Managing Leafy Spurge Flea Beetle Releases in South Dakota

The leafy spurge flea beetle (Aphthona species) has been an effective means of controlling leafy spurge in South Dakota since the mid-1980s. Of the six Aphthona flea beetle species approved and released for controlling leafy spurge, only the A. nigriscutis and A. lacertosa have had significant effect. This group of flea beetles are hostspecific to the leafy spurge plant, thereby making them an ideal biological control choice. The flea beetles typically take 3 to 5 years to establish and impact leafy spurge infestations. Once established, the adult flea beetles can be collected with sweep nets and moved to other leafy spurge infestations. The leafy spurge flea beetle has a one-year life cycle. Adults will emerge from the soil in early- to mid-June. These adults will live for about 45 to 65 days, at which time they mate and the females lay eggs. Although adults feed on the leaves and stems of the leafy spurge plants, it is the newly hatched larvae feeding on roots and root hairs that do the most damage. Larvae hatch about 14 to 19 days after the eggs are laid. The larvae will then spend the rest of the summer and early fall feeding on the leafy spurge root system

Characterization of the joint effects of tridiphane and paraquat in soybean

Visual ratings of percent injury indicated that exposure to tridiphane may increase herbicide-induced oxidative stress in field-grown plants. The objectives of these studies were to characterize the combined effects of tridiphane and paraquat-induced oxidative stress and to determine the physiological factors that underlie these combined effects. Field studies indicate that, under certain conditions, exposure to tridiphane can increase paraquat-induced leaf injury and inhibition of soybean plant height accumulation compared to the injury produced by paraquat applied alone. However, chlorophyll bleaching studies conducted in the field, and electrolyte leakage studies conducted under controlled environmental conditions indicate that exposure to tridiphane does not induce an oxidative stress or increase the potency of paraquat-induced oxidative stress in soybean leaf tissue. In addition, greenhouse studies indicated the combined effects of tridiphane and paraquat are additive both in terms of paraquat\u27s effect on tridiphane activity and tridiphane\u27s effect on paraquat activity. It was hypothesized that tridiphane-induced inhibition of new leaf growth and paraquat-induced oxidative stress in mature leaf tissue combine to retard the recovery of soybean plants from herbicide injury, and may increase plant mortality. Investigations of the effects of tridiphane on soybean leaf growth and structural development indicate that tridiphane primarily affects growing and developing leaf tissue and thus may inhibit recovery from herbicide injury

An integrated approach for the characterization of groundwater quality using multivariate statistical techniques and spatial analysis

ABSTRACT. Ground water accessed via wells in areas of Tiruvallur district of the southern Indian state of Tamil Nadu has been a subject to increase sea-water intrusion. The present study highlights the potable water crisis in the northern district evaluated using GIS-assisted determination of water quality parameters across fifty sampling sites. The most informative parameters evaluated within this study were TDS, EC, TH, Na+, Mg2+, Ca2+, Cl- and SO42- while parameters such as pH, CO32-, etc. had limited correlated significance to water quality. The total dissolved solids (TDS) and electrical conductivity (EC) determined in the study area indicated significantly elevated levels across the sampling sites. Weighted arithmetical indexing (WAI) of the water quality parameters indicated 30 out of 50 water sources meet the tolerance limits for both drinking and irrigation. Based on BIS standards, only 13 sites met acceptable limits for safe drinking water. Principal component analysis and piper plot analysis revealed a significant involvement of Mg2+, Na+, Cl- and SO42- in the impairment of water quality, particularly in the coastal zones. Spatial hydro-chemical profiles developed in this study reveal ‘hot-spots’ of sea-water tainted water sources, and the hydro-chemical dominance of alkali earth components. Altogether, the study findings indicate a widening water crisis on top of over-exploited water resources and discuss possible factors and remedial steps in addressing the situation.   KEY WORDS: Ground water, Principal component analysis, Piper Plot, Water quality index, Irrigation suitability   Bull. Chem. Soc. Ethiop. 2022, 36(2), 241-260.                                                           DOI: https://dx.doi.org/10.4314/bcse.v36i2.1                                                       &nbsp

Relationships between gamma-ray attenuation and soils in SW England

Soil studies using radiometric data typically employ one or more of the main, naturally occurring radioelement estimates (Potassium, Thorium and Uranium) to undertake a variety of soil property assessments. This study concerns an attenuation assessment of high-resolution radiometric data obtained by a recent airborne geophysical survey in SW England. These data provide continuous measurements over a wide-range of region-specific soils and their parent bedrock materials. A prime motivation for this study is the observed complexity of the spatial variance in the radiometric signal level. Although such data may be jointly classified according to soil and bedrock type, variable attenuation levels in the signal levels remain to be explained. The data appear to carry information on soil properties additional to that of texture or other available soil descriptors. Existing gamma-ray theory indicates that the attenuation behaviour of radiometric data is jointly controlled by soil density and wetness in the upper ~60 cm of the soil profile. Low density, highly organic soils (e.g. peat) produce readily identifiable and variable attenuation zones. All soil types are predicted to attenuate radiometric signal levels but at lower density-wetness sensitivities. The broad radiometric response level is, as expected, found to be controlled by bedrock. Clay mineral soils provide the most uniform response behaviour with respect to bedrock type. Peat soils display the lowest amplitude and most variable signal levels. The data from similar bedrock formations, even with the same lithological descriptor (e.g. argillaceous), can display distinctly different geostatistical behavior when the same soil type is considered. A variety of inferred attenuation zones are discussed in relation to supporting information on soil property and soil and land-use classifications. Spatial inconsistencies in existing database descriptors of organic rich zones are demonstrated and it is evident that the radiometric data can assist in resolving such ambiguities. The supporting control information has been found to be often ambiguous or unavailable at a scale appropriate to the field-of-view of the airborne measurements. Within this wider context, it is suggested that an observational database, such as that supplied by the radiometric data, may assist in providing enhanced spatial assessments of the soils and soil properties encountered

Soil textural heterogeneity impacts bacterial but not fungal diversity

Soils harbour high levels of microbial diversity, underpinning their ability to provide key soil functions and ecosystem services. The extreme variety of soil microbial life is often explained by reference to the physical and chemical heterogeneity of the soil environment. However, detailed understanding of this link is still lacking, particularly as micro-scale studies are difficult to scale up to the soil profile or landscape level. To address this, we used soil samples collected from a wide range of temperate oceanic habitats (e.g. arable, grassland, coniferous and deciduous woodland, heathland; 335 sites in total) to evaluate the link between soil texture and microbial diversity. Soil particle size distribution was measured in each sample using laser granulometry (i.e. sand, silt, clay), while the diversity of bacterial and fungal communities were determined by metabarcoding with an Illumina MiSeq using16S and ITS1 taxonomy marker gene regions, respectively. Multifractal analysis of the soil particle size distribution was then used to describe the heterogeneity of the soil particle sizes. Overall, our results showed no impact of habitat type upon textural heterogeneity indicating that it is an aspect of soil quality resistant to management decisions. Using a structural equation modelling approach, we show that soil textural heterogeneity positively influences bacterial diversity but had little impact upon fungal diversity. We also find that textural composition impacts both bacterial and fungal composition, with many specific microbial taxa showing co-occurrence relationships with clay and fine-silt sized particles. Our results strongly indicate that soil textural heterogeneity influences microbial community diversity regardless of soil management practices and biophysical activities. The close linkages between different groups of soil organisms can obscure the mechanisms driving the development of biodiversity, however, it is clear that the soil physical environment has differential impacts on organisms with different life history strategies

Environmental radioactivity in the UK: the airborne geophysical view of dose rate estimates

This study considers UK airborne gamma-ray data obtained through a series of high spatial resolution, low altitude surveys over the past decade. The ground concentrations of the naturally occurring radionuclides Potassium, Thorium and Uranium are converted to air absorbed dose rates and these are used to assess terrestrial exposure levels from both natural and technologically enhanced sources. The high resolution airborne information is also assessed alongside existing knowledge from soil sampling and ground-based measurements of exposure levels. The surveys have sampled an extensive number of the UK lithological bedrock formations and the statistical information provides examples of low dose rate lithologies (the formations that characterise much of southern England) to the highest sustained values associated with granitic terrains. The maximum dose rates (e.g. >300 nGy h−1) encountered across the sampled granitic terrains are found to vary by a factor of 2. Excluding granitic terrains, the most spatially extensive dose rates (>50 nGy h−1) are found in association with the Mercia Mudstone Group (Triassic argillaceous mudstones) of eastern England. Geological associations between high dose rate and high radon values are also noted. Recent studies of the datasets have revealed the extent of source rock (i.e. bedrock) flux attenuation by soil moisture in conjunction with the density and porosity of the temperate latitude soils found in the UK. The presence or absence of soil cover (and associated presence or absence of attenuation) appears to account for a range of localised variations in the exposure levels encountered. The hypothesis is supported by a study of an extensive combined data set of dose rates obtained from soil sampling and by airborne geophysical survey. With no attenuation factors applied, except those intrinsic to the airborne estimates, a bias to high values of between 10 and 15 nGy h−1 is observed in the soil data. A wide range of technologically enhanced, localised contributions to dose rate values are also apparent in the data sets. Two detailed examples are provided that reveal the detectability of site-scale environmental impacts due to former industrial activities and the high dose values (>500 nGy h−1) that are associated with former, small-scale Uranium mining operations

Spatial transferability of the physically based model TRIGRS using parameter ensembles

The development of better, more reliable and more efficient susceptibility assessments for shallow landslides is becoming increasingly important. Physically based models are well-suited for this, due to their high predictive capability. However, their demands for large, high-resolution and detailed input datasets make them very time-consuming and costly methods. This study investigates if a spatially transferable model calibration can be created with the use of parameter ensembles and with this alleviate the time-consuming calibration process of these methods. To investigate this, the study compares the calibration of the model TRIGRS in two different study areas. The first study area was taken from a previous study where the dynamic physically based model TRIGRS was calibrated for the Laternser valley in Vorarlberg, Austria. The calibrated parameter ensemble and its performance from this previous study are compared with a calibrated parameter ensemble of the model TRIGRS for the Passeier valley in South Tyrol, Italy. The comparison showed very similar model performance and large similarities in the calibrated geotechnical parameter values of the best model runs in both study areas. There is a subset of calibrated geotechnical parameter values that can be used successfully in both study areas and potentially other study areas with similar lithological characteristics. For the hydraulic parameters, the study did not find a transferable parameter subset. These parameters seem to be more sensitive to different soil types. Additionally, the results of the study also showed the importance of the inclusion of detailed information on the timing of landslide initiation in the calibration of the model

Le Vigneron, Volume 3, issue 3

Horticulture and Landscape Architectur