首页   按字顺浏览 期刊浏览 卷期浏览 NEGATIVE HEAD HYDRAULIC PROPERTIES OF THE SOIL SURFACE AT DIFFERENT TIMES
NEGATIVE HEAD HYDRAULIC PROPERTIES OF THE SOIL SURFACE AT DIFFERENT TIMES

 

作者: S. LOGSDON,  

 

期刊: Soil Science  (OVID Available online 1993)
卷期: Volume 156, issue 6  

页码: 373-379

 

ISSN:0038-075X

 

年代: 1993

 

出版商: OVID

 

数据来源: OVID

 

摘要:

Tension infiltrometers have become popular for determining unsaturated hydraulic conductivity (K) and associated measures in situ. The objective of this study was to use tension infiltrometers to determine K, sorptivity (S), macroscopic capillary length (Λc—a characteristic negative head), and gravity time (tgrav) several times over a growing season for different negative heads and infiltrometer base sizes. Infiltration was measured on seven dates, within 20 m. on a Webster clay loam (Fine, mixed, mesic, Typic Haplaquoll). The soil had been disked before planting corn (Zea maysL.) and cultivated twice after planting. All measurements were made in nonwheel-tracked interrows. Infiltration was measured for ascending heads (-150, −60, and −30 mm) at the same location. Both K and S fluctuated over the growing season with no relation to initial soil water content, which varied from 0.04 to 0.36 m/m. Over the growing season, large-base infiltrometers consistently had smaller calculated Λc(80 mm) than small-base infiltrometers (182 mm), which indicated more influence of gravity for large-base infiltrometers and more influence of capillarity for small base. Pooled across dates, there was no significant difference in base size for S or K. Gravity time is a crude estimate of the time necessary to reach steady-state, and calculated tgravwas usually less than 1 h. Tension infiltration indirectly indicates pore arrangement, suggesting that pore arrangements varied over a growing season.

 

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