scholarly journals A Laboratory Device for Continual Measurement of Water Retention and Shrink/Swell Properties during Drying/Wetting Cycles

HortScience ◽  
2011 ◽  
Vol 46 (9) ◽  
pp. 1298-1302 ◽  
Author(s):  
Guifang Qi ◽  
Jean-Charles Michel ◽  
Pascal Boivin ◽  
Sylvain Charpentier
Keyword(s):  
Water Retention ◽  
Inflection Point ◽  
Precise Measurement ◽  
Effective Management ◽  
Drying Process ◽  
Growing Media ◽  
New Apparatus ◽  
Laboratory Device ◽  
Hysteresis Phenomena ◽  
Over Time

The precise measurement of the water retention and shrink/swell properties of growing media or soil over time is important for the effective management of irrigation and fertilization. A new apparatus was developed for simultaneously and continuously measuring the water retention and shrink/swell properties of growing media during several drying/wetting cycles with varying intensities (0↔–5 kPa, 0↔–10 kPa, 0↔–32 kPa). The measurements on slightly decomposed Sphagnum peat showed encouraging results. Regardless of the intensity of drying, water retention and shrink/swell properties are mainly modified after the first drying process, resulting in degradation of density and water retention, whereas these properties are unaffected by the other cycles, even if hysteresis phenomena are always shown to take place. Variations in drying intensity reveal different physical behaviors with an inflection point observed (i.e., a change in physical behavior) for the shrink/swell and water retention curves for the highest intensity tested (from –20 kPa).

scholarly journals Super Absorbent polymers and their Composites for Application in Agriculture

2021 ◽  
Vol 9 (9) ◽  
pp. 665-672
Author(s):  
Aryan Dwivedi
Keyword(s):  
Mechanical Property ◽  
Water Absorption ◽  
Soil Water ◽  
Water Retention ◽  
Hydraulic Parameters ◽  
Dryland Agriculture ◽  
Superabsorbent Polymers ◽  
Over Time

Abstract: In dryland agriculture, Superabsorbent Polymers (SAPs) are popular. However, the mechanical property, repetitive soil water absorption and release, regularly affects the water retention and hydraulic parameters of the soil, and since this property decreases progressively over time, the results of the property appear to be unpredictable. Polymers use to in agriculture field.

Quantifying the pore structure of different biochars and their impacts on the water retention properties of Sphagnum moss growing media

2020 ◽  
Vol 191 ◽  
pp. 96-106 ◽  
Author(s):  
Mika Turunen ◽  
Jari Hyväluoma ◽  
Jaakko Heikkinen ◽  
Riikka Keskinen ◽  
Janne Kaseva ◽  
...  
Keyword(s):  
Pore Structure ◽  
Water Retention ◽  
Sphagnum Moss ◽  
Growing Media ◽  
Water Retention Properties

Incidence and Cumulative Incidence as Supplemental Measures of the Scale of Imprisonment

2017 ◽  
Vol 64 (7) ◽  
pp. 888-916 ◽  
Author(s):  
William Rhodes ◽  
Gerald G. Gaes ◽  
Jeremy Luallen ◽  
Ryan Kling ◽  
Tom Rich ◽  
...  
Keyword(s):  
Administrative Data ◽  
Cumulative Incidence ◽  
Inflection Point ◽  
Estimation Method ◽  
New Method ◽  
Blacks And Whites ◽  
Over Time

Prison growth has primarily been measured as a prevalence over time. We propose cohort-specific supplemental measures: incidence based on the age of first adult admission into prison, and cumulative incidence, based on the proportion of people who will be imprisoned during their lifetime. We present a new estimation method using administrative data. Prior research derived estimates from inmate surveys. The main advantages of this new method are that estimates can be updated every year with little cost and minimal imputation. We present results showing that we have likely reached an inflection point in the growth of cumulative incidence, and the ratio between Blacks and Whites is declining although the disparity is still large—roughly 4.5 to 1.

Implications for coral reef conservation of diver specialization

2006 ◽  
Vol 33 (4) ◽  
pp. 353-363 ◽  
Author(s):  
PHILIP DEARDEN ◽  
MICHELLE BENNETT ◽  
RICK ROLLINS
Keyword(s):  
Management Strategies ◽  
Scuba Diving ◽  
Effective Management ◽  
Client Characteristics ◽  
Reef Management ◽  
Industry Competition ◽  
History Of ◽  
Conservation Activity ◽  
Negative Impacts ◽  
Over Time

One activity with potential to provide a direct incentive for reef conservation is scuba diving. In the absence of effective management, diving can also have negative impacts. This study shows how an understanding of diver specialization can be used to help manage diving and increase its effectiveness as an incentive-driven conservation activity. Surveys were used to assess motivations, satisfactions and dive history of divers in Phuket (Thailand) and categorize divers by degree of specialization. Highly specialized divers were more likely to be on a live-aboard trip than less specialized divers and placed greater importance on the characteristics of the dive itself rather than the trip. Less specialized divers put more emphasis on non-dive characteristics. Satisfaction levels differed significantly among specialization groups in terms of overall satisfaction with the dive experience, satisfactions compared with motivations and satisfactions with specific trip characteristics. Overall there was a decline in satisfaction levels with increasing specialization. These finding are compared to a wildlife tourism model that links impacts with client characteristics and suggests a displacement of specialists by generalists and changes in the limits of acceptable change (LAC) over time. The dive data supported this progression leading to increased industry competition and reduced opportunities to sustain a broad-based dive industry that will act as an incentive-driven mechanism for reef conservation. Specific actions related to reef access and zoning according to a diver opportunity spectrum (DOS), establishing LAC and monitoring programmes, enforcing safety and environmental regulations are suggested to promote a more sustainable approach to dive management. Social science insights can be used to aid reef management strategies and increase the potential for diving to contribute towards reef conservation.

Evaluation of physical properties of several growing media for use in aerial seeding containers

1987 ◽  
Vol 17 (2) ◽  
pp. 165-173 ◽  
Author(s):  
Tanya L. Lennox ◽  
Glen P. Lumis
Keyword(s):  
Water Retention ◽  
Total Porosity ◽  
Linear Increase ◽  
Buffering Capacity ◽  
Tree Seedlings ◽  
Growing Media ◽  
Available Water ◽  
Air Space ◽  
The Media ◽  
Hydrophilic Gel

Several personally blended and commercially prepared growing media were evaluated as potential substrates for coniferous tree seedlings in specialized seeding containers (aerial darts). Water retention curves were developed using a porous pressure plate apparatus. Bark–vermiculite–sand and Ball Growing Mix II retained less water at pressures from 0 to 0.1 MPa than all other media observed. At pressures less than 20 × 10−3 MPa the greatest water retention was in Pro-mix A, while above 33 × 10−3 MPa the greatest water retention was in bark–vermiculite. As the proportion of bark in bark–vermiculite was increased, the air space increased significantly but water retention was unaffected. Addition of a hydrophilic gel to media containing a surfactant significantly increased water retention. The easily available water, water buffering capacity, and air space were unaffected by gel but total porosity increased in some of the media. When the surfactant was excluded the addition of gel at the recommended rate did not significantly increase water retention. As the concentration of gel increased there was an increase in water retention, a linear increase in total porosity, a slight increase in air space, a decrease in easily available water, and no change in water buffering capacity. Media amended with gels of different absorbing capacities retained water similarly, releasing approximately 50% of the absorbed water at pressures less than 10 × 10−3 MPa.

scholarly journals Water retention characteristics of soil bio-amendments used as growing media in pot culture

2012 ◽  
Vol 14 (02) ◽  
pp. 92-97 ◽  
Author(s):  
S.S. Kukal ◽  
Debasish Saha ◽  
Arnab Bhowmik ◽  
R.K. Dubey
Keyword(s):  
Water Retention ◽  
Growing Media ◽  
Retention Characteristics ◽  
Pot Culture

scholarly journals Effect of H2O Activity on Zeolite Formation

Materials ◽  
2020 ◽  
Vol 13 (21) ◽  
pp. 4780
Author(s):  
Claudia Belviso ◽  
Francesco Cavalcante
Keyword(s):  
Liquid Nitrogen ◽  
Sodium Aluminate ◽  
Drying Process ◽  
X Ray Diffraction ◽  
X Ray ◽  
Lta Zeolite ◽  
Zeolite Formation ◽  
Silica Alumina ◽  
Over Time ◽  
Scanning Electron

In an effort to understand the effects of H2O activity on zeolite formation, we have synthesized LTA zeolite using a combination of freezing processes and varying drying temperatures. Sodium aluminate and sodium silicate were used to form LTA zeolite, according to the IZA (International Zeolite Association) protocol. The synthesis steps were modified by adding the precursor frozen process by a rapid liquid nitrogen (−196 °C) treatment or slow conventional freezer treatment (−20 °C). The samples were subsequently sonicated and then dried at 80 °C or 40 °C. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were performed on the samples immediately after the drying process as well as after 2 weeks and 1 month of aging the solid products. The results indicated that LTA zeolite does not form. The silica-alumina precursor after both freezing processes and after being dried at 80 °C showed the presence of sodalite displaying stable behavior over time. Both sets of samples dried at 40 °C and did not show the presence of zeolite immediately after the drying process. However, after 2 weeks, the liquid nitrogen–frozen precursor was characterized by the presence of EMT whereas zeolites never formed in the −20 °C samples. These results suggest that freezing processes differently control the H2O activity during the drying and aging processes in the solid state. Thus, although the precursor chemical composition is the same, the type of zeolite formed is different.

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