Search results for "soil"
showing 10 items of 3493 documents
Climatic changes in yield index and soil water deficit trends in China
2000
Long-term trends of the combined effects of evapotranspiration and precipitation effect surface hydrology and soil water and consequently natural and agricultural ecosystems. This paper analyses yield index and soil water deficit time series derived from water balance calculations for multiple cropping systems with FAO methodology. The analysis shows that yield index values have increased and soil water deficits have consequently decreased over much of China during 1954‐1993. The likely parameters contributing to this trend are precipitation changes north of 35 N and maximum evapotranspiration as well as available soil water trends south of this line. Increasing the assumed maximum soil wat…
Soil erosion susceptibility assessment and validation using a geostatistical multivariate approach: a test in southern Sicily
2008
A certain number of studies have been carried out in recent years that aim at developing and applying a model capable of assessing water erosion of soil. Some of these have tried to quantitatively evaluate the volumes of soil loss, while others have focused their efforts on the recognition of the areas most prone to water erosion processes. This article presents the results of a research whose objective was that of evaluating water erosion susceptibility in a Sicilian watershed: the Naro river basin. A geomorphological study was carried out to recognize the water erosion landforms and define a set of parameters expressing both the intensity of hydraulic forces and the resistance of rocks/so…
Calibrating storage tanks for soil erosion measurement from plots
1998
Many plots for soil loss measurements are equipped with a sequence of tanks for measuring runoff volume and sediment concentration. The stored water volume is easily determined by a water depth measurement while the sediment concentration is often measured by collecting samples of the mixed suspension. In this paper, using the Π-theorem of dimensional analysis, the functional relationship describing the mixing of the suspension in the tank is expressed in a dimensionless form. The recognized dimensionless groups allow the establishment, for given soil and water depth in the tank, of the relationship (calibration curve) between the actual and the measured concentration. The calibration curve…
MANUAL SAMPLING AND TANK SIZE EFFECTS ON THE CALIBRATION CURVE OF PLOT SEDIMENT STORAGE TANKS
2004
In many experimental soil erosion plots, runoff is collected and carried by a conveyance system to a sequence of storage tanks. If the soil loss is measured by collecting, after mixing, samples of the stored suspension, then a calibration curve between the actual mean concentration (C) and the measured concentration (Cm) in the storage tank occurs. The aim of this article was to evaluate experimentally the factors affecting the relationship between C and Cm. For a sandy loam soil, the replicated measurements of Cm (20 samples) for two values of the actual concentration (C = 5 and 25 g/L) showed that the variability of the measurements of Cm is low and confirmed the reliability of a calibrat…
Carbon input threshold for soil carbon budget optimization in eroding vineyards
2016
Abstract Previous studies have documented that, relative to conventional tillage (CT), alternative soil management (reduced tillage, mulching, or cover crops) decreases soil erosion and increases soil organic matter (SOM) in vineyards. These previous studies, however, failed to consider the loss of soil organic carbon (SOC) with erosion that could occur with the adoption of agro-environmental measures (AEM) in a semiarid environment. Accordingly, the aims of this study were to determine whether changes in SOC content under AEM management are always positive and to develop a conceptual model for estimating the “SOC threshold”. The SOC threshold was defined as that level of SOC in an AEM-mana…
A Rainfall Simulator Laboratory Approach to Determine the Impact of Ash Depth on Runoff Generation and Soil Losses
2020
Ash cover the forest fire affected soil for some weeks or months and act as a key factor to determine the soil and water losses. Ash depth is researched here to determine how affect the soil detachment and the runoff generation. Seventy rainfall simulation experiments on paired 0.50 m2 plots (five plots with 0, 1, 2, 3, 5, 10, 15- and 30-mm ash depth), and repeated one week later) under thunderstorms of 48 mmh-1 for one hour were carried out under laboratory conditions. In the first experiment, after the bed of ash was applied, the results show that ash depth determines the runoff rates as they reduce the discharge from 23.1% to 13.9%. The sediment concentration increased from 23.8 till 38.…
The need for harmonizing methodologies for assessing soil threats in Europe
2010
Central to the EU thematic strategy for soil protection is that areas affected by soil degradation through erosion, soil organic matter (SOM) decline, compaction, salinization and landslides should be identified in a clear and consistent way. However, the current methodologies to achieve this often differ and this can result in different perceptions of risks amongst EU Member States. The aims of this paper are to: (i) assess the current status of assessment methodologies in Europe (EU27) associated with erosion, SOM decline, compaction, salinization and landslides and (ii) discuss the issues associated with harmonization of these methodologies throughout the EU27. The need for harmonization…
Assessment of nitrate contamination risk: The Italian experience
2009
16 páginas, 19 figuras, 10 tablas.-- El PDF es el manuscrito aceptado para su publicación.-- et al.
Is land-use change a cause of loss of pedodiversity? The case of the Mazzarrone study area, Sicily
2011
Anthropogenic soils created ex novo by land-us e change in large scale farming are, from a pedogenetic point of view, catastrophic events that bring the soils to time zero and change the natural pattern of the soilscape, remarkably, in some cases. The qu antitative aspects of pedodiversity of a soilsc ape in South-East Sicily, where some types of soils, in recent decades, have suffered a consistent reduction due to the transformations by large scale farming, are considered. The evolution of pedodiversity over a 53-year period (1955 to 2008 ) is examined using a dedicated statistical method and a space – time model based on Markov analysis and cellular autom ata in order to predict the evolu…
European small portable rainfall simulators: A comparison of rainfall characteristics
2013
28 páginas, 6 figuras, 2 tablas.- The definitive version is available on: http://www.sciencedirect.com/science/article/pii/S0341816213001252