Search results for " Soil water"

Application of minidisk infiltrometer to estimate water repellency in Mediterranean pine forest soils

2017

Assessment of soil water repellency (SWR) was conducted in the decomposed organic floor layer (duff) and in the mineral soil layer of two Mediterranean pine forests, one in Italy and the other in Spain, by the widely-used water drop penetration time (WDPT) test and alternative indices derived from infiltration experiments carried out by the minidisk infiltrometer (MDI). In particular, the repellency index (RI) was calculated as the adjusted ratio between ethanol and water soil sorptivities whereas the water repellency cessation time (WRCT) and the specifically proposed modified repellency index (RIm) were derived from the hydrophobic and wettable stages of a single water infiltration experi…

Transpiration/Evaporation Ratio in Prunus Fremontii and Marianna 2624 over a 4-Day Period of Drought

2017

Drought stress represents one of the major environmental limitations to crop production in a large portion of the Earth’s surface. Natural genetic resources are one of the most powerful weapons against environmental stress. In such contest, the behavior in terms of water loss of two species, P. fremontii (slower-growing) and Marianna 2624 (faster-growing), native to arid and humid regions respectively, was tested. Transpiration (T) and evapotranspiration (ET) rates and soil water content (SWC) were measured in the two species under controlled conditions. Evaporation rate from the soil surface was obtained by difference, and an average transpiration/evaporation ratio (T/E) was calculated to …

Evaluation of soil physical quality under different soil land uses in a small Sicilian watershed

2013

Sustainability of extensive rain fed agriculture needs assessment of land use effects on soil physical and hydraulic properties. Several soil physical quality indices were determined for four adjacent areas in a small Sicilian watershed, that were characterized by a different land use, namely cropland (C), olive grove (O), grassland (G) and eucalyptus plantation (E). Soil texture was similar for the considered areas, even if the no-tilled soils (G and E) showed a higher clay content in the top layer (0-20 cm) than in the lower layer (20-40 cm). The bulk density of the top layer ranged between 1.20-1.43 g cm-3 (C < G < O < E), with significant differences between C and E. In the lower layer,…

Assessing Field and Laboratory Calibration Protocols for the Diviner 2000 Probe in a Range of Soils with Different Textures

2016

Frequency domain reflectometry (FDR) downhole sensors have been increasingly used for soil moisture field monitoring because they allow measurement, even continuously, along a soil profile. Moreover, they can also be installed with minimal soil disturbance around the access tube. The objectives of the paper were to assess the field and laboratory calibration protocols for a FDR capacitance probe (Diviner 2000) for a range of soils characterized by different particle size distributions and shrink/swell potential and to propose a practical and effective protocol on the basis of undisturbed soil samples, accounting for soil shrinkage/swelling processes characterizing swelling clay soils. The e…

The crucial interactions between climate and soil

2022

Since the birth of soil science, climate has been recognized as a soil-forming factor, along with parent rock, time, topography, and organisms (from which humans were later kept distinct), often prevalent on the other factors on the very long term. But the climate is in turns affected by soils and their management. This paper describes the interrelationships between climate – and its current change – and soil, focusing on each single factor of its formation. Parent material governs, primarily through the particle size distribution, the capacity of soil to retain water and organic matter, which are two main soil-related drivers of the climate. Time is the only unmanageable soil-forming facto…

Power sensitivity analysis of multi-frequency, multi-polarized, multi-temporal SAR data for soil-vegetation system variables characterization

2017

Abstract: The knowledge of spatial and temporal variability of soil water content and others soil-vegetation variables (leaf area index, fractional cover) assumes high importance in crop management. Where and when the cloudiness limits the use of optical and thermal remote sensing techniques, synthetic aperture radar (SAR) imagery has proven to have several advantages (cloud penetration, day/night acquisitions and high spatial resolution). However, measured backscattering is controlled by several factors including SAR configuration (acquisition geometry, frequency and polarization), and target dielectric and geometric properties. Thus, uncertainties arise about the more suitable configurati…

Mulching practices for reducing soil water erosion: A review

2016

Abstract Among the soil conservation practices that are used, mulching has been successfully applied to reduce soil and water losses in different contexts, such as agricultural lands, fire-affected areas, rangelands and anthropic sites. In these contexts, soil erosion by water is a serious problem, especially in semi-arid and semi-humid areas of the world. Although the beneficial effects of mulching are known, further research is needed to quantify them, especially in areas where soil erosion by water represents a severe threat. In the literature, there are still some uncertainties about how to maximize the effectiveness of mulching to reduce the soil and water loss rates. Given the serious…

Influence of soil surface sealing and hydrophobicity on water infiltration

Nella tesi viene affrontato lo studio dell’impatto dei fenomeni di sealing superficiale e di idrofobicità sui processi di infiltrazione dell’acqua nel suolo. A tal fine vengono utilizzati diversi tipi di esperimenti infiltrometrici che consentono di determinare le modificazioni delle proprietà idrauliche del suolo indotte da questi due fenomeni permettendo di valutare così le loro ripercussioni negative sui processi idrologici. The thesis aims at investigating the effects of soil sealing and hydrophobicity on the water infiltration process. Different field infiltrometric techniques are applied at this end due to their ability to characterize modifications of soil hydraulic properties that d…

Analytical Solution of the Richards Equation under Gravity-Driven Infiltration and Constant Rainfall Intensity

2020

In the field of soil hydrology, the Richards equation is commonly used to model water flow in unsaturated soils. The high nonlinearity of the Richards equation makes it very challenging to solve analytically for situations that are meaningful in practical applications. In this paper, an exact and simple analytical solution of the Richards equation under gravity-driven infiltration and constant rainfall intensity is derived. First, the solution is presented under Torricelli's law, which mimics the soil hydraulic conductivity function and describes the emptying or filling process of a nonlinear water reservoir. Then, following a similar approach, the solution is extended to the Brooks and Cor…

Application of minidisk infiltrometer to estimate soil water repellency

2016

Soil water repellency (SWR) reduces affinity of soils to water resulting in detrimental implication for plants growth as well as for hydrological processes. During the last decades, it has become clear that SWR is much more widespread than formerly thought, having been reported for a wide variety of soils, land uses and climatic conditions. The repellency index (RI), based on soil-water to soil-ethanol sorptivity ratio, was proposed to characterize subcritical SWR that is the situation where a low degree of repellency impedes infiltration but does not prevent it. The minidisk infiltrometer allows adequate field assessment of RI inherently scaled to account for soil physical properties other…