Nitrous Oxide Emissions in Response to ESN and Urea Application in a No-Till Barley Cropping System

We investigated the effect of environmentally smart nitrogen (ESN) fertilizer on nitrous oxide (N₂O) emissions under no-till barley (Hordeum vulgare L.) production over 3 years at three sites in Alberta, Canada. Treatments included two barley cultivars, with ESN and urea applied at 1× and 1.5× the recommended rate, and herbicide at 50% and 100% of registered in-crop rates. Cumulative N₂O emissions over the growing season were low (0.11 to 1.32 kg nitrogen (N) per hectare or 0.05–0.22 g N kg^?1 grain yield), and not affected by barley cultivars or herbicide rates in all nine site-years, nor by fertilizer type or rate in seven out of nine site-years. However, average N₂O emissions from ESN were 15% lower (P = 0.05) than urea across all site-years. Our results suggest ESN could play a role in reducing N₂O emissions, but the reduction will depend on rainfall events and crop N utilization.     

Habituation Performance of Two Percids Under Turbid and Clear Water Culture

Advanced walleye (Sander vitreus) and yellow perch (Perca flavescens) fingerlings are produced by habituating pond-reared fingerlings to commercial feed. Success of the habituation phase depends on many variables. Among these, diet contrast/visibility is an important variable for habituation success. The objective of this study was to compare the effect of turbid water (≥100 nephelometric turbidity unit, NTU) and clear water culture conditions during the habituation phase for these two species. In 2005, 12 150 L black-cuboidal tanks with in-tank lighting were stocked at a rate of 2 g/L age 0 of either walleye or yellow perch fingerlings with half of the tanks receiving turbidity (clay slurry) and cultured for 28 d. All fish were fed a commercial diet every 5 min during a 16 h daylight interval at 10%?body weight/d. Walleye in the clear treatment had higher survival (83?±?2.0%) than the turbid treatment (57?±?6.0%). The yellow perch exhibited opposite survival results: turbid treatment rates at 79?±?2.1%?and clear treatment rates at 54?±?9.2%. These results demonstrate that the addition of clay may enhance the contrast of the feed and thus improve the habituation phase for yellow perch.     

Review of research methodologies for tigers: Telemetry

Over the past half century, wildlife research has relied on technological advances to gain additional insight into the secretive lives of animals. This revolution started in the 1960s with the development of radio telemetry and continues today with the use of Global Positioning System (GPS)-based research techniques. In the present paper we review the history of radio telemetry from its origins with grizzly bears in Yellowstone to its early applications in tiger research and conservation in Asia. We address the different types of data that are available using radio telemetry as opposed to using other research techniques, such as behavioral observations, camera trapping, DNA analysis and scat analysis. In the late 1990s, the rapid development of GPS collar technology revolutionized wildlife research. This new technology has enabled researchers to dramatically improve their ability to gather data on animal movements and ecology. Despite the ecological and conservation benefits of radio telemetry, there have been few telemetry studies of tigers in the wild, and most have been on the Bengal or Amur subspecies. We close with an assessment of the current tiger conservation efforts using GPS technology and discuss how this new information can help to preserve tigers for future generations.     

Biomechanics of the Distal Interphalangeal Joint

This article summarizes the kinematics of the distal interphalangeal (DIP) joint during locomotion at walk and trot. The patterns and ranges of motion in flexion and extension are very similar at walk (range of motion: 46±40) and trot (range of motion: 47±40). In both gaits there is a cucle of flexion that peaks in the first half of stance. The joint is extended through the remainder of stance in opposition to a palmar moment generated by the deep digital flexor tendon and its accessory ligament and the navicular ligaments. During locomotion in a straight line, small amounts of abduction/adduction (∼50) and internal/external rotation (5-60) occur, especially around the times of contact and breakover. Extra-sagittal motions increase as a consequence of hoof imbalance, during turning or when the horse moves over uneven terrain.     

Habitat variables explain Loggerhead Shrike occurrence in the northern Chihuahuan Desert,but are poor correlates of fitness measures

Conservation efforts should be based on habitat models that identify areas of high quality and that are built at spatial scales that are ecologically relevant. In this study, we developed habitat models for the Loggerhead Shrike (Lanius ludovicianus) in the Chihuahuan Desert of New Mexico to answer two questions: (1) are highly used habitats of high quality for shrikes in terms of individual fitness? and (2) what are the spatial scales of habitat associations relevant to this species? Our study area was Fort Bliss Army Reserve (New Mexico). Bird abundance was obtained from 10 min point counts conducted at forty-two 108 ha plots during a 3-year period. Measures of fitness were obtained by tracking a total of 73 nests over the 3 years. Habitat variables were measured at spatial scales ranging from broad to intermediate to local. We related habitat use and measures of fitness to habitat variables using Bayesian model averaging. We found a significant relationship between bird abundance and measures of fitness averaged across nesting birds in each plot (correlation up to 0.61). This suggests that measures of habitat use are indicative of habitat quality in the vicinity of Fort Bliss. Local- and intermediate-scale variables best explained shrike occurrence. Habitat variables were not related to any measures of fitness. A better understanding of the factors that limit individual bird fitness is therefore necessary to identify areas of high conservation value for this species.     

Model organic compounds differ in their effects on pH changes of two soils differing in initial pH

The mechanisms by which organic materials affect soil pH are not fully understood. This study for the first time compared the short-term effect of various model organic compounds on pH change of two soils differing in initial pH (Podosol of pH 4.4 and Tenosol of pH 6.1). Eight organic compounds, representing common compounds in plant residues, were selected based on the number and type of chemical functional groups. The addition of organic acids (acetic, malic, citric, and benzoic acid) reduced soil pH immediately due to H⁺ dissociation. The magnitude of pH decrease depended on the rate of application, degree of dissociation of the acids, and initial soil pH. During a subsequent incubation, pH was slowly restored as these compounds were decomposed. The degree to which pH was restored was reduced with increasing addition rate. The production of H⁺ ions was increased with increasing rate of acid addition and decreased over time. When potassium citrate (organic anion) was added, soil pH increased due to H⁺ consumption upon decomposition. Compounds with amine groups (glucosamine hydrochloride) and less easily decomposable compounds (phenol) did not significantly alter pH during 16-day shaking. Changes in pH after glucose addition were relatively small compared with other compounds and were not expected because hydroxyl chemical groups of glucose are neutral. The present study demonstrated that the addition of model organic compounds to soil caused soil pH to increase, decrease, or remains unaffected. The extent and direction of pH change was dependent on the chemical functional group, addition rate, decomposition, and the initial soil pH.     

Content and uptake of phosphorus and copper by spring wheat: Effect of environment,genotype, and management

Copper (Cu) deficiency in grain crops grown on the Canadian Prairie has increased recently, while nearly 50% of the soils have low available phosphorus (P) levels. This study was conducted to quantify the variation in Cu and P uptake among some common Canadian wheat (Triticum aestivum L.) cultivars due to the effects of nitrogen (N) fertilizer and the environment. The effects of N fertilizer application at 0,50, and 100 kg N ha^‐1 and seeding in early May or mid‐May on the P and Cu contents of four wheat cultivars were determined in an experiment conducted over two years at Fort Vermilion (58°24'N, 116°0’ W). Cultivar and N fertilizer produced similar variances in P concentration. Phosphorus uptake was increased by N fertilizer, but was not affected by the cultivars tested. Nitrogen fertilizer produced four times as much variability in Cu concentration and uptake as did the effect of genotypes. Date of sowing within the recommended time frame had no effect on plant P and Cu contents. There was no treatment interaction effect on plant P or Cu content. In a second experiment, situated near Grande Prairie (55°10'N, 118°48'W) and conducted over two years, P and Cu uptake and concentrations were determined for 10 agronomically diverse spring wheat cultivars. The range was 1.2‐ to 1.4‐fold for P and 1.5‐ to 1.7‐fold for Cu concentration. Plant Cu, but not plant P, was correlated with grain yield (r=0.64 to 0.86), suggesting that either varietal differences in Cu uptake may affect yield or prior selection for yield may have resulted in the selection for Cu‐efficient plants as well. Environmental, i.e., site‐year, effects on plant P, and particularly Cu concentrations, were larger than the varietal effects in both studies. These studies indicate that selection of Canadian wheat cultivars should be based on their yield potential rather than their efficiency in Cu or P uptake since crop nutrition can be more readily managed by optimal fertilization.     

Reduced fungicide inputs to controlPhytophthora infestans in potato cultivars with high levels of polygenic resistance

Summary Final disease ratings, apparent infection rates and areas under disease progress curves were used to calculate lower fungicide rates for potato cultivars with high levels of polygenic resistance toPhytophthora infestans. Areas under disease progress curves offered more reliable indications than final disease ratings or apparent infection rates. Control of epidemic development was achieved using 20–80% of the recommended application rates of mancozeb on plots of cvs Brodick. Cara and Torridon compared with full application rates on cv. Maris Piper.     

Pink bollworm of cotton (Pectinophora gossypiella (Saunders)): male moth catches in gossyplure-baited traps and relationships to oviposition, boll infestation and moth emergence

Pheromone-baited traps are an important sampling tool in integrated pest management programmes. Studies were conducted to determine the relationship between catches of male insects in these traps, and crop infestation. Numbers of male moths of the pink bollworm, Pectinophora gossypiella (Saunders) (Lepidoptera: Gelechiidae), caught daily in cotton fields at the University of Arizona Cotton Research Center, Phoenix, Arizona, in gossyplure-baited traps were variable. However, average catches of male moths for 3–7 days between boll-sampling periods were strongly correlated with oviposition on cotton bolls, percentages of infested bolls and numbers of larvae per boll. Average weekly numbers of moths emerging from infested cotton were also strongly correlated with the number of males caught: the number of females emerging was strongly correlated with oviposition on cotton bolls. Insecticide applications of carbaryl and fenvalerate reduced catches of male moths of pink bollworm in gossyplure-baited traps compared with catches in traps in untreated fields (average 56%). However, 13–48 male moths/trap per night were caught in the treated fields after applications. Thus, scheduling treatments on the basis of male moth trap catches, except for the initial treatment, was not feasible. Small field sizes, moth immigration and/or continuing emergence from the infested cotton in the fields may have obscured the impact of the insecticide treatments on adult moth populations.