Titre de série :	Technical Bulletins (New series), 6
Titre :	Root water update model depending on soil water pressure head and maximum extraction rate
Type de document :	texte imprimé
Auteurs :	Hoogland, J. C. ; Feddes, R. A. ; Belmans, C.
Mention d'édition :	Institute for Land and Water Management Research
Editeur :	Institute for Land and water Management Research
Année de publication :	1981
ISBN/ISSN/EAN :	CI-04950
Note générale :	Many present day models describing water uptake by root system are based on an analogy with ohm's law. These models require rather detailed information about root distribution, root densities, conductivities of the soil-root system, soil and plant resistances, etc. Often these parameters vary with type of soil and, also, with defth and time. A rather simple approach has been proposed by Feddes, Kowalik and Zaradny (1978). They compute root water extraction at the various defth depending on potential transpiration rate, rooting depth and the local prevailing soil water presure head. In this paper a modification is proposed in such a way that the maximum root water extraction is taken to be a decreasing function with depth. this functions starts at the soil surface with a value derived from literature data.
Langues :	Anglais (eng)
Mots-clés :	Eau souterraine  Pression  Taux d'extraction
Index. décimale :	551.49 Eaux souterraines
Résumé :	Many present day models describing water uptake by root system are based on an analogy with ohm's law. These models require rather detailed information about root distribution, root densities, conductivities of the soil-root system, soil and plant resistances, etc. Often these parameters vary with type of soil and, also, with defth and time. A rather simple approach has been proposed by Feddes, Kowalik and Zaradny (1978). They compute root water extraction at the various defth depending on potential transpiration rate, rooting depth and the local prevailing soil water presure head. In this paper a modification is proposed in such a way that the maximum root water extraction is taken to be a decreasing function with depth. this functions starts at the soil surface with a value derived from literature data.
Note de contenu :	Many present day models describing water uptake by root system are based on an analogy with ohm's law. These models require rather detailed information about root distribution, root densities, conductivities of the soil-root system, soil and plant resistances, etc. Often these parameters vary with type of soil and, also, with defth and time. A rather simple approach has been proposed by Feddes, Kowalik and Zaradny (1978). They compute root water extraction at the various defth depending on potential transpiration rate, rooting depth and the local prevailing soil water presure head. In this paper a modification is proposed in such a way that the maximum root water extraction is taken to be a decreasing function with depth. this functions starts at the soil surface with a value derived from literature data.

Technical Bulletins (New series), 6. Root water update model depending on soil water pressure head and maximum extraction rate [texte imprimé] / Hoogland, J. C. ; Feddes, R. A. ; Belmans, C.  . -  Institute for Land and Water Management Research . - Institute for Land and water Management Research, 1981.
ISSN : CI-04950
Many present day models describing water uptake by root system are based on an analogy with ohm's law. These models require rather detailed information about root distribution, root densities, conductivities of the soil-root system, soil and plant resistances, etc. Often these parameters vary with type of soil and, also, with defth and time. A rather simple approach has been proposed by Feddes, Kowalik and Zaradny (1978). They compute root water extraction at the various defth depending on potential transpiration rate, rooting depth and the local prevailing soil water presure head. In this paper a modification is proposed in such a way that the maximum root water extraction is taken to be a decreasing function with depth. this functions starts at the soil surface with a value derived from literature data.
Langues : Anglais (eng)

Mots-clés :	Eau souterraine  Pression  Taux d'extraction
Index. décimale :	551.49 Eaux souterraines
Résumé :	Many present day models describing water uptake by root system are based on an analogy with ohm's law. These models require rather detailed information about root distribution, root densities, conductivities of the soil-root system, soil and plant resistances, etc. Often these parameters vary with type of soil and, also, with defth and time. A rather simple approach has been proposed by Feddes, Kowalik and Zaradny (1978). They compute root water extraction at the various defth depending on potential transpiration rate, rooting depth and the local prevailing soil water presure head. In this paper a modification is proposed in such a way that the maximum root water extraction is taken to be a decreasing function with depth. this functions starts at the soil surface with a value derived from literature data.
Note de contenu :	Many present day models describing water uptake by root system are based on an analogy with ohm's law. These models require rather detailed information about root distribution, root densities, conductivities of the soil-root system, soil and plant resistances, etc. Often these parameters vary with type of soil and, also, with defth and time. A rather simple approach has been proposed by Feddes, Kowalik and Zaradny (1978). They compute root water extraction at the various defth depending on potential transpiration rate, rooting depth and the local prevailing soil water presure head. In this paper a modification is proposed in such a way that the maximum root water extraction is taken to be a decreasing function with depth. this functions starts at the soil surface with a value derived from literature data.