Vineyard Soils Research Articles

Stability of exogenous Cadmium in different vineyard soils and its effect on grape seedlings

Cadmium (Cd) being potentially toxic heavy metal, has become increasingly serious to vineyard soil and grapes in recent years. Soil type is one of the main factors affecting the absorption of Cd in grapes. To investigate the stabilization characteristics and form changes of Cd in different types of vineyard soils, a 90-days incubation experiment was conducted after exogenous Cd addition to 12 vineyard soils from typical vineyards in China. The inhibition of exogenous Cd on grape seedlings was determined based on the pit-pot incubation experiment (200 kg soil per pot). The results demonstrate that Cd concentration in all the sampling sites did not exceed the national screening values (GB15618-2018; i.e., 0.3 mg/kg when pH was lower than 7.5, 0.6 mg/kg when pH was higher than 7.5);. Cd in Fluvo-aquic soil 2, Red soils1, 2, 3 and Grey-Cinnamon soil is dominated by acid-soluble fraction, but was mainly in residual fraction in the remain soils. Throughout the aging process, proportion of the acid-soluble fraction increased and then decreased, while proportion of the residual fraction decreased and then increased, after exogenous Cd was added. The mobility coefficients of Cd in Fluvo-aquic soil 2 and Red soil 1, 2 increased 2.5, 3 and 2 folds, after exogenous Cd addition, respectively. Compared with CK (control), the correlation between total Cd content and its different fractions was relatively weak in the Cdl (low concentration) and Cdh (high concentration) groups. Poor Cd stabilization and strong inhibition of seedling growth rate were observed in Brown soil 1, black soil, red soil 1 and cinnamomic soil. Fluvo-aquic soil 2, 3 and Brown soil 2 showed good Cd stability and small inhibition effect on grape seedlings. These results show that Cd stability in soils and inhibition rate of grape seedlings by Cd are strongly influenced by soil type.

Long-term under-vine coverage by spontaneous vegetation changed plant community and soil dynamics without impacting yield at two South Australian vineyards

Under-vine management practices have traditionally consisted of herbicide applications or cultivation to manage weeds, thus limiting competition for resources with grapevines. However, increasing awareness of detrimental impacts of herbicides and cultivation on agricultural landscapes are shifting practices towards alternative options, including an unmanaged under-vine area where spontaneous vegetation proliferates. How this practice may affect the suite of soil, water, and nutrient relations and corresponding grapevine performance in a Mediterranean climate in the long-term is relatively unknown. Thus, this study utilised a unique opportunity to explore how undisturbed under-vine spontaneous vegetation compared to traditional herbicide (Eden Valley, loamy sand soil) or cultivation (McLaren Vale, silty loam soil) practices at two commercial vineyards. After five years of treatments, assessments were made on under-vine plant community and soil dynamics, grapevine responses, and juice composition. At Eden Valley, the spontaneous vegetation changed the plant community by increasing total plant coverage and biomass, while at McLaren Vale there was a lesser effect; however, the plant communities at both sites were similarly dominated by perennial grasses compared to higher proportions of broad-leaf, fast-growing species in the traditional herbicide and cultivation treatments. Soil water and nutrient availability were decreased by spontaneous vegetation in Eden Valley, while in McLaren Vale, the spontaneous vegetation enhanced soil phosphorus, water infiltration, and increased organic carbon by 40%. In Eden Valley, spontaneous vegetation decreased juice yeast available nitrogen; yet phenolics, anthocyanins, and total soluble solids were higher. At both sites, there was no significant impact of maintaining under-vine spontaneous vegetation on yields, however it decreased pruning weights at Eden Valley, while no effects were quantified on pruning weights or juice composition at McLaren Vale. We demonstrate that in the long-term, maintaining undisturbed spontaneous vegetation as an alternative to using herbicides or cultivation in the under-vine row can benefit the vineyard agroecosystem, while not adversely impacting grapevine yields depending on vineyard soil type and target winemaking outcomes.

Vineyard renewal reduces copper and zinc bioavailability and increases microbial diversity in southern Brazil

The long-term use of vineyards and their renewal causes numerous chemical changes in the bioavailable copper, zinc levels, carbon and microbial properties of the soil. However, there is still a gap in relation to the impacts of vineyard renewal on the bioavailability of Cu and Zn and on the microbial structure of the soil. Thus, the purpose was to evaluate the bioavailability of Cu and Zn, activity, richness and microbial diversity of the soil of renewed vineyards in southern Brazil. Three treatments were established: old cultivation, i.e., a well-established vineyard; renewed vineyard; and reference, a native forest located adjacent to the vineyards. The physical-chemical properties clay level, moisture, pH, organic matter (OM), carbon (C), nitrogen (N), phosphorus (P), potassium (K), copper (Cu), and zinc (Zn) level; the basal respiration (BR), microbial biomass Carbon (MBC), microbial biomass Nitrogen (MBN), hydrolysis of fluorescein diacetate (FDA), microbial quotient (qMic), and metabolic quotient (qCO2); and microbial richness and Shannon diversity were determined. The organic C level influenced the microbial activity and richness. The change in microbial diversity indexes impacted soil biological activity in two locations. Vineyard renewal promotes the reduction of Cu (− 48.8%) and zinc (− 20%) bioavailability and increases microbial diversity in subtropical soils in southern Brazil.

Sustainable management of vineyard soils: an experimental approach to investigate the responses of the edaphic arthropod community

Sustainable management of vineyard soils: an experimental approach to investigate the responses of the edaphic arthropod community

Modelling the influence of climate change on characterization factors for copper terrestrial ecotoxicity

The use of copper-based preparations is a long-standing practice in viticulture to control vine fungal diseases, which has led to high copper concentrations in vineyard soils and impacts on off-target terrestrial organisms. Under projected climate change, some of the mechanisms and properties of soils that influence the extent of metals ecotoxicity impacts are projected to be altered, namely soil erosion, rainfall, temperature, and organic carbon content. In this context, and within the framework of life cycle assessment, this study aims to simulate the influence of projected changes in soil organic carbon, soil erosion, and rainfall on characterization factors (CFs) for copper terrestrial ecotoxicity across non-calcareous European vineyard soils. We employed empirical regression models to account for metal speciation and bioavailability as determined by soil characteristics. CFs were computed for a current scenario and mid-term future scenarios by 2050 determined across three Representative Concentration Pathways (RCP2.6, RCP4.5, and RCP8.5). Although future scenarios suggest that CFs may either increase or decrease, CFs are projected to increase for a larger share of the European vineyard surface, which may lead to higher terrestrial ecotoxicity impacts. The RCP4.5 scenario projects the highest increases in CFs, with a 27% rise in the median CF in comparison with the current scenario. Whereas the RCP8.5 and RCP2.6 scenarios project a 19% and 14% increase in median CFs, respectively. The changes in CFs were determined principally by the changes in copper bioavailability driven by projected changes in soil organic carbon. However, the spatial variability of CFs was larger than the temporal variation, with a variation of roughly 2 orders of magnitude across the analyzed scenarios. This study highlights the relevance of integrating spatial differentiation and the influence of projected climate change in the characterization modelling of copper terrestrial ecotoxicity.

Vineyard floor management intensity impacts soil health indicators and plant diversity across South Australian viticultural landscapes

Throughout the last thirty years, major shifts in vineyard floor management have been observed. Challenges initially posed by intensive tillage included high rates of soil erosion and the degeneration of soil structure and soil organic matter, which lead viticulturists to depend more heavily on herbicide use as an effective weed control strategy. However, an increase in herbicide persistence and toxicity in water, soils, and grapevines, increasing resistance of common weeds; and pressure from consumers and regulators to reduce their use is directing a shift towards an overall reduction in herbicide usage. This has led to more frequent tillage to manage vegetation in vineyards, while in some instances, cultural practices including slashing and animal grazing are used solely or in conjunction. However, little is known about the holistic effects of these varying practices on vineyard soils and biodiversity across landscapes in Australia. Thus, to comparatively assess the environmental impacts of different floor management practices, soil health indicators and plant dynamics were seasonally measured in the mid- and under-vine rows at twenty-four vineyard sites and four native sites in the Barossa Valley, Eden Valley, and McLaren Vale, all located in South Australia, where different intensities of floor management were implemented. Vineyard sites were categorised based on the frequency of herbicide and/or tillage passes particularly in the under-vine area into Low (no annual management passes), Medium (one annual management pass), and High (two to four annual management passes) intensity groups. Findings revealed similarities in the vineyard mid-rows across the management intensities, yet the under-vine rows displayed many differences; in particular, there were more plant species, higher plant coverage, and greater plant biomass in the Low management intensity group. Furthermore, as management intensity decreased, the relative richness of ruderal plant species also decreased, giving way to a plant community mainly comprised of slow-growing, perennial Poaceae and Fabaceae species in the Low-intensity management group. These differences in plant dynamics drove a suite of soil responses including faster water infiltration, higher soil ammonium-N and total nitrogen, and a tendency of higher soil gravimetric water content at the time of sampling. These results suggest that after an initial period of establishing these more extensive vineyard floor management practices, low levels of soil disturbance in the under-vine rows may contribute positively to improving natural ecosystem synergy and functionality between soil and plants. Therefore, our findings lend insights into how the varying intensity of floor management practices, rather than differing management ideologies per se, across a viticultural landscape can be intrinsic supporters of agroecosystem resilience under South Australian conditions.

Effect of Grape Pomace Varieties and Soil Characteristics on the Leaching Potential of Total Carbon, Nitrogen and Polyphenols

Grape pomace (GP) has an added value because of its contribution to carbon (C) and nitrogen (N) in soils when applied as an organic fertilizer. Macronutrients from GP are translocated into the soil after amendment, but little is known about the factors that may influence the mobility of C, N and bioactive molecules, i.e., polyphenols, in the soil column. We investigated the mobility of the macronutrient content of GP, derived from two red (Dornfelder and Pinot noir) and two white grape varieties (Riesling and Pinot blanc). For that, three different soils (loamy sand RefeSol01A, silt loam RefeSol02A and a vineyard soil) were evaluated in a column model using a GP application rate of 30 t ha−1. The three-step lab-scale approach included the analysis of total C, N and polyphenols expressed as total polyphenolic content (TPC) in: (a) the fresh GP, representing the total amount of C, N and TPC; (b) the mobility with rainwater, representing the aqueous extractable fraction and (c) the mobility in the soil column and leaching potential. Our results showed that total C/N ratios were wider in the white GP varieties compared with the red ones. Higher TPC values were measured in Dornfelder and Pinot noir compared with white varieties. Analysis of the water-extractable fraction showed that the C recovery may reach up to 48% in Pinot blanc, which also corresponds to the highest N contribution. Extractable polyphenols were higher in the red compared with the white varieties by a factor of 2.4. C and N were mobilized with rainwater from the GP through the soil column. However, the application rate used in the experiment was not indicative of an accumulation in the soil. Compared with the control (no GP application), C values were significantly higher in the leachates from GP-treated soils, in contrast to N values. Up to 10% of the TPC of the pomace was leached into the soil. The TPC recovery in the soils strongly depended on the combination of soil type and GP variety. Generally, the sandy and more acidic soil showed an even distribution of phenolics with a high recovery rate (up to 92%) compared with more neutral and silty soil. Most of the polyphenol content could accumulate in the upper soil layer (0–10 cm). These results provide the first insights on the mobility of macronutrients in the soil using a column model and point out the need to relate those experiments to soil and GP properties in order to avoid the accumulation of nutrients in soil or mobility to adjacent ecosystems.

Grass sward cover improves soil organic carbon and nitrogen in a vineyard

ABSTRACT Historical depletion of agricultural soils must be remedied to maintain their long-term food production function, including soils in intensive vineyards traditionally kept without plant cover to limit resource competition. This paper reports on the impact of five contrasting soil management regimes on indicators of soil quality such as soil organic carbon, nitrogen and their indices. We exposed sandy loam Rendzic Leptosol under a vineyard in Nitra-Dražovce (Slovakia, central Europe) to the following five treatments for 14 years: no-till sward, no-till sward+NPK100, no-till sward+NPK125, plowed tillage and (5) plowed tillage+manure. We found that grass swards continuously increased the total soil organic carbon in the topsoil, but plowed tillage resulted in no change. The availability of potentially mineralizable nitrogen was also increased by grass cover; but was not modified by manure but by mineral fertilizer addition. We tested the usefulness of carbon and management indices as indicators of changing soil C and N status and found them no better than tracking total and labile forms of both elements. In conclusion, the recovery of degraded vineyard soils under no-till grass sward cover is detectable within 14 years and is not affected by fertilization or manure addition.

Cover Image, Volume 87, Issue 3

Soil Science Society of America JournalVolume 87, Issue 3 COVER IMAGEFree Access Cover Image, Volume 87, Issue 3 First published: 15 May 2023 https://doi.org/10.1002/saj2.20445AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Graphical Abstract On the cover: Vineyard greenstone. One of Chrysalis Vineyards' sites is planted on soils formed from metabasalt in the Blue Ridge Mountains of Virginia. Such parent rocks may provide grapevines with too much potassium, which can negatively affect wine quality. See J.C. Fiola et al., “Improving methods for evaluating potassium availability in vineyard soils,” https://doi.org/10.1002/saj2.20522. Photo by Jaclyn C. Fiola. Volume87, Issue3May/June 2023 RelatedInformation

Effect of Applying an Organic Amendment on the Persistence of Tebuconazole and Fluopyram in Vineyard Soils

The persistence of fluopyram and tebuconazole has been studied in different crops and agricultural soils. However, the behaviour of these fungicides may be altered when they are applied as a combined formulation in organically amended vineyard soils under field conditions. The purpose of this study is to evaluate the effect of applying spent mushroom substrate (SMS) or this residue re-composted with ophite (SMS + OF) on the adsorption, dissipation, and mobility of the fungicides fluopyram and tebuconazole in vineyard soils. Triplicate 10 m2 plots per treatment were set up in two different vineyard soils in the eastern La Rioja region: silt loam (ARN1) and sandy loam (ARN2), respectively, with low organic carbon (OC) content. The organic residues SMS and SMS + OF were applied at doses of 25 and 100 Mg ha−1. The adsorption distribution coefficients (Kd) increased when SMS and SMS + OF were applied, especially at the higher dose (100 Mg ha−1). The dissipation curve of both compounds fitted a two-phase kinetic model, with a very fast initial dissipation rate, followed by slower prolonged dissipation during the second phase. The dissipation half-lives (DT50) ranged between 4.7 and 26.3 days for fluopyram and between 2.3 and 6.3 days for tebuconazole in the different soils, increasing for fluopyram in the ARN1 amended with SMS and SMS + OF. The fungicide residues at 15–30 cm depth were lower in the unamended and amended sandy loam soil (ARN2), indicating that fungicides are dissipated mainly in the topsoil. The results indicate different dissipation mechanisms for both fungicides, as the adsorption by soil OC prevented the dissipation of fluopyram but facilitated the dissipation of tebuconazole, probably due to the formation of non-extractable residues.

Improving methods for evaluating potassium availability in vineyard soils

AbstractVineyard soils often contain mineralogy that can confound predictions of plant‐available potassium (K). Too little or too much K uptake into wine‐grape (Vitis varieties) tissues can negatively affect fruit chemistry, making it important to have soil tests that accurately quantify plant‐available K. Our goal was to determine the best soil sampling, processing, and extraction methods for predicting K availability in vineyard soils. We sampled soil and grapevine tissue in 39 vineyard blocks from 22 vineyards in Virginia, Maryland, and New Jersey. Plant tissue sampling included petioles at bloom and both petioles and leaf blades at veraison. Soil samples were collected from 0 to 10‐ and 0 to 38‐cm depths. We tested three soil extraction methods—Mehlich 1, Mehlich 3, and sodium tetraphenylboron (NaTPB)—on both oven‐dried and field‐moist samples. The different sampling, processing, and extracting procedures produced distinct K concentrations, with shallow 0–10 cm samples and NaTPB extraction resulting in higher K concentrations than their counterparts. Upon drying, three soils fixed K and 24 samples released K. Whole leaf (petiole plus leaf blade) samples collected at veraison had the best relationships with most soil K concentrations. The best soil testing method for predicting tissue K concentration in whole leaves at veraison was Mehlich 1 extractions of field‐moist soils from 0 to 38‐cm depth. This sampling combination appears to be best suited for growers to use when assessing K concentrations in vineyard soils.

Copper accumulation in five weed species commonly found in the understory vegetation of Mediterranean vineyards

Copper (Cu) concentration in agricultural soils often exceeds toxicological limits due to application of Cu-based fungicides. The potential of weeds for their use as functional cover plants in vineyard management and phytoremediation practices is little explored. We identified five weed species widely present in vineyards and assessed their Cu accumulation from eleven Mediterranean vineyards (soil Cu: 60–327 μg g−1) and two adjacent control sites (soil Cu: 15–30 μg g−1). Soils and plants were characterized by their physico-chemical properties and nutrient content. We applied multivariate techniques to analyze relationships between soil properties and leaf nutrient composition. Copper tolerance and accumulation traits were further tested in hydroponics using a series of CuSO4 concentrations (0.1–16 μM).Under field conditions, the highest Cu concentration in both roots and leaves were found in Lolium perenne (221 and 461 μg g−1, respectively), followed by Plantago lanceolata, Rumex obtusifolius and Taraxacum officinale (>100 μg g−1 Cu in leaves). Only one species, Trifolium repens, did not accumulate remarkable Cu concentrations. Overall, and as revealed by the multivariate analyses, leaf Cu concentration was driven by soil Cu content, soil texture, organic matter, nitrogen, and Cu uptake into roots. However, functional regression analysis and controlled experiments suggested that Cu might be additionally absorbed from the deposits on the leaf surface related to the Cu-fungicide treatments and soil dust. Our study highlights the importance of intra-specific variability in Cu accumulation among weed species in Cu-contaminated agricultural soils. Further validation of these findings under controlled conditions could provide essential insights for optimizing management and remediation strategies.

Cover crop response to increased concentrations of copper in vineyard soils: Implications for copper phytoextraction

The use of cover crops (CCs) in viticulture is threatened by the contamination of vineyard soils by copper (Cu). This study investigated the response of CCs to increased concentrations of Cu in soil as a way to assess their sensitivity to Cu and their Cu phytoextraction ability. Our first experiment used microplots to compare the effect of increasing soil Cu content from 90 to 204 mg kg−1 on the growth, Cu accumulation level, and elemental profile of six CC species (Brassicaceae, Fabaceae and Poaceae) commonly sown in vineyard inter-row. The second experiment quantified the amount of Cu exported by a mixture of CCs in vineyards with contrasted soil characteristics. Experiment 1 showed that increasing the soil Cu content from 90 to 204 mg kg−1 was detrimental to the growth of Brassicaceae and faba bean. The elemental composition of plant tissues was specific to each CC and almost no change in composition resulted from the increase in soil Cu content. Crimson clover was the most promising CC for Cu phytoextraction as it produced the most aboveground biomass, and, along with faba bean, accumulated the highest concentration of Cu in its shoots. Experiment 2 showed that the amount of Cu extracted by CCs depended on the availability of Cu in the topsoil and CC growth in the vineyard, and ranged from 25 to 166 g per hectare. Taken together, these results emphasize the fact that the use of CCs in vineyards may be jeopardised by the contamination of soils by Cu, and that the amount of Cu exported by CCs is not sufficiently high to offset the amount of Cu supplied by Cu-based fungicides. Recommendations are provided for maximizing the environmental benefits provided by CCs in Cu-contaminated vineyard soils.

Disentangling the mixed effects of soil management on microbial diversity and soil functions: A case study in vineyards

Promoting soil functioning by maintaining soil microbial diversity and activity is central for sustainable agriculture. In viticulture, soil management often includes tillage, which poses a multifaceted disturbance to the soil environment and has direct and indirect effects on soil microbial diversity and soil functioning. However, the challenge of disentangling the effects of different soil management practices on soil microbial diversity and functioning has rarely been addressed. In this study, we investigated the effects of soil management on soil bacterial and fungal diversity as well as soil functions (soil respiration and decomposition) using a balanced experimental design with four soil management types in nine vineyards in Germany. Application of structural equation modelling enabled us to investigate the causal relationships of soil disturbance, vegetation cover, and plant richness on soil properties, microbial diversity, and soil functions. We could show that soil disturbance by tillage increased bacterial diversity but decreased fungal diversity. We identified a positive effect of plant diversity on bacterial diversity. Soil respiration showed a positive response to soil disturbance, while decomposition was negatively affected in highly disturbed soils via mediated effects of vegetation removal. Our results contribute to the understanding of direct and indirect effects of vineyard soil management on soil life and aids designing targeted recommendations for agricultural soil management.

Elevated atmospheric CO2 concentrations caused a shift of the metabolically active microbiome in vineyard soil

BackgroundElevated carbon dioxide concentrations (eCO2), one of the main causes of climate change, have several consequences for both vine and cover crops in vineyards and potentially also for the soil microbiome. Hence soil samples were taken from a vineyard free-air CO2 enrichment (VineyardFACE) study in Geisenheim and examined for possible changes in the soil active bacterial composition (cDNA of 16S rRNA) using a metabarcoding approach. Soil samples were taken from the areas between the rows of vines with and without cover cropping from plots exposed to either eCO2 or ambient CO2 (aCO2).ResultsDiversity indices and redundancy analysis (RDA) demonstrated that eCO2 changed the active soil bacterial diversity in grapevine soil with cover crops (p-value 0.007). In contrast, the bacterial composition in bare soil was unaffected. In addition, the microbial soil respiration (p-values 0.04—0.003) and the ammonium concentration (p-value 0.003) were significantly different in the samples where cover crops were present and exposed to eCO2. Moreover, under eCO2 conditions, qPCR results showed a significant decrease in 16S rRNA copy numbers and transcripts for enzymes involved in N2 fixation and NO2− reduction were observed using qPCR. Co-occurrence analysis revealed a shift in the number, strength, and patterns of microbial interactions under eCO2 conditions, mainly represented by a reduction in the number of interacting ASVs and the number of interactions.ConclusionsThe results of this study demonstrate that eCO2 concentrations changed the active soil bacterial composition, which could have future influence on both soil properties and wine quality.

Microbiome in soils of Mendoza: microbial resources for the development of agroecological management in viticulture

Rhizosphere microorganisms are considered an extension of plants, representing critical actors involved in the promotion of plant nutrient intake from the surrounding environment. Consequently, a great focus is being made on soil microorganisms since they are considered a promising source for crop resilience improvements under a global climate change scenario. To explore bacterial and fungal communities from arid soils in vineyards and their surroundings from two regions with very different climate and tillage histories, an amplicon sequencing analysis was performed. Specifically, Santa Rosa (SR) is in a region commonly known as the first zone, characterised by low altitude (607 m.a.s.l., Winkler V), while Gualtallary (G) is in the Uco Valley Zone, a region with high altitude (1245 m.a.s.l., Winkler III); both in the productive wine region of Mendoza. SR is characterised by its long cultivation history, while G is a recently cultivated region. Topsoil samples were collected and used for bacterial and fungal community profile characterisation. Ascomycota was the predominant phylum (38–97 %) in mycobiome composition, whereas Proteobacteria was the most abundant bacterial phylum (26–34 %) in both regions. Moreover, the main factor explaining microbiome differences between regions was the carbon-to-nitrogen ratio. Anaerolineae and Gammaproteobacteria were a distinctive bacterial class in SR-cultivated soils. Azospirillales were highly abundant in SR uncultivated soils, while Rhizobiales were differentially abundant in G uncultivated soils. Regarding functional analysis, soils from SR showed a higher denitrification activity of nitrifiers as well as glucose-related metabolism, while in G soils, bacterial photosynthesis activities were a differential trait. In addition, Actinobacteria abundance was lower in SR-cultivated soils, indicating a higher susceptibility of this phylum to grapevine crop practices. These results allow the development of hypothetical models of the local microbial resources and their contribution to grapevine nutrition, which is highly important to elaborate recommendations for grapevine management to preserve soil health in vine areas of Mendoza.

Investigation of Hillslope Vineyard Soil Water Dynamics Using Field Measurements and Numerical Modeling

Soil heterogeneities can impact hillslope hydropedological processes (e.g., portioning between infiltration and runoff), creating a need for in-depth knowledge of processes governing water dynamics and redistribution. The presented study was conducted at the SUPREHILL Critical Zone Observatory (CZO) (hillslope vineyard) in 2021. A combination of field investigation (soil sampling and monitoring campaign) and numerical modeling with hydrological simulator HYDRUS-1D was used to explore the water dynamics in conjunction with data from a sensor network (soil water content (SWC) and soil-water potential (SWP) sensors), along the hillslope (hilltop, backslope, and footslope). Soil hydraulic properties (SHP) were estimated based on (i) pedotransfer functions (PTFs), (ii) undisturbed soil cores, and (iii) sensor network data, and tested in HYDRUS. Additionally, a model ensemble mean from HYDRUS simulations was calculated with PTFs. The highest agreement of simulated with observed SWC for 40 cm soil depth was found with the combination of laboratory and field data, with the lowest average MAE, RMSE and MAPE (0.02, 0.02, and 5.34%, respectively), and highest average R2 (0.93), while at 80 cm soil depth, PTF model ensemble performed better (MAE = 0.03, RMSE = 0.03, MAPE = 7.55%, R2 = 0.81) than other datasets. Field observations indicated that heterogeneity and spatial variability regarding soil parameters were present at the site. Over the hillslope, SWC acted in a heterogeneous manner, which was most pronounced during soil rewetting. Model results suggested that the incorporation of field data expands model performance and that the PTF model ensemble is a feasible option in the absence of laboratory data.

Response of nematode community structure to different restoration practices in two vineyard soils in Tuscany (Italy)

ABSTRACT Inappropriate land preparation before vineyard establishment can lead to soil degradation and vine health issues, with consequent reductions in the quantity and quality of the grapes. In the present short-term trial, the effects of dry mulching, green manure and compost treatments were evaluated as restoration strategies to enhance soil functionality in degraded vineyard areas at two Tuscan farms that had been under organic management for different lengths of time. Soil nematode community, soil physical and chemical properties were monitored as indicators of soil quality. The restoration treatments scarcely affected soil chemical or physical qualities; only the compost application increased soil total organic carbon (TOC). Bacterial feeder nematodes increased under dry mulching in response to the organic carbon inputs on the farm in conversion. Plant-parasitic nematodes decreased only after the first year of the restoration treatments and predators decreased during all 3 years. Nematode indicators showed only a few differences between the different management regimes; the diversity weighted abundance expressed as biomass indicated that the restoration practices sometimes represented a disturbing factor in ecosystem services regulation. The abundance of nematode taxa was differently affected by soil physico-chemical properties. On the farm that had been managed organically for longer, the higher proportion of large sized stable aggregates and greater soil porosity benefitted large nematodes such as predators, while the higher moisture levels were unfavourable for some plant-parasitic nematodes. However, on the farm still in conversion, increases in TOC and C/N ratio values were associated with a reduction in plant-parasitic nematodes.

Levels of Heavy Metals in Grapevine Soil and Leaf Samples in Response to Seasonal Change and Farming Practice in the Cape Winelands

Heavy metal toxicity is a major threat to the health of both humans and ecosystems. Toxic levels of heavy metals in food crops, such as grapes, can have devastating effects on plant health and the market value of the produce. Two important factors that may influence the prevalence of heavy metals in grapevines are seasonal change and farming practices. The objectives of this study were (i) to conduct a detailed pioneer screening of heavy metal levels in soils and grapevine leaf tissues in selected wine farms and (ii) to study the influence of season and farming on heavy metal levels in soils and grapevine leaf tissues. Soil and grapevine leaf samples were collected from demarcated areas in selected vineyards in the Cape Winelands region of South Africa. The sampling was conducted in winter and summer from the same sites. The soil and leaf samples were analysed using inductively coupled plasma mass spectrometry (ICP-MS) techniques. The pooled data from the farms practising conventional or organic farming showed that seasonal variation had no significant effect (DF = 1, 22; p > 0.05) on the heavy metal contents in the soil. When the soil data from the winter and summer months were compared separately or pooled, the influence of agricultural practice was well-pronounced in As (DF = 1, 22, or 46; p < 0.05) and Cu (DF = 1, 22, or 46; p <0.05). The agricultural practice greatly influenced (DF = 1, 22; p< 0.05) Cu, As, Cr, and Hg uptake, with little effect on Ni, Co, Cd, and Hg leaf contents. Generally, the heavy metals studied (Cr, Co, Ni, Zn, As, Cd, Hg, and Pb) were substantially below the maximum permitted levels in plant and soil samples, per the recommendations of the WHO and Er indices, respectively. However, moderate contamination of the soils was recorded for Cr, Ni, Zn, and Pb. Remarkably, the Cu levels in the organic vineyard soils were significantly higher than in the conventional vineyards. Furthermore, based on the Igeo index, Cu occurred at moderate to heavy contamination levels.

Copper Bioavailability and Leaching in Conventional and Organic Viticulture under Environmental Stress

The continuous use of Cu-based fungicides in viticulture has caused Cu accumulation in soils, which represents a major environmental and toxicological concern. The purpose of this study was to verify whether the organic management would be more resilient to temperature and moisture stresses in comparison to conventional practices. Two organic and two conventional vineyard soils, contrasting in pH, were exposed for six months to temperature stress (29 °C), moisture stress (10% water holding capacity—WHC), and combined stresses (29 °C—10% WHC). Main soil properties, Cu speciation, bioavailability, and leaching were monitored before and after 6 months’ incubation. Results confirm that the increase of temperature caused a decrease in both total organic carbon (TOC) and dissolved organic carbon (DOC) (up to 19% and 49%, respectively), a decrease in available ammonium, and an increase in nitrate. Moisture stress tends to mitigate some of these changes. Despite that, changes of Cu bioavailability and leaching were limited and rarely significant. Moreover, no regular trends between conventional and organic management could be observed. Changes in soil pH and total N (TN) appeared as the most influencing properties to regulate Cu behavior in vineyard soils. Calcareous soils were more resistant to environmental stresses compared to acid soils, regardless of the type of management (conventional or organic).