Effect of soil salinity on growth of irrigated plantation Eucalyptus in south-eastern Australia

Management of salinity may include establishing trees in saline areas to enhance discharge and may enable productive use of saline land. Field studies of the performance of trees in saline conditions are generally confined to the initial years after planting, and little quantitative data are available on the relationship between the growth rates of eucalypt species to soil salinity in field conditions at later ages (e.g. 10 years). In this study, the growth of irrigated Eucalyptus globulus, E. grandis and E. camaldulensis is examined in relation to soil salinity measured using an electromagnetic induction device (EM38).The EM38 was found to be an effective tool in determining survival and growth responses of three Eucalyptus species to levels of soil salinity. Differences in measured tree survival, stand volume and leaf area index were correlated with soil salinity. Of the three species, E. globulus performed best in terms of survival and volume growth to age 10 years under slight to moderate salinity conditions, while E. camaldulensis performed best under moderate to severe soil salinity. The ranking of these species for salinity tolerance is consistent with pot trials and younger field trials.This study highlighted the high spatial variability associated with soil salinity, and studies relating the growth of trees in the field should best be analysed on an areal or stand basis, thereby accounting for variability of salt stored in the soil, and reducing the influence of inter-tree competition on growth-salinity relationships. These results have implications for site selection and management of eucalypts in saline areas.     

Translocation as a tool for conservation of the Hawaiian monk seal

The deteriorating demographic status of the endangered Hawaiian monk seal has motivated renewed and expanded proposals for conservation action, including translocation of seals to improve survival. Over the past three decades, numerous monk seal translocations have been conducted with a variety of objectives, including mitigating shark predation and conspecific male aggression, reducing human–seal interactions, and taking advantage of favorable foraging habitats to improve survival. Here, we analyze our cumulative experience with translocation of Hawaiian monk seals. We found a strong correlation between the time seals remained in the vicinity of the release site and their age. Recently weaned pups (with little or no at-sea foraging experience) exhibited high fidelity to release sites commensurate with that shown by untranslocated pups to their birth location. In contrast, juvenile and adult seals tended to stray from their release locations farther and sooner. Nevertheless, when 21 adult male seals were moved more than 1000 km from Laysan Island in the Northwestern Hawaiian Islands (NWHI), to the main Hawaiian Islands (MHI), they subsequently dispersed among the MHI; however, only one was observed to return to the NWHI. Translocated seals appeared to survive at rates comparable to seals native to the release site. Outcomes suggest that in most cases the intended objectives of translocations were achieved. Except for one notable case, translocations within the MHI to arrest human–seal interactions were mostly unsuccessful. These findings will be essential for informing successful large-scale translocation plans in the future.     

Racing and sales performance after unilateral or bilateral single transphyseal screw insertion for varus angular limb deformities of the carpus in 53 thoroughbreds

Objective: To evaluate the racing and sales performance of Thoroughbred horses with varus angular limb deformities of the carpus treated by unilateral or bilateral single transphyseal screw (STS) placement. Study Design: Case series. Animals: Thoroughbred horses (n=53). Methods: Medical records (January 1, 2005–December 31, 2006) of yearling Thoroughbreds treated for carpal angular limb deformity by transphyseal screw insertion in the distal aspect of the radius were reviewed. Retrieved data were sex, surgery, and screw removal dates, surgical site, appearance, limb(s) affected, type of angular limb deformity, and degree of angular deviation measured by a goniometer. Racing and sales data were collected for analysis from an online racing site for all treated horses and their maternal siblings. Results: No significant differences were identified between treated horses and their maternal siblings in yearling sale price, 2‐year‐olds in training sale price, percent starters, percent winners, and starts, earnings, and earnings/start made during the 2‐ and 3‐year old years. Conclusions: No deleterious effects on sales or racing performance were identified after use of STS in the distal aspect of the radius of Thoroughbreds for the treatment of varus angular limb deformities of the carpus.     

Efficacy of a novel topical combination of fipronil, amitraz and (S)-methoprene for treatment and control of induced infestations with four North American tick species (Dermacentor variabilis, Ixodes scapularis, Amblyomma americanum and Amblyomma maculatum) on dogs

Five laboratory studies were conducted to confirm that a single topical dose of the novel combination of fipronil, amitraz and (S)-methoprene, CERTIFECT? (Merial Limited, GA, USA), is efficacious for the rapid control of pre-existing infestations and the prevention of new infestations with Ixodes scapularis, Dermacentor variabilis, Amblyomma americanum and Amblyomma maculatum for at least 28 days on dogs. In each study, 8 male and 8 female purpose-bred, laboratory beagles were randomly assigned to one of two study groups (treated and untreated). Starting on the day before treatment, each dog was infested weekly with about 30 or 50 ticks, depending on the study. Treatment with the novel combination rapidly eliminated pre-existing infestations and controlled weekly re-infestations for at least 28 days. Pre-existing infestations with all four tick species were rapidly and effectively reduced, with post-treatment therapeutic efficacies ranging from 91.7 to 99.5% within 18-48 h post treatment. Amblyomma maculatum numbers were significantly (p<0.05) reduced on treated dogs from the first tick counts as early as 6h post-treatment. All subsequent infestations with each of the 4 tick species were quickly disrupted, with prophylactic efficacies greater than 90% within 18-48 h post-infestation for at least a full month. Because the combination of fipronil, amitraz and (S)-methoprene quickly starts disrupting and killing ixodid ticks within hours of treatment, with similar high levels of efficacy maintained for at least 28 days in these and other studies, the authors conclude that a single topical treatment with CERTIFECT may prevent the transmission of most infectious agents carried by ixodid ticks for at least one month.     

Structure of agricultural simulators: A philosophical view

Model building is as much an art as a science. We attempt in this paper to define modelling terminology and discuss major steps in model building, analysis and synthesis and the sequence in which they are commonly undertaken in agricultural simulation projects. Model building tends to be an iterative process, meaning that at any point in the sequence the model builder may return to a previous step. This illustrates one of the important steps of a successful simulation—the earlier steps are always subject to revision as additional information is obtained. For example, a review of data often causes some reformulation of the problem. This reformulation may involve only a change in problem emphasis, or it may result in complete restructuring. In dealing with complex systems, analysts sometimes find that the first definition of the problem needs later revisions because it included too many (or sometimes too few) factors to represent adequately the alternatives and, therefore, a return to design.Availability of data is always an important consideration and is part of the problem formulation step of model building. Model constants and parameters, as well as initial values for all variables, are derived from these data. In addition, model assumptions are based on available data, giving model predictions some level of credibility. Finally, data must be available for model validation studies. Therefore, as pointed out in this paper, data sources should be located and their adequacy evaluated early in the model building sequence.The programmer or analyst programming the model should size up the task as an initial step. The result is serious if the size or complexity of the job is underestimated and the model will probably never function as economically or as efficiently as it should. Programming language choices and computing systems available are a part of this task.Consideration of model results may not be the end product of the modelling effort. We stress in this paper that the model building process should be an inter-disciplinary effort, so that when the team considers model results, each member has some realisation of their derivation. It is entirely possible at this point that the team decides more detailed or different results are necessary and that the model building process returns to the beginning with new objectives in mind.We attempt to give a detailed and thorough discussion of the model building process as discussed above. However, we hope the process discussed in this paper will be taken only as a philosophical view and should not be treated as a method that automatically produces the creative thinking required to translate a complicated real-world agricultural system into a more compact and usable simulation model.     

Aspects of meat and eating quality of broiler chickens reared under standard, maize-fed, free-range or organic systems

1. The effects of rearing chickens using standard, maize-fed, free-range or organic production systems on meat quality and sensory characteristics were evaluated. The standard system used either Ross or Cobb birds with a slaughter age of approximately 40 d, the other systems in the trial used Hubbard birds with considerably older slaughter ages, up to 72 d in the case of organic systems. 2. Paired breast fillets from 120 birds, 30 from each rearing system, were used. The meat quality variables, ultimate pH, colour coordinates L*, a*, b* and water-holding capacity were measured and taste panel assessments were made using 8-point category scales of texture, juiciness, abnormal flavour, flavour liking and overall flavour. 3. There were significant differences between rearing systems, with fillet muscles from birds grown under the standard system having a higher ultimate pH. Differences were also seen in colour with fillets from birds reared under a standard system having a smaller hue angle than those grown using the maize-fed system which had the highest. 4. Fillets from birds reared in the standard system were rated by the taste panel as more tender and juicy. There were no significant differences in chicken flavour. Based on hedonic assessments of flavour liking and overall liking, by a small panel of assessors, meat from birds produced in the standard system was most preferred and that from organic systems the least preferred. Meat from free-range and maize-fed systems was intermediate in preference. This result reveals a trend, but does not infer consumer acceptance.     

A review of earthworm impact on soil function and ecosystem services

Biodiversity is responsible for the provision of many ecosystem services; human well‐being is based on these services, and consequently on biodiversity. In soil, earthworms represent the largest component of the animal biomass and are commonly termed ‘ecosystem engineers’. This review considers the contribution of earthworms to ecosystem services through pedogenesis, development of soil structure, water regulation, nutrient cycling, primary production, climate regulation, pollution remediation and cultural services. Although there has been much research into the role of earthworms in soil ecology, this review demonstrates substantial gaps in our knowledge related in particular to difficulties in identifying the effects of species, land use and climate. The review aims to assist people involved in all aspects of land management, including conservation, agriculture, mining or other industries, to obtain a broad knowledge of earthworms and ecosystem services.     

Nitrogen fertilization and plant development of cotton as determined by nodes above white flower 1

Early maturation is very beneficial in successfully harvesting a high‐quality, high‐yielding cotton (Gossypium hirstum L.) crop. If harvest is delayed until inclement weather patterns are established, both yield and fiber quality may be lost. The objective of these studies was to determine the maturity differences that occur in cotton differentially fertilized with nitrogen (N). Field experiments with irrigated cotton were conducted in 1990 and 1991 in three locations to study the effects of soil applied N rates on cotton maturity as estimated by nodes above white flower (NAWF) measurements. The test sites and soils were a production field near Manila, AR, on a Dundee sandy loam (fine‐silty, mixed, thermic Aeric Ochraqualfs), the Southeast Branch Experiment Station (SEBES) near Rohwer, AR, on an Hebert silt loam (fine‐silty, mixed, thermic Aeric Ochraqualfs), and the Northeast Research and Extension Center (NEREC) near Keiser, AR, on a Sharkey silty clay (very fine, montmorillonitic, nonacid, thermic Vertic Haplaquepts). Criteria used as indicators of crop maturity and earliness in these studies were the time in days after planting (DAP) and the accumulated heat units (HU) for the crop to reach NAWF=5. Increasing N rates delayed maturity at SEBES both years and at Manila in 1991 but not at NEREC either year. Differences in maturity between N treatments of 168 and 224 kg N/ha were minimal at all locations both years. Smaller differences in time for the plants to achieve NAWF=5 were observed in the cotton grown at Manila in 1990 and at NEREC both years. The smaller differences at Manila are assumed to be due to high levels of residual N from previous crops. Early‐season vegetative growth was indicated by NAWF extrapolated to first flower (60 DAP or 945 HU). A trend of higher NAWF at the extrapolated first flower stage with increasing N rate was observed, but generally differences were minimal. The NAWF values at DAP=60 were lower in 1991 than in 1990 for all locations.