scholarly journals Estimation of Soil-Water Characteristic Curve for Cohesive Soils with Methylene Blue Value

2018 ◽  
Vol 2018 ◽  
pp. 1-7 ◽  
Author(s):  
Junhui Zhang ◽  
Junhui Peng ◽  
Yejuan Chen ◽  
Jue Li ◽  
Feng Li
Keyword(s):  
Methylene Blue ◽  
Soil Water ◽  
Estimation Method ◽  
Degree Of Saturation ◽  
Cohesive Soils ◽  
Regression Equations ◽  
Plate Test ◽  
Pressure Plate ◽  
Methylene Blue Value ◽  
Fitting Parameters

This study described a new methylene blue test to measure the methylene blue value (MBV) for 15 cohesive soils and established the relationship between MBV and plasticity index (PI) and between MBV and percent passing No. 200 sieve (P200), respectively. Thereafter, the soil-water characteristic curves (SWCCs) for 15 cohesive soils based on Fredlund and Xing’s model were generated by the pressure plate test. Then, regression equations for determining the four fitting parameters in a previously developed SWCC equation by using the measured MBV were utilized to generate the SWCC for the cohesive soils. At the same time, the slope parameter, bf, in the SWCC equations was found to be associated with the moisture susceptibility of cohesive soils. A higher bf value indicates that the material is more moisture susceptible. In addition, a lower MBV/PI/P200 shows a lower suction at the same degree of saturation; on the other hand, a higher MBV/PI/P200 presents a higher suction. Therefore, the moisture-holding capacity of cohesive soils increases with increasing MBV, PI, and P200. Finally, the proposed estimation method was validated by a comparison between the four determined fitting parameters from MBV and the pressure plate test.

scholarly journals Effects of Irrigation Regimes on Yield and Water Use by Sweetpotato

1990 ◽  
Vol 115 (5) ◽  
pp. 712-714 ◽  
Author(s):  
Doyle A. Smittle ◽  
Melvin R. Hall ◽  
James R. Stansell
Keyword(s):  
Water Stress ◽  
Soil Water ◽  
Water Use ◽  
Ipomoea Batatas ◽  
Regression Equations ◽  
Marketable Yield ◽  
Water Regimes ◽  
Soil Water Tension ◽  
Water Tension ◽  
Storage Root Development

Sweetpotatoes [Ipomoea batatas (L.) Lam cv. Georgia Jet] were grown on two soil types in drainage lysimeters under controlled soil water regimes during 1982 and 1983. Water regimes consisted of irrigating the sweetpotatoes throughout growth when soil water tension at 23 cm exceeded 25, 50, or 100 kPa or by allowing a 100-kPa water stress before root enlargement, during early root enlargement, or throughout root enlargement. Water use and marketable yields were greater when sweetpotatoes were grown on a Tifton loamy sand (fine loamy, siliceous, thermic, Plinthitic Paleudult) than when grown on a Bonifay sand (loamy, siliceous, thermic, Grossarenic, Plinthitic Paleudult). Water use, marketable yield, and yield of U.S. #1 grade roots generally decreased when soil water tensions exceeded 25 kPa before irrigation, although soil water stress of 100 kPa during storage root development did not significantly affect yield. Regression equations are provided to describe the relationships of water use to plant age and to compute daily evapotranspiration: pan evaporation ratios (crop factors) for sweetpotatoes irrigated at 25, 50, and 100 kPa of soil water tension.

scholarly journals Comparative value of various methods of approximating the permanent wilting percentage

1969 ◽  
Vol 36 (2) ◽  
pp. 122-133
Author(s):  
M. A. Lugo López
Keyword(s):  
Puerto Rico ◽  
Organic Matter Content ◽  
Clay Content ◽  
Matter Content ◽  
Regression Equations ◽  
Accurate Approximation ◽  
Time Saving ◽  
Laboratory Equipment ◽  
Pressure Plate ◽  
Humid Region

Very accurate estimations of the permanent wilting percentage can be obtained for soils of all regions of Puerto Rico by use of regression equations based on the hygroscopic coefficient. Reliable estimates can also be obtained for humid-region soils by using the clay content as a basis. Attempts to correlate permanent wilting-percentage values with moisture equivalents and organic-matter content did not give such satisfactory results. The 15-atmosphere percentage as determined by using pressure plates gives an accurate approximation of permanent wilting-percentage values. It is time-saving, but initial expense in laboratory equipment is rather high. This approach is to be preferred whenever feasible. A regression equation is given relating pressure-plate values to the permanent wilting percentage. Whenever less precise estimates are acceptable and time is not a factor, advantage should be taken of the established correlation between the hygroscopic coefficient and the permanent wilting percentage.

scholarly journals INFLUÊNCIA DA TEXTURA E PROFUNDIDADE DO SOLO NA CALIBRAÇÃO DA SONDA DE NÊUTRONS

Irriga ◽  
1998 ◽  
Vol 3 (1) ◽  
pp. 6-12
Author(s):  
Reginaldo Ferreira Santos ◽  
Reimar Carlesso
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Soil Texture ◽  
Correlation Coefficients ◽  
Regression Equations ◽  
Transparent Plastic ◽  
Neutron Probe ◽  
Calibration Curves ◽  
Santa Maria

INFLUÊNCIA DA TEXTURA E PROFUNDIDADE DO SOLO NA CALIBRAÇÃO DA SONDA DE NÊUTRONS   Reginaldo Ferreira SantosDepartamento de Engenharia Rural - UNESP, CP: 237 - CEP:18603 970, Botucatu, SP Reimar CarlessoDepartamento de. Engenharia da Universidade Federal de Santa Maria, - UFSM, Campus Universitário, CEP: 97119 900, Santa Maria - RS  1 RESUMO A sonda de nêutrons é um equipamento usado na determinação do conteúdo de água do solo baseado no espalhamento e atenuação de nêutrons rápidos. Para tanto, há necessidade de calibração no campo e, conseqüentemente, verificar a influência da textura e da profundidade do solo e determinar as curvas de calibração em relação ao conteúdo de umidade. O trabalho foi desenvolvido na Universidade Federal de Santa Maria em um conjunto de lisímetros, protegidos das precipitações pluviométricas com plástico transparente. Foram usados três solos de diferentes texturas e quatro repetições e em três profundidades (10, 30 e 50 cm) a partir da superfície do solo. Foram determinadas as equações de regressão lineares entre as contagens propiciadas pela sonda e o conteúdo de umidade do solo respectivos pelo método gravimétrico. Os resultados demonstraram que houve interferência da textura e da profundidade do solo, analisados conjuntamente, nas curvas de calibração, sendo que os valores observados e os estimados variaram entre 0,02 e 0,06 cm3/ cm3 do conteúdo de água do solo e os coeficientes de correlação foram 0,86, 0,95 e 0,89 para os solos de textura argilosa, franco-argilo-siltoso e franco-arenoso, respectivamente. Já para os fatores textura e profundidade dos solos, analisados separadamente, as diferenças entre os valores observados no campo e os estimados, variaram entre 0,0 e 0,02 cm31cm3 do conteúdo de água do solo e apresentaram coeficientes de correlação entre 0,97 e 1,0. UNITERMOS: sonda de nêutrons. umidade do solo. textura e profundidade do solo  SANTOS, R.F., CARLESSO, R. Soil texture and depth influence on the neutron probe calibration   2 SUMMARY  The neutron probe is an equipment used on determination of the soil water content, based on the fast neutron attenuation. Therefore, there is a calibration need in the field and, consequently, to verify the soil texture and depth influence for to determining the calibration curves in relation to the water content. The study was developed at Santa Maria's Federal University in a lisímeter group, protected from the rains with transparent plastic. Three different soil textures, three depths (10, 30 and 50 cm from the soil surface) and four replicates were used. Linear regression equations between neutron counts and soil water contents were made. The results showed that there was interference of the texture and depth of the soil, analyzed jointly, on the calibration curves, and the observed and estimated values varied from 0,02 to 0,06 cm3 / cm3 of the soil water content and the correlation coefficients were 0,86, 0,95 and 0,89 for clayay, franc-silt-clayay and franc-sandy, respectively. For soil texture and depth, analyzed separately, the differences among the values observed in the field and the estimated ones, varied from 0,0 to 0,02 cm3/cm3 soil water content and presented correlation coefficients between 0,97 and 1,0. KEYWORDS: neutron probe, soil water content, soil texture and depth.

scholarly journals Soil Water Characteristic Curve Using Volumetric Pressure Plate Extractor Incorporated with TDR System

2015 ◽  
Vol 31 (8) ◽  
pp. 17-28
Author(s):  
Young-Seok Jung ◽  
Hee-Dong Sa ◽  
Seonghun Kang ◽  
Se-Boong Oh ◽  
Jong-Sub Lee
Keyword(s):  
Soil Water ◽  
Characteristic Curve ◽  
Pressure Plate ◽  
Soil Water Characteristic Curve

Soil-water characteristics of compacted sandy and cemented soils with and without vegetation

2015 ◽  
Vol 52 (9) ◽  
pp. 1331-1344 ◽  
Author(s):  
W.M. Yan ◽  
Guanghui Zhang
Keyword(s):  
Soil Water ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Rapid Development ◽  
Characteristic Curve ◽  
Degree Of Saturation ◽  
Material Density ◽  
Water Characteristics ◽  
Field And Laboratory Conditions ◽  
Humidity Monitoring

Experiments were undertaken to study the soil-water characteristics of compacted sandy soil (SS) and cemented soil (CS) in field and laboratory conditions. The influence of vegetation and material density on the development of negative pore-water pressure (PWP) and degree of saturation (Sr) in the studied materials was investigated. The field planting experiments demonstrated a promising survival rate of Schefflera heptaphylla in both types of material, while the (SS) promoted better growth of the seedlings than the cemented one. In the field study, PWP and Sr of the compacted SS responded noticeably and promptly to natural drying–wetting cycles. However, the responses in the CS were relatively mild. When subjected to the same drying–wetting cycles, PWP responded more slowly and to a smaller magnitude compared with that of the uncemented counterpart. In addition, Sr changed little in CS. An increase in the density of the SS promoted rapid development of negative PWP, while an opposite trend was observed for CS. Attempts have been made to explain the observations from the perspectives of material permeability and change in water content during a drying period in both soil types. Furthermore, in SS, the development of PWP (with a measurement limit of −90 kPa) was minimally affected by the presence of vegetation, while vegetation noticeably helped the development of negative PWP in CS. Bounds of the soil-water characteristic curve (SWCCs) of the studied materials were presented based on estimates from the drying and wetting scanning curves derived from the field monitoring. A corresponding laboratory study was carried out in an environmental chamber with controllable temperature and humidity. Monitoring results from the laboratory agreed qualitatively with those obtained from the field.

scholarly journals Correlation between Plasticity Index and Methylene Blue Value to Determining Soil Classification

2020 ◽  
Vol 852 ◽  
pp. 012012
Author(s):  
Andrias Suhendra Nugraha ◽  
Paulus P. Rahardjo ◽  
Bigman M. Hutapea ◽  
Imam A. Sadisun
Keyword(s):  
Methylene Blue ◽  
Soil Classification ◽  
Plasticity Index ◽  
Methylene Blue Value
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