HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Abstract Full Text Free Full Text (PDF) Free Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in ISI Web of Science Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via ISI Web of Science (1) Citing Articles via Google Scholar Google Scholar Articles by Vaz, C. M. P. Articles by Cooper, M. Search for Related Content PubMed Articles by Vaz, C. M. P. Articles by Cooper, M. Agricola Articles by Vaz, C. M. P. Articles by Cooper, M. Related Collections Soil Physics Soil Hydrology Soil Methods/Instrumentation

Validation of the Arya and Paris Water Retention Model for Brazilian Soils

^a Embrapa Agricultural Instrumentation, P.O. Box 741, Sao Carlos, SP, 13560-970, Brazil
^b Univ. of São Paulo, ESALQ-USP, P.O. Box 9, Piracicaba, SP, 13418-900, Brazil
^c Federal Univ. of Santa Maria, 97105-900, Santa Maria, RS, Brazil

View larger version (30K): [in a new window]   Fig. 1. Soil textural classes of the Brazilian data set.

View larger version (16K): [in a new window]   Fig. 2. Frequency distribution of the estimated -values for the 104 soil samples. A total of 1821 -values were obtained because each sample provide up to 20 -values relative to the particle-size segmentation used.

View larger version (17K): [in a new window]   Fig. 3. Dependence of average -values with the (a) sand and (b) clay contents for the Brazilian data sets.

View larger version (43K): [in a new window]   Fig. 4. Dependence of -values with soil water content for two textural groups. The solid line is the best fit with a first-order exponential decay equation.

View larger version (18K): [in a new window]   Fig. 5. Soil water retention curves for two sandy soils, measured and estimated with the Arya and Paris (AP) model using constant and variable (Fig. 4) approaches. The continuous curves are obtained by fitting the van Genuchten (1980) equation to the discrete AP estimated values (20 points for the soil particle size segmentation used).

View larger version (18K): [in a new window]   Fig. 6. Soil water retention curves for two clay soils, measured and estimated with the Arya and Paris (AP) model using constant and variable (Fig. 4) approaches. The continuous curves are obtained by fitting the van Genuchten (1980) equation to the discrete AP estimated values (20 points for the soil particle size segmentation used).

View larger version (40K): [in a new window]   Fig. 7. Soil water content values, measured and estimated with the Arya and Paris (AP) model using constant (a-c) and variable (d) approaches.