Prediction of soil water retention properties after stratification by combining texture, bulk density and the type of horizon

Abstract

. Prediction of soil water retention properties after stratification by combining texture, bulk density and the type of horizon. Soil Use and Management, Wiley, 2008, 24 (4) show that performance of class-PTFs can be similar to the more popular continuous-PTFs. In this study, we compare the performance of PTFs that were derived from a set of 456 horizons collected in France grouped by combinations of texture, bulk density and type of horizon (topsoil and subsoil). The performance of these class-PTFs was validated against water retained at -33 and -1500 kPa. Our results show that the best performance was obtained with 2 class-PTFs that used both texture and bulk density (texture-structural class-PTFs). They showed also that incorporation of horizon type into the PTF did not improve prediction performance. Comparison of performance at -33 and -1500 kPa showed very little difference, thus indicating no bias according to the value of water potential. Finally, the class-PTFs developed are well suited for predicting water retention properties at continental and national scales because only very basic soils data is available at these scales. A map of the available water capacity (AWC) was established for France using the 1:1 000 000 Soil GeographicalDatabase of France and an averaged AWC of 104 mm was computed for France.

Predicting available water of soil from particle-size distribution and bulk density in an oasis–desert transect in northwestern China

“…However, the AW values for silty clay, silty clay loam and silt loam approximated to each other. This is consistent with the report that soils with a high clay fraction showed a high proportion of water unavailable for plants (Al Majou et al, 2008;Ramos et al, 2014).…”

“…Pachepsky et al (2015) comprehensively summarized the trends in PTF development and in input and output data, and methods to build PTFs. Various PTFs are usually given in the form of either a tabulation (Schaap and Leij, 1998;Soet and Stricker, 2003;Al Majou et al, 2008) or continuous functions (Wösten et al, 1999;Bayat et al, 2013;Haghverdi et al, 2015) to predict either a single point on the SWCC (Skaggs et al, 2001;Ramos et al, 2014) or parameters for the entire SWCC (Schaap et al, 2001). For example, the PTFs in the Rosetta program allow the estimation of parameters of van Genuchten equation for describing SWCC (van Genuchten, 1980) using limited (textural classes only) to more extended (texture, bulk density, and one or two water retention points) input data (Schaap et al, 2001).…”

Comparação de dispersantes químicos na análise granulométrica de solos do Estado de Pernambuco

“…A determinação acurada do valor de argila é de extrema importância nos mais diversos ramos da ciência do solo. Em alguns trabalhos (Al Majou et al, 2008;Klein et al, 2010;Medeiros et al, 2014) tem-se utilizado desta propriedade de argila para correlação com outras variáveis de interesse na pesquisa em solos. O intercepto negativo e significativo na relação D2 = f(D1) indicam maior valor de argila quando a amostra é dispersa por D1, frente à dispersão utilizando D2.…”

Talajok víztartó képességét becslő módszerek

“…A megfelelő ptf kiválasztásához TRANTER és munkatársai (2009) a következő eljárást javasolják: a) a ptf kalibrációs adatbázisának független változóira adjuk meg az átlagértékek és a szórások értékeit és vizsgáljuk meg a variancia-kovariancia mátrixukat; b) határozzuk meg a kalibrációs adatbázis kiugró adatait és számítsuk ki a kiugró adatok távolságát az adatbázis számtani átlagától; c) számítsuk ki a Mahalanobis távolságot a ptf kalibrációs adatbázisának számtani átlaga és a vizsgálandó talajminták között; d) amennyiben c > b, ne használjuk a pedotranszfer függvényt. A ptf-ek becslési hatékonyságát és adatigényét több szerző is (RAJKAI & KABOS, 1999;CORNELIS et al, 2001;WÖSTEN et al, 2001;BØRGESEN & SCHAAP, 2005;AL MAJOU et al, 2008) összehasonlította különböző adatbázisokon. Egyöntetű megállapítá-suk, hogy a becslőeljárások pontosságának alapja a kalibrációs adatbázis és becslő adatbázis tulajdonságainak hasonlósága.…”