A. Jordán

The immediate effectiveness of barley straw mulch in reducing soil erodibility and surface runoff generation in Mediterranean vineyards.

Soil and water loss in agriculture is a major problem throughout the world, and especially in Mediterranean areas. Non-conservation agricultural practices have further aggravated the situation, especially in vineyards, which are affected by one of the highest rates of soil loss among cultivated lands. Therefore, it is necessary to find the right soil practices for more sustainable viticulture. In this regard, straw mulching has proven to be effective in other crop and fire affected soils, but, nonetheless, little research has been carried out in vineyards. This research tests the effect of barley straw mulching on soil erosion and surface runoff on vineyards in Eastern Spain where the soil and water losses are non-sustainable. An experiment was setup using rainfall simulation tests at 55 mm h(-1) over 1h on forty paired plots of 0.24 m(2): twenty bare and twenty straw covered. Straw cover varied from 48 to 90% with a median value of 59% as a result of the application of 75 g of straw per m(2). The use of straw mulch resulted in delayed ponding and runoff generation and, as a consequence, the median water loss decreased from 52.59 to 39.27% of the total rainfall. The straw cover reduced the median sediment concentration in runoff from 9.8 to 3.0 g L(-1) and the median total sediment detached from 70.34 to 15.62 g per experiment. The median soil erosion rate decreased from 2.81 to 0.63 Mg ha(-1)h(-1) due to the straw mulch protection. Straw mulch is very effective in reducing soil erodibility and surface runoff, and this benefit was achieved immediately after the application of the straw.

Use of barley straw residues to avoid high erosion and runoff rates on persimmon plantations in Eastern Spain under low frequency-high magnitude simulated rainfall events

Soil and water losses due to agricultural mismanagement are high and non-sustainable in many orchards. An experiment was set up with rainfall simulation at 78 mm h–1 over 1 hour on 20 paired plots of 2 m2 (bare and straw covered) in new persimmon plantations in Eastern Spain. Effects of straw cover on the control of soil and water losses were assessed. An addition of 60% straw cover (75 g m–2) resulted in delayed ponding and runoff generation and consequently reduced water losses from 60% to 13% of total rainfall. The straw cover reduced raindrop impact and thus sediment detachment from 1014 to 47 g plot–1 h–1. The erosion rate was reduced from 5.1 to 0.2 Mg ha–1 h–1. The straw mulch was found to be extremely efficient in reducing soil erosion rates.

Changes in land cover and vegetation carbon stocks in Andalusia, Southern Spain (1956-2007)

Land use has significantly changed during the recent decades at global and local scale, while the importance of ecosystems as sources/sinks of C has been highlighted, emphasizing the global impact of land use changes. Land use changes can increase C loss rates which are extremely difficult to reverse, in the short term, opposite to organic carbon (OC) which accumulates in soil in the long-term. The aim of this research is to improve and test methodologies to assess land cover change (LCC) dynamics and temporal and spatial variability in C stored in vegetation at a wide scale. LCCs between 1956 and 2007 in Andalusia (Southern Spain) were selected for this pilot study, assessed by comparison of spatial data from 1956 to 2007 and were reclassified following land cover flows (LCFs) reported in major areas in Europe. Carbon vegetation densities were related to land cover, and C vegetation stocks for 1956 and 2007 were calculated by multiplying C density for each land cover class with land cover areas. The study area has supported important changes during the studied period with significant consequences for vegetation C stocks, mainly due to afforestation and intensification of agriculture, resulting in a total vegetation C stock of 156.08Tg in 2007, with an increase of 17.24Tg since 1956. This study demonstrates the importance of LCC for C sequestration in vegetation from Mediterranean areas, highlighting possible directions for management policies in order to mitigate climate change as well as promoting land conservation. The methodologies and information generated in this project will be a useful basis for designing land management strategies helpful for decision makers.

Relationships between rock fragment cover and soil hydrological response in a Mediterranean environment

Abstract Rock fragments are a key factor for determining erosion rates, particularly in arid and semiarid environments where vegetation cover is very low. However, the effect of rock fragments in non-cultivated bare soils is still not well understood. Currently, there is a need for quantitative information on the effects of rock fragments on hydrological soil processes, in order to improve soil erosion models. The main objective of the present research was to study the influence of rock fragment cover on run-off and interrill soil erosion under simulated rainfall in Mediterranean bare soils in south-western Spain. Thirty-six rainfall simulation experiments were carried out at an intensity of 26.8 mm h−1 over 60 min under three different classes of rock fragment cover (<50%, 50–60% and >60%). Ponding and run-off flow were delayed in soils with high rock fragment cover. In addition, sediment yield and soil erosion rates were higher in soils with a low rock fragment cover. The relationship between soil loss rate and rock fragment cover was described by an exponential function. After this first set of experiments, rock fragments were removed from sites with the highest cover (>60%) and the rainfall simulation experiments were repeated. The steady-state run-off rate and soil loss increased significantly, showing that run-off and soil erosion were partly conditioned by rock fragment cover. These results have significant implications for erosion modelling and soil conservation practices in areas with the same climate and soil characteristics.

Small variations of soil properties control fire-induced water repellency

La repelencia al agua (WR) inducida por el fuego es una propiedad controlada por muchos factores diferentes (temperaturas alcanzadas, cantidad y tipo de combustible, etc.). Algunas propiedades del suelo pueden determinar la presencia y la intensidad de esta propiedad en los suelos quemados. Los objetivos principales son: avanzar en el estudio de la influencia de algunas propiedades clave en el control del comportamiento de la WR en suelos quemados, asi como estudiar la influencia de la cantidad y la calidad de la materia organica del suelo en su desarrollo cuando es afectada por el calentamiento. En este estudio, hemos realizado quemas controladas en laboratorio utilizando muestras de suelo de diferentes sitios con litologias y tipos de suelos diferentes y recogidas bajo distintas especies vegetales. Las muestras recogidas en diferentes sitios difieren en algunas propiedades del suelo, mientras que las muestras de suelo tomadas del mismo sitio solo se diferencian en la cantidad y la calidad de la materia organica del suelo, ya que se recogieron bajo distintas especies de plantas. Todas las muestras de suelo se calentaron en horno de mufla a 200, 250, 300 y 350 oC. La repelencia al agua se midio mediante el test del tiempo de penetracion de la gota de agua (WDPT). Los resultados mostraron diferencias significativas entre los tipos de suelos y especies vegetales, y se comprobo que pequenas diferencias en algunas propiedades del suelo pueden actuar como factores clave controlando el desarrollo y persistencia de la repelencia al agua, con muestras de suelo quemadas que variaban entre hidrofilicas a extremadamente repelentes al agua. La propiedad que principalmente controlo el comportamiento de la repelencia al calentamiento fue la textura y mas concretamente el contenido de arena. Por otro lado se observo que la calidad de la materia organica tambien afecta, ya que muestras de suelo de mismo sitio y con contenido de materia organica similar, pero tomadas bajo diferentes especies vegetales mostraron valores muy diferentes de repelencia al agua tras la quema.

Role of rock fragment cover on runoff generation and sediment yield in tilled vineyards

&NA; The soil in conventional Mediterranean vineyards is an active and non‐sustainable source of sediment and water. Lack of vegetation cover, small soil organic matter content and intense ploughing result in large rates of erosion in a millennia‐old tillage system. There is a need for soil conservation strategies that enable sustainability of wine and grape production; therefore, it is essential to measure the rates and to investigate the processes and factors of soil erosion. This study evaluated factors that can reduce soil losses in traditional Mediterranean vineyards. The investigation was carried out with 96 rainfall simulation experiments at the pedon scale (0.24 m2) to measure soil detachment and runoff yield under low frequency‐high magnitude rainfall events of 1 hour at 55 mm hour−1. On average, runoff was 40.6% of the rainfall, and the rate of soil erosion (i.e. amount of soil lost) was 71.5 g m−2. The key factor controlling erosion was the rock fragment cover. There was a clear decrease in soil losses with increased rock fragment cover on the soil surface, but an increase in surface runoff. The results of our study showed that rock fragments at the pedon scale reduced soil erosion in Mediterranean vineyards, but when a layer of embedded rock fragments developed, large rates of runoff were triggered. HighlightsWe investigated soil erosion factors in Mediterranean vineyards.Rainfall simulation at the pedon scale achieved accurate measurements.Rock fragment cover reduces soil losses.Embedded rock fragment cover will trigger large runoff rates.

Temporal changes in soil water repellency after a forest fire in a Mediterranean calcareous soil: Influence of ash and different vegetation type

Forest fires usually modify soil water repellency (SWR), and its persistence and intensity show a high variability both in space and time. This research studies the evolution of SWR in a Mediterranean calcareous soil affected by a forest fire, which occurred in Gorga (SE Spain) in July 2011, comparing the effect of the main vegetation cover between pine (Pinus halepensis) and shrubs species (Quercus coccifera, Rosmarinus officinalis, Cistus albidus, Erica arborea and Brachypodium retusum) and the relationship with soil moisture content (SMC). Also the study analyzed the effect of ash on SWR dynamics under field conditions. Six plots were established on the fire-affected area and the unburned-control-adjacent area to monitoring SWR with the water drop penetration time (WDPT) test, SMC through moist sensors (5cm depth) and three different ash treatments: ash presence, ash absence and incorporation of ash into the soil. An immediate increase of SWR was observed in the fire-affected area, mainly in pine plots. SWR changes in control (unburned) plots were quite similar between different types of vegetation influence, despite higher SWR values being observed on pine plots during the study period. A noticeable decrease of SWR was observed during the first months after fire in the affected areas, especially after the first rainy period, both in pine and shrubs plots. SWR increase was registered in all plots, and the highest levels were in March 2012 in burned pine plots. SWR decrease was higher in plots where ash was removed. Fire-affected soils became wettable 1year and a half after the fire.

Classification of landforms in Southern Portugal (Ria Formosa Basin)

A Geographic Information Systems-based tool is used for macro-landform classification following the Hammond procedure, based upon a Digital Terrain Model (DTM) created from ordinary Kriging. Gentle slopes, surface curvature, highlands and lowlands areas are derived from the DTM. Combining this information allows the classification of terrain units (landforms). The procedure is applied to the Ria Formosa basin (Southern Portugal), with five different terrain types classified (plains, tablelands, plains with hills, open hills and hills).

Soil Mapping and Processes Models for Sustainable Land Management Applied to Modern Challenges

Abstract In the context of growing population and global change, increasing demands for food production are an enormous challenge that we face in the modern world. At the same time the need to prevent land degradation, restore lands that are already degraded, and maintain soil quality and health is critical to a sustainable use of land resources. Accurate maps and adequate models are indispensable tools to assist managers, scientists, and decision makers in addressing these challenges. In this chapter, we outline the main impacts of climate change on soils, key adaptation, and mitigation strategies and provide an overview of key issues in sustainable agricultural production as well as land degradation and restoration.

Wildfire effects on lipid composition and hydrophobicity of bulk soil and soil size fractions under Quercus suber cover (SW-Spain)

ABSTRACT Soil water repellency (hydrophobicity) prevents water from wetting or infiltrating soils, triggering changes in the ecosystems. Fire may develop, enhance or destroy hydrophobicity in previously wettable or water‐repellent soils. Soil water repellency is mostly influenced by the quality and quantity of soil organic matter, particularly the lipid fraction. Here we report the results of a study on the effect of fire on the distribution of soil lipids and their role in the hydrophobicity grade of six particle size fractions (2–1, 1–0.5, 0.5–0.25, 0.25–0.1, 0.1–0.05 and <0.05 mm) of an Arenosol under Quercus suber canopy at the Doñana National Park (SW‐Spain). Hydrophobicity was determined using water drop penetration time test. Field emission scanning electron microscopy (FESEM) was used to assess the presence and morphology of the inorganic and organic soil components in the particle size fractions. Soil lipids were Soxhlet extracted with a dichloromethane‐methanol mixture. Fatty acids (FAs) and neutral lipids were separated, derivatized, identified and quantified by gas chromatography/mass spectrometry and gas chromatography/flame ionization detection. The hydrophobicity values of soil samples and fractions were statistically different (P < 0.05), for both, the unburnt and burnt soils, and particle size fractions. All samples displayed a similar distribution of FAs, straight‐chain saturated acids in the C14–C32 range, and neutral lipids (n‐alkan‐1‐ols, n‐alkanes), only differing in their relative abundances. Among possible biogeochemical mechanisms responsible for the changes in soil lipids, the observed depletion of long chain FAs (C≥24) in the coarse fraction is best explained by thermal cracking caused by the heat of the fire. The enrichment of long chain FAs observed in other fractions suggests possible exogenous additions of charred, lipid‐rich, material, like cork suberin or other plant‐derived macromolecules (cutins). Principal component analysis was used to study the relationships between hydrophobicity with soil organic matter and its different components. Extractable organic matter (EOM) and specifically long chain FAs content were positively correlated to soil hydrophobicity. Therefore, the latter could be used as biomarkers surrogated to hydrophobicity in sandy soils. Graphical abstract: Figure. No Caption available. HighlightsSoil fractions affected or not by fire shows heterogeneous hydrophobicity behavior.The study of free lipids fractions detected the presence of different carbon pools.Fire caused a transfer of partly charred compounds from coarse to fine fractions.Hydrophobicity was positively correlated with long chain fatty acids.