scholarly journals The Characteristics of Swelling Pressure for Superabsorbent Polymer and Soil Mixtures

Materials ◽  
2020 ◽  
Vol 13 (22) ◽  
pp. 5071
Author(s):  
Jakub Misiewicz ◽  
Arkadiusz Głogowski ◽  
Krzysztof Lejcuś ◽  
Daria Marczak
Keyword(s):  
Soil Structure ◽  
Water Retention ◽  
Swelling Pressure ◽  
Coarse Sand ◽  
Loamy Sand ◽  
Superabsorbent Polymer ◽  
Soil Water Retention ◽  
Proposed Model ◽  
Soil Mixtures ◽  
Time Required

Superabsorbent polymers (SAPs) are used in agriculture and environmental engineering to increase soil water retention. Under such conditions, the swelling pressure of the SAP in soil affects water absorption by SAP, and soil structure. The paper presents the results of swelling pressure of three cross-linked copolymers of acrylamide and potassium acrylate mixed at the ratios of 0.3%, 0.5% and 1.0% with coarse sand and loamy sand. The highest values of swelling pressure were obtained for the 1% proportion, for coarse sand (79.53 kPa) and loamy sand (78.23 kPa). The time required to reach 90% of swelling pressure for each type of SAP differs. Samples of coarse sand mixed with SAP K2 in all concentrations reached 90% of total swelling pressure in 100 min, while the loamy sand mixtures needed only about 60 min. The results were the basis for developing a model for swelling pressure of the superabsorbent and soil mixtures, which is a fully stochastic model. The conducted research demonstrated that the course of pressure increase depends on the available pore capacity and the grain size distribution of SAPs. The obtained results and the proposed model may be applied everywhere where mixtures of SAPs and soils are used to improve plant vegetation conditions.

scholarly journals Biochar Amended Soils and Water Systems: Investigation of Physical and Structural Properties

2021 ◽  
Vol 11 (24) ◽  
pp. 12108
Author(s):  
Giorgio Baiamonte ◽  
Giuseppina Crescimanno ◽  
Francesco Parrino ◽  
Claudio De Pasquale
Keyword(s):  
Soil Water ◽  
Structural Properties ◽  
Water Retention ◽  
Waste Treatment ◽  
Aggregate Stability ◽  
Application Rate ◽  
Loamy Sand ◽  
Soil Water Retention ◽  
Biomass Waste ◽  
Bet Analysis

There are significant regional differences in the perception of the problems posed by global warming, water/food availability and waste treatment recycling procedures. The study illustrates the effect of application of a biochar (BC) from forest biomass waste, at a selected application rate, on water retention, plant available water (PAW), and structural properties of differently standard textured soils, classified as loamy sand, loam and clay. The results showed that soil water retention, PAW, and aggregate stability were significantly improved by BC application in the loamy sand, confirming that application of BC to this soil was certainly beneficial and increased the amount of macropores, storage pores and residual pores. In the loam, BC partially improved water retention, increasing macroporosity, but decreased the amount of micropores and improved aggregate stability and did not significantly increase the amount of PAW. In the clay, the amount of PAW was increased by BC, but water retention and aggregate stability were not improved by BC amendment. Results of the BET analysis indicated that the specific surface area (BET-SSA) increased in the three soils after BC application, showing a tendency of the BET-SSA to increase at increasing PAW. The results obtained indicated that the effects of BC application on the physical and structural properties of the three considered soils were different depending on the different soil textures with a BET-SSA increase of 950%, 489%, 156% for loamy sand, loam and clay soil respectively. The importance of analysing the effects of BC on soil water retention and PAW in terms of volumetric water contents, and not only in terms of gravimetric values, was also evidenced.

Relating soil structure and hydrophysical characteristics to aerobic and anaerobic soil respiration

2020 ◽  
Author(s):  
Teamrat Ghezzehei ◽  
Jennifer Alvarez ◽  
Yocelyn Villa ◽  
Rebecca Ryals
Keyword(s):  
Organic Matter ◽  
Soil Moisture ◽  
Soil Water ◽  
Soil Structure ◽  
Water Retention ◽  
Water Retention Curve ◽  
Soil Water Retention Curve ◽  
Soil Water Retention ◽  
Retention Curve ◽  
Aerobic And Anaerobic

<p>The dynamics of soil organic matter is strongly controlled by the hydrophysical environmental factors, including motility, aqueous diffusivity of substrates, gaseous diffusivity, and energetic constraints on microbial physiology. The relationships among these physical factors depend on soil moisture and the architecture of the soil pores. In this regard, the soil water retention curve can serve as a macroscopic signature of pore-size distribution. Therefore, the sensitivity of aerobic and anaerobic microbial activity must be closely associated with the shape of the soil water retention curve. The soil water retention curve is, in turn, strongly dependent on soil texture and structure. Here, we present a physically-based model of aerobic and anaerobic microbial respiration rates. We also present a novel experimental technique for the characterization of the soil-moisture sensitivity of soil microbial activity. The proposed experimental and modeling approaches allow direct coupling of the fate soil organic matter with the nature of soil structure.</p>

Soil Water Retention in the Semiarid Region of Brazil

2018 ◽  
Vol 10 (9) ◽  
pp. 105
Author(s):  
Antonio Carlos da Silva ◽  
Jeane Cruz Portela ◽  
Rafael Oliveira Batista ◽  
Rutilene Rodrigues da Cunha ◽  
Joaquim Emanuel Fernandes Gondim ◽  
...  
Keyword(s):  
Soil Structure ◽  
Water Retention ◽  
Field Capacity ◽  
Water Retention Curve ◽  
Soil Water Retention ◽  
Retention Curve ◽  
Available Water ◽  
Permanent Wilting Point ◽  
Physical Attributes ◽  
Wilting Point

From the physics point of view, soil structure is a dynamic attribute that is affected by genetic conditions and anthropogenic changes and requires an integrated approach. Soil water retention curve is one of the main tools used in soil structure evaluations. The objective of this work was to evaluate the structural and chemical attributes of soils of different classes and agroecosystems in the Terra de Esperança Settlement (Governador Dix Sept Rosado, Rio Grande do Norte, Brazil) to distinguish these environments. Disturbed and undisturbed soil samples were collected in horizons of 10 soil profiles of the soil classes: Cambissolo Háplico (Haplustepts), Latossolo Vermelho-Amarelo (Eutrustox), Chernossolo Rêndzico (Calciustolls), and Neossolo Flúvico (Usticfluvents). The soil physical attributes evaluated were granulometry, soil density, total porosity, aeration porosity, macroporosity, microporosity, field capacity, permanent wilting point, available water, and water retention curve. The results were expressed in averages of four replicates per horizon (in laboratory) by multivariate analysis, which detected the most sensitive attributes for the distinction of the environments. The soil physical attributes of the different classes and its inorganic fractions, especially silt and clay, were determinant to distinguish the environments; they affected the microporosity; aeration porosity; and available water. The source material of the Chernossolo Rêndzico, which is rich in calcium and magnesium, affected its physical attributes, characterized by the predominance of the silt fraction. Clay was the determinant fraction of the Cambissolo Háplico, and Neossolo Flúvico; and the sand fraction on the surface layer, and clay fraction in the Bw horizon were determinant of the Latossolo Vermelho-Amarelo. The more expressive physical attributes were soil density, sand content, macroporosity (Latossolo Vermelho-Amarelo), microporosity, field capacity, available water, permanent wilting point, total organic carbon, mass-based moisture, volume-based moisture, clay, aeration porosity (Cambissolo Háplico, and Neossolo Flúvico), and silt (Chernossolo Rêndzico).

Impact of regression methods on improved effects of soil structure on soil water retention estimates

2015 ◽  
Vol 525 ◽  
pp. 598-606 ◽  
Author(s):  
Phuong Minh Nguyen ◽  
Jan De Pue ◽  
Khoa Van Le ◽  
Wim Cornelis
Keyword(s):  
Soil Water ◽  
Soil Structure ◽  
Water Retention ◽  
Soil Water Retention ◽  
Regression Methods

Using categorical soil structure information to improve soil water retention estimates of tropical delta soils

Soil Research ◽  
2014 ◽  
Vol 52 (5) ◽  
pp. 443 ◽  
Author(s):  
Phuong Minh Nguyen ◽  
Khoa Van Le ◽  
Wim M. Cornelis
Keyword(s):  
Soil Water ◽  
Soil Structure ◽  
Water Retention ◽  
Structural Information ◽  
Mekong Delta ◽  
Pedotransfer Functions ◽  
Organic Carbon Content ◽  
Structural Development ◽  
Soil Water Retention ◽  
Structure Information

Models of soil water and solute transport require input data of soil hydraulic properties (e.g. soil water retention and hydraulic conductivity curves). Lack of such data, especially in tropical delta regions, has usually been the main constraint for the application of simulation models. Direct field or laboratory measurement of soil water retention is costly, laborious and time-consuming; therefore, indirect estimation from other easily measured soil properties has received great interest. However, indirect estimates are often unreliable. In this study, we hypothesise that including basic descriptive information of soil structure such as aspect of presence or absence of pedality can improve the prediction of the soil water retention characteristic (SWRC). Stepwise multiple linear regression was used to develop point pedotransfer functions (PTFs) to estimate soil water retention at eight pressure potentials (e.g. –1, –3, –6, –10, –20, –34, –100, –1500 kPa). Soil structural information was exploited as a preliminary grouping criterion to test our hypothesis. Soil samples were taken from 160 horizons distributed along the Mekong Delta, Vietnam. The results reveal that SWRC of tropical Mekong Delta soils could be satisfactorily estimated by typical predictors of PTFs (e.g. soil texture, organic carbon content and bulk density). Moreover, incorporating soil structure in developing PTFs did improve the prediction accuracy of SWRC, especially in the wet moisture range. Plastic limit was found to be a promising predictor for SWRC-PTFs of soils having a given degree of structural development.

Prediction of the variation of swelling pressure and one-dimensional heave of expansive soils with respect to suction using the soil-water retention curve as a tool

2016 ◽  
Vol 53 (8) ◽  
pp. 1213-1234 ◽  
Author(s):  
Hongyu Tu ◽  
Sai K. Vanapalli
Keyword(s):  
Soil Water ◽  
Water Retention ◽  
Expansive Soils ◽  
Swelling Pressure ◽  
Water Retention Curve ◽  
Soil Water Retention Curve ◽  
Soil Water Retention ◽  
Retention Curve ◽  
One Dimensional ◽  
Oedometer Tests

The one-dimensional (1-D) potential heave (or swell strain) of expansive soil is conventionally estimated using the swelling pressure and swelling index values that are determined from different types of oedometer test results. The swelling pressure of expansive soils is typically measured at saturated condition from oedometer tests. The experimental procedures of oedometer tests are cumbersome as well as time-consuming for use in conventional geotechnical engineering practice and are not capable of estimating heave under different stages of unsaturated conditions. To alleviate these limitations, semi-empirical models are proposed to predict the variation of swelling pressure of both compacted and natural expansive soils with respect to soil suction using the soil-water retention curve (SWRC) as a tool. An empirical relationship is also suggested for estimating the swelling index from plasticity index values, alleviating the need for conducting oedometer tests. The predicted swelling pressure and estimated swelling index are then used to estimate the variation of 1-D heave with respect to suction for expansive soils by modifying Fredlund’s 1983 equation. The proposed approach is validated for eight field sites from six countries — namely, Saudi Arabia, Australia, Canada, China, USA, and UK — and on six different compacted expansive soils from USA.

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