The interaction of crop rotations and soil quality: an economic analysis

Non-Peer ReviewedA model is briefly described that integrates an environmental component that simulates crop yields and changes in soil quality and an economic component that calculates rotation scale costs and revenues based on yield and input data provided by the environmental component. The model is used to simulate crop yield, soil quality and economic performance of a number of alternative annual crop rotations over a 50 year period. This information is used to quantify the impact of alternative crop rotations on soil organic carbon and the economic value of on-site SOC to the rotations, with values ranging from $0.20 to$2.50/ton SOC/hectare/yr

The carbon life cycle assessment of the production of shelterbelt species in Saskatchewan

Non-Peer ReviewedShelterbelt tree and shrub adoption has been a major landscape management practice on agricultural land in Saskatchewan throughout the 1900s. Shelterbelt trees were distributed to landowners, free of charge, from 1901 to 2002 by the Canadian government's prairie shelterbelt centre, which was located in Indian Head, Saskatchewan. Though the shelterbelt centre at Indian Head closed in 2013, many other shelterbelt centres and forestry nurseries still exist to serve this purpose. Saskpower's Shand Greenhouse, operated out of Estevan, Saskatchewan, provides approximately 500,000 seedlings a year, both free of charge for those eligible and for purchase. Shelterbelt tree and shrubs are important for carbon sequestration and storage efforts within Saskatchewan and Canada, however it is important to note the carbon produced in the production of these seedlings. Using data collected from Shand Greenhouse and an LCA software program (SimaPro), the overall carbon produced by this stage of the shelterbelt life cycle can be determined. With this information, the net carbon balance of shelterbelt production and use will be better understood. This may serve as beneficial information regarding future decision-making for individual landowners and governmental policies regarding the production as well as the removal/retention of shelterbelt trees

Modelling soil dynamics and the effect of nitrogen levels on potato yield function

Non-Peer ReviewedCrop yield is maximized when optimal levels of nutrients, water, and other inputs are available to the crop and the influence of disease and weeds has been minimized. While each crop has differing responses to nutrient availability, modelling soil dynamics and the effect of nitrogen levels on potato yield is very important. The objective of this study was to model several environmental components of potato yield function including soil characteristics and organic matter content, soil nitrogen, temperature component, moisture component, solum and nitrogen mineralization, nitrogen fertilizer, and nitrogen sufficiency. The interaction of these components with moisture availability and nitrogen sufficiency was shown to impact potato yield

Economics of crop diversification opportunities for the Brown and Dark Brown Soil Zones of Saskatchewan

Non-Peer ReviewedProducers, particularly in the Brown and drier parts of the Dark Brown soil zones, have begun to extend and diversify their crop rotations, becoming less reliant on summerfallow and monoculture cereal cropping. The areas planted to crops such as canola, mustard, flax, field pea, chickpea and lentil expanded dramatically in recent years, often into new or non-traditional production areas. These changes in land use practices are expected to continue, and perhaps grow in future years. This study determines and compares the economic merits and relative riskiness (both production and market) of producing chickpea, field pea, lentil, mustard, canola, and flax with spring wheat, durum wheat or barley when grown on chemical fallow and zero-till stubble for various plausible product price scenarios. Field data collected at Swift Current, Scott and Congress were extended with use of a STELLA® model, to elucidate the short-term and the longer-term economic and environmental impacts of these newer cropping systems. Our findings indicate that under current market conditions, risk averse producers in the Brown soil zone would typically choose either a 4-year Fallow-Chickpea-Wheat-Wheat rotation or a 5-year Durum-Chickpea-Mustard-Wheat-Lentil rotation. In the Dark Brown soil zone, risk averse producers would choose a 4-year Canola-Wheat-Lentil- Wheat rotation

Intermittency and the passive nature of the magnitude of the magnetic field

It is shown that the statistical properties of the magnitude of the magnetic field in turbulent electrically conducting media resemble, in the inertial range, those of passive scalars in fully developed three-dimensional fluid turbulence. This conclusion, suggested by the data from Advanced Composition Explorer, is supported by a brief analysis of the appropriate magnetohydrodynamic equations

Clinical significance of medial vs lateral compartment patellofemoral osteoarthritis: cross-sectional analyses in an adult population with knee pain

Objective To determine the comparative prevalence, associations with selected patient characteristics, and clinical outcomes of medial and lateral compartment patellofemoral (PF) joint osteoarthritis (OA). Methods Information was collected by questionnaires, clinical assessment, and radiographs from 745 eligible community‐dwelling symptomatic adults age ≥50 years. PF joint space narrowing (JSN) and osteophytes were scored from skyline radiographs using the Osteoarthritis Research Society International atlas. Multilevel models were used to assess associations of compartmental PF joint OA with age, sex, body mass index (BMI) and varus–valgus malalignment, while median regression was used to examine associations with clinical outcomes (current pain intensity on a numeric rating scale [0–10] and the function subscale of the Western Ontario and McMaster Universities Osteoarthritis Index [0–68]). Results Isolated lateral PF joint OA was more common than isolated medial PF joint OA, particularly at higher severity thresholds. Irrespective of severity threshold, age (≥2 odds ratio [OR] 1.19 [95% confidence interval (95% CI) 1.12, 1.26]), BMI (≥2 OR 1.15 [95% CI 1.07, 1.24]), and valgus malalignment (≥2 OR 2.58 [95% CI 1.09, 6.07]) were associated with increased odds of isolated lateral JSN, but isolated medial JSN was only associated with age (≥2 OR 1.20 [95% CI 1.14, 1.27]). The pattern of association was less clear for PF joint osteophytes. Isolated lateral PF joint OA, defined by JSN or osteophytes, was associated with higher pain scores than isolated medial PF joint OA, but these differences were modest and were not significant. A similar pattern of association was seen for functional limitation but only when PF joint OA was defined by JSN. Conclusion Isolated lateral PF joint OA is more common than isolated medial PF joint OA, and it is more consistently associated with established OA risk factors. It is also associated with higher, but clinically nonsignificant, pain and function scores than isolated medial PF joint OA, particularly when PF joint OA is defined using JSN

Comparison of electromagnetic and gravitational radiation: What we can learn about each from the other

We compare the nature of electromagnetic fields and gravitational fields in linearized general relativity. We carry out this comparison both mathematically and visually. In particular, the “lines of force” visualizations of electromagnetism are contrasted with the recently introduced tendex/vortex eigenline technique for visualizing gravitational fields. Specific solutions, visualizations, and comparisons are given for an oscillating point quadrupole source. Among the similarities illustrated are the quasistatic nature of the near fields, the transverse 1/r nature of the far fields, and the interesting intermediate field structures connecting these two limiting forms. Among the differences illustrated are the meaning of field line motion and of the flow of energy

Diversion of prescribed opioids by people living with chronic pain: Results from an Australian community sample

Introduction and Aims There has been an increase in prescription of opioids for chronic non‐cancer pain, and concern exists over possible diversion of prescription opioids to the illicit marketplace. Recent media coverage suggests that elderly patients sell their prescribed opioids for additional income. This study investigated the extent to which an Australian community sample of chronic pain patients prescribed opioids reported supplying their prescribed opioids to others. Design and Methods Participants living with chronic non‐cancer pain and prescribed opioids for their pain (n = 952) were recruited across Australia via advertisements at pharmacies. A telephone interview included questions about their pain condition and opioid medication. Results Participants had been living with pain for a mean of 14.2 years; most common conditions included chronic back/neck problems and arthritis/rheumatism. Around half (43%) were currently prescribed one opioid, and 55% had been prescribed 2-5 opioids; the most common was oxycodone. Forty‐two participants (4%) reported ever supplying prescribed opioids to another person; one participant reported receiving payment. Participants who supplied opioids to others were younger (odds ratio 0.97, 95% confidence interval 0.95-0.99) and engaged in a greater number of aberrant behaviours relating to their opioid medication (odds ratio 1.77, 95% confidence interval 1.45-2.17), including tampering with doses, taking opioids by alternative routes, seeing doctors to obtain extra opioids and refilling prescriptions early. Discussion and Conclusion Few people with chronic non‐cancer pain divert their opioids to others. Media reports of elderly patients selling their opioids to supplement their income may be reflective of exceptional cases. Future studies may investigate the extent to which other patient groups divert prescription opioids to the illicit marketplace