Baseline element concentrations in soils and plants,Wattenmeer National Park,North and East Frisian Islands,Federal Republic of Germany

Baseline element concentrations are given for dune grass (Ammophilia arenaria), willow (Salix repens), moss (Hylocomium splendens) and associated surface soils. Baseline and variability data for pH, ash, Al, As, Ba, C, Ca, Cd, Ce, Co, Cr, Cu, Fe, Hg, K, La, Li, Mg, Mn, Na, Nb, Nd, Ni, P, Pb, S, Sc, Se, Sr, Th, Ti, V, Y, Yb, and Zn are reported; however, not all variables are reported for all media because, in some media, certain elements were below the analytical detection limit. Spatial variation in element concentration between five Frisian Islands are given for each of the sample media. In general, only a few elements in each media showed statistically significant differences between the islands sampled. The measured concentrations in all sample media exhibited ranges that cannot be attributed to anthropogenic additions of trace elements, with the possible exception of Hg and Pb in surface soils.     

Accumulation soils like “Ockererde”—forgotten soil units in soil‐classification systems

Accumulation soils like those known as “Ockererde” are not yet represented in the German and in international soil‐classification systems, even though they represent important members of catenas found in humid low‐mountain areas influenced by the translocation of interpedon matter. Currently, this soil is referred to as “(Hang‐)Oxigley”, though this does not take into account its water and matter dynamics. Six representative catenas in the Black Forest (SW Germany) will be used to describe the occurrence, extent, and properties of the accumulation‐affected “Ockererde” derived from a variety of parent materials at specific altitudes. On the basis of their morphological, chemical, and physical properties as well as matter dynamics, it is possible to distinguish “Ockererde” clearly from soil units with similar characteristics (“Lockerbraunerde”, Andosols). Finally, suggestions will be given for the classification of “Ockererde”.     

Bodengesellschaften von geomorphen Einheiten unter Berücksichtigung des Gefügestils im Stormarner Jungmoränengebiet (Brandenburger Stadium) in Nordwestdeutschland

Soil associations of different geomorpholocical units of a younger‐moraine area in Schleswig‐Holstein (NW Germany) considering matter fluxes As result of a detailed mapping work, the soil association of different geomorpholocical units of a younger‐moraine area (“Stormarner Jungmoränengebiet”) in Schleswig‐Holstein (NW Germany) is analyzed taking into account soil development in vertical and horizontal direction. The consequences for classification of soil types and soil associations are discussed. We distinguished between different patterns of matter fluxes (unilateral coupling, mutual coupling, no coupling of soils). By morphometric analysis of the relief, five geomorpholocical units were distinguished: till‐plains with dead‐ice kettles (I), tongue‐like basin with moraine slopes (II), terminal‐push moraine (III), moraine slopes with gutter valley (IV), und terminal‐push moraine valley with steep slopes (V). In the examination area with its intense agricultural land use, the regular sequence of erosion and accumulation of soils is a typical consequence of unilateral water‐flow direction. Thus, the truncated Stagnic Luvisols/Anthrosols association is dominating. We suggest to classify the truncated Luvisol with a Bt horizon exposed directly to the surface at the level of soil subtypes in the German soil‐classification system. Additionally soils in depressions such as Calcic Gleysols, Histosols and “subhydric soils”, which are influenced by solute and solid‐matter input, are frequently encountered. Within the till‐plains, a compensation of the relief by (historical) soil erosion took place, recognizable by the high percentage of Anthrosols (20 %). Therefore, no recent lateral transport of solid material can be found. The steep moraine slopes partly already show Regosols, thus indicating a high erosion potential (erosion rate for geomorphical unit IV: 13 t ha^–1 y^–1). In the depressions intersected with small streams, the afflux caused by mills led to an additional peat development.     

Pedobiochemical indicators for eutrophication and the development of ”︁black spots” in tidal flat soils on the North Sea coast

The increasing eutrophication of tidal flat soils on the North Sea coast and the appearance of ”︁black spots” gave rise to this study. The aim was to find pedobiochemical indicators for the development of ”︁black spots”. Artificially eutrophicated soils were compared with untreated soils in the field and laboratory. The pH values of the artificially eutrophicated and natural soils often differed by nearly one unit. The treated soils mostly showed lower redox potentials (˜ —300 mV) than the untreated samples (˜ —250 mV). The mean sulfate concentrations were 2.2 mM in the eutrophicated laboratory soils and 13.1 mM in the eutrophicated field soils, compared with 12.5 mM and 20.2 mM in the untreated ones. Consequently, the SO₄^2—:Cl^— ratios and SO₄^2— differences were lower in the treated soils. Non‐eutrophicated soils showed methane concentrations of < 5 nmol cm^—3, whereas the eutrophicated soils showed up to 217.0 nmol cm^—3 in the field and 479.1 nmol cm^—3 in the laboratory. Differences between field and laboratory data were mainly due to a continuous sulfate supply and reoxidation process only possible in the field. Although all parameters showed differences between the eutrophicated and untreated soils, only the methane data did not overlap with their interquartile ranges. Those of the untreated soils were 2—7 nmol cm^—3 and those of the treated were 12—360 nmol cm^—3. Thus, threshold values can be defined. Methane concentrations of approximately > 10 nmol cm^—3 refer to the beginning eutrophication process and those in the range of > 100 nmol cm^—3 to advanced processes, phenologically forming ”︁black spots”.     

Erosion processes and erodibility of cultivated soils in North Rhine‐Westphalia under artificial rain. II. Results of field experiments and comparison with laboratory trials

In the densely populated state of North Rhine‐Westphalia, soil erosion by water causes substantial on‐site degradation and off‐site damages. The implementation of soil‐conservation measures is improved, if soil erodibilities and erosion processes are known. In a state‐wide investigation, we aimed to representatively assess soil‐erosion processes and erodibilities of cultivated soils. For this purpose, we measured surface runoff and soil‐loss rates of 28 cultivated soils with field plots under artificial rain. In the field experiments, surface runoff and soil loss indicated high sealing susceptibilities and high erodibilities on soils of quite different textures including a clay silt, a loam silt, a loam sand, a sand loam, and two standard loams. Rill formation causing high soil‐loss rates was observed on a clay silt (soil BM) and on a loam silt (soil RB), the latter yielding an empirical K‐factor of 1.66 t ha^–1 h N^–1. K‐factors of other silty soils ranged from 0.04 to 0.48, whereas sandy soils and clayey soils had K‐factors ranging from 0.00 to 0.32, and 0.00 to 0.12, respectively. Comparatively high erodibilities of two silt clays were due to saturation overland flow. Erosion processes and erodibilities of soils with similar texture varied to a large extent, possibly caused in part by seasonal differences in the timing of erosion tests. Surface runoff was different in field experiments compared with laboratory experiments (companion paper) conducted with topsoil material taken from the field plots. In addition, higher concentrations of suspended sediment were recorded on average in the field than in the laboratory. These differences might reflect the influence of the subsoil and are due to higher transport capacities on longer plots in the field. Thus, laboratory experiments can complement but not replace costly field trials for K‐factor determination. Empirical K‐factors derived from field and laboratory experiments are in general lower than K‐factors of other soils in Germany or calculated K‐factors derived from pedotransfer functions, which might be attributed to a more maritime‐type climate in North Rhine‐Westphalia. Since the temporal variability of erodibility was not assessed, the reported K‐factors should be regarded as preliminary.     

Nitrogen mineralization from mature bio‐waste compost in vineyard soils II. Test of N‐mineralization parameters in a long‐term in situ incubation experiment

A field incubation experiment was carried out to test the applicability of N‐mineralization parameters for mature bio‐waste compost for use in a simulation model. The parameters were previously obtained from a laboratory experiment. Micro‐lysimeters were used for incubation, containing four different vineyard soils that were treated with three different compost‐application rates (0, 30, and 50 Mg compost ha^–1). Between 2.0% and 45.2% of total bio‐waste compost N was mineralized and leached from the micro‐lysimeters during the two‐year investigation period. The application of a simulation model for soil N dynamics revealed two major drawbacks of the model: (1) in most of the soils, extraordinary high mineralization rates were observed within a few weeks after compost amendment, which could not be explained by the model, and (2) the average compost‐N‐mineralization rates were estimated as being close to the observed rates (–6%), but distinct deviations in some cases (–46% to +29%) led to considerable miscalculations in long‐term simulations. Excluding the effect of these two processes from the data set, the remaining variance could be well explained by the model for all soils treated with compost (modeling efficiency ≥0.98). Based on the average performance, the mineralization parameters for mature bio‐waste compost are considered to be applicable for use in any simulation model based on the double‐exponential approach for calculating fertilizer recommendations, whereas the functions calculating the impact of environmental factors on N mineralization in the model need to be revised. The initial mineralization flush observed in most of the compost treatments was attributed to a priming effect. The experiment showed that such a priming effect can cause exceptionally high rates of N mineralization from mature bio‐waste compost in a viticultural environment, which exceed the potential mineralization rates known for bio‐waste compost applied to arable soils in Germany.     

Effect of vegetation restoration on ant nest‐building activities following mobile dune stabilization in the Horqin Sandy land,Northern China

Measurements of the density and characteristics (size and height) of ant mounds were carried out on mobile, semi‐mobile, semi‐fixed and fixed dunes in the Horqin Sandy Land, Northern China. The relationships between the distribution of ant mounds and the plant community (abundance and cover) were investigated, for areas within and across the dune stages. Changes in spatial pattern of ant mounds were also analysed following mobile dune stabilization. The results showed no ant mounds on mobile dunes; the mound density was significantly higher on fixed dunes than on semi‐fixed or semi‐mobile dunes. The mound density depended on plant density and cover across all dune stages, but not within any dune stage. The mound diameter increased but the mound height decreased from semi‐mobile dunes to fixed dunes. However, the mound diameter and height were not related to plant cover and density within any stabilization stage or across all dune stages. The spatial pattern of ant mounds tended to change from more clumped (semi‐mobile and semi‐fixed dunes) to less clumped and approached a random pattern (fixed dunes) along the dune stabilization gradient, which was related to the changing vegetation pattern during succession. Although the quantification of the number of ant species present was not attempted on each dune, the observed differences in ant colour and size suggest at least eight species were present. Fixed dunes were more attractive for different kinds of ant species, but the mound distribution exhibited a more random pattern with more continuous vegetation. Thus, different environmental conditions, especially in terms of the plant communities present at different dune stages, affected the activities and behaviour of the ants (including the distribution of mounds), but did not affect mound size and height. Copyright © 2009 John Wiley & Sons, Ltd.     

Arsenic phytotoxicity and accumulation in rice seedlings grown in arsenic‐contaminated soils as influenced by the characteristics of organic matter amendments and soils

Organic matter (OM) application into soils is a common agricultural practice. Previous studies have shown that in arsenic (As)‐contaminated paddy soils, OM has the potential to alter the behavior of As and affects the growth and As accumulation of rice plants. In this study, pot experiments were conducted to investigate the differences in the amounts of As released into soil solutions, its toxicity, and accumulation in rice seedlings caused by application of three different OM amendments [soybean meal (SB), sugarcane dreg compost (SC), and cattle‐dung compost (CD)]. These OM amendments were each applied to three As‐contaminated soils, Guandu (Gd), Pinchen (Pc), and Chengchung (Cf), which have different characteristics. The results indicate that after addition of two easily decomposable OMs (SB and SC), the As toxicity and concentrations increased in rice plants, especially in As‐spiked Cf soils which had low As retention capacity. This was the result of elevated As concentration in soil solutions due to a decrease in soil redox potential and competition between dissolved organic carbon (DOC) and As for sorption sites, as well as the formation of As–DOC complexes. However, there were no significant effects on plant growth and As accumulation in rice seedlings after treatments with CD (not easily decomposable OM). Another important finding was that the amount of iron plaque on the surface of rice roots increased with OM amendments in the Gd soils rich in iron oxides and hydroxides, thus reducing the As uptake by rice plants. These results suggest that the characteristics of OM and soils should be considered when OM amendments are applied to As‐contaminated soils.     

Non‐invasive characterization of pore‐related and elastic properties of soils in linear Biot–Stoll theory using acoustic‐to‐seismic coupling

Soil structure, moisture content and strength have profound effects on plant growth. Traditional methods for monitoring soil condition are invasive and therefore may affect the samples of interest. We have demonstrated the potential of a non‐invasive measurement technique for the in situ monitoring of soil physical properties in the field. When soils are regarded as porous and elastic media, sub‐surface wave propagation can be indicative of the soil status. Such propagation can be initiated by airborne sound through acoustic‐to‐seismic (A–S) coupling. Measurements of near‐surface sound pressure and acoustically induced soil particle motion can be exploited to estimate the pore‐related and elastic properties of soils. We have conducted laboratory measurements on dry and wet sand and field measurements on an arable soil growing wheat using a compression driver, microphones and a laser Doppler vibrometer. The excitation levels were chosen so as to reduce the influence of soil non‐linearity while still yielding sufficient signal‐to‐noise ratios. Measured data were compared with model predictions based on wave propagation in layered homogeneous isotropic poro‐elastic media described by linear Biot‐Stoll theory. Soil properties were estimated through an optimization process minimizing the differences between the measurements and predictions. Latin hypercube sampling was adopted to ensure uniform seeding for optimization throughout the multi‐dimensional search space. The fitted soil characteristics are air permeability, porosity, P‐/S‐wave speeds (related to bulk and rigidity moduli) and a loss factor. Layer depth was also estimated for multi‐layered samples. The current work has demonstrated that soil can be characterized non‐invasively by using A–S coupling. It is also shown that field soils can be represented adequately by multiple homogeneous layers.     

Distribution pattem,genesis and classification of soils of an arid dune area in Northern Negev

A dune area of 2 km² in the Negev (Israel) with an annual precipitation of 90 mm was mapped. The soils developed from eolic and fluviatile sediments were Arenosols, Calcisols. Solonchaks, Regosols and Fluvisols. The Arenosols of the dunes are more homogeneous in texture and salt content than the soils of the interdunal corridors: Besides the Fluvisols, also the Calcisols, Solonchaks and Regosols are stratified due to episodic flooding by a wadi, and are rich in salts and lime. The soils are of minor development. Aggregation and enrichment of lime, enrichment and movement of salts, and the enrichment of organic substances are indications of soil formation. The distribution of salts within the profiles was calculated by their solubility. High and low soluble salts appear together in thin layers of Calcisols, Solonchaks and Fluvisols, while the most-soluble salts appear in deeper layers. The salts, therefore, must have accumulated by lateral movement, precipitation and temporal flooding. Influence of groundwater can therefore be excluded. The Arenosols also show the same sequence of salt types, indicating the accumulation due to precipitation and eolic mass movement. Abandoned arable land sites did not show any different soil characteristics from the unused soils. On the basis of the distribution of salts in the profiles and soil types genesis and classification of the soils is discussed.     

Benzene polycarboxylic acids—A ubiquitous class of compounds in soils

Black carbon (BC) occurs ubiquitously in the environment. Its oxidation in the laboratory yields a suite of benzene polycarboxylic acids (BPCAs), suggesting similar oxidation products in soils. Since only for a few soils the occurrence of BPCAs in the free form has been documented, screening for them in a broad range of contrasting soils was conducted. They were extracted from soil samples with 0.5 M NaOH and quantified using gas chromatography–mass spectrometry. As expected, BPCAs turned out to be as ubiquitous as BC. They were detected not only in every soil sample investigated so far, but also in samples from drill cores up to a depth of 10 m and in recently deposited calcareous tufa. The concentrations covered a range similar to that of some phenolic acids. The range exceeded those reported for low‐molecular‐weight aliphatic acids or simple sugars in soils. The distribution of BPCAs in soil profiles indicated a considerable potential of translocation within, and export from, soil, in particular of benzene hexacarboxylic (mellitic) acid. Mellitic acid may therefore be present in almost any geochemical sample affected by seepage water from soils. Its high water solubility and strong metal‐complexing ability suggest it may be involved in metal‐transport processes, at least on geological timescales.     

Integrating geospatial and multi‐depth laboratory spectral data for mapping soil classes in a geologically complex area in southeastern Brazil

Soil mapping across large areas can be enhanced by integrating different methods and data sources. This study merges laboratory, field and remote sensing data to create digital maps of soil suborders based on the Brazilian Soil Classification System, with and without additional textural classification, in an area of 13 000 ha in the state of São Paulo, southeastern Brazil. Data from 289 visited soil profiles were used in multinomial logistic regression to predict soil suborders from geospatial data (geology, topography, emissivity and vegetation index) and visible–near infrared (400–2500 nm) reflectance of soil samples collected at three depths (0–20, 40–60 and 80–100 cm). The derived maps were validated with 47 external observations, and compared with two conventional soil maps at scales of 1:100 000 and 1:20 000. Soil suborders with and without textural classification were predicted correctly for 44 and 52% of the soil profiles, respectively. The derived suborder maps agreed with the 1:100 000 and 1:20 000 conventional maps in 20 and 23% (with textural classification) and 41 and 46% (without textural classification) of the area, respectively. Soils that were well defined along relief gradients (Latosols and Argisols) were predicted with up to 91% agreement, whereas soils in complex areas (Cambisols and Neosols) were poorly predicted. Adding textural classification to suborders considerably degraded classification accuracy; thus modelling at the suborder level alone is recommended. Stream density and laboratory soil reflectance improved all classification models, showing their potential to aid digital soil mapping in complex tropical environments.     

Upscaling spatio‐temporal patterns of cation fluxes in acid forest soils

One main problem with current research on spatio‐temporal modeling of ion fluxes in forest soils is the separation of space and time effects in the soil‐monitoring concept. This article describes an approach to overcome this weakness. Time trends of point information on soil‐solution data (base‐cation concentrations and fluxes) are scaled by linking them to soil‐chemical data which is available in higher spatial resolution and can be upscaled to an area base. This approach is based on a combined evaluation of bulk soil and soil‐solution data using both statistical and process‐oriented methods. Multiple‐linear‐regression analyses coupled with geostatistics were developed to predict spatial patterns of exchangeable cation percentages. In a second step, empirical ion‐distribution coefficients were adapted according to Gapon using data of suction‐cup plots and bulk‐soil samples. Seasonally adjusted time‐series data of soil‐solution chemistry were then connected with the maps of the predicted exchangeable‐cation percentages by means of the Gapon equations. This evaluation step provided both time‐ and space‐dependent maps of cation concentrations in the soil solution. Finally, using the results of a water‐budget model it was possible to derive spatio‐temporal patterns of soil cation fluxes. Methodological limitations and the results of verification processes are discussed. The methods described can only be used in acidic soils and should not be used in soil layers rich in humus, since adsorption to C compounds differs from adsorption to clay minerals. The time increments of the models should be not shorter than yearly in order to suppress annual periodicity. Although the Gapon equations were not based on laboratory‐determined exchange solutions at quasi‐equilibrium, but rather on field data from the suction‐cup technique, the exchangeable‐cation percentages showed steady functions of selectivity coefficients. The methods tested at a watershed scale may be flexible enough to be applied at other scales as well.     

Characterization of some Middle European soil textures by gamma‐spectrometry

Information about the variability of different soil attributes within a field is essential for sustainable land management and precision agriculture. Mobile proximal gamma‐ray spectrometry can map soil characteristics of vast areas at different scales rapidly and cost‐effectively. This study aims at investigating reliability and capability of mobile‐gamma‐spectrometry (radiometrics) data to map typical soils of Middle Europe. In this paper, we investigate relationships between the radioelement concentrations (K, U, Th, and dose rate) and soil parameters (texture, CEC, pH, and organic‐C content) at four different field sites and soil textures. The data reliability is confirmed at the survey start. Mobile data have an excellent linear correlation (nearly 1:1) with the stationary readings (of identical devices, acquisition setups, and soil conditions) but moderate correlation with laboratory data (of different devices, setups, and sample conditions). Dried lab samples have systematically higher radioelement concentrations than the field soils (normally wet). Consequently, the mobile‐gamma‐spectrometric data is sufficiently accurate for soil mapping, and its calibration by laboratory data is less useful due to the varying environmental conditions. Single absolute radioelement concentrations show only moderate correlations with the different soil parameters, particularly clay content and CEC. This may be related to varying environmental conditions (soil moisture, soil structure, vegetation, land use, etc.) between the study sites. Investigations of the ratios of radioelement concentrations yield a clear improvement of their correlations to soil parameters, especially for sand and clay contents, CEC, and organic C. Additionally, multiple‐linear‐regression models were established using the element concentrations of potassium and thorium to predict silt content and pH. The results of the highly correlated models were confirmed by comparing with clay and silt content and pH value, respectively, to six additional independent field samples. Briefly, applications of gamma‐ray data for soil mapping offers the possibility of the development of quantitative relationships regarding soil parameters like sand and clay contents, CEC, and organic C. Classification of soil textures by gamma‐ray data seems to be promising, though a broader database of soils is needed for further research. We recommend gamma‐ray mapping as a complementary or even an alternative to common mapping techniques.     

Estimation of PAH bioavailability to Lepidium sativum using sequential supercritical fluid extraction – a case study with industrial contaminated soils

For the determination of PAH availability to plants a plant accumulation test with Lepidium and sequential supercritical fluid extraction (SSFE) with carbon dioxide as extraction solvent was used, during which the extraction conditions were changed from mild to harsh in order to represent a broad range of potential pollutant-soil interactions. Both approaches were applied in laboratory experiments on industrial contaminated soils which, in addition, were also freshly spiked with PAHs in order to increase the bioavailability. Only Naphthalene, Phenanthrene and, in some cases, Pyrene accumulated from the industrial contaminated soils. Accumulation experiments with spiked industrial soils showed that other PAHs, for example Anthracene, Fluorene and even high weight PAHs like Benzo(a)pyrene, also could be taken up by plants. SSFE extraction data were compared to accumulated amounts of PAHs in the plants. Strong correlations were found for Phenanthrene between plant accumulation and extractability under very mild extraction conditions. For Naphthalene, accumulation did not correlate with its extractability in the industrial soils. The possibility exists that bioavailability in soil was eclipsed by an accumulation in the gas phase due to the high volatility of Naphthalene. Supercritical fluid extraction appears to be a promising tool to estimate Phenanthrene availability to plants, but further studies for the evaluation of other PAHs are recommended. This could be helpful for the determination of the feasibility of phytoremediation applications on industrially contaminated soils.     

SEVERITY OF SALINITY ACCURATELY DETECTED AND CLASSIFIED ON A PADDOCK SCALE WITH HIGH RESOLUTION MULTISPECTRAL SATELLITE IMAGERY

We hypothesised that digital mapping of various forms of salt‐affected soils using high resolution satellite imagery, supported by field studies, would be an efficient method to classify and map salinity, sodicity or both at paddock level, particularly in areas where salt‐affected patches are small and the effort to map these by field‐based soil survey methods alone would be inordinately time consuming. To test this hypothesis, QuickBird satellite data (pan‐sharpened four band multispectral imagery) was used to map various forms of surface‐expressed salinity in an agricultural area of South Australia. Ground‐truthing was performed by collecting 160 soil samples over the study area of 159 km². Unsupervised classification of the imagery covering the study area allowed differentiation of severity levels of salt‐affected soils, but these levels did not match those based on measured electrical conductivity (EC) and sodium adsorption ratio (SAR) of the soil samples, primarily because the expression of salinity was strongly influenced by paddock‐level variations in crop type, growth and prior land management. Segmentation of the whole image into 450 paddocks and unsupervised classification using a paddock‐by‐paddock approach resulted in a more accurate discrimination of salinity and sodicity levels that was correlated with EC and SAR. Image‐based classes discriminating severity levels of salt‐affected soils were significantly related with EC but not with SAR. Of the spectral bands, bands 2 (green, 520–600 nm) and 4 (near‐infrared, 760–900 nm) explained the majority of the variation (99 per cent) in the spectral values. Thus, paddock‐by‐paddock classification of QuickBird imagery has the potential to accurately delineate salinity at farm level, which will allow more informed decisions about sustainable agricultural management of soils. Copyright © 2011 John Wiley & Sons, Ltd.     

Soil Potassium Indices and Clay‐Sized Particles affecting Banana‐Wilt Expression Caused by Soil Fungus in Banana Plantation Development on Transported Volcanic Soils

Abstract

Relations among the expression of banana disease symptoms caused by the soil fungus Fusarium oxysporum f. sp. cubense, soil potassium (K)–sodium (Na) properties [soluble K‐Na ratios (SK/SS), potential buffering capacity for K (KBC), potassium adsorption ratio (KAR)], and clay‐sized particles were evaluated in Sorribas plots from the Canary Islands. Soils were sampled in areas of Sorribas where banana plants show positive or negative wilting symptoms characteristic of Panama disease. The Bartoli method was used for soil dispersion (Na resin). This method was able to show a clear separation between diseased and disease‐free areas by the amount of clay‐sized particles. Results also show that the greatest SK/SS ratios and clay‐sized particles in soils from diseased areas could explain the increase of water‐stable aggregate mass in these soils and the release of available iron (Fe) to soil solution in diseased areas, at least in Sorribas cultivated soils under the arid climate conditions of the Canary Islands.