Transport of Agrichemicals by Wind Eroded Sediments to Nontarget Areas

Water and wind erosion are the primary mechanisms by which surface soil is removed from agricultural fields. Wind erosion accounts for as much or more soil loss (tons/acre/year) than does water erosion. Sediments moved by wind may carry agrichemicals from agricultural fields to nontarget areas. Nontarget areas may include road ditches, shelterbelts, and waterways. The objective of this study was to determine if agrichemical movement via wind blown sediment is a potential pollutant of surface and/or groundwater. Samples of sediment that had been deposited in ditches on top of snow were collected during winters of 1994 and 1995 near or around Brookings, SD. Soil samples from adjacent fields (top 1 inch) were also collected. Soil and sediment samples were extracted and alachlor, atrazine, and atrazine metabolites, desethylatrazine and desisopropylatrazine were quantified. Alachlor was detected in about 30% of soil and sediment samples in both years with an average concentration of 2.2 ppb in soil and 5.44 ppb in sediment in 1995. In 1994, atrazine, desethylatrazine, and desisopropylatrazine were detected in 70%, 100%, and 50% of the sediment samples and 70%, 90%, and 60% of the soil samples, respectively. In 1995, atrazine, desethylatrazine, and desisopropylatrazine were detected in 73%, 27%, and 9% of the sediment samples at average concentrations of 8.9, 0.89, and 56.4 ppb, respectively. Atrazine, desethylatrazine, and desisopropylatrazine were detected in 70%, 40%, and 10% of the soil samples in 1995 at average concentrations of 11.9, 2.0, and 0.9 ppb, respectively. Herbicides were detected in most of the sediment samples. This suggests that wind erosion may be a transport mechanism by which herbicides are deposited into nontarget areas

Do Precision Chemical Amendment Applications Impact Sodium Movement in Dryland Semiarid Saline Sodic Soils?

Expanding sodicity and salinity problems have placed many northern Great Plains (NGP) soils at the sustainability tipping point. This study assessed the impact of chemical restoration on water and salt transport in undisturbed soil columns collected from three hillslope model landscape positions. The backslope (Redfield), footslope (White Lake), and toeslope (Pierpont) soils had moderate (3.27 ± 0.59), high (7.3 ± 3.34), and very high (13.29 ± 3.2) sodium adsorption ratio (SARe) values, respectively. The soils were treated with KBr and one of four soil amendments (none, H2SO4, CaSO4, and CaCl2). The rapid movement of Br−through the columns suggested that bypass water flow occurred. In addition, a comparison with widely used salinity models (final EC = 0.8 × initial EC/pore volume [PV]) underestimated the leaching requirements by 69, 79, and 41% in the backslope, footslope, and toeslope soils. In the footslope soils with high SAR values, H2SO4 was more effective at promoting Na+leaching than gypsum or CaCl2. However, in back slope and toeslope soils with moderate and very high SAR values, the chemical amendments were not, and were equally effective at facilitating Na+ leaching, respectively. These findings suggest that chemical amendments should target treatments to problem areas, and that bypass flow can influence their effectiveness. The LOESS regression model suggested that the electrical conductivity (ECe)/SARe ratio was useful for assessing Na+ risks, and that to maintain a water flow rate of 1 mm h–1 in a soil with a SARe value of 1, an ECe value of ≥2 was required

W(h)ither Fossils? Studying Morphological Character Evolution in the Age of Molecular Sequences

A major challenge in the post-genomics era will be to integrate molecular sequence data from extant organisms with morphological data from fossil and extant taxa into a single, coherent picture of phylogenetic relationships; only then will these phylogenetic hypotheses be effectively applied to the study of morphological character evolution. At least two analytical approaches to solving this problem have been utilized: (1) simultaneous analysis of molecular sequence and morphological data with fossil taxa included as terminals in the analysis, and (2) the molecular scaffold approach, in which morphological data are analyzed over a molecular backbone (with constraints that force extant taxa into positions suggested by sequence data). The perceived obstacles to including fossil taxa directly in simultaneous analyses of morphological and molecular sequence data with extant taxa include: (1) that fossil taxa are missing the molecular sequence portion of the character data; (2) that morphological characters might be misleading due to convergence; and (3) character weighting, specifically how and whether to weight characters in the morphological partition relative to characters in the molecular sequence data partition. The molecular scaffold has been put forward as a potential solution to at least some of these problems. Using examples of simultaneous analyses from the literature, as well as new analyses of previously published morphological and molecular sequence data matrices for extant and fossil Chiroptera (bats), we argue that the simultaneous analysis approach is superior to the molecular scaffold approach, specifically addressing the problems to which the molecular scaffold has been suggested as a solution. Finally, the application of phylogenetic hypotheses including fossil taxa (whatever their derivation) to the study of morphological character evolution is discussed, with special emphasis on scenarios in which fossil taxa are likely to be most enlightening: (1) in determining the sequence of character evolution; (2) in determining the timing of character evolution; and (3) in making inferences about the presence or absence of characteristics in fossil taxa that may not be directly observable in the fossil record. Published By: Missouri Botanical Garde

Chemical Amendments of Dryland Saline–Sodic Soils Did Not Enhance Productivity and Soil Health in Fields without Effective Drainage

A common restoration treatment for saline–sodic soils involves improving soil drainage, applying soil amendments (e.g., CaSO4, CaCl2, or elemental S), and leaching with water that has a relatively low electrical conductivity. However, due to high subsoil bulk densities and low drainable porosities, these treatments many not be effective in glaciated dryland systems. A 3-yr field study conducted in three model systems determined the impact of chemical amendments (none, CaCl2, CaSO4, and elemental S) on plant growth, microbial composition, temporal changes in electrical conductivity (ECe ), and the relative sodium content (%Na). Chemical amendments (i) either reduced or did not increase maize (Zea mays), soybean (Glycine max), and sorghum (Sorghum bicolor) yields; (ii) did not increase water infiltration or microbial biomass as determined using the phospholipid-derived fatty acid (PLFA) technique; and (iii) did not reduce ECe or %Na. These results were attributed to high bulk densities and low drainable porosities that reducing the drainage effectiveness in the model backslope and footslope soils, the presence of subsurface marine sediments that provided a source for sodium and other salts that could be transported through capillary action to the surface soil, high sulfate and gypsum contents in the surface soil, and relatively low microbial biomass values. The results suggests that an alternative multistep saline sodic soil restoration approach that involves increasing exchangeable Ca+2 through enhanced microbial and root respiration and increasing transpiration and soil drainage by seeding full season deep rooted perennial vegetation should be tested

Linking micro‐ and macroevolutionary perspectives to evaluate the role of Quaternary sea‐level oscillations in island diversification

With shifts in island area, isolation, and cycles of island fusion–fission, the role of Quaternary sea‐level oscillations as drivers of diversification is complex and not well understood. Here, we conduct parallel comparisons of population and species divergence between two island areas of equivalent size that have been affected differently by sea‐level oscillations, with the aim to understand the micro‐ and macroevolutionary dynamics associated with sea‐level change. Using genome‐wide datasets for a clade of seven Amphiacusta ground cricket species endemic to the Puerto Rico Bank (PRB), we found consistently deeper interspecific divergences and higher population differentiation across the unfragmented Western PRB, in comparison to the currently fragmented Eastern PRB that has experienced extreme changes in island area and connectivity during the Quaternary. We evaluate alternative hypotheses related to the microevolutionary processes (population splitting, extinction, and merging) that regulate the frequency of completed speciation across the PRB. Our results suggest that under certain combinations of archipelago characteristics and taxon traits, the repeated changes in island area and connectivity may create an opposite effect to the hypothesized “species pump” action of oscillating sea levels. Our study highlights how a microevolutionary perspective can complement current macroecological work on the Quaternary dynamics of island biodiversity.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/141544/1/evo13384.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/141544/2/evo13384_am.pd

Photography-based taxonomy is inadequate, unnecessary, and potentially harmful for biological sciences

The question whether taxonomic descriptions naming new animal species without type specimen(s) deposited in collections should be accepted for publication by scientific journals and allowed by the Code has already been discussed in Zootaxa (Dubois & Nemésio 2007; Donegan 2008, 2009; Nemésio 2009a–b; Dubois 2009; Gentile & Snell 2009; Minelli 2009; Cianferoni & Bartolozzi 2016; Amorim et al. 2016). This question was again raised in a letter supported by 35 signatories published in the journal Nature (Pape et al. 2016) on 15 September 2016. On 25 September 2016, the following rebuttal (strictly limited to 300 words as per the editorial rules of Nature) was submitted to Nature, which on 18 October 2016 refused to publish it. As we think this problem is a very important one for zoological taxonomy, this text is published here exactly as submitted to Nature, followed by the list of the 493 taxonomists and collection-based researchers who signed it in the short time span from 20 September to 6 October 2016

Land-Use Change Impact on Soil Sustainability in a Climate and Vegetation Transition Zone

A growing world population and climate change are expected to influence future agricultural productivity and land use. Th is study determined the impact of land-use change on soil sustainability and discussed the factors contributing to these changes. South Dakota was selected as a model system because corn (Zea mays L.) grain prices tripled between 2006 and 2012 and it is located in a climate and grassland/cropland transition zone. High resolution imagery was used to visually determine land uses (cropland, grassland, nonagricultural, habitat, and water) at 14,400 points in 2006 and 2012. At each point, land-use change and the USDA land capability class (LCC) were determined. Over the 6-yr study period, 6.87% of the grasslands (730,000 ha) were converted to cropland, with 93% occurring on lands generally considered suitable for crop production (LC

Atrazine, Alachlor, and Total inOrganic Nitrogen Concentrations of Winter Wind‐eroded Sediment Samples

he objective of this study was to determine if atrazine (2‐chloro‐4‐ethylamino‐6‐isopropyl‐1,3,5‐triazine), alachlor [2‐chloro‐N‐(2,6‐diethylphenyl‐N‐(methoxymethyl)acetamide], or inorganic nitrogen was present on wind‐eroded sediments collected from road ditch areas in mid to late winter. Sediment samples that had been deposited in ditches on top of snow were collected during the winters of 1994, 1995, and 1996 at randomly selected sites in eastern South Dakota and western Minnesota. Atrazine, atrazine metabolites [deethylatrazine (DEA)(6‐chloro‐N‐l‐methylethyl‐l,3,5‐triazine‐2,4‐diamine], and deisopropylatrazine (DIA) (6‐chloro‐N‐ethyl‐l,3,5‐triazine‐2,4‐diamine), and alachlor were determined by gas chromatography. Total inorganic N (NO3 ‐ + NH4 +) concentration was determined with a nitrogen analyzer. In all years, atrazine was detected in at least 72% of the samples, with a mean concentration of 8.9 ug kg‐1 and, while DEA was detected in at least 18% of the samples. Alachlor was detected in at least 27% of the soil samples for all three years with mean sediment concentration of \u3e5 ug kg‐1. Inorganic N concentration of all samples averaged 33 mg kg‐1. These data suggest that deposition of wind‐eroded sediment contributes to nonpoint source contamination of nontarget areas by agrichemicals