Effect of soil pore size distribution on plant-available water and least limiting water range as soil physical quality indicators

Understanding the effects of agricultural management practices on soil functionality is an ongoing challenge in environmental science and agricultural practice. In the present study we quantified the effects of changes in tillage intensity on soil physical quality and pore size distribution after 6, 10 and 23 years. At three long-term tillage experimental sites in central Europe we analysed soils under four different soil management systems: conventional mouldboard tillage; chiselling + rotary harrow; rotary harrow; and no till. These treatments differed in mechanical intensity and depth. Pore size distributions were calculated from soil water retention curves based on high-resolution measurements. Subsequently, fractions of functional pore size classes and indicators of soil physical quality were determined and compared between the treatments. In addition, we evaluated the performance of two calculation approaches for pore size distribution: (1) fitting of a smoothing cubic spline; and (2) a bimodal van Genuchten function. The parametric function yielded a higher proportion of storage pores by approximately 3–5%. The combination of multiple measurement and evaluation methods enabled detailed comparison of soil physical characteristics between different tillage treatments. No-till soils showed a distinct lack of transmissive pores and higher bulk density, but similar plant-available water capacity, compared with the other treatments. Under all soil management systems, aeration deficits were observed, emphasising the high vulnerability for compaction of silt-dominated arable soils with a low organic matter content. Hence, the design of agricultural soil management strategies on such soils needs to consider the risks of compaction as thoroughly as erosion or chemical degradation.

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The effect of soil conditioners on pore size distribution and water retention of a calcareous soil

Soil Research ◽

10.1071/sr9780277 ◽

1978 ◽

Vol 16 (3) ◽

pp. 277

Author(s):

MH Khoury ◽

AH Sayegh ◽

NJ Atallah

Keyword(s):

Pore Size Distribution ◽

Pore Size ◽

Size Distribution ◽

Calcareous Soil ◽

Water Retention ◽

Available Water ◽

Soil Conditioners

The application of soil conditioners on a calcareous soil resulted in an increase in the diameter of pores and a decrease in the available water. A diameter of 140 �m was suggested to be the dividing point between micropores and very fine pores.

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Least limiting water range and soil pore-size distribution related to soil organic carbon dynamics following zero and conventional tillage of a black soil in Northeast China

The Journal of Agricultural Science ◽

10.1017/s0021859614000161 ◽

2014 ◽

Vol 153 (2) ◽

pp. 270-281 ◽

Cited By ~ 3

Author(s):

X. W. CHEN ◽

X. H. SHI ◽

A. Z. LIANG ◽

X. P. ZHANG ◽

S. X. JIA ◽

...

Keyword(s):

Pore Size Distribution ◽

Pore Size ◽

Bulk Density ◽

Size Distribution ◽

Northeast China ◽

Soil Bulk Density ◽

Black Soil ◽

Tillage Practices ◽

Least Limiting Water Range ◽

Soc Mineralization

SUMMARYThe present work built on a previous study of tillage trials, which found the effectiveness of least limiting water range (LLWR) as an indicator of soil organic carbon (SOC) mineralization under different tillage practices in a black soil of Northeast China in 2009. To improve the understanding of soil structure controls over SOC dynamics, a study was conducted to explore the relationship between LLWR, which was calculated based on soil bulk density and soil pore-size distribution, and the effects of LLWR, which was calculated based on soil bulk density and soil pore-size distribution on SOC mineralization following no tillage (NT) and mouldboard ploughing (MP). In contrast to MP, NT had a significantly greater volume of large macropores (>100 μm) at depths of 0–0·05 and 0·2–0·3 m, but a significantly lower volume of small macropores (30–100 μm) at depths of 0–0·05, 0·05–0·1, 0·1–0·2 and 0·2–0·3 m. The volume of meso- (0·2–30 μm) and micro-pores (<0·2 μm) at different depths under the two tillage practices were similar. Tillage-induced changes in soil bulk density and pore-size volumes affected the ability of soil to fulfil essential soil functions in relation to organic matter turnover. Soil pore-size distribution, especially small macropores greatly affected LLWR and there was a significant correlation between LLWR, which was calculated based on soil bulk density, and the proportion of small macropores. The proportion of small macropores were used to calculate LLWR instead of soil bulk density and the values for NT and MP soils ranged from 0·073 to 0·148 m3water/m3soil. Using the proportion of small macropores rather than bulk density in the calculation of LLWR resulted in more sensitive indications of SOC mineralization. Variation in the proportion of small macropores can help characterize the impacts of tillage practices on dynamics of LLWR and SOC sequestration.

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Integral energy of conventional available water, least limiting water range and integral water capacity for better characterization of water availability and soil physical quality

Geoderma ◽

10.1016/j.geoderma.2011.06.009 ◽

2011 ◽

Vol 166 (1) ◽

pp. 34-42 ◽

Cited By ~ 25

Author(s):

H. Asgarzadeh ◽

M.R. Mosaddeghi ◽

A.A. Mahboubi ◽

A. Nosrati ◽

A.R. Dexter

Keyword(s):

Water Availability ◽

Physical Quality ◽

Water Capacity ◽

Available Water ◽

Soil Physical Quality ◽

Integral Energy ◽

Least Limiting Water Range

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pyGAPS: A Python-Based Framework for Adsorption Isotherm Processing and Material Characterisation

10.26434/chemrxiv.7970402.v1 ◽

2019 ◽

Author(s):

Paul Iacomi ◽

Philip L. Llewellyn

Keyword(s):

Pore Size Distribution ◽

Pore Size ◽

Size Distribution ◽

Surface Area ◽

Isosteric Heat ◽

Material Characterisation ◽

Mixture Adsorption ◽

Surface Energetics ◽

Adsorption Processing ◽

User Friendly

Material characterisation through adsorption is a widely-used laboratory technique. The isotherms obtained through volumetric or gravimetric experiments impart insight through their features but can also be analysed to determine material characteristics such as specific surface area, pore size distribution, surface energetics, or used for predicting mixture adsorption. The pyGAPS (python General Adsorption Processing Suite) framework was developed to address the need for high-throughput processing of such adsorption data, independent of the origin, while also being capable of presenting individual results in a user-friendly manner. It contains many common characterisation methods such as: BET and Langmuir surface area, t and α plots, pore size distribution calculations (BJH, Dollimore-Heal, Horvath-Kawazoe, DFT/NLDFT kernel fitting), isosteric heat calculations, IAST calculations, isotherm modelling and more, as well as the ability to import and store data from Excel, CSV, JSON and sqlite databases. In this work, a description of the capabilities of pyGAPS is presented. The code is then be used in two case studies: a routine characterisation of a UiO-66(Zr) sample and in the processing of an adsorption dataset of a commercial carbon (Takeda 5A) for applications in gas separation.

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