Estimating crop coefficients from fraction of ground cover and height
Autor(a) principal: | |
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Data de Publicação: | 2009 |
Outros Autores: | |
Tipo de documento: | Artigo |
Idioma: | eng |
Título da fonte: | Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos) |
Texto Completo: | http://hdl.handle.net/10400.5/9041 |
Resumo: | The FAO-56 procedure for estimating the crop coefficient Kc as a function of fraction of ground cover and crop height has been formalized in this study using a density coefficient Kd. The density coefficient is multiplied by a basal Kc representing full cover conditions, Kcb full, to produce a basal crop coefficient that represents actual conditions of ET and vegetation coverage when the soil surface is dry. Kcb full is estimated primarily as a function of crop height. Kcb full can be adjusted for tree crops by multiplying by a reduction factor (Fr) estimated using a mean leaf stomatal resistance term. The estimate for basal crop coefficient, Kcb, is further modified for tree crops if some type of ground-cover exists understory or between trees. The single (mean) crop coefficient is similarly estimated and is adjusted using a Ksoil coefficient that represents background evaporation from wet soil. The Kc estimation procedure was applied to the development periods for seven vegetable crops grown in California. The average root mean square error between estimated and measured Kc was 0.13. The Kc estimation procedure was also used to estimate Kc during midseason periods of horticultural crops (trees and vines) reported in the literature. Values for mean leaf stomatal resistance and the Fr reduction factor were derived that explain the literature Kc values and that provide a consistent means to estimate Kc over a broad range of fraction of ground cover |
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Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos) |
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Estimating crop coefficients from fraction of ground cover and heightcrop coefficientsground covercrop heightThe FAO-56 procedure for estimating the crop coefficient Kc as a function of fraction of ground cover and crop height has been formalized in this study using a density coefficient Kd. The density coefficient is multiplied by a basal Kc representing full cover conditions, Kcb full, to produce a basal crop coefficient that represents actual conditions of ET and vegetation coverage when the soil surface is dry. Kcb full is estimated primarily as a function of crop height. Kcb full can be adjusted for tree crops by multiplying by a reduction factor (Fr) estimated using a mean leaf stomatal resistance term. The estimate for basal crop coefficient, Kcb, is further modified for tree crops if some type of ground-cover exists understory or between trees. The single (mean) crop coefficient is similarly estimated and is adjusted using a Ksoil coefficient that represents background evaporation from wet soil. The Kc estimation procedure was applied to the development periods for seven vegetable crops grown in California. The average root mean square error between estimated and measured Kc was 0.13. The Kc estimation procedure was also used to estimate Kc during midseason periods of horticultural crops (trees and vines) reported in the literature. Values for mean leaf stomatal resistance and the Fr reduction factor were derived that explain the literature Kc values and that provide a consistent means to estimate Kc over a broad range of fraction of ground coverSpringerRepositório da Universidade de LisboaAllen, Richard G.Pereira, L.S.2015-07-22T13:20:02Z20092009-01-01T00:00:00Zinfo:eu-repo/semantics/publishedVersioninfo:eu-repo/semantics/articleapplication/pdfhttp://hdl.handle.net/10400.5/9041eng"Irrigation Science". ISSN 0342-7188. 28 (2009) 17-3410.1007/s00271-009-0182-zinfo:eu-repo/semantics/openAccessreponame:Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)instname:Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informaçãoinstacron:RCAAP2024-11-20T19:05:29Zoai:repositorio.ul.pt:10400.5/9041Portal AgregadorONGhttps://www.rcaap.pt/oai/openairemluisa.alvim@gmail.comopendoar:71602024-11-20T19:05:29Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos) - Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informaçãofalse |
dc.title.none.fl_str_mv |
Estimating crop coefficients from fraction of ground cover and height |
title |
Estimating crop coefficients from fraction of ground cover and height |
spellingShingle |
Estimating crop coefficients from fraction of ground cover and height Allen, Richard G. crop coefficients ground cover crop height |
title_short |
Estimating crop coefficients from fraction of ground cover and height |
title_full |
Estimating crop coefficients from fraction of ground cover and height |
title_fullStr |
Estimating crop coefficients from fraction of ground cover and height |
title_full_unstemmed |
Estimating crop coefficients from fraction of ground cover and height |
title_sort |
Estimating crop coefficients from fraction of ground cover and height |
author |
Allen, Richard G. |
author_facet |
Allen, Richard G. Pereira, L.S. |
author_role |
author |
author2 |
Pereira, L.S. |
author2_role |
author |
dc.contributor.none.fl_str_mv |
Repositório da Universidade de Lisboa |
dc.contributor.author.fl_str_mv |
Allen, Richard G. Pereira, L.S. |
dc.subject.por.fl_str_mv |
crop coefficients ground cover crop height |
topic |
crop coefficients ground cover crop height |
description |
The FAO-56 procedure for estimating the crop coefficient Kc as a function of fraction of ground cover and crop height has been formalized in this study using a density coefficient Kd. The density coefficient is multiplied by a basal Kc representing full cover conditions, Kcb full, to produce a basal crop coefficient that represents actual conditions of ET and vegetation coverage when the soil surface is dry. Kcb full is estimated primarily as a function of crop height. Kcb full can be adjusted for tree crops by multiplying by a reduction factor (Fr) estimated using a mean leaf stomatal resistance term. The estimate for basal crop coefficient, Kcb, is further modified for tree crops if some type of ground-cover exists understory or between trees. The single (mean) crop coefficient is similarly estimated and is adjusted using a Ksoil coefficient that represents background evaporation from wet soil. The Kc estimation procedure was applied to the development periods for seven vegetable crops grown in California. The average root mean square error between estimated and measured Kc was 0.13. The Kc estimation procedure was also used to estimate Kc during midseason periods of horticultural crops (trees and vines) reported in the literature. Values for mean leaf stomatal resistance and the Fr reduction factor were derived that explain the literature Kc values and that provide a consistent means to estimate Kc over a broad range of fraction of ground cover |
publishDate |
2009 |
dc.date.none.fl_str_mv |
2009 2009-01-01T00:00:00Z 2015-07-22T13:20:02Z |
dc.type.status.fl_str_mv |
info:eu-repo/semantics/publishedVersion |
dc.type.driver.fl_str_mv |
info:eu-repo/semantics/article |
format |
article |
status_str |
publishedVersion |
dc.identifier.uri.fl_str_mv |
http://hdl.handle.net/10400.5/9041 |
url |
http://hdl.handle.net/10400.5/9041 |
dc.language.iso.fl_str_mv |
eng |
language |
eng |
dc.relation.none.fl_str_mv |
"Irrigation Science". ISSN 0342-7188. 28 (2009) 17-34 10.1007/s00271-009-0182-z |
dc.rights.driver.fl_str_mv |
info:eu-repo/semantics/openAccess |
eu_rights_str_mv |
openAccess |
dc.format.none.fl_str_mv |
application/pdf |
dc.publisher.none.fl_str_mv |
Springer |
publisher.none.fl_str_mv |
Springer |
dc.source.none.fl_str_mv |
reponame:Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos) instname:Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informação instacron:RCAAP |
instname_str |
Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informação |
instacron_str |
RCAAP |
institution |
RCAAP |
reponame_str |
Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos) |
collection |
Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos) |
repository.name.fl_str_mv |
Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos) - Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informação |
repository.mail.fl_str_mv |
mluisa.alvim@gmail.com |
_version_ |
1817549448773894144 |