Preliminary remarks on porosity of soil aggregates in air-dry state and at pF 2.

1961 ◽  
Vol 9 (3) ◽  
pp. 168-173 ◽  
Author(s):  
H. Kuipers
Keyword(s):  
Organic Matter ◽  
Moisture Content ◽  
Water Content ◽  
Pore Volume ◽  
Pore Space ◽  
Soil Aggregates ◽  
Aggregate Size ◽  
Field Conditions ◽  
Swelling Properties ◽  
Air Voids

In pycnometer determinations of the pore volume of 2-5-mm air-dry aggregates from various soils of 1.5-2.5 and 2.6-3.5% organic-matter levels and various clay contents, the use of kerosene (S. & F. XVII [1897]) gave as good values as, and was more convenient than, the use of sand or mercury (the latter giving low porosities). The pore-space percentage of aggregates could be calculated from the water content at pF 2, when no air voids in the small aggregates are likely to occur and water between the aggregates is of no importance. Dry aggregates were only slightly denser in cores of light soils than under field conditions, and swelling was small; dry aggregates were very dense in heavy soils in which moisture content and density of aggregates appeared so closely related that it was difficult to distinguish between the effect of either on the strength of aggregates. Swelling properties and aggregate size are likely to be important factors in the structure of heavy soils. (Abstract retrieved from CAB Abstracts by CABI’s permission)

scholarly journals Simulating microbial degradation of organic matter in a simple porous system using the 3-D diffusion-based model MOSAIC

2014 ◽  
Vol 11 (8) ◽  
pp. 2201-2209 ◽  
Author(s):  
O. Monga ◽  
P. Garnier ◽  
V. Pot ◽  
E. Coucheney ◽  
N. Nunan ◽  
...  
Keyword(s):  
Experimental Data ◽  
Organic Matter ◽  
Water Content ◽  
Microbial Degradation ◽  
Diffusion Processes ◽  
Pore Space ◽  
High Water Content ◽  
Porous System ◽  
Micro Computed Tomography ◽  
Bacterial Strains

Abstract. This paper deals with the simulation of microbial degradation of organic matter in soil within the pore space at a microscopic scale. Pore space was analysed with micro-computed tomography and described using a sphere network coming from a geometrical modelling algorithm. The biological model was improved regarding previous work in order to include the transformation of dissolved organic compounds and diffusion processes. We tested our model using experimental results of a simple substrate decomposition experiment (fructose) within a simple medium (sand) in the presence of different bacterial strains. Separate incubations were carried out in microcosms using five different bacterial communities at two different water potentials of −10 and −100 cm of water. We calibrated the biological parameters by means of experimental data obtained at high water content, and we tested the model without changing any parameters at low water content. Same as for the experimental data, our simulation results showed that the decrease in water content caused a decrease of mineralization rate. The model was able to simulate the decrease of connectivity between substrate and microorganism due the decrease of water content.

Effect of biochar and compost on soil properties and organic matter in aggregate size fractions under field conditions

2020 ◽  
Vol 295 ◽  
pp. 106882 ◽  
Author(s):  
Jennifer Cooper ◽  
Isabel Greenberg ◽  
Bernard Ludwig ◽  
Laura Hippich ◽  
Daniel Fischer ◽  
...  
Keyword(s):  
Organic Matter ◽  
Soil Properties ◽  
Aggregate Size ◽  
Field Conditions ◽  
Size Fractions

The volume-changes associated with variations of water content in soil

1923 ◽  
Vol 13 (3) ◽  
pp. 296-310 ◽  
Author(s):  
William B. Haines
Keyword(s):  
Specific Gravity ◽  
Moisture Content ◽  
Linear Relationship ◽  
Water Content ◽  
Pore Space ◽  
Moist Soil ◽  
Volume Changes ◽  
Simple Method ◽  
Wetting And Drying ◽  
Two Stages

(1) A new and simple method of measuring the shrinkage of moist soil on drying is described, which at the same time gives values for the pore space and specific gravity of the soil.(2) Diagrams for a number of diverse soils are given, illustrating the character of soil shrinkage.(3) The shrinkage is shown to take place in two stages in both of which there is a linear relationship to the moisture content.(4) Tentative explanations of these two stages are advanced, based on the well-known colloidal-coating hypothesis, and confirmatory experiments described.(5) By means of the method the effect of alternate wetting and drying of soil in producing a good tilth is illustrated.

Long-term effects of biochar amount on the content and composition of organic matter in soil aggregates under field conditions

2016 ◽  
Vol 16 (5) ◽  
pp. 1481-1497 ◽  
Author(s):  
Xinliang Dong ◽  
Tianyu Guan ◽  
Guitong Li ◽  
Qimei Lin ◽  
Xiaorong Zhao
Keyword(s):  
Organic Matter ◽  
Soil Aggregates ◽  
Field Conditions ◽  
Long Term Effects

Macro ATR-FTIR imaging for better understanding of organic matter dynamics in soil

2021 ◽  
Author(s):  
Milda Pucetaite ◽  
Carlos Arellano ◽  
Pelle Ohlsson ◽  
Per Persson ◽  
Edith Hammer
Keyword(s):  
Organic Matter ◽  
Soil Structure ◽  
Pore Space ◽  
Soil Aggregates ◽  
Chemical Properties ◽  
Spectroscopic Imaging ◽  
High Refractive Index ◽  
Attenuated Total Reflection ◽  
Grand Challenge ◽  
Ir Spectroscopic

<p>A grand challenge for mankind is to fight climate change, which involves both reducing and reverting CO<sub>2</sub> emissions. Soils store more carbon (C) than the atmosphere and biosphere combined, and it is microorganisms that govern whether C compounds remain in the soil, or whether they are decomposed and released to the atmosphere as CO<sub>2</sub>. The microbial influence on C cycling range from the way they decompose soil organic matter (SOM) to their contributions on the formation of soil aggregates that are particularly important for physical C stabilization in soils. However, the relationship between the microbial activity, SOM properties and physicochemical microenvironment, including complexity of soil structure (i.e., arrangement of pore space in and between soil aggregates), and how each of these factors contribute to the prolonged residence of C in soils, is not well understood. Therefore, the aim of this work has been to develop and make use of an analytical approach for studying the influence of pore space architecture on microbial SOM decomposition and dynamics by integrating two novel tools in soil sciences – microfluidic chips, which mimic soil structure, and infrared (IR) spectroscopic imaging, which provides detailed information about chemical properties of materials within these chips.</p><p>We have used several microchip designs to simulate different levels of complexity of soil pore space. The hypothesis is that the more complex the chip structures – the less decomposition of SOM will be observed, as more of it will be ‘hidden’ from its decomposers within hard-to-reach spaces. For the IR spectroscopic imaging, macro attenuated total reflection (ATR) accessory has been used. In this mode, an ATR element of high refractive index is put in contact with a sample – the microchip - and total internal reflection signal at the boundary between the element and the sample is recorded. The signal is detected with an imaging focal plane array (FPA) detector and carries information about IR absorptions in the sample. With IR spectra serving as fingerprints for identifying molecules, spatially and temporally resolved observation of chemistry and chemical changes of a SOM substrate initially filling the microchip structures and undergoing decomposition by subsequently inoculated microbial cultures can be made. Our pilot data suggests feasibility of the approach for analysis of complex substrates such as lignin, maize leaves or SOM from real soils and its dependence on the complexity of chip. Evaluating molecular changes in parts of the larger molecules or of the compound mixture under decomposition could even contribute to quantifying, e.g., N mining within the compounds. Eventually, knowing the influence of spatial structure on the decomposition rate and pathways can help us understand how important is the spatial heterogeneity when we study organic matter degradation in soils.</p>

ALTERATIONS OF SOIL STRUCTURE UPON FREEZING AND THAWING AND SUBSEQUENT DRYING

1968 ◽  
Vol 48 (2) ◽  
pp. 193-197 ◽  
Author(s):  
W. C. Hinman ◽  
Frederick Bisal
Keyword(s):  
Moisture Content ◽  
Soil Structure ◽  
Room Temperature ◽  
Clay Soil ◽  
Soil Aggregates ◽  
Initial Moisture Content ◽  
Aggregate Size ◽  
Freezing And Thawing ◽  
Initial Size ◽  
Freeze Dried

A laboratory investigation of a clay soil indicated that the percentage of aggregates < 1 mm in diameter might be increased, decreased or unaffected by freezing and thawing depending on the initial moisture content, the initial size of soil aggregates and the method of drying the sample. Little or no changes in aggregate size occurred if the initial moisture content was at 15 atmospheres. At 0.1 atm, aggregates which were initially coarse (> 4 mm) tended to break down slightly when exposed to alternate freezing and thawing followed by air-drying at room temperature. On the other hand, a substantial decrease in aggregates < 1 mm in diameter occurred when aggregates which were originally fine received the same sequence of treatments. However, if the samples were freeze-dried following the same treatments, all aggregates were reduced to < 1 mm in diameter. Similar trends were established with samples which were continuously frozen and when the initial moisture content was at 0.33 atm, although the magnitude of the change was much smaller. It is proposed that forces engendered during freezing disrupt aggregates, but this process is reversed during thawing and drying at room temperatures.

scholarly journals Pengaruh Penambahan EM-4 Terhadap Kualitas Pupuk Kompos Kotoran Gajah

2021 ◽  
Vol 9 (1) ◽  
pp. 130
Author(s):  
Irfan Fadel ◽  
Ida Ayu Gede Bintang Madrini ◽  
Sumiyati Sumiyati
Keyword(s):  
Organic Matter ◽  
Moisture Content ◽  
Water Content ◽  
National Standard ◽  
Randomized Design ◽  
Completely Randomized Design ◽  
Elephant Dung ◽  
Temperature Water ◽  
Food Consumed

ABSTRAK Kotoran gajah kaya akan selulosa dan lignin. Kotoran gajah memiliki warna yang bervariasi mulai dari kehijauan hingga kehitaman, tergantung dari makanan yang dikonsumsi (Mathew and Mary 2015). Sementara ini kotoran gajah belum banyak dimanfaatkan Maka dari itu kotoran gajah belum dimanfaatkan secara maksimal. kotoran gajah belum banyak dimanfaatkan secara maksimal. Pengomposan menjadi salah satu pilihan untuk menjadikan kotoran gajah lebih bermanfaat. Tujuan penelitian ini adalah untuk mengetahui pengaruh penambahan bioaktivator EM-4 terhadap suhu, pH, kadar air, ratio C/N, bahan organik yang dihasilkan dan untuk menentukan konsentrasi larutan bioaktivator EM-4 yang menghasilkan kualitas kompos yang terbaik dari kotoran gajah dan sesuai dengan Standar Nasional Indonesia (SNI) 19-7030-2004). Penelitian ini menggunakan Rancangan Acak Lengkap (RAL). Perlakuan dengan menggunakan 50 kg kotoran gajah untuk satu perlakuan dan masing masing konsentrasi EM-4 0 ml (kontrol), 50 ml, 100 ml dan 150 ml. Keempat perlakuan tersebut   dilakukan   pengulangan   sebanyak   2 kali sehingga didapatkan 8 unit percobaan. Parameter pengamatan meliputi suhu kompos, pH, Kadar Air, Bahan Organik, Karbon, Nitrogen,C/N ratio. Hasil pengomposan kotoran gajah dengan larutan EM-4 selama 2 bulan, maka dapat dilihat penambahan larutan EM-4 berpengaruh terhadap suhu, kadar air, ratio C/N dan bahan organik sedangkan pH tidak menunjukkan pengaruh yang signifikan. Pada perlakuan penambahan 150 ml EM-4 pada 50 kg kotoran gajah, suhu mencapai termofilik pada hari ke 28 yaitu 46,1 ?C, ratio C/N 19,63 dan bahan organik 35%. Semua perlakuan memenuhi SNI 19-7030-2004. ABSTRACT Elephant dung is rich in cellulose and lignin. Elephant dung has a color that varies from greenish to blackish, depending on the food consumed (Mathew & Mary, 2015). Meanwhile, elephant dung has not been used much. Therefore, elephant dung has not been fully utilized. elephant dung has not been fully utilized. Composting is an option to make elephant dung more useful. The purpose of this study was to determine the effect of the addition of EM-4 bioactivator on temperature, pH, moisture content, C / N ratio, organic matter produced and to determine the concentration of the EM-4 bioactivator solution which produces the best quality compost from elephant dung and in accordance with Indonesian National Standard (SNI) 19-7030-2004). This study used a completely randomized design (CRD). The treatment used 50 kg of elephant dung for one treatment and each concentration of EM-4 0 ml (control), 50 ml, 100 ml and 150 ml. The four treatments were repeated 2 times in order to obtain 8 experimental units. Observation parameters include compost temperature, pH, moisture content, organic matter, carbon, nitrogen, C / N ratio. The results of composting elephant dung with EM-4 solution for 2 months, it can be seen that the addition of EM-4 solution has an effect on temperature, water content, C / N ratio and organic matter while pH does not show a significant effect. In the treatment of adding 150 ml of EM-4 to 50 kg of elephant manure, the temperature reached thermophilic on day 28, namely 46.1 ?C, C / N ratio 19.63 and 35% organic matter. All treatments comply with SNI 19-7030-2004.

scholarly journals Effects of ageing under field conditions on soil organic matter in earthworm casts produced by the anecic earthworm Amynthas adexilis in northern Vietnam

2021 ◽  
Author(s):  
Nicolas Jean Bernard Puche ◽  
Cornelia Rumpel ◽  
Nicolas Bottinelli
Keyword(s):  
Organic Matter ◽  
Particulate Organic Matter ◽  
Soil Aggregates ◽  
Ct Images ◽  
Field Conditions ◽  
Strong Positive Correlation ◽  
Micro Ct ◽  
Earthworm Casts ◽  
Biogeochemical Models ◽  
And Control

&lt;p&gt;Carbon sequestration in soils became a major issue that governments have to face under their sustainable development objectives and the international 4p1000 program. Although, earthworms are recognized to play a key role in the structure and dynamics of organic matter (OM) in soils, their contribution to soil OM cycling is not taken into account in biogeochemical models nor well understood. In particular, the fate of OM protected in earthworm casts is unknown. In this study, we investigated the effects of ageing under field conditions on the OM dynamics contained in casts produced by the anecic earthworm Amynthas adexilis in North Vietnam. To this end we investigated (1) the microscale organisation of particulate organic matter and pores during the exposure of casts and control aggregates during 12 months and (2) compared it to the potential OM mineralisation during a laboratory incubation.&lt;/p&gt;&lt;p&gt;Our results indicated that fresh casts contained significantly more particulate organic matter (POM) than control soil aggregates and field aged earthworm casts. Conversely, the porosity was higher in soil control aggregates than in casts and the porosity of casts tended to increase with their ageing. The analyses of micro-CT images also revealed that POM and Pores contents between casts samples presented strong variabilities even in the youngest casts category. We found, on average, higher mineralisation rates for casts than for controls and a reduction of the OM mineralisation with the ageing of casts. Our results also highlighted a strong positive correlation (r&lt;sup&gt;2&lt;/sup&gt; = 0.89) between POM contents determined by the segmentation of micro CT images and CO&lt;sub&gt;2&lt;/sub&gt; emissions from the incubation experiment. We conclude that earthworms impact the microscale organisation of POM and pores in their casts and thereby influence soil OM dynamics.&lt;/p&gt;

scholarly journals Microstructural strength of tidal soils – a rheometric approach to develop pedotransfer functions

2018 ◽  
Vol 66 (1) ◽  
pp. 87-96 ◽  
Author(s):  
Nina Stoppe ◽  
Rainer Horn
Keyword(s):  
Organic Matter ◽  
Water Content ◽  
Physicochemical Parameters ◽  
Soil Aggregates ◽  
Pedotransfer Functions ◽  
Microstructural Stability ◽  
North Germany ◽  
Statistical Relationships ◽  
The Elbe River ◽  
Soil Behaviour

Abstract Differences in soil stability, especially in visually comparable soils can occur due to microstructural processes and interactions. By investigating these microstructural processes with rheological investigations, it is possible to achieve a better understanding of soil behaviour from the mesoscale (soil aggregates) to macroscale (bulk soil). In this paper, a rheological investigation of the factors influencing microstructural stability of riparian soils was conducted. Homogenized samples of Marshland soils from the riparian zone of the Elbe River (North Germany) were analyzed with amplitude sweeps (AS) under controlled shear deformation in a modular compact rheometer MCR 300 (Anton Paar, Germany) at different matric potentials. A range physicochemical parameters were determined (texture, pH, organic matter, CaCO3 etc.) and these factors were used to parameterize pedotransfer functions. The results indicate a clear dependence of microstructural elasticity on texture and water content. Although the influence of individual physicochemical factors varies depending on texture, the relevant features were identified taking combined effects into account. Thus, stabilizing factors are: organic matter, calcium ions, CaCO3 and pedogenic iron oxides; whereas sodium ions and water content represent structurally unfavorable factors. Based on the determined statistical relationships between rheological and physicochemical parameters, pedotransfer functions (PTF) have been developed.

Quantity and biodegradability of dissolved organic matter released from sequentially leached soils, as influenced by the extent of soil drying prior to rewetting

Soil Research ◽  
2019 ◽  
Vol 57 (4) ◽  
pp. 374 ◽  
Author(s):  
Tihana Vujinović ◽  
Timothy J. Clough ◽  
Denis Curtin ◽  
Esther D. Meenken ◽  
Niklas J. Lehto ◽  
...  
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Pore Volume ◽  
Arable Soil ◽  
The Other ◽  
Grassland Soil ◽  
Soil C

Soil rewetting can induce a flush of organic matter mineralisation, but the factors underpinning this mineralisation response are poorly understood. We investigated the effects of antecedent soil water content, before rewetting, on the quantity, quality and biodegradability of dissolved organic matter present in the leachate pore volumes from a soil under two different management histories: arable and grassland. Soils were collected at field capacity (FC) and dried to give four soil gravimetric water contents (θg): 22% (not dried, left at FC), 15%, 8% and &lt;2% (air dry, AD). Soils were repacked to the same bulk density (1.1 g cm–3) and each core was sequentially leached, with four pore volumes collected. The total amount of dissolved organic carbon (DOC) leached increased (P &lt; 0.001) only in the soils that had been air-dried before rewetting (3.8 and 5.3 mg g–1 soil C, for arable and grassland respectively), while among the other θg treatments differences were relatively small (1.6–2.4 mg g–1 soil C). The pre-rewetting θg treatment affected the DOC content of the pore volume leached (P &lt; 0.001): in the grassland soil, the DOC of the AD treatment was consistently twice as high as the other θg treatments, but this trend was not as consistent in the arable soil. For all θg treatments and both soils, specific ultraviolet absorbance at 254 nm increased as leaching progressed. Biodegradability, expressed as cumulative CO2 produced per unit of DOC in leachates, was significantly lower in the first pore volume of all treatments in the grassland soil and increased with sequential leaching. In the arable soil, differences were small or insignificant across the pore volumes leached, but were large and inconsistent across the θg treatments. These findings improve our understanding of how antecedent soil water content affects the quantity and quality of dissolved organic matter released when soils are rewetted, and the potential for soil carbon losses.

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