Interpolation type and data computation of crop yield maps is important for precision crop production

Technological advances in precision agriculture in the last two decades have made yield monitoring and mapping an economically feasible option or practice for farmers. Differentially corrected Global Positioning System (GPS)-equipped yield monitoring system on a combine allows collection of georeferenced yield data which when coupled with a geographic information system (GIS) can generate yield maps via several interpolation techniques. Scientists and practitioners have reported to use multiple different types of interpolation techniques to process yield data. However, one of the aspects that still need to be elucidated is the influence of the different interpolation methods on the quality of the resulting thematic yield maps. The objective of this study was to investigate the influence of three interpolation methods (i.e., inverse of distance, inverse of square distance, and ordinary kriging) commonly used in developing yield maps. An index for the comparison of errors (ICE) was proposed to provide an objective criterion for selecting an experimental variogram model to use with the kriging. Results indicate that inverse distance squared performed slightly better in predicting yields than either inverse distance or ordinary kriging. With a mean absolute difference varying from 0.04 to 0.32 t ha^?1 corresponding to a relative deviation from 1.20 to 7.53%, the management decisions can differ in some cases based on the type of interpolation implemented.     

Long-term organic farming fosters below and aboveground biota: Implications for soil quality, biological control and productivity

Organic farming may contribute substantially to future agricultural production worldwide by improving soil quality and pest control, thereby reducing environmental impacts of conventional farming. We investigated in a comprehensive way soil chemical, as well as below and aboveground biological parameters of two organic and two conventional wheat farming systems that primarily differed in fertilization and weed management strategies. Contrast analyses identified management related differences between “herbicide-free” bioorganic (BIOORG) and biodynamic (BIODYN) systems and conventional systems with (CONFYM) or without manure (CONMIN) and herbicide application within a long-term agricultural experiment (DOK trial, Switzerland). Soil carbon content was significantly higher in systems receiving farmyard manure and concomitantly microbial biomass (fungi and bacteria) was increased. Microbial activity parameters, such as microbial basal respiration and nitrogen mineralization, showed an opposite pattern, suggesting that soil carbon in the conventional system (CONFYM) was more easily accessible to microorganisms than in organic systems. Bacterivorous nematodes and earthworms were most abundant in systems that received farmyard manure, which is in line with the responses of their potential food sources (microbes and organic matter). Mineral fertilizer application detrimentally affected enchytraeids and Diptera larvae, whereas aphids benefited. Spider abundance was favoured by organic management, most likely a response to increased prey availability from the belowground subsystem or increased weed coverage. In contrast to most soil-based, bottom-up controlled interactions, the twofold higher abundance of this generalist predator group in organic systems likely contributed to the significantly lower abundance of aboveground herbivore pests (aphids) in these systems. Long-term organic farming and the application of farmyard manure promoted soil quality, microbial biomass and fostered natural enemies and ecosystem engineers, suggesting enhanced nutrient cycling and pest control. Mineral fertilizers and herbicide application, in contrast, affected the potential for top-down control of aboveground pests negatively and reduced the organic carbon levels. Our study indicates that the use of synthetic fertilizers and herbicide application changes interactions within and between below and aboveground components, ultimately promoting negative environmental impacts of agriculture by reducing internal biological cycles and pest control. On the contrary, organic farming fosters microbial and faunal decomposers and this propagates into the aboveground system via generalist predators thereby increasing conservation biological control. However, grain and straw yields were 23% higher in systems receiving mineral fertilizers and herbicides reflecting the trade-off between productivity and environmental responsibility.     

Applications of satellite remote sensing to forested ecosystems

Since the launch of the first civilian earth-observing satellite in 1972, satellite remote sensing has provided increasingly sophisticated information on the structure and function of forested ecosystems. Forest classification and mapping, common uses of satellite data, have improved over the years as a result of more discriminating sensors, better classification algorithms, and the use of geographic information systems to incorporate additional spatially referenced data such as topography. Land-use change, including conversion of forests for urban or agricultural development, can now be detected and rates of change calculated by superimposing satellite images taken at different dates. Landscape ecological questions regarding landscape pattern and the variables controlling observed patterns can be addressed using satellite imagery as can forestry and ecological questions regarding spatial variations in physiological characteristics, productivity, successional patterns, forest structure, and forest decline.     

Sample collection and handling: getting accurate results.

Results of many routine laboratory assays supply important diagnostic information and are an important part of patient care in many situations. Ensuring the accuracy of these results is not only important from a diagnostic standpoint but can prevent the frustration inherent when the effort of collecting and submitting samples does not yield interpretable results. This article discusses some of the routinely encountered problems (and how to avoid them) associated with performing the more commonly requested tests: complete blood cell counts, chemistry profiles, coagulation testing, and cytology specimens. The article presents a general discussion of sample collection and handling and then some specific considerations for the handling of the previously mentioned tests.     

MAGNETIC RESONANCE IMAGING FEATURES OF CERVICAL STENOTIC MYELOPATHY IN 21 DOGS

The cervical spine of 21 dogs with clinical signs of cervical stenotic myelopathy was evaluated using magnetic resonance (MR) imaging. Spin echo T1, T2 and gradient echo T2 weighted images were obtained with a 1.5 Tesla magnet in 12 dogs and a 1.0 Tesla magnet in 9 dogs. Sagittal or parasagittal T1W and T2W images were helpful in determining the presence of spinal cord compression or degenerative disease of the articular processes. Transverse T1W and T2W images were the most useful for the identification of dorsolateral spinal cord compression secondary to soft tissue and ligament hypertrophy, as well as synovial cysts, associated with the articular processes. The MR imaging findings were consistent with the surgical findings in all 14 dogs that underwent surgery. Magnetic resonance imaging provided a safe, non-invasive method of evaluating the cervical spine in dogs suspected of having cervical stenotic myelopathy. Veterinary     

Electrocardiographic assessment of antianxiety medication in dogs and correlation with serum drug concentration

OBJECTIVES: To determine effects of tricyclic antidepressants (TCA) on the ECG of dogs treated for behavioral conditions and to examine correlations between ECG findings and serum concentrations of these medications. DESIGN: Repeated-measures study. ANIMALS: 39 client-owned dogs with behavioral problems. PROCEDURE: Two groups of dogs with behavioral problems were evaluated. In group 1 (n = 20), ECG tracings were recorded before starting treatment with TCA and again after treatment for > or = 1 month. Dogs in group 2 were already on long-term maintenance amounts of antianxiety medication when ECG tracings were recorded and serum concentrations of medications were obtained. RESULTS: Significant differences were not detected for dogs in group 1 between ECG values measured before and after TCA administration. The ECG values for dogs in group 2 did not differ significantly from the mean of group-1 dogs before receiving medication or from the reference range used at our facility. Duration of the P wave had a significant positive correlation with serum concentrations of clomipramine but significant negative correlation with serum concentrations of amitriptyline. The QT interval corrected for heart rate had a significant negative correlation with serum concentrations of amitriptyline. CONCLUSIONS AND CLINICAL RELEVANCE: Amitriptyline and clomipramine administered at standard dosages apparently do not cause ECG abnormalities in healthy dogs with behavioral problems. These medications should be used cautiously in dogs with conduction abnormalities, and clinicians should periodically monitor ECG and use good clinical judgment to weigh risks and benefits of medications for the safety of each dog.     

Emigration and mortality of juvenile brown trout in a New Zealand headwater tributary

We investigated juvenile brown trout migration and mortality in a headwater tributary of the Motueka River, New Zealand, by tracking 1000 young‐of‐the‐year passive integrated transponder (PIT) tagged fish over autumn to summer to (i) partition total loss into emigration and mortality and (ii) determine the influence of season and flow on emigration. Fish were tracked using mobile and fixed PIT tag readers. Of the 1000 fish tagged, 173 remained within the Rainy River; emigration contributed 60% and mortality 29% to loss. Only 11% of fish tagged in autumn were predicted to remain in the upper reaches of the stream by early summer, and this agreed with density data collected in a parallel study. We identified a two‐phase downstream migration pattern with early movement of large young‐of‐the‐year fish in autumn (mainly during floods). This was followed by another substantial period of movement in spring (during floods and lower flows) by fish that were initially smaller at the time of PIT tagging. The management implications for damming and fish screening in headwater tributaries are discussed.