Data/hora: 12/06/2024 03:27:53

Biblioteca(s): | Embrapa Hortaliças; Embrapa Pantanal.
Data corrente: | 12/03/1996
Data da última atualização: | 19/07/2018
Autoria: | SILVA, H. R.
Afiliação: | Utah State University (Logan, Utah).
Título: | Wetting-induced changes in near surface soil physical properties affecting surface irrigation.
Ano de publicação: | 1995
Fonte/Imprenta: | Logan: Utah State University, 1995.
Páginas: | 188p.il.
Idioma: | Inglês
Notas: | Ph.D. Dissertation.
Conteúdo: | Intermittent application of water into many soils produces changes in soil structure and hydraulic properties, resulting in faster advance with less volume of applied water as compared with continuous application. Two distinct soils, a Millville silt loam and a Red-yellow oxisol, were used to study the susceptibility of soil structure to the effects of wetting and drying. Ethanol was used to characterize the condition prior to water application and to distinguish between effects of wetting and drying (by water) on the structure of an unstable soil. The objective of this study was to quantify and show structural changes that affect soil hydraulic properties. Air entrapment effects on infiltration processes during intermittent and continuous water application were also studied. Laboratory and field experiments were carried out to achieve the objectives of this study. Important aspects of soil structural changes were identifyied by measurements with water and ethanol. The major changes were (a) reduction in porosity and (b) pore size distribution. Results reconfirmed that intermittent application of water is an efficiency way to decrease intake rates. An accentuated reduction in intake during the first surge was followed by a smaller reduction in subsequent surges. Similar trends were observed between first and second irrigations for continuous application. The Philip's infiltration model parameters (sorptivity and the parameter A), obtained from the best-fit-of-all measured infiltration data, were used to indicate effects of wetting and drying on soil structure, hence on soil physical properties. Using a Millville silt loam pre-wetting characterization, we verified that ethanol showed little or no effect on soil structure. This allowed study of differential effetcs on the saturated hydraulic conductivity for an unstable soil under wetting and drying conditions. The excepcional predictability of advance trajectories under intermittent and continnuous flow, based on infiltration information only, was demonstrated by a simple advance model. This model emphasized the dominant role of the infiltration process on the performance of surface irrigation systems. The major advantages of the model reside in modest parameter requirements and simplicity, while retaining the main features of the physical process.
Palavras-Chave: | Conductivity; Condutividade; Furrwo; Hydraulic; Infiltration; Physic; Physical; Property; Regime; Sulco; Superficie; Surface.
Thesagro: | Água; Engenharia Agrícola; Física; Hidráulica; Infiltração; Irrigação; Solo.
Thesaurus Nal: | agricultural engineering; irrigation; soil; water.
Categoria do assunto: | --
Registro original: | Embrapa Pantanal (CPAP)

Exemplares:

CNPH - (5920-1) - UPC - TS - PP - T SIL 14/95 -  - 1996.014 - DIS
CPAP - (32894-1) - ADD - TS - PP - TS96.00022 -  - 1996.00022 - DIS