José Manuel Hernández-Moreno

Physical properties of “sorriba”-cultivated volcanic soils from Tenerife in relation to andic diagnostic parameters

In volcanic regions, soils containing both noncrystalline materials and layer silicates are widespread. Although the respective contribution of these components to soil physical behaviours is difficult to quantify, it is an important issue in the Canary Islands, where Andisols and andic soils are transported to the low lands for cultivation (‘‘sorriba’’). In this new soil environment, salinisation and sodification processes, induced by irrigation and heavy fertilisation, are potential threats to soil degradation. The purpose of this work was to evaluate some relevant physical properties of the sorriba-cultivated volcanic soils from Tenerife in order to relate them to salinity and sodicity soil conditions, amounts of layer silicates and remaining andic properties, characterised by: bulk density (qb), Al and Fe extracted with ammonium oxalate (Alo ,F eo) and P retention. An Andisol under forest was included in the study as a representative natural reference. Clay dispersion, water release curves and saturated hydraulic conductivity, Ks, were the selected physical properties. Four distinctive types of water release curves were identified, showing sandy behaviour at low suctions while retaining large water holding capacity at large suctions. The van Genuchten parameters helped to differentiate these curves and identify the main pore-size ranges. Under certain combinations of exchangeable cations distribution, salinity and clay mineralogy, very low Ks values were observed for Alo contents lower than 3%. The results suggest that the aggregating effect of Alo (allophanes) could not counterbalance soil structure deterioration. Furthermore, only a multivariable analysis carried out on chemistry, mineralogy and physical data had the merit to classify the studied sorriba-cultivated volcanic soils in terms of soil quality and soil functioning. D 2003 Elsevier Science B.V. All rights reserved.

Ibuprofen adsorption in four agricultural volcanic soils

Ibuprofen (IB) is a high environmental risk drug and one of the most frequently prescribed in human medicine. Recently, IB has been detected in Gran Canaria in reclaimed water for irrigation and in groundwater. Adsorption was studied in four volcanic soils from three islands of the Canarian Archipelago. Once the biodegradation process has been excluded from the experimental conditions, a batch method was applied using initial concentrations of 1-5-10-20-50-100-200 mg L(-1) and two soil/water ratios (w/V): 1:5 (OECD, 2000) and 1:1. Non-linear and linearized Langmuir and Freundlich equations were well fitted. The wide IB range tested in our batch studies allowed us to measure experimental adsorption values close to the maximum adsorption capacity (S(max)) as estimated by Langmuir, making it possible thereby to validate the use of the Langmuir equation when there is a burst of contamination at high concentration. The distribution coefficient (Kd), S(max) and Retardation Factor (RF) varied from 0.04 to 0.5 kg L(-1), 4-200 mgk g(-1) and 1.2-1.9, respectively. The lowest S(max) and Kd values were found for the 1:1S/W ratio whereas most batch studies employ 1:5S/W ratios, thus obtaining higher adsorption parameters than when considering field conditions (1:1). Despite the high anion retention of andic soils, similar Kd and RF to those reported for other soils were obtained in 1:5, while high S(max) was found. Our results demonstrate that IB adsorption in volcanic areas responds not only to the soil properties commonly cited in adsorption studies, but also depends on andic properties, sorbent concentration and Dissolved Organic Carbon, the higher values of which are related to the lower Kd and S(max). The low RF and low detection frequency of the IB in groundwater suggests that a) reclaimed water irrigation is not the main source of IB, and b) the existence of some uncontrolled water disposal points in the zone.

Soils of volcanic systems in Spain

The Canary Islands are the most important volcanic zone anywhere in Spain, considering both extension and age of the eruptive events. On mainland Spain, the most important volcanic areas are found in Campo de Calatrava (Ciudad Real, Central Spain), Cabo de Gata (Almería, Southeast) and Olot (Girona, Northeast). In former two, which are older, soils do not present andic characteristics (Vizcayno Muñoz et al. 1979ab, Simón 2005). In Olot, Andisols developed on basaltic scoria and lapilli under perudic climatic conditions have been described (Bech 1976ab). Andisols on non-volcanic materials have also been described in Galicia, on easily weatherable parent rocks such as gabbros, amphibolites and fine grained schist rich in biotite (García Rodeja et al. 1987). The soils are well drained and formed under a udic moisture and mesic temperature regime. They are non-allophanic Andisols in which the colloidal fraction is dominated by Al-humus complexes. Of a similar nature are the Andisols described in Navarre on phyllites under perudic conditions (Iñiguez and Barragán 1974). Given the already mentioned greater significance of the soils of the Canary Islands, the variety of soil forming factors, the importance and peculiarity of land use in recent volcanic landscapes and the extensive research performed in the soils of the archipelago from different Soil Science disciplines, this chapter will focus mainly in canarian soils, with brief description of the others-limited by the scarcity of the research. We will describe the environmental conditions in the Canaries, the soil types and their distribution, with special attention to Andisols, and will situate in this context the Canarian reference profiles used in the COST622 European project.

Edaphic heterogeneity related to below-canopy water and solute fluxes in a Canarian laurel forest

AimTo study the differences in the edaphic properties between stemflow infiltration areas around different tree species and between these and other areas of the forest.MethodsSoil samples were collected in stemflow infiltration areas and other areas only exposed to throughfall. pH, soluble salt concentration, soil organic carbon and nitrogen, exchangeable bases and Al3+, soluble and available phosphorus and phosphate retention were measured in the soil samples. The inputs of water and H+, Na+, K+, Ca2+, Mg2+, TOC, Fe, NO3−, SO42−, PO43−, and Cl− that reached these areas were calculated.ResultsComparison of the soil properties measured in the throughfall and stemflow infiltration areas corresponding to each species revealed significant differences (p < 0.05), except for exchangeable Mg2+ and Al3+. Differences were observed between i) the stemflow infiltration areas around Morella faya and around each of the other species, and ii) the throughfall infiltration area and the stemflow infiltration area around each of the different species. pH, electric conductivity and available phosphorus of sampled soils were correlated with the corresponding stemflow inputs.ConclusionsThe edaphic properties varied in different below-canopy infiltration areas (mainly between the stemflow infiltration area around M. faya and other parts of the forest soil).

Potassium selectivity in Andic soils in relation to induced acidity, sulphate status and layer silicates

Abstract Potassium exchange was studied in different types of uncultivated and cultivated Andisols and Andic soils (Entisols, Inceptisols and Ultisols) with high amounts of sorbed sulphate. Halloysite was the dominant layer silicate. Cultivated soils showed induced acidity. Potassium selectivity coefficients ( K G ) generally decreased with increase of allophane and organic C content, and increased with acidity and layer silicate content. K G was not related to allophane composition. Soil solution compositions suggested the presence of alunite-like phases. This could account for the apparently high K G values in Al-rich allophane soils and highly potassium saturated, overfertilized cultivated soils.