ALBERT

Description: For the C4 perennial grasses, Miscanthus  ×  giganteus and Panicum virgatum (switchgrass) to be successful for bioenergy production they must maintain high yields over the long term. Previous studies under the less conducive climate for productivity in N.W. Europe found little or no yield decline in M . ×  giganteus in the long term. This study provides the first analysis of whether yield decline occurs in M . ×  giganteus under United States. Midwest conditions in side-by-side trials with P. virgatum over 8–10 years at seven locations across Illinois. The effect of stand age was determined by using a linear regression model that included effects of weather. Miscanthus  ×  giganteus produced yields more than twice that of P. virgatum averaging 23.4 ± 1.2 Mg ha −1  yr −1 and 10.0 ± 0.9 Mg ha −1  yr −1 , respectively, averaged over 8–10 years. Relationships of yield with precipitation and growing degree days were established and used to estimate yields corrected for the stochastic effects of weather. Across all locations and in both species, yield initially increased until it reached a maximum during the fifth growing season and then declined to a stable, but lower level in the eighth. This pattern was more pronounced in M . ×  giganteus . The mean yields observed over this longer term period of 8–10 years were lower than the yields of the first 5 years. However, this decline was proportionately greater in M . ×  giganteus than in P. virgatum, suggesting a stronger effect of stand age on M . ×  giganteus . Based on the average yield over the period of this study, meeting the United States Renewable Fuel Standard mandate of 60 billion liters of cellulosic ethanol by 2022, would require 6.8 Mha of M . ×  giganteus or 15.8 Mha of P. virgatum . These appear manageable numbers for the United States, given the 16.0 Mha in the farmland Conservation Reserve Program in addition to another 13.0 Mha abandoned from agriculture in the last decade.

Description: [1]  We have measured the bidirectional reflectance of analogs of dry, wet and frozen Martian soils over a wide range of phase angles in the visible spectral range. All samples were produced from two geologic samples: the standard JSC Mars-1 soil simulant and Hawaiian basaltic sand. In a first step, experiments were conducted with the dry samples to investigate the effects of surface texture. Comparisons with results independently obtained by different teams with similar samples showed a satisfying reproducibility of the photometric measurements as well as a noticeable influence of surface textures resulting from different sample preparation procedures. In a second step, water was introduced to produce wet and frozen samples and their photometry investigated. Optical microscope images of the samples provided information about their micro-texture. Liquid water, even in relatively low amount, resulted in the disappearance of the backscattering peak and the appearance of a forward scattering peak whose intensity increases with the amount of water. Specular reflections only appeared when water was present in an amount large enough to allow water to form a film at the surface of the sample. Icy samples showed a wide variability of photometric properties depending on the physical properties of the water ice. We discuss the implications of these measurements in terms of the expected photometric behavior of the Martian surface, from equatorial to circum-polar regions. In particular, we propose some simple photometric criteria to improve the identification of wet and/or icy soils from multiple observations under different geometries.

Description: Chemical Reviews DOI: 10.1021/acs.chemrev.6b00180

Description: Chemical Reviews DOI: 10.1021/acs.chemrev.5b00669

Description: Bacterial assemblages, especially diazotroph assemblages residing in the rhizomes and the rhizosphere soil of Miscanthus ×giganteus contribute to plant growth and nitrogen use efficiency. However, the composition of these microbial communities has not been adequately explored, nor have the potential ecological drivers for these communities been sufficiently studied. This knowledge is needed for understanding and potentially improving M. ×giganteus - microbe interactions, and further enhancing sustainability of M. ×giganteus production. In this study, cultivated M. ×giganteus from four sites in Illinois, Kentucky, Nebraska, and New Jersey were collected to examine the relative influences of soil conditions and plant compartments on assembly of the M. ×giganteus -associated microbiome. Automated ribosomal intergenic spacer (ARISA) and terminal restriction fragment length polymorphism (T-RFLP) targeting the nifH gene were applied to examine the total bacterial communities and diazotroph assemblages that reside in the rhizomes and the rhizosphere. Distinct microbial assemblages were detected in the endophytic and rhizosphere compartments. Site soil conditions had strong correlation with both total bacterial and diazotroph assemblages, but in different ways. Nitrogen treatments showed no significant effect on the composition of diazotroph assemblages in most sites. Endophytic compartments of different M . × giganteus plants tended to harbor similar microbial communities across all sites, whereas, the rhizosphere soil of different plant tended to harbor diverse microbial assemblages that were distinct among sites. These observations offer insight into better understanding of the associative interactions between M. ×giganteus and diazotrophs, and how this relationship is influenced by agronomic and edaphic factors. This article is protected by copyright. All rights reserved.

Description: We examined the lunar swirls using data from the Moon Mineralogy Mapper (M3). The improved spectral and spatial resolution of M3 over previous spectral imaging data facilitates distinction of subtle spectral differences, and provides new information about the nature of these enigmatic features. We characterized spectral features of the swirls, interswirl regions (dark lanes), and surrounding terrain for each of three focus regions: Reiner Gamma, Gerasimovich, and Mare Ingenii. We used Principle Component Analysis to identify spectrally distinct surfaces at each focus region, and characterize the spectral features that distinguish them. We compared spectra from small, recent impact craters with the mature soils into which they penetrated to examine differences in maturation trends on- and off-swirl. Fresh, on-swirl crater spectra are higher albedo, exhibit a wider range in albedos and have well-preserved mafic absorption features compared with fresh off-swirl craters. Albedoand mafic absorptions are still evident in undisturbed, on-swirl surface soils, suggesting the maturation process is retarded. The spectral continuum is more concave compared with off-swirl spectra; a result of the limited spectral reddening being mostly constrained to wavelengths less than ∼1500 nm. Off-swirl spectra show very little reddening or change in continuum shape across the entire M3 spectral range. Off-swirl spectra are dark, have attenuated absorption features, and the narrow range in off-swirl albedos suggests off-swirl regions mature rapidly. Spectral parameter maps depicting the relative OH surface abundance for each of our three swirl focus regions were created using the depth of the hydroxyl absorption feature at 2.82 μm. For each of the studied regions, the 2.82 μm absorption feature is significantly weaker on-swirl than off-swirl, indicating the swirls are depleted in OH relative to their surroundings. The spectral characteristics of the swirls and adjacent terrains from all three focus regions support the hypothesis that the magnetic anomalies deflect solar wind ions away from the swirls and onto off-swirl surfaces. Nanophase iron (npFe0) is largely responsible for the spectral characteristics we attribute to space weathering and maturation, and is created by vaporization/deposition by micrometeorite impacts and sputtering/reduction by solar wind ions. On the swirls, the decreased proton flux slows the spectral effects of space weathering (relative to nonswirl regions) by limiting the npFe0 production mechanism almost exclusively to micrometeoroid impact vaporization/deposition. Immediately adjacent to the swirls, maturation is accelerated by the increased flux of protons deflected from the swirls.

Description: Analysis of spectra from the Clementine ultraviolet-visible and near-infrared cameras of small, immature craters and surface soils both on and adjacent to the lunar swirls at Mare Ingenii has yielded the following conclusions about space weathering at a magnetic anomaly. (1) Despite having spectral characteristics of immaturity, the lunar swirls are not freshly exposed surfaces. (2) The swirl surfaces are regions of retarded weathering, while immediately adjacent regions experience accelerated weathering. (3) Weathering in the off-swirl regions darkens and flattens the spectrum with little to no reddening, which suggests that the production of larger (〉40 nm) nanophase iron dominates in these locations as a result of charged particle sorting by the magnetic field. Preliminary analysis of two other lunar swirl regions, Reiner Gamma and Mare Marginis, is consistent with our observations at Mare Ingenii. Our results indicate that sputtering/vapor deposition, implanted solar wind hydrogen, and agglutination share responsibility for creating the range in npFe0 particle sizes responsible for the spectral effects of space weathering.

Description: The Moon Mineralogy Mapper (M3) provided the first global hyperspectral data of the lunar surface in 85 bands from 460 to 2980 nm. The Clementine mission provided the first global multispectral maps the lunar surface in 11 spectral bands across the ultraviolet-visible (UV-VIS) and near-infrared (NIR). In an effort to understand how M3 improves our ability to analyze and interpret lunar data, we compare M3 spectra with those from Clementine's UV-VIS and NIR cameras. The Clementine mission provided the first global multispectral maps the lunar surface in 11 spectral bands across the UV-VIS and NIR. We have found that M3 reflectance values are lower across all wavelengths compared with albedos from both of Clementine's UV-VIS and NIR cameras. M3 spectra show the Moon to be redder, that is, have a steeper continuum slope, than indicated by Clementine. The 1 μm absorption band depths may be comparable between the instruments, but Clementine data consistently exhibit shallower 2 μm band depths than M3. Absorption band minimums are difficult to compare due to the significantly different spectral resolutions.

Description: The U.S. Department of Energy has mandated the production of 16 billion gallons (60.6 billion liters) of renewable biofuel from cellulosic feedstocks by 2022. The perennial grass, Miscanthus x giganteus , is a potential candidate for cellulosic biofuel production because of high productivity with minimal inputs. This study determined the effect of three different spring fertilizer treatments (0, 60, and 120 kg N ha −1 yr −1 as urea) on biomass production, soil organic matter (SOM), and inorganic N leaching in Illinois, Kentucky, Nebraska, New Jersey, and Virginia, along with N 2 O and CO 2 emissions at the IL site. There were no significant yield responses to fertilizer treatments, except at the IL site in 2012 (yields in 2012, year 4, varied from 10 to 23.7 Mg ha −1 across all sites). Potentially mineralizable N increased across all fertilizer treatments and sites in the 0 – 10 cm soil depth. An increase in permanganate oxidizable carbon (POX-C, labile C) in surface soils occurred at the IL and NJ sites, which were regularly tilled before planting. Decreases in POX-C were observed in the 0 – 10 cm soil depth at the KY and NE sites where highly managed turfgrass was grown prior to planting. Growing M . x giganteus altered SOM composition in only four years of production by increasing the amount of potentially mineralizable N at every site, regardless of fertilization amount. Nitrogen applications increased N leaching and N 2 O emission without increasing biomass production. This suggests that for the initial period (4 yr) of M . x giganteus production, N application has a detrimental environmental impact without any yield benefits and thus should not be recommended. Further research is needed to define a time when N application to M . x giganteus results in increased biomass production. This article is protected by copyright. All rights reserved.