Water Retention Equations and Their Relationship to Soil Organic Matter and Particle Size Distribution for Disturbed Samples

Abstract

DeJouc, R., Cerrapset-t-, C. A. eNlNrcuolercuur. W. 1983. Waterretention equations and their relationship to soil organic matter and particle size distribution for disturbed samples. Can. J. Soil Sci. 63 291-302. Functional relationships between soil water content and water suction were examined and related to textural and organic carbon content data. Soil water retention curves between 5 and 10 000 kPa were determined on disturbed samples of 18 soils representing various soil Great Groups in the Canadian prairies. The best fit was obtained with a two-straight-line regression model. Correlation and regression analysis showed that texture was the main soil property influencing the shape and position of the water retention curve. Organic matter influenced primarily the water content at which a break in the curve occurred. Soil zone and cultivation historv had little effect on water retention. (Mav 1983)

Water infiltration and hydraulic conductivity in sandy cambisols: impacts of forest transformation on soil hydrological properties

“…This is because soil organic matter minimizes soil compaction, provides pores, and is able to store a quantity of water which corresponds to a multiple of the organic matter's weight (De Jong et al 1983;Hudson 1994;Emerson 1995). At sites with sandy substrates, the soil organic matter is the main storage component for water.…”

Testing Some Pedo-Transfer Functions (PTFs) in Apulia Region. Evaluation on the Basis of Soil Particle Size Distribution and Organic Matter Content for Estimating Field Capacity and Wilting Point

“…content greater than 1.9% and than 2%, respectively; 2) model II in Loamy soils and in loamy and tendency silty soils with O.M. between 1.0 and 1.9%; 3) model III (De Jong et al, 1983) in Clayey soils; 4) model IV (Rawls and Brakensiek, 1985) in Silty clay, Sandy clay, Clay loam, Silty clay loam, Sandy clay loam soils and generally in tendency clayey soils with whatever O.M. content and in tendency sandy soils with O.M.…”

“…Jong et al, 1983; in dm for Rawls andBrakensiek, 1985 andVereecken et al, 1989; in KPa for Saxton et al, 1986); h b : air entry potential; λ: pore size distribution index; θ r : residual water content; θ s : saturation water content; it is assumed to be equal to porosity (Ø) which is:…”

“…In a previous work carried out by Buccigrossi et al, (still in press) the applicability of six literature' PTFs (Gupta and Larson, 1979, b;Rawls et al, 1982;De Jong et al, 1983;Rawls and Brakensiek, 1985;Saxton et al, 1986;Vereecken et al, 1989) has been evaluated in soils of Apulia Region (361 soil samples deriving from 185 pedons) regardless of their particle size distribution and organic matter content. The best accuracy of soil moisture predictions has been obtained: at the Field Capacity (-33 kPa) with Rawls PTF that shows the lowest values of WSEE (weighted standard error of estimate), MD (mean deviation) and RMSD (root mean squared deviation) (0.044, -0.007 e 0.059 m 3 water m -3 soil, respectively); at the Wilting Point (-1500 kPa) with Rawls and Brakensiek model with values of WSEE, MD and RMSD of 0.034, -0.016 and 0.046 m 3 water m -3 soil, respectively.…”

“…To measure field capacity and wilting point is expensive, laborious and is time consuming, so, frequently, matemathic models, called pedo-transfer functions (PTFs) are utilized to estimate field capacity and wilting point through physical-chemical soil characteristics. Six PTFs have been evaluated (Gupta and Larson, 1979;Rawls et al, 1982;De Jong et al, 1983;Rawls and Brakensiek, 1985;Saxton et al, 1986;Vereecken et al, 1989) by comparing measured soil moisture values with estimated ones at soil water matric potential of -33 and -1500 kPa. Soil samples were collected (361) …”