scholarly journals The living soil ? an agricultural perspective

2007 ◽  
Vol 28 (3) ◽  
pp. 104 ◽  
Author(s):  
Margaret M Roper ◽  
Vadakattu V S R Gupta
Keyword(s):  
Biological Control ◽  
Porous Medium ◽  
Organic Matter ◽  
Plant Growth ◽  
Ecosystem Function ◽  
Soil Structure ◽  
Biological Function ◽  
Decomposition Of Organic Matter ◽  
Wide Range ◽  
Biodiversity And Ecosystem Function

Soils are much more than a porous medium for supporting plant growth. Soils are living, because they contain a wide range of microorganisms including bacteria, fungi, algae, protozoa, nematodes and other fauna including microarthropods, macroarthropods, termites and earthworms. All play a crucial role in the biological function of soils including decomposition of organic matter, nutrient transformations, biological control, development of soil structure to mention a few. Until recently the complexity of life in the soil has been difficult to unravel, but new DNA and biochemical tools are providing insights into its phenotypic and functional diversity and capability, and should drive the development of managements that nurture biodiversity and ecosystem function.

The impact of porosity on organic matter cycling in a two-dimensional porous medium 

2021 ◽  
Author(s):  
Hanbang Zou ◽  
Pelle Ohlsson ◽  
Edith Hammer
Keyword(s):  
Porous Medium ◽  
Organic Matter ◽  
Carbon Sequestration ◽  
Soil Carbon ◽  
Pore Network ◽  
Pore Scale ◽  
Decomposition Of Organic Matter ◽  
Organic Matter Cycling ◽  
The Impact

<p>Carbon sequestration has been a popular research topic in recent years as the rapid elevation of carbon emission has significantly impacted our climate. Apart from carbon capture and storage in e.g. oil reservoirs, soil carbon sequestration offers a long term and safe solution for the environment and human beings. The net soil carbon budget is determined by the balance between terrestrial ecosystem sink and sources of respiration to atmospheric carbon dioxide. Carbon can be long term stored as organic matters in the soil whereas it can be released from the decomposition of organic matter. The complex pore networks in the soil are believed to be able to "protect" microbial-derived organic matter from decomposition. Therefore, it is important to understand how soil structure impacts organic matter cycling at the pore scale. However, there are limited experimental studies on understanding the mechanism of physical stabilization of organic matter. Hence, my project plan is to create a heterogeneous microfluidic porous microenvironment to mimic the complex soil pore network which allows us to investigate the ability of organisms to access spaces starting from an initial ecophysiological precondition to changes of spatial accessibility mediated by interactions with the microbial community.</p><p>Microfluidics is a powerful tool that enables studies of fundamental physics, rapid measurements and real-time visualisation in a complex spatial microstructure that can be designed and controlled. Many complex processes can now be visualized enabled by the development of microfluidics and photolithography, such as microbial dynamics in pore-scale soil systems and pore network modification mimicking different soil environments – earlier considered impossible to achieve experimentally. The microfluidic channel used in this project contains a random distribution of cylindrical pillars of different sizes so as to mimic the variations found in real soil. The randomness in the design creates various spatial availability for microbes (preferential flow paths with dead-end or continuous flow) as an invasion of liquids proceeds into the pore with the lowest capillary entry pressure. In order to study the impact of different porosity in isolation of varying heterogeneity of the porous medium, different pore size chips that use the same randomly generated pore network is created. Those chips have the same location of the pillars, but the relative size of each pillar is scaled. The experiments will be carried out using sterile cultures of fluorescent bacteria, fungi and protists, synthetic communities of combinations of these, or a whole soil community inoculum. We will quantify the consumption of organic matter from the different areas via fluorescent substrates, and the bio-/necromass produced. We hypothesise that lower porosity will reduce the net decomposition of organic matter as the narrower pore throat limits the access, and that net decomposition rate at the main preferential path will be higher than inside branches</p>

The nature and management of the poorer tropical latosols

1979 ◽  
Vol 10 (1) ◽  
pp. 27-32 ◽  
Author(s):  
Anthony Young
Keyword(s):  
Organic Matter ◽  
Rain Forest ◽  
Shifting Cultivation ◽  
Soil Structure ◽  
Fertilizer Application ◽  
Population Densities ◽  
Climatic Zones ◽  
Wide Range ◽  
The Tropics

The latosols, or ‘red and yellow’ soils of the tropics, encompass a wide range of properties and fertility. The poorer types occupy large areas both in the rain forest and in savanna climatic zones. The various systems of shifting cultivation traditionally practised are now inadequate with regard to increasing population densities, and management should be based on fertilizer application at moderate levels together with methods of maintaining organic matter and hence soil structure.

Controlling Erosion

1999 ◽  
Author(s):  
Robert F. Keefer
Keyword(s):  
Organic Matter ◽  
Organic Material ◽  
Soil Structure ◽  
Soil Microorganisms ◽  
Soil Aggregation ◽  
Water Infiltration ◽  
Root Penetration ◽  
Animal Remains ◽  
Decomposition Of Organic Matter ◽  
Structure Improvement

Erosion can be controlled by four main means, that is, improving soil structure, covering soil with plants, covering soil with mulch, and using special structures. Soil structure is related to the soil tilth, or physical condition of a soil, with respect to ease of tillage or workability as shown by the fitness of a soil as a seedbed and the ease of root penetration. Other terms relating to soil structure improvement are soil aggregation and the formation of aggregates. Aggregates form when a cementing substance is present in a soil. The most important cementing substances in soil are soil polysaccharides and soil polyuronides produced as by-products from microorganisms during decomposition of organic matter. Other less important cementing substances in soil include clays, Ca, and Fe. Formation of aggregates results in improved water infiltration with reduction in erosion. Decomposition of organic matter in soils can be shown as an equation: . . . Plant and animal remains + O2 + soil microorganisms → CO2 + H2O + elements + humus + synthates + energy . . . The decomposition process has the following features: . . . 1. Oxygen is required; thus soil aeration is important. Anytime a soil is stirred or mixed by cultivation, spading, plowing, some organic matter decomposition occurs. 2. Readily available decomposable organic material is required for the microbes to work on. Green organic material, such as grass clippings, is an excellent substrate. 3. Many different types of soil microorganisms are involved in this process. Decomposition is more rapid in soils at pH 7 (neutral). 4. A product of organic decomposition is humus. Humus has many desirable features that improve a soil for plant growth. 5. Plant or animal remains are not effective in soil aggregation until they begin to decompose. 6. The more rapid the decomposition, the greater effect of soil aggregation. . . . Microbial synthates consist of polymers called “polysaccharides” and “polyuronides.” A polymer is a long-chain compound made up of single monomer units hooked together acting as a unit. The term “poly” means “many” and “saccharide” means “sugar.”

scholarly journals A review of the use of composted municipal solid waste in agriculture

2010 ◽  
Vol 2 (1) ◽  
pp. 145-158
Author(s):  
S.P. Gautam ◽  
P.S. Bundela ◽  
A. K. Pandey ◽  
R.K. Jain ◽  
P.R. Deo ◽  
...  
Keyword(s):  
Organic Matter ◽  
Plant Growth ◽  
Municipal Solid Waste ◽  
Solid Waste ◽  
Metal Content ◽  
Soil Structure ◽  
Main Concern ◽  
Municipal Solid Waste Compost ◽  
Industry Standards ◽  
Msw Compost

Municipal solid waste (MSW) compost is increasingly used in agriculture as a soil conditioner but also as a fertilizer. Proponents of this practice consider it an important recycling tool since MSW would otherwise be land ûlled and critics are concerned with its often elevated metal concentrations. Large amounts of MSW compost are frequently used in agriculture to meet crop N requirements and for the addition of organic matter. The main concern is loading the soil with metals that can result in increased metal content of crops. Furthermore, in some cases, metals and excess nutrients can move through the soil proûle into groundwater. Municipal solid waste compost has also been reported to have high salt concentrations, which can inhibit plant growth and negatively affect soil structure. A review of relevant agricultural studies is presented as well as recommendations for improving MSW compost quality. Its safe use in agriculture can be ensured with source separation (or triage of MSW to be composted) as well as the development and implementation of comprehensive industry standards.

scholarly journals Shifts in Soil Structure, Biological, and Functional Diversity Under Long-Term Carbon Deprivation

2021 ◽  
Vol 12 ◽  
Author(s):  
Paul B. L. George ◽  
David B. Fidler ◽  
Joy D. Van Nostrand ◽  
Jonathan A. Atkinson ◽  
Sacha J. Mooney ◽  
...  
Keyword(s):  
Organic Matter ◽  
Soil Structure ◽  
Phospholipid Fatty Acid ◽  
Organic C ◽  
Scarce Resources ◽  
Gene Copies ◽  
Fatty Acid Profiling ◽  
Wide Range ◽  
X Ray Computed

Soil organic matter is composed of a variety of carbon (C) forms. However, not all forms are equally accessible to soil microorganisms. Deprivation of C inputs will cause changes in the physical and microbial community structures of soils; yet the trajectories of such changes are not clear. We assessed microbial communities using phospholipid fatty acid profiling, metabarcoding, CO2 emissions, and functional gene microarrays in a decade-long C deprivation field experiment. We also assessed changes in a range of soil physicochemical properties, including using X-ray Computed Tomography imaging to assess differences in soil structure. Two sets of soils were deprived of C inputs by removing plant inputs for 10 years and 1 year, respectively. We found a reduction in diversity measures, after 10 years of C deprivation, which was unexpected based on previous research. Fungi appeared to be most impacted, likely due to competition for scarce resources after exhausting the available plant material. This suggestion was supported by evidence of bioindicator taxa in non-vegetated soils that may directly compete with or consume fungi. There was also a reduction in copies of most functional genes after 10 years of C deprivation, though gene copies increased for phytase and some genes involved in decomposing recalcitrant C and methanogenesis. Additionally, soils under C deprivation displayed expected reductions in pH, organic C, nitrogen, and biomass as well as reduced mean pore size, especially in larger pores. However, pore connectivity increased after 10 years of C deprivation contrary to expectations. Our results highlight concurrent collapse of soil structure and biodiversity following long-term C deprivation. Overall, this study shows the negative trajectory of continuous C deprivation and loss of organic matter on a wide range of soil quality indicators and microorganisms.

A Study on the Farmers’ Awareness and Acceptance of Biofertilizers in Kottayam District

GIS Business ◽  
2019 ◽  
Vol 14 (6) ◽  
pp. 425-431
Author(s):  
Subin Thomas ◽  
Dr. M. Nandhini
Keyword(s):  
Organic Matter ◽  
Nitrogen Fixation ◽  
Plant Growth ◽  
Plant Growth Promoting Rhizobacteria ◽  
Nutrient Cycle ◽  
Plant Growth Promoting ◽  
Promote Plant Growth ◽  
Growth Promoting ◽  
Structured Questionnaire ◽  
Area Data

Biofertilizers are fertilizers containing microorganisms that promote plant growth by improving the supply of nutrients to the host plant. The supply of nutrients is improved naturally by nitrogen fixation and solubilizing phosphorus. The living microorganisms in biofertilizers help in building organic matter in the soil and restoring the natural nutrient cycle. Biofertilizers can be grouped into Nitrogen-fixing biofertilizers, Phosphorous-solubilizing biofertilizers, Phosphorous-mobilizing biofertilizers, Biofertilizers for micro nutrients and Plant growth promoting rhizobacteria. This study conducted in Kottayam district was intended to identify the awareness and acceptance of biofertilizers among the farmers of the area. Data have been collected from 120 farmers by direct interviews with structured questionnaire.

Coagulation/flocculation/ultrafiltration for natural organic matter removal in drinking water production

2004 ◽  
Vol 4 (5-6) ◽  
pp. 215-222 ◽  
Author(s):  
A.R. Costa ◽  
M.N. de Pinho
Keyword(s):  
Drinking Water ◽  
Organic Matter ◽  
Natural Organic Matter ◽  
Membrane Fouling ◽  
Membrane Filtration ◽  
Membrane Surface ◽  
Water Production ◽  
Cellulose Acetate Membranes ◽  
Wide Range ◽  
Drinking Water Production

Membrane fouling by natural organic matter (NOM), namely by humic substances (HS), is a major problem in water treatment for drinking water production using membrane processes. Membrane fouling is dependent on membrane morphology like pore size and on water characteristics namely NOM nature. This work addresses the evaluation of the efficiency of ultrafiltration (UF) and Coagulation/Flocculation/UF performance in terms of permeation fluxes and HS removal, of the water from Tagus River (Valada). The operation of coagulation with chitosan was evaluated as a pretreatment for minimization of membrane fouling. UF experiments were carried out in flat cells of 13.2×10−4 m2 of membrane surface area and at transmembrane pressures from 1 to 4 bar. Five cellulose acetate membranes were laboratory made to cover a wide range of molecular weight cut-off (MWCO): 2,300, 11,000, 28,000, 60,000 and 75,000 Da. Severe fouling is observed for the membranes with the highest cut-off. In the permeation experiments of raw water, coagulation prior to membrane filtration led to a significant improvement of the permeation performance of the membranes with the highest MWCO due to the particles and colloidal matter removal.

scholarly journals Growth Promotion or Osmotic Stress Response: How SNF1-Related Protein Kinase 2 (SnRK2) Kinases Are Activated and Manage Intracellular Signaling in Plants

Plants ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 1443
Author(s):  
Yoshiaki Kamiyama ◽  
Sotaro Katagiri ◽  
Taishi Umezawa
Keyword(s):  
Protein Kinase ◽  
Plant Growth ◽  
Osmotic Stress ◽  
Protein Function ◽  
Intracellular Signaling ◽  
Growth Promotion ◽  
Research Field ◽  
Dependent Manner ◽  
Related Protein ◽  
Wide Range

Reversible phosphorylation is a major mechanism for regulating protein function and controls a wide range of cellular functions including responses to external stimuli. The plant-specific SNF1-related protein kinase 2s (SnRK2s) function as central regulators of plant growth and development, as well as tolerance to multiple abiotic stresses. Although the activity of SnRK2s is tightly regulated in a phytohormone abscisic acid (ABA)-dependent manner, recent investigations have revealed that SnRK2s can be activated by group B Raf-like protein kinases independently of ABA. Furthermore, evidence is accumulating that SnRK2s modulate plant growth through regulation of target of rapamycin (TOR) signaling. Here, we summarize recent advances in knowledge of how SnRK2s mediate plant growth and osmotic stress signaling and discuss future challenges in this research field.

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