Conventional Plots Research Articles

UAV and Structure-From-Motion Photogrammetry Enhance River Restoration Monitoring: A Dam Removal Study

Dam removal is a river restoration technique that has complex landscape-level ecological impacts. Unmanned aerial vehicles (UAVs) are emerging as tools that enable relatively affordable, repeatable, and objective ecological assessment approaches that provide a holistic perspective of restoration impacts and can inform future restoration efforts. In this work, we use a consumer-grade UAV, structure-from-motion (SfM) photogrammetry, and machine learning (ML) to evaluate geomorphic and vegetation changes pre-/post-dam removal, and discuss how the technology enhanced our monitoring of the restoration project. We compared UAV evaluation methods to conventional boots-on-ground methods throughout the Bellamy River Reservoir (Dover, NH, USA) pre-/post-dam removal. We used a UAV-based vegetation classification approach that used a support vector machine algorithm and a featureset composed of SfM-derived elevation and visible vegetation index values to map other, herbaceous, shrub, and tree cover throughout the reservoir (overall accuracies from 83% to 100%), mapping vegetation succession as well as colonization of exposed sediments that occurred post-dam removal. We used SfM-derived topography and the vegetation classifications to map erosion and deposition throughout the reservoir, despite its heavily vegetated condition, and estimate volume changes post-removal. Despite some limitations, such as influences of refraction and vegetation on the SfM topography models, UAV provided information on post-dam removal changes that would have gone unacknowledged by the conventional ecological assessment approaches, demonstrating how UAV technology can provide perspective in restoration evaluation even in less-than-ideal site conditions for SfM. For example, the UAV provided perspective of the magnitude and extent of channel shape changes throughout the reservoir while the boots-on-ground topographic transects were not as reliable for detecting change due to difficulties in navigating the terrain. In addition, UAV provided information on vegetation changes throughout the reservoir that would have been missed by conventional vegetation plots due to their limited spatial coverage. Lastly, the COVID-19 pandemic prevented us from meeting to collect post-dam removal vegetation plot data. UAV enabled data collection that we would have foregone if we relied solely on conventional methods, demonstrating the importance of flexible and adaptive methods for successful restoration monitoring such as those enabled via UAV.

Photochemical anisotropy and direction-dependent optical absorption in semiconductors.

Photochemical reactions on semiconductors are anisotropic, since they occur with different rates on surfaces of different orientations. Understanding the origin of this anisotropy is crucial to engineering more efficient photocatalysts. In this work, we use hybrid density functional theory to identify the surfaces associated with the largest number of photo-generated carriers in different semiconductors. For each material, we create a spherical heat map of the probability of optical transitions at different wave vectors. These maps allow us to identify the directions associated with the majority of the photo-generated carriers and can, thus, be used to make predictions about the most reactive surfaces for photochemical applications. The results indicate that it is generally possible to correlate the heat maps with the anisotropy of the bands observed in conventional band structure plots, as previously suggested. However, we also demonstrate that conventional band structure plots do not always provide all the information and that taking into account the contribution of all possible transitions weighted by their transition dipole moments is crucial to obtain a complete picture.

Representasi Konflik Sosial dalam Novel Burung Kayu Karya Niduparas Erlang

As a homo conflicus creature, humans cannot avoid conflict. Conflict is a part of human life that inspire literary writer to write story. The novel Burung Kayu (Wood Bird, 2021) by Niduparas Erlang set in a region in Mentawai, North Sumatera, and expresses social conflicts that reflect the local situation. This article discusses three issues related to the novel, including (1) how is the structure of the novel Burung Kayu by Niduparas Erlang related to plot, characterization, and setting; (2) how is the representation of social conflict in Burung Kayu by Niduparas Erlang; (3) what is the meaning of the representation of social conflict in the novel Burung Kayu by Niduparas Erlang. The theory used is the theory of social conflict from the view of Lewis A. Coser, besides that, the theory of structure from the view of Stanton is used to examine the structure of the novel Burung Kayu. The data was collected using the literature study method with reading, listening, and note-taking techniques. Data analysis was carried out by interpretive descriptive method. Based on the analysis results of the novel Burung Kayu by Niduparas Erlang, it is built on conventional plots and flashbacks, the characterizations consist of main and complementary characters, then the setting is divided into place, time, atmosphere, and social. All of these elements are intertwined in the inter-element relationship and reflected social conflict of community where the story is set.
 

Influence of tillage and fertilizer management practices on productivity and resource use efficiency of groundnut (Arachis hypogaea) in Thar Desert of Rajasthan

Conventional tillage practices in Thar Desert of Rajasthan are posing a serious threat of natural resource degradation due to soil erosion induced by high temperature and winds. A 2-year study was conducted to explore the efficient tillage and nutrient management practices evaluate the effects of these practices on groundnut crop performance and resource use efficiency. It consisted 18 treatment combinations; 3 tillage practices, viz. T1 - minimum tillage, T2 - deep tillage, and T3 - conventional tillage main plots; and six fertilizer management practices, viz. F0 - no fertilization, F1 -recommended dose of NK fertilizer, F2 - recommended dose of NPK fertilizer (RDF), F3 - RDF + PSB @2.5 kg/ha, F4 - F3+ AMF @2 kg/ha, and F5 - F3+ AMF @4 kg/ha as sub plots. The highest LAI, crop growth rate and relative growth rate was recorded with deep tillage (T2) and F5 treatment combination. Deep tillage (T2) produced significant at par yields (pod and haulm) with conventional tillage (2981 and 4878 kg/ha). Higher water use efficiency of 4.72% and 13.25% were recorded with T3 compared to T2 and T1, respectively. Fertilizer management practices F5 and F4 recorded significantly at par and higher yields (pod, kernel, haulm and biological) compared to other combinations. The F5 treatment notable increased 16.7% and 90.2% water and nutrient use efficiency over RDF (6.69 kg/ha mm and 14.95 kg/kg), respectively. In Thar Desert, deep tillage along with chemical fertilizers and bio-inoculants found best management practices in terms of productivity and resource use efficiency.

Effects of Organic Agriculture in Structure and Organic Carbon Adsorption at Colloidal Scale in Marginal Olive Groves, Characterized by the Extended DLVO Model

Relationship between macroscopic and microscopic behavior of soils is a difficult issue, especially when dealing with complex properties such as structure or carbon sequestration, but it is necessary for a suitable understanding of the agricultural soil quality. In this work, we used the extended-DLVO theory to compute total energy of interaction between particles (kT), of three soils over granodiorites. This parameter allows predicting the tendency to aggregate formation at the colloidal scale, being the basis of soil structure. Furthermore, we characterized the mechanism and adsorption capacity of humic molecules on mineral surfaces, and its influence in the interaction energy, by means of the adsorption isotherms. The aim was to compare first the effects of organic farming on conventionally managed soils and, second, to compare these with a non-cultivated forest soil under Mediterranean climate. When total energies are negative (particle attraction), or positive (particle repulsion) but near 0 kT (<100 kT), then particle flocculation occurs and the structure at colloidal scale can be developed. Total energy was less in the forest sample and greater in the soil of conventional groves, with intermediate values in organic farming soil. This indicates a tendency toward particle flocculation and more stability of the structure at colloidal scale in less disturbed soils, agreeing with other soil physical properties such as the total porosity (50, 41 and 37% in forest, organic and conventional plots, respectively) or the aggregate stability index (0.94, 0.73 and 0.66, respectively), which followed the same trend. Of the three components of the total energy of interaction, the acid-base force was a key factor. This component, related with the electron-donor component of surface free energy, γ−, yielded a strong attractive force (−150 kT at 3 nm) when calcium solutions were analyzed for the forest soil. This indicates a clear hydrophobic character of this sample. Because the mineralogical composition of the samples is quite similar, hydrophobicity should be attributed to the organic carbon content of the forest soil, which is much higher than that of the cultivated ones (12.03 vs. 1.44% and 0.88% in organic and conventional farms, respectively), proving to be an essential element for the development of the structure at the colloidal level.

Estimation and Spatial Mapping of Residue Biomass following CTL Harvesting in Pinus radiata Plantations: An Application of Harvester Data Analytics

The utilization of forest harvest residues for renewable bioenergy production and bioproducts has increasingly become an integrated part of forestry that helps to meet the needs of climate change mitigation and a future carbon neutral economy. An essential element in the planning of any harvesting residue recovery operation is a reliable assessment of the quantity and quality of residue biomass and its composition over a harvest area. With the now widely adopted cut-to-length (CTL) at the stump harvesting system in Pinus radiata plantations in Australia, harvesting residues left on site are significantly larger in quantity and spatially more dispersed over a harvest area in comparison to the more traditional whole-tree harvesting. The conventional approach of assessing forest harvest residues through sample plots, transects, or small study blocks has provided site-specific estimates of residue biomass. However, these estimates cannot be readily extrapolated over the plantation landscape, which varies in silviculture, site, and stand conditions. To overcome this limitation, this study relied on harvester data analytics to obtain spatially explicit estimates of residue biomass using an example data set from harvested plantations of three stand types: unthinned (T0), thinned once (T1), and thinned twice (T2). Three methods of integrating biomass equations with harvester data were compared for residue biomass estimation: (1) applying individual tree biomass equations to harvested stems, (2) applying stand-level biomass equations to gridded harvester data, and (3) integrating estimates from the first approach with recorded and estimated waste volumes of harvested stems. The estimates of total residue biomass obtained using the three methods through harvester data analytics varied between 56.2 and 156.4 t/ha in green weight across the three stand types. These estimates were validated indirectly through ex situ sample plots and proved to be comparable to the quantities of residue biomass assessed using conventional sample plots, transects, or small blocks following CTL harvesting of rotation age P. radiata plantations elsewhere in Australia. Among the three methods, the third method made the most intensive use of the harvester data and provided the most realistic estimates of residue biomass. Spatial mapping of the estimated total and component residue biomass will assist the operational planning of residue recovery and site-specific nutrient management for the long-term sustainability of P. radiata plantations.

What Can Brinley Plots Tell Us About Cognitive Aging? Exploring Simulated Data and Modified Brinley Plots.

Cognitive aging researchers have been challenged with demonstrating age-related effects above and beyond global slowing ever since Cerella raised this issue in 1990. As the literature has made clear, this has indeed proved to be a difficult task and continues to plague the field. One way that researchers have attempted to test for disproportionate age differences across task conditions is by using Brinley plots, or plotting the mean response latencies of older adults against the mean latencies for younger adults. The simplicity and large proportion of variance accounted for by these models has led to the widespread use of Brinley plots over the years. However, as systematically tested here through eight cases of simulated data, it is clear that the Brinley technique is not well suited to either identify or display the underlying structure of datasets examining age-related differences in attentional control. Some of the problems with conventional Brinley plots can be resolved by using a modified Brinley plot that includes study-specific slopes linking trial types and a no-age-difference reference line. Multilevel models find all of the relevant effects, especially if applied to trial-level data, and have the advantage of incorporating study-level moderators that might account for slope heterogeneity. Ultimately, we encourage fellow cognitive aging researchers to access the code and data for this project on OSF (https://osf.io/zxus8/) and employ the use of multilevel models over Brinley plots.

Effects of Plastic versus Straw Mulching Systems on Soil Microbial Community Structure and Enzymes in Strawberry Cultivation

This study aimed to evaluate changes in abundance, structure, and enzyme activity of the soil microbiome in response to 4 years of mulching using either black polyethylene plastic film (PM) or wheat straw (SM). Soil samples (depth 0–5 and 5–10 cm) were collected from conventional strawberry plots, in two samplings: 1 week prior (S1) and 7 weeks after straw application (S2). Selected soil properties were monitored in each system and the abundance and structure of microbial communities were characterized via phospholipid fatty acid (PLFA) analysis. The investigation of soil microbial functions included activities of the enzymes chitinase, leucine aminopeptidase, and acid phosphatase, as well as function genes involved in nitrogen transformation. Each mulch system resulted in distinct physicochemical properties. In particular, a pH value higher by one-unit under PM (7.6 ± 0.3) compared to SM (6.5 ± 0.3) was observed. Values for SOC, DOC, and total-N were 15%, 22%, and 16% higher in PM than in SM. The microbial biomass (total PLFAs) was 1.5-fold higher in SM compared to PM. The abundance of soil fungi (F) and bacteria (B) increased by 37% and 44% after straw incorporation compared to PM (S2). In particular, Gram-negative bacteria (gr–) increased by twofold in SM. Consequently, wider F:B and gr+:gr– ratios were observed in PM. According to the shifts in microbial abundance, the activity of the enzyme chitinase was lower by 27% in PM, while the activity of the acid phosphatase increased by 32%. Denitrification genes were not affected by the mulching systems. In conclusion, the abundance and structure of the investigated microbial groups and the enzyme activities were strongly influenced by the mulching system. In detail, effects on microbiota were primarily attributed to the altered soil pH and probably the input of degradable organic matter with straw mulching in SM. This resulted in higher abundance of soil microorganisms in SM, although measures within this cultivation system such as fungicide application may have exerted adverse effects on the microbiota.

Application of Murphy – Good Plot Parameters Extraction Method on Electron Emission from Carbon Fibers

The significance of the Fowler-Nordheim-type plots lies in the possibility of extracting useful and reliable physical parameters of the field electron emitters. This is achieved by the parameter's extraction methods. We report on the application of two parameters extraction methods on field emission data from bundles of carbon fibers (CFs) grouped in nickel tubes and operated inside a typical field emission microscope setup. These methods are the Murphy-Good plot and the conventional Fowler-Nordheim plot iterative method. The physical parameters include the area extraction parameter, the notional (actual) emission area, the formal area efficiency factor and the voltage conversion length. The results obtained from the two methods are discussed and compared to shed light on the controversial nature of these methods. The mechanism of field electron emission is analyzed based on the parameters extracted.

Design and Testing of a Novel Unoccupied Aircraft System for the Collection of Forest Canopy Samples

Unoccupied Aircraft Systems (UAS) are beginning to replace conventional forest plot mensuration through their use as low-cost and powerful remote sensing tools for monitoring growth, estimating biomass, evaluating carbon stocks and detecting weeds; however, physical samples remain mostly collected through time-consuming, expensive and potentially dangerous conventional techniques. Such conventional techniques include the use of arborists to climb the trees to retrieve samples, shooting branches with firearms from the ground, canopy cranes or the use of pole-mounted saws to access lower branches. UAS hold much potential to improve the safety, efficiency, and reduce the cost of acquiring canopy samples. In this work, we describe and demonstrate four iterations of 3D printed canopy sampling UAS. This work includes detailed explanations of designs and how each iteration informed the design decisions in the subsequent iteration. The fourth iteration of the aircraft was tested for the collection of 30 canopy samples from three tree species: eucalyptus pulchella, eucalyptus globulus and acacia dealbata trees. The collection times ranged from 1 min and 23 s, up to 3 min and 41 s for more distant and challenging to capture samples. A vision for the next iteration of this design is also provided. Future work may explore the integration of advanced remote sensing techniques with UAS-based canopy sampling to progress towards a fully-automated and holistic forest information capture system.

Temperature Dependent Current Transport Mechanism of Photopolymer Based Al/NOA60/p-Si MPS Device

A photopolymer based Al/Norland Optical Adhesive 60 (NOA60)/p-Si MPS (metal-polymer-semiconductor) device was fabricated by a combination of vacuum evaporation and smear technique. The current transport properties of the device were investigated by using the forward bias current–voltage (I-V) characteristic in the temperature range of 80–300 K. The cross-sectional structure of polymer/semiconductor was revealed by the scanning electron microscope (SEM) image and it was seen that the NOA60 photopolymer was tidily coated on the p-Si surface. According to the I-V measurements at room temperature, the MPS device exhibits a good rectification ratio of 8140 at ± 1 V. The temperature-dependent I-V measurements (I-V-T) were analyzed based on the thermionic emission (TE) theory and an abnormal increase in zero-bias barrier height (BH) and a decrease in ideality factor (n) was observed with increasing temperature. Additionally, two different linear regions with distinct values from the theoretical value of the Richardson constant (A*) were observed in the conventional Richardson plot. Such deviations from the ideal TE theory have been attributed to the effect of BH inhomogeneities. Gaussian distribution (GD) of the BH model has applied the I-V-T results and the double GD BH with mean values of 0.75 ± 0.08 eV (80–140 K) and 1.02 ± 0.11 eV (140–300 K) were calculated. Moreover, the A* value of 31.4 A/cm2K2 was calculated close to the known value of p-Si from the modified Richardson plot. Thus, it has been concluded that the current transport of the Al/NOA60/p-Si MPS device can be explained by TE with a double GD BH model for a wide temperature region.

An experimental study on base pressure behavior during bistability characterisation for a bluff body vehicle close to the ground

The present experimental investigation is concerned with the existence of Bi-stability behaviour at various ground clearances in the wake of Square Back Ahmed Body geometry (SBAB). The experiments were performed at a Reynolds number of 7.2 × 104 in a subsonic open-type wind tunnel facility. The raw readings from the pressure scanner alone were used to predict the existence of bistability character. The bistability behavior in the wake was explored in two different ways (i) The conventional base-pressure contours and pressure gradient plot, and (ii) The wavelet analysis. The minimum ground clearance for the wake to exhibit bistability was found to be 0.468H, much higher than the values determined in the previous experimental works. The discrepancy was due to relatively high turbulence intensity in the test section and experimental setup. We also found that the bi-stability switching rate was found to increase with a decrease in ground clearance. The wavelet analysis helped in determining the existence of long time-scale frequencies associated with the Bi-stability behavior.

Two sides of one medal: Arable weed vegetation of Europe in phytosociological data compared to agronomical weed surveys

AbstractQuestionsTwo scientific disciplines, vegetation science and weed science, study arable weed vegetation, which has seen a strong diversity decrease in Europe over the last decades. We compared two collections of plot‐based vegetation records originating from these two disciplines. The aim was to check the suitability of the collections for joint analysis and for addressing research questions from the opposing domains. We asked: are these collections complementary? If so, how can they be used for joint analysis?LocationEurope.MethodsWe compared 13 311 phytosociological relevés and 13 328 records from weed science, concerning both data collection properties and the recorded species richness. To deal with bias in the data, we also analysed different subsets (i.e., crops, geographical regions, organic vs conventional fields, center vs edge plots).ResultsRecords from vegetation science have an average species number of 19.0 ± 10.4. Metadata on survey methodology or agronomic practices are rare in this collection. Records from weed science have an average species number of 8.5 ± 6.4. They are accompanied by extensive methodological information. Vegetation science records and the weed science records taken at field edges or from organic fields have similar species numbers. The collections cover different parts of Europe but the results are consistent in six geographical subsets and the overall data set. The difference in species numbers may be caused by differences in methodology between the disciplines, i.e., plot positioning within fields, plot sizes, or survey timing.ConclusionThis comparison of arable weed data that were originally sampled with a different purpose represents a new effort in connecting research between vegetation scientists and weed scientists. Both collections show different aspects of weed vegetation, which means the joint use of the data is valuable as it can contribute to a more complete picture of weed species diversity in European arable landscapes.

Process Fault Diagnosis Method Based on MSPC and LiNGAM and its Application to Tennessee Eastman Process

This paper proposes a new fault diagnosis method that combines Multivariate statistical process control (MSPC) and a linear non-gaussian acyclic model (LiNGAM), referred to as MSPC-LiNGAM. MSPC is a widely adopted process monitoring method based on principal component analysis (PCA). In MSPC, T 2 and Q statistics are used as monitoring indexes for fault detection. Contribution plots based on T 2 and Q statistics have been proposed for fault diagnosis. However, contribution plots do not always appropriately diagnose causes of faults. In this study, a new fault diagnosis method based on MSPC and a Linear Non-Gaussian Acyclic Model (LiNGAM) is proposed. In the proposed method, referred to as MSPC-LiNGAM, the causality among the T 2 or Q statistic in addition to process variables is calculated by LiNGAM without prior knowledge of processes, and process variables that have the strength of causality to the T 2 or Q statistic are identified as candidates of the causes of the fault. The proposed MSPC-LiNGAM was applied to a simulation data of the Tennessee Eastman (TE) process. The result showed that the proposed method appropriately diagnosed faults even when the conventional contribution plots did not correctly identify causes of faults.

A semi‐automatic workflow for plot boundary extraction of irregularly sized and spaced field plots from UAV imagery

AbstractAdvances in high‐throughput platforms such as UAVs (unoccupied aerial vehicles) facilitate rapid image‐based phenotypic data acquisition. However, existing plot‐level data extraction methods are unreliable if field plots differ in size and spacing, as often occurs in early‐generation plant breeding trials. To overcome the limitations of conventional plot extraction techniques, a combinational approach with both field‐map information and image classification techniques can be used to optimize plot extraction. The objective of this study was to develop a plot boundary extraction workflow for irregularly sized and spaced field plots from UAV imagery using plot spacing data and vegetation index‐based classifiers. An herbicide screening experiment consisting of three replications of 780 lentil (Lens culinaris Medik.) populations was foliar sprayed with saflufenacil. Aerial image acquisition was conducted during the peak vegetation stage using a RedEdge multispectral camera. A semi‐automatic workflow was compiled in eCognition software to extract lentil plot boundaries. Normalized difference vegetation index (NDVI) was calculated to locate the plots with vegetation and those with low NDVI or no vegetation, and pixel resizing based on plot size and orientation was used to draw the plot boundary. The extraction results showed a precise estimation of plot boundary for all the plots with a wide range of herbicide damage, including the plots with complete loss of vegetation. By using a simple convolutional filter (line filter), image thresholding, and pixel resizing, this approach avoided the use of complex algorithm‐based methodologies. Results suggest that this workflow can be extended to a wide range of phenotyping studies.

Compost topdressing to suppress necrotic ringspot and improve the overall health of Kentucky bluegrass lawns

AbstractA study was conducted in northern Colorado to evaluate the effectiveness of two compost products on the improvement of turfgrass color and quality, necrotic ringspot (NRS) disease suppression, and thatch reduction. Two Kentucky bluegrass (Poa pratensis L.) home lawns with a history of NRS were chosen for the study. Treatments were applied twice during the 2018 growing season after all plots were aerated and consisted of (a) inoculated compost topdressing at a rate of 66 m3 ha–1, (b) dairy manure compost topdressing at a rate of 66 m3 ha–1, (c) urea fertilizer at 49 kg N ha–1, and (d) a control (aeration only with no fertilizer or compost applied). Data were collected every 2 wk from May to October in 2018, and included the percentage of disease‐affected turf, and turfgrass color and quality. Thatch depth was measured monthly. The inoculated and conventional compost plots had less disease than the control, and the inoculated compost showed significant disease suppression earlier than conventional compost. Season‐long averages showed that the plots treated with either of the compost products had better color and turf quality than the control. When data were pooled over the course of the growing season, there were no significant differences between the two compost treatments with regard to NRS disease severity or quality. Thatch depth in plots that received inoculated compost was 17% less than in plots that received conventional compost and fertilizer. This study demonstrated that compost decreased NRS incidence and improved turf color and quality.

Hybrid analysis for excessive water production problem

The production performance of wells should be studied in order to extend the production plateau period which can lead to an increase in revenue. The pool performance plot of a reservoir is a pictorial representation of the pressure-production history of a reservoir. Water-coning, near wellbore problem and multilayer channeling are the three basic mechanisms associated with high water-cut wells. Identification of the water sources is quite important to perform any remedial operation to extend oil production. This paper is a case study on the application of two methods to determine the accurate mechanism for high water-cut in an oil field ‘A’ of the upper Assam basin. Based on the study of conventional plotting of water-cut vs. time with well card data (History of all the jobs performed on the well) and log-log plots of WOR and WORꞌ vs. time, it was observed that the problems were due to multilayer channeling and coning. These plots show the problems associated with high water cut wells and they serve as an effective tool for the selection of water control treatment processes to enhance treatment. However, a failed treatment job will alter the conditions for the next job whereby the expenditure increases significantly.

Understanding Arbuscular Mycorrhizal Colonization in Walnut Plantations: The Contribution of Cover Crops and Soil Microbial Communities

Soil microorganisms play a central role in biological soil functioning. One of the beneficial microbiota that has a symbiotic association with most of the plants is arbuscular mycorrhizal fungi (AMF). Nevertheless, little is known about the impact of cover crops—widely used in conservation agriculture or organic farming—on native mycorrhizal fungi. This study was conducted in Southern France, in 20-year-old walnut orchards, where faba bean (Vicia faba Roth) was intercropped. To find whether the native AM fungal community associated with walnut trees was influenced by cover crops and soil microbial communities, analyses of soil physicochemical and microbiological indicators were carried out with roots and soil samples collected from four modalities (walnut in conventional farming with and without cover crops, and walnut in organic farming with and without cover crops). Our results showed that the presence of cover crops mainly influenced the soil microbial abundance and activities in conventional plots. In contrast, cover crops stimulated AM fungal colonization of walnut roots in organic plots, reaching 35% and 54% for arbuscule abundance and mycorrhizal intensity, respectively. In conventional plots, ergosterol and mineral nitrogen contents were mainly correlated with mycorrhizal colonization, while only acid phosphatase activity in soil was positively correlated with mycorrhizal colonization in organic plots. The use of the faba bean showed the great role played by cover crops in the enhancement of walnut trees’ mycorrhizal colonization. Identification of the functional traits of AM fungi sensitive to walnut trees is required to inform decisions in specific agricultural practices.

New findings of ancient Greek silver sources

Over the last 60 years, much analytical research has sought to determine the ore sources of ancient Greek silver artefacts. Lead isotopic analysis has played a key role in this endeavor. While most studies so far have limited their search to places mentioned in historical sources, the present study takes a different approach by first identifying Ag-bearing ore sources in the Aegean world based on their geological characteristics and then using Pb isotopes to determine whether they were exploited in antiquity. To this end, we have geolocated, sampled, and measured high-precision Pb isotopic compositions of 17 Ag-bearing mineralizations in Greece for which we have evidence of ancient mining activity, and a further 10 exhibiting minor Ag occurrences that may also have been exploited in ancient times. We found that Pb model ages provide better discrimination of ore sources than the more conventional plots of raw Pb isotope data.Our study establishes Lavrion, northeast Chalkidiki, Pangaeon, Thasos, Siphnos, Palaea Kavala, Angistron, and south Euboea as the most important ancient silver mining districts in Greece. Two previously undiscovered ancient mining areas in Pelion and in the Kroussia mountain range are also documented. The latter may be identified with ancient Mount Dysoron, from which King Alexander I of Macedon reportedly extracted the fabulous sum of a talent of silver per day. For the first time, we isotopically differentiate some of the mining districts in Thraco-Macedonia, and show that the mines of Thasos include geologically different silver-bearing ore sources. We further identify the hitherto unrealized importance of Euboean silver mines and demonstrate that they isotopically overlap those of Siphnos, with major implications for our understanding of ancient Greek history.

Oat Cover Crop and No-tillage Can Provide Weed Suppression and Alter Weed Community Dynamics in Sweet Corn

Along with the many known benefits of cover crops, they may be an effective ecological weed management strategy in low-input agriculture. This research aimed to determine the effect of cover crops, combined with reduced-tillage and nitrogen inputs on sweet corn (Zea mays) yield and weed communities. During the 2-year study, the impact of the cover crop on yield varied. Yield within the no-till conventional treatment plots was not significantly different from the conventional treatment [6844 and 7721 lb/acre (P = 0.592)] in year 1 but differed in year 2 (P = 0.003). Weed density and experimental area covered by weeds were not significantly different between conventional and no-till conventional treatments. Multivariate analyses showed associations between specific weed species and management practices. Weeds were greatest in no-till organic treatments, and they had significantly lower yields, suggesting additional weed control beyond cover crops may be necessary for organic vegetable systems under reduced tillage.