Subsurface application of poultry litter in pasture and no-till soils

Poultry litter provides a rich nutrient source for crops, but the usual practice of surface-applying litter can degrade water quality by allowing nutrients to be transported from fields in surface runoff while much of the ammonia (NH3)-N escapes into the atmosphere. Our goal was to improve on conventional titter application methods to decrease associated nutrient losses to air and water while increasing soil productivity. We developed and tested a knifing technique to directly apply dry poultry litter beneath the surface of pastures. Results showed that subsurface litter application decreased NH3-N volatilization and nutrient losses in runoff more than 90% (compared with surface-applied litter) to levels statistically as low as those from control (no litter) plots. Given this success, two advanced tractor-drawn prototypes were developed to subsurface apply poultry litter in field research. The two prototypes have been tested in pasture and no-till experiments and are both effective in improving nutrient-use efficiency compared with surface-applied litter, increasing crop yields (possibly by retaining more nitrogen in the soil), and decreasing nutrient losses, often to near background (control plot) levels. A paired-watershed study showed that cumulative phosphorus losses in runoff from continuously grazed perennial pastures were decreased by 55% over a 3-yr period if the annual poultry litter applications were subsurface applied rather than surface broadcast. Results highlight opportunities and challenges for commercial adoption of subsurface poultry litter application in pasture and no-till systems.     

Metacommunity assembly and sorting in newly formed lake communities

new habitats are created, community assembly may follow independent trajectories, since the relative importance of dispersal limitation, priority effects, species interactions, and environmental gradients can vary as assembly proceeds. Unfortunately, tracking community colonization and composition across decades is challenging. We compiled a multiyear community composition data set and reconstructed past communities with remains from sediment cores to investigate cladoceran assembly dynamics in six older (1920s) and two more recently formed (1950s) lakes. We found that current communities cluster along a gradient of thermal stratification that is known to influence predation intensity. Assembling communities showed evidence for a greater influence of species sorting and a reduced influence of spatial structure since the first colonizations. However, lake community trajectories varied considerably, reflecting different colonization sequences among lakes. In the older lakes, small-bodied cladocerans often arrived much earlier than large-bodied cladocerans, while the two younger lakes were colonized much more rapidly, and one was quickly dominated by a large-bodied species. Thus, by combining contemporary community data with paleoecological records, we show that assembly history influences natural community structure for decades while patterns of ecological sorting develop.     

Ambient concentrations of airborne endotoxin in two cities in the interior of British Columbia, Canada

This study measured and analyzed the outdoor airborne endotoxin concentration, on particulate matter (PM2·? and PM1?), for two cities in the interior of British Columbia, Canada. Samples were collected throughout one seasonal cycle, from October 2005 to September 2006. It was found that concentrations were generally highest in the summer and fall, and lowest in the winter and spring. Temperature and relative humidity were found to be most influential, with highest endotoxin concentrations recorded during warm periods and moderate relative humidity (35 to 75 percent). No clear association of concentration with wind direction was observed. Results were comparable between the two cities considered in this study, and concentrations were similar to or slightly higher than those reported by other studies considering urban locations. Endotoxin concentration was also found to be positively associated with agricultural dust sources identified by a source apportionment study conducted at one of the sampling locations.     

Assessing Calibration Uncertainty and Automation for Estimating Evapotranspiration from Agricultural Areas Using METRIC

Agricultural irrigation accounts for a large fraction of the total water use in the western United States. The Mapping Evapotranspiration at high Resolution with Internalized Calibration (METRIC) remote sensing energy balance model is being used to estimate historical agricultural water use in western Nevada to evaluate basin‐wide water budgets. Each METRIC evapotranspiration (ET) estimate must be calibrated by a trained user, which requires some iterative time investment and results in variation in ET estimates between users. An automated calibration algorithm for the METRIC model was designed to generate ET estimates comparable to those from trained users by mimicking the manual calibration process. Automated calibration allows for rapid generation of METRIC ET estimates with minimal manual intervention, as well as uncertainty and sensitivity analysis of the model. The variation in ET estimates generated by the automated calibration algorithm was found to be similar to the variation in manual ET estimates. Results indicate that uncertainty was highest for fields with low ET levels and lowest for fields with high ET levels, with a seasonal mean uncertainty of approximately 5% for all fields. In addition, in a blind comparison, automated daily and seasonal ET estimates compared well with flux tower measurement ET data at multiple sites. Automated methods can generate first‐order ET estimates that are similar to time intensive manual efforts with less time investment.     

Susceptibility of Eucalyptus globulus to Mnesampela privata defoliation in relation to a specific foliar wax compound

Summary. Increased abundance of several aliphatic benzyl and phenylethyl alkanoates were previously associated with reduced defoliation of Eucalyptus globulus Labill. by the autumn gum moth (Mnesampela privata Guenée) in two clonally replicated F₂ families. We examine the robustness of this association by comparing the abundance of the implicated foliar wax compounds with defoliation levels in three plantation sites and a genetics trial in northern Tasmania. At all locations, the aliphatic alkanoate, benzyl n-tetracosanoate (C₂₄), was found in significantly higher abundance in the foliar wax of E. globulus trees that had displayed low M. privata damage (designated resistant) compared to trees that had displayed high damage (designated susceptible). Further, when sites were combined, benzyl n-tetracosanoate (C₂₄) accounted for 16 % of variation in field defoliation. Field defoliation was also positively correlated to M. privata oviposition both in the field and on foliage sprigs in a cage. In the cage bioassay, oviposition accounted for 20 % of variation in field defoliation making it a better predictor of tree defoliation in the field than either field oviposition, which accounted for 9 % of variation, or screening foliage for the abundance of benzyl n-tetracosanoate (C₂₄). Despite both benzyl n-tetracosanoate (C₂₄) and oviposition being related to field defoliation, there was no statistically significant relationship between the abundance of benzyl n-tetracosanoate (C₂₄) and oviposition in the field or cage bioassay. Further work is therefore required to determine if increased levels of this compound in the foliar wax operates as a direct deterrent to M. privataoviposition.     

Association patterns and kinship in female Indo-Pacific bottlenose dolphins (Tursiops aduncus) of southeastern Australia

Kinship has been shown to be an important correlate of group membership and associations among many female mammals. In this study, we investigate association patterns in female Indo-Pacific bottlenose dolphins (Tursiops aduncus) inhabiting an embayment in southeastern Australia. We combine the behavioral data with microsatellite DNA and mitochondrial DNA data to test the hypotheses that genetic relatedness and maternal kinship correlate with associations and social clusters. Mean association between females was not significantly different from a random mean, but the standard deviation was significantly higher than a random standard deviation, indicating the presence of nonrandom associates in the dataset. A neighbor-joining tree, based on the distance of associations between females, identified four main social clusters in the area. Mean genetic relatedness between pairs of frequent female associates was significantly higher than that between pairs of infrequent associates. There was also a significant correlation between mtDNA haplotype sharing and the degree of female association. However, the mean genetic relatedness of female pairs within and between social clusters and the proportion of female pairs with the same and different mtDNA haplotypes within and between clusters were not significantly different. This study demonstrates that kinship correlates with associations among female bottlenose dolphins, but that kinship relations are not necessarily a prerequisite for membership in social clusters. We hypothesize that different forces acting on female bottlenose dolphin sociality appear to promote the formation of flexible groups which include both kin and nonkin.     

Simulated marine respirometry of biodegradable polymers

Eleven microorganisms were isolated from several temperate marine locations in the northeast Altantic coast of the United States and one tropical location in the Pacific Ocean (Hawaii) for the purpose of developing a rapid and accurate method of screening biodegradable materials for their susceptibility to mineralization. The materials evaluated in this study included chemically modified starch, amylose and pullulan, poly(3-hydroxybutyrate-co-valerate), (PHB/V), cellulose acetate, and a modified lignin/styrene. Some of the soluble, unmodified, biologically produced substrates such as starch, pullulan, and amylose mineralized rapidly. In general, the synthetic, insoluble polymers and the chemically modified polymers, such as acetylated and chlorinated amylose and pullulan, mineralized more slowly, although the ultimate mineralization of some of the substituted polysaccharides equaled or exceeded that of the unmodified substrate. The insoluble bacterial polyester, PHB/V, degraded rapidly after a short induction period. Initial respiration rate data, in general, could not be used as a predictor of ultimate mineralization. It was found that the cumulative level of carbon dioxide evolved signifies the minimum extent of biodegradation of the substrate, and the oxygen consumed is a good indicator of the maximum extent of substrate degradation.Paper presented at the Biodegradable Materials and Packaging Conference, September 22–23, 1993, Natick, Massachusetts.     

Low or absent unconjugated estriol in pregnancy: an indicator for steroid sulfatase deficiency detectable by fluorescence in situ hybridization and biochemical analysis

It has been previously reported that a low or absent maternal serum unconjugated estriol (uE3) level is associated with placental steroid sulfatase (STS) deficiency. Here we report a correlation between patients who present with a very low or absent maternal serum uE3 and a deletion of the STS gene as assessed by fluorescence in situ hybridization (FISH). We studied nine prenatal cases that presented to the clinical laboratory with an abnormal triple screen, specifically low or absent maternal serum uE3 and a 46,XY karyotype. FISH analysis showed complete deletion of a probe containing the STS gene in six cases and one case had a partial deletion (reduced but not absent signal). The remaining two cases were not deleted for the STS probe. All mothers tested whose fetus showed a deletion were shown to be STS deletion carriers using FISH. Biochemical analysis was performed on 7/9 prenatal specimens. All fetuses deleted for the STS probe were also found to be deficient for STS by biochemical analysis of cultured amniotic fluid (5/5). Of the two fetuses not deleted for the STS probe, one was deficient for STS activity, while the other had a normal result. The abnormal result of enzyme deficiency by biochemical analysis in a non-deletion case likely represents a mutation in the STS gene, not detectable by this FISH assay. Postnatal FISH confirmation of the STS deletion was performed in 1/7 cases. Clinical follow-up was available for 4/9 cases following birth. Copyright © 2002 John Wiley & Sons, Ltd.     

Pulmonary function changes in Chinese hamsters exposed six months to diesel exhaust

Chinese hamsters were exposed for eight hours per day to automotive diesel exhaust emissions which were diluted with air (18 to 1) and had a particulate level of 6.4 mg/m³. Pulmonary function measurements were made after six months exposure. Body weight (BW), lung weight (LW), vital capacity (VC), residual volume by water displacement (RV_w) and by gas dilution (RV_D), alveolar volume (V_A), and carbon monoxide transfer factor (D_LCO) were measured. LW showed a significant increase in the diesel exposed animals (P < 0.01) while VC, RV_W, and D_LCO showed decreases (P < 0.01). Static deflation volume-pressure curves showed depressed deflation volumes for diesel exposed animals when volumes were corrected for body weight and even greater depressed volumes when volumes were corrected for lung weight. However, when volumes were expressed as percent vital capacity, the diesel exposed animals had higher lung volumes at 0 and 5 cm H₂O. Results of the pathological examination of the lung tissue will be necessary for final analysis of our findings. However, preliminary interpretation indicates possible emphysematous changes which are compatible with the observed decrease in D_LCO.