understand environmental securities

2014 ◽  
Vol 369 (1639) ◽  
pp. 20120286 ◽  
Author(s):  
Ferdinando Villa ◽  
Brian Voigt ◽  
Jon D. Erickson
Keyword(s):  
Ecosystem Services ◽  
State Of The Art ◽  
Water Security ◽  
Minimum Level ◽  
Natural Ecosystems ◽  
Methodological Innovation ◽  
Natural Systems ◽  
Promising Tool ◽  
Dynamic Expression ◽  
Services Science

As societal demand for food, water and other life-sustaining resources grows, the science of ecosystem services (ES) is seen as a promising tool to improve our understanding, and ultimately the management, of increasingly uncertain supplies of critical goods provided or supported by natural ecosystems. This promise, however, is tempered by a relatively primitive understanding of the complex systems supporting ES, which as a result are often quantified as static resources rather than as the dynamic expression of human–natural systems. This article attempts to pinpoint the minimum level of detail that ES science needs to achieve in order to usefully inform the debate on environmental securities, and discusses both the state of the art and recent methodological developments in ES in this light. We briefly review the field of ES accounting methods and list some desiderata that we deem necessary, reachable and relevant to address environmental securities through an improved science of ES. We then discuss a methodological innovation that, while only addressing these needs partially, can improve our understanding of ES dynamics in data-scarce situations. The methodology is illustrated and discussed through an application related to water security in the semi-arid landscape of the Great Ruaha river of Tanzania.

Assimilation of CO2 by soil microorganisms and transformation into soil organic matter

2004 ◽  
Vol 35 (9) ◽  
pp. 1015-1024 ◽  
Author(s):  
Anja Miltner ◽  
Hans-Hermann Richnow ◽  
Frank-Dieter Kopinke ◽  
Matthias Kästner
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Soil Microorganisms

Soil microbial biomass—Interpretation and consideration for soil monitoring

Soil Research ◽  
2011 ◽  
Vol 49 (4) ◽  
pp. 287 ◽  
Author(s):  
V. Gonzalez-Quiñones ◽  
E. A. Stockdale ◽  
N. C. Banning ◽  
F. C. Hoyle ◽  
Y. Sawada ◽  
...  
Keyword(s):  
Organic Matter ◽  
Microbial Biomass ◽  
Soil Microorganisms ◽  
Soil Microbial Biomass ◽  
Biological Function ◽  
Anthropogenic Change ◽  
Soil Monitoring ◽  
Soil Microbial ◽  
Quality Assessments ◽  
The Impact

Since 1970, measurement of the soil microbial biomass (SMB) has been widely adopted as a relatively simple means of assessing the impact of environmental and anthropogenic change on soil microorganisms. The SMB is living and dynamic, and its activity is responsible for the regulation of organic matter transformations and associated energy and nutrient cycling in soil. At a gross level, an increase in SMB is considered beneficial, while a decline in SMB may be considered detrimental if this leads to a decline in biological function. However, absolute SMB values are more difficult to interpret. Target or reference values of SMB are needed for soil quality assessments and to allow ameliorative action to be taken at an appropriate time. However, critical values have not yet been successfully identified for SMB. This paper provides a conceptual framework which outlines how SMB values could be interpreted and measured, with examples provided within an Australian context.

Mineralization of organic matter and the carbon sequestration capacity of zonal soils

2008 ◽  
Vol 41 (7) ◽  
pp. 717-730 ◽  
Author(s):  
V. M. Semenov ◽  
L. A. Ivannikova ◽  
T. V. Kuznetsova ◽  
N. A. Semenova ◽  
A. S. Tulina
Keyword(s):  
Organic Matter ◽  
Carbon Sequestration ◽  
Mineralization Of Organic Matter ◽  
Zonal Soils

scholarly journals Chemical Compounds and Decomposition Process from Four Species Leaf Litter As a Source of Organic Matter Soil in Anggori Education Forest, Manokwari

2020 ◽  
Vol 3 (02) ◽  
pp. 60-67
Author(s):  
Aditya Rahmadaniarti ◽  
Wolfram Y. Mofu
Keyword(s):  
Organic Matter ◽  
Soil Microorganisms ◽  
Litter Quality ◽  
Lignin Content ◽  
Chemical Compounds ◽  
Decomposition Process ◽  
Quality Factors ◽  
Polyphenol Content ◽  
Simple Change ◽  
Physical And Chemical

Decomposition is a simple change of physical and chemical processes by soil microorganisms—the rate of decomposition process influenced by climate and litter quality factors. Litter content of chemical compounds is essential to determine the litter's quality so that it can be estimated the decomposition process. Leaves litter of Magnolia tsiampacca, Intsia bijuga, Cinnamomum cullilawan, and Aglaia sp., were collected and analyzed for their chemical compounds. Based on lignin and nitrogen content (L/N) value, Cinnamomum cullilawan have the fastest decomposition process. On the contrary, Intsia bijuga has low litter quality, so that has the slowest decomposition process. However, it has the lowest lignin content and high polyphenol content. Our research found that four observed species were able to be used as sources of soil organic matter, although the litter quality is relatively low.

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