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Vertisols are widely used for irrigated rice in the Senegal River Basin, where farmers are increasingly reporting problems with soil salinization. Water movement at the onset of the growing season, when soils are dry and cracked, may have a large impact on soil salinity and water economy. Water movement and soil swelling processes were studied in a dry, cracked Vertisol in the Senegal River Valley...
Despite numerous studies, the relationship between slope angle and infiltration rate remains unclear. Under different experimental conditions, new processes may be introduced which influence the relationship. The presence of rills, for example, may significantly affect the relationship between slope angle and infiltration rate, so distinct relationships may exist for rill and interrill areas. The...
The sustainability of land management was assessed for a sugar cane plantation using soil chemical and physical properties as indicators. The plantation (6000 ha) was established in 1979 on a broad alluvial plain and the majority of the soils are classified as Eutric and Mollic Fluvisols (73%) and Eutric Vertisols (23%). Average annual rainfall is about 2000 mm with a dry season from May to November...
Imported fire ants comprise two introduced species which build large mounds at high densities throughout the southeastern United States. They represent a new soil-forming factor for these soils. A study was conducted to quantify the channel network geometry, clod density, aggregate stability, and micromorphology of the mounds on three texturally different soils, and examine the moisture relationships...
The use of disc permeameter in the field often requires the placement of a layer of sand in order to provide good contact between the soil surface and disc supply membrane. The effect of the contact sand on water infiltration into the soil and the estimate of sorptivity (S) was investigated. A numerical study using a loam and clay, and a field experiment on heavy clay was conducted. Placement of the...
In sahelian regions, termites are the most important component of soil macrofauna, as judged by population density and their impacts on soil structure. This paper is an attempt to quantify the effect of termite activity on infiltration in natural conditions and to provide an analysis of the various processes involved. A mulch was used to attract termites to crusted soil sites. Runoff measurements...
The effects of the activity of seed harvesting ants (Messor bouvieri) on the fertility, rainfall infiltration, structural properties and water repellency of top soils were investigated in a semi-arid rangeland in SE Spain. The soil surfaces had a low vegetative cover and bare areas had a sieving crust. Rainfall simulation experiments were carried out over ants' nest mounds and on control areas without...
Micromorphological techniques have frequently been used to describe processes leading to surface crusting. Image analysis can be helpful in quantifying changes in porosity necessary for estimating hydraulic parameters in crust infiltration models. The objective of this study was to quantify changes in pore area and frequency for three pore shapes (round, irregular, and elongate) and four size classes...
The accurate determination of the wetting soil hydraulic properties for a wide range of water contents is essential for studying and predicting infiltration processes. We present a laboratory infiltration method for determining hydraulic conductivity function, K(θ), in the low-to-medium water content range. An initially air-dry soil core is subjected to infiltration from the bottom where the pressure...
Savannas and grasslands in South Africa are adapted to fire, yet long-term effects of fire on soil, water and nutrients remain largely unknown. To determine whether frequent burning increases the tendency of soils to crust and alters soil chemistry, topsoils from 19 sites were examined in Mpumalanga, KwaZulu-Natal and the Eastern Cape where annual burning and fire exclusion experiments had been conducted...
Currently, most of the research focused on general pedotransfer functions (PTFs) has been generated under humid climatic conditions. Nevertheless, this article proposes an estimation of pedotransfer functions for a great variety of climatic and physiographic conditions, with a predominance of soils developed under semi-arid conditions, such as those occurring in Spain. The results obtained, in spite...
Long-term high resolution measurements of precipitation, soil water budget, surface runoff, and sediment transport as well as rainfall simulations at plot scale have been accomplished on a non-vegetated lignite mining dump (Germany, Lusatia, Schlabendorf-North), completed by measurements of infiltration and water drop penetration time. The investigations revealed that the distribution of hydraulic...
Falling head (FH) infiltration procedures can give rapid estimates of the field saturated hydraulic conductivity (K fs ) of soils. The objectives of this investigation were to develop a procedure for estimating both the K fs and the α ⁎ parameter of the exponential hydraulic conductivity function from a FH experiment, and to compare FH procedures differing by experimental and...
The field tension infiltrometer (TI) and the laboratory unit hydraulic gradient (UHG) methods are widely applied to determine the near-saturated soil hydraulic conductivity, K. Comparison between the two methods is relevant given that they differ in the explored soil volume (undetached or detached) and in the flow process (unconfined or confined). The objective of this investigation was to compare...
The single-ring pressure infiltrometer (PI) with the steady-state Two-Ponding-Depth (TPD) application method were developed to simultaneously determine the saturated soil hydraulic conductivity, K fs , and the α⁎-parameter in the field. Methods of analysis of transient PI data are also available but they have received little testing so far. The transient WU method and the TPD method were compared...
After decades of research into the subject, preferential flow in soils still plagues those of us who hope to provide better solutions to society's natural resource management conundrums. To that end, simulation models that strike the balance between simplicity and robustness are a high priority. We present the two-domain, Mesopore and Matrix (M&M), water-infiltration module based on soil structure...
The changing nature of soil water repellency and its apparent affect on hydrologic processes in the vadose zone are regularly reported upon, yet the fundamental mechanisms governing these changes over time and how they are manifested during infiltration are poorly understood. To address this knowledge gap, we investigate dynamic soil water repellency and report upon the concerted roles of contact...
South African riparian systems are threatened by major alien plant invasions through the widespread replacement of native plant species by fast-growing alien species, including several Eucalyptus species. Since Eucalyptus species are known to cause soil water repellency, this study examined the occurrence of soil water repellency coupled with soil moisture and infiltration under laboratory conditions...
Forest fires are a major environmental concern, especially in the semiarid Mediterranean regions, where the long dry and hot summers and mild winters favor outbreaks of wildfires. The objective of this work was to study the effects of different fire treatments on physical, chemical, and physicochemical properties of Pale rendzina, and their impact on infiltration rate (IR), runoff and soil loss under...
Researchers seek a more renewable and natural alternative for water soluble anionic polyacrylamide (PAM), a highly-effective, petroleum-derived polymer used in agriculture to control erosion and reduce water seepage from unlined irrigation structures. This study evaluated four anionic polymers including low- (0.5Mgmol−1) or high molecular-weight (MW) (10–20Mgmol−1), bacteria-produced polysaccharides...
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