INFILTRATION INTO HOMOGENEOUS AND LAYERED COLUMNS OF AGGREGATED LOAM, SILT LOAM, AND CLAY SOIL

1966 ◽  
Vol 46 (3) ◽  
pp. 293-305 ◽  
Author(s):  
W. J. Staple ◽  
R. P. Gupta

Infiltration rates and moisture profiles were measured during vertical infiltration into three soils of differing texture and aggregate structure. The measurements were made both for homogeneous columns of the air-dry soil and for columns made up of two-layer combinations of the three soils. Infiltration rates and profiles for the same soils were computed on the basis of tension, diffusivity and conductivity data obtained on wetting. Agreement between measured and computed moisture profiles was satisfactory considering the high variability in moisture movement found in packed columns of coarsely aggregated soils. Differences in aggregate-size distribution and bulk density produced variation in tension and conductivity which in turn had a marked influence on infiltration rate.

2010 ◽  
Vol 7 (1) ◽  
pp. 1431-1457
Author(s):  
G. Lilbæk ◽  
J. W. Pomeroy

Abstract. Meltwater ion concentration and infiltration rate into frozen soil both decline rapidly as snowmelt progresses. Their temporal association is highly non-linear and a covariance term must be added in order to use time-averaged values of snowmelt ion concentration and infiltration rate to calculate chemical infiltration. The covariance is labelled enhanced infiltration and represents the additional ion load that infiltrates due to the timing of high meltwater concentration and infiltration rate. Previous assessment of the impact of enhanced infiltration has been theoretical; thus, experiments were carried out to examine whether enhanced infiltration can be recognized in controlled laboratory settings and to what extent its magnitude varies with soil moisture. Three experiments were carried out: dry soil conditions, unsaturated soil conditions, and saturated soil conditions. Chloride solution was added to the surface of frozen soil columns; the concentration decreased exponentially over time to simulate snow meltwater. Infiltration excess water was collected and its chloride concentration and volume determined. Ion load infiltrating the frozen soil was specified by mass conservation. Results showed that infiltrating ion load increased with decreasing soil moisture as expected; however, the impact of enhanced infiltration increased considerably with increasing soil moisture. Enhanced infiltration caused 2.5 times more ion load to infiltrate during saturated conditions than that estimated using time-averaged ion concentrations and infiltration rates alone. For unsaturated conditions, enhanced infiltration was reduced to 1.45 and for dry soils to 1.3. Reduction in infiltration excess ion load due to enhanced infiltration increased slightly (2–5%) over time, being greatest for the dry soil (45%) and least for the saturated soil (6%). The importance of timing between high ion concentrations and high infiltration rates was best illustrated in the unsaturated experiment, which showed large inter-column variation in enhanced ion infiltration due to variation in this temporal covariance.


Soil Research ◽  
1988 ◽  
Vol 26 (1) ◽  
pp. 111 ◽  
Author(s):  
SF Glanville ◽  
GD Smith

Wet sieving was used to separate aggregate-size distributions of four clay soils after pre-treatments of simulated rainfall, tension wetting and immersion wetting. Infiltration rates of columns of the soils were also measured under simulated rainfall. During rainfall, samples for wet sieving and the infiltrating columns were either bare or covered with a cloth mesh designed to absorb raindrop impact without affecting rates of wetting. Two swelling clay soils, one non-swelling clay soil and one clay soil dominated by sesquioxides, were used. For the first three soils, rate of wetting was the major factor governing aggregate breakdown. Significant changes in Mean Weight Diameter (MWD) occurred during the first few minutes of rainfall whether the samples were covered or not. As the rain continued, further breakdown was detected only in the uncovered samples. MWD of the sesquioxide soil decreased slightly during immersion, but most aggregate breakdown resulted from the impact of raindrops. Infiltration into the soil columns was virtually unrestricted if the soils were covered. Slaking without drop impact did not interfere with water entry. On bare soils, positive correlations were found between cumulative rainfall and the per cent of soil particles <0.12 mm diameter. An inverse relationship was found between this particle size range and infiltration rates. It is suggested that 25% of the <0.12 mm fraction must be present before infiltration rates decline.


1982 ◽  
Vol 13 (1) ◽  
pp. 13-26 ◽  
Author(s):  
J. K. Dharmasiri ◽  
K. G. Dharmawardena ◽  
M. W. P. Wijesinghe ◽  
P. Thiranagama ◽  
I. D. T. De Mel ◽  
...  

Tritium tracer, injected below the surface soil, is used to follow the movement of soil moisture in the unsaturated zone at several geo-hydrologically different sites in Sri Lanka. Depth profiles of tritium activity and moisture contents have been measured after rainfall. For two well-established aquifers, Vanathavillu and Mannar, the recharge to groundwater is close to 30% of the rainfall. Infiltration is much higher. The moisture movement is apparently like piston flow. In the central highland regions, where the surface cover is composed of an overburden of fractured rocks overlain by a few metres of soil cover, the infiltration rate is very high.


2010 ◽  
Vol 14 (7) ◽  
pp. 1365-1374 ◽  
Author(s):  
G. Lilbæk ◽  
J. W. Pomeroy

Abstract. Meltwater ion concentration and infiltration rate into frozen soil both decline rapidly as snowmelt progresses. Their temporal association is highly non-linear and a covariance term must be added in order to use time-averaged values of snowmelt ion concentration and infiltration rate to calculate chemical infiltration. The covariance is labelled enhanced ion infiltration and represents the additional ion load that infiltrates due to the timing of high meltwater concentration and infiltration rate. Previous assessment of the impact of enhanced ion infiltration has been theoretical; thus, experiments were carried out to examine whether enhanced infiltration can be recognized in controlled laboratory settings and to what extent its magnitude varies with soil moisture. Three experiments were carried out: dry soil conditions, unsaturated soil conditions, and saturated soil conditions. Chloride solutions were added to the surface of frozen soil columns; the concentration decreased exponentially over time to simulate snow meltwater. Infiltration excess water was collected and its chloride concentration and volume determined. Ion load infiltrating the frozen soil was specified by mass conservation. Results showed that infiltrating ion load increased with decreasing soil moisture as expected; however, the impact of enhanced ion infiltration increased considerably with increasing soil moisture. Enhanced infiltration caused 2.5 times more ion load to infiltrate during saturated conditions than that estimated using time-averaged ion concentrations and infiltration rates alone. For unsaturated conditions, enhanced ion infiltration was reduced to 1.45 and for dry soils to 1.3. Reduction in infiltration excess ion load due to enhanced infiltration increased slightly (2–5%) over time, being greatest for the dry soil (45%) and least for the saturated soil (6%). The importance of timing between high ion concentrations and high infiltration rates was best illustrated in the unsaturated experiment, which showed large inter-column variation in enhanced ion infiltration due to variation in this temporal covariance.


2006 ◽  
Vol 21 (1) ◽  
pp. 15-25 ◽  
Author(s):  
J.L. Pikul ◽  
R.C. Schwartz ◽  
J.G. Benjamin ◽  
R.L. Baumhardt ◽  
S. Merrill

AbstractAgricultural systems produce both detrimental and beneficial effects on soil quality (SQ). We compared soil physical properties of long-term conventional (CON) and alternative (ALT) cropping systems near Akron, Colorado (CO); Brookings, South Dakota (SD); Bushland, Texas (TX); Fargo, North Dakota (ND); Mandan (ND); Mead, Nebraska (NE); Sidney, Montana (MT); and Swift Current, Saskatchewan (SK), Canada. Objectives were to quantify the changes in soil physical attributes in cropping systems and assess the potential of individual soil attributes as sensitive indicators of change in SQ. Soil samples were collected three times per year from each treatment at each site for one rotation cycle (4 years at Brookings and Mead). Water infiltration rates were measured. Soil bulk density (BD) and gravimetric water were measured at 0–7.5, 7.5–15, and 15–30 cm depth increments and water-filled pore space ratio (WFPS) was calculated. At six locations, a rotary sieve was used to separate soil (top 5 cm) into six aggregate size groups and calculate mean weight diameter (MWD) of dry aggregates. Under the CON system at Brookings, dry aggregates (>19 mm) abraded into the smallest size class (<0.4 mm) on sieving. In contrast, the large aggregates from the ALT system abraded into size classes between 2 and 6 mm. Dry aggregate size distribution (DASD) shows promise as an indicator of SQ related to susceptibility of soil to wind erosion. Aggregates from CON were least stable in water. Soil C was greater under ALT than CON for both Brookings and Mead. At other locations, MWD of aggregates under continuous crop or no tillage (ALT systems) was greater than MWD under CON. There was no crop system effect on water infiltration rates for locations having the same tillage within cropping system. Tillage resulted in increased, decreased, or unchanged near-surface BD. Because there was significant temporal variation in water infiltration, MWD, and BD, conclusions based on a single point-in-time observation should be avoided. Elevated WFPS at Fargo, Brookings, and Mead may have resulted in anaerobic soil conditions during a portion of the year. Repeated measurements of WFPS or DASD revealed important temporal characteristics of SQ that could be used to judge soil condition as affected by management.


1996 ◽  
Vol 21 (1) ◽  
pp. 352-352
Author(s):  
Stanley R. Swier

Abstract The trial was conducted 10 May on a golf course rough, Amherst, NH. Plots were 10 X 10 ft, replicated 4 times, in a RCB design. Merit WP was applied in 4 gal water/1000 ft2 with a watering, can. Merit G granules were applied with a homemade salt shaker. Treatments were irrigated with 0.5 inch water after application. Plots were rated 30 Sep by counting the number of live grubs per 1 ft2. Conditions at the time of treatment were: air temperature 70°F; wind, 3 MPH; sky, clear; soil temperature, 1 inch, 60°F; thatch depth, 0.5 inch soil pH, 5.4; slope 0%; soil texture, silt loam, 47% sand, 50% silt, 3% clay; soil organic matter, 6.9%; soil moisture, 21.8%.


2020 ◽  
Vol 9 (1) ◽  
pp. 26 ◽  
Author(s):  
Dongdong Yang ◽  
Haijun Qiu ◽  
Yanqian Pei ◽  
Sheng Hu ◽  
Shuyue Ma ◽  
...  

Infiltration plays an important role in influencing slope stability. However, the influences of slope failure on infiltration and the evolution of infiltration over time and space remain unclear. We studied and compared the infiltration rates in undisturbed loess and disturbed loess in different years and at different sites on loess landslide bodies. The results showed that the average initial infiltration rate in a new landslide body (triggered on 11 October 2017) were dramatically higher than those in a previous landslide body (triggered on 17 September 2011) and that the infiltration rates of both landslide types were higher than the rate of undisturbed loess. The initial infiltration rate in the new landslide body sharply decreased over the 4–5 months following the landslide because of the appearance of physical crusts. Our observations indicated that the infiltration rate of the disturbed soil in a landslide evolved over time and that the infiltration rate gradually approached that of undisturbed loess. Furthermore, in the undisturbed loess, both the initial and quasi-steady infiltration rates were slightly higher in the loess than in the paleosol, and in the previous landslide body, the infiltration rate was highest in the upper part, intermediate in the middle part, and lowest in the lower part. This study can help us to better understand the evolution process of infiltration in undisturbed loess, previous landslides, and new landslides.


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