Constructing a nitrogen fertilizer recommendation system using a dynamic model: what do farmers want?     

J. U. Smith  A. G. Dailey  M. J. Glendining  N. J. Bradbury  T. M. Addiscott  P. Smith  A. Bide  D. Boothroyd  E. Brown  R. Cartwright  R. Chorley  S. Cook  S. Cousins  S. Draper  M. Dunn  A. Fisher  P. Griffith  C. Hayes  A. Lock  S. Lord  J. Mackay  C. Malone  D. Mitchell  D. Nettleton  D. Nicholls  H. Overman  J. Purslow  A. Scholey  S. Senior  L. Sim  P. Taylor 《Soil Use and Management》1997,13(4):225-228

Abstract. An effective fertilizer recommendation system requires information on seasonal, soil-related and cultural variations in soil mineral nitrogen (N) and nutrient requirements of the crop. This can be provided by dynamic N turnover models, such as listed by Plentinger & Penning De Vries (1996). In this paper, we describe a survey of farmer opinion designed to ascertain what farmers want from such a decision support system. Over 100 farmers were surveyed. Surveyed farmers requested that default values be available for all model inputs. Inputs should be entered both by windows-based menu (for clarity) and tabular format (for speed), have user-selected units, and be fully supported by context-sensitive help. The system should have a hierarchical structure allowing access to fixed parameters, and be compatible with commonly used farm recording packages. Recommendations should be provided both for the field (single and optional application rates), and in tabular format across the whole farm. Simulations should be easily rerun using more recent crop and weather data. Turnover processes underlying recommendations should be illustrated by flow diagrams of flux between pools, pie charts of fertilizer fate, bar charts of movement down the soil profile and graphical plots of changes in N status against time.  相似文献   

Microbiological evaluation of dressing procedures for crocodile carcases in Queensland     

MW RICKARD  AD THOMAS†  S. BRADLEY‡  J. FORBES-FAULKNER†  RJ MAYER† 《Australian veterinary journal》1995,72(5):172-176

SUMMARY Microbiological testing of crocodiles during the dressing procedure has shown that sanitising the skin before skinning reduces the bacterial count on the skin and that dipping crocodile meat in 1.3% acetic acid solution effectively reduces bacterial levels. The total bacterial count on the processed meat sample was comparable with that obtained in the beef, pork and lamb industries. Salmonellae were isolated from 14 of the 72 carcases. Most (65%) of these isolates were in Salmonella subspecies III, formerly classified as Arizona.  相似文献   

Spontaneous triploids in forage kale,Brassica oleracea var. acephala     

G. R. Mackay  R. J. Low 《Euphytica》1975,24(2):525-529

Summary On screening samples of seed of commercial kale for spontaneous haploids, unexpectedly large numbers of triploid seeds were found in the small seed fractions. These are presumed to have arisen from unreduced gametes and may be similar in origin to diploid maternals, more usually obtained via interspecific pollination.  相似文献   

Pasture production and composition under poplar in a hill environment in New Zealand     

Aurelio Guevara-Escobar  Peter D. Kemp  Alec D. Mackay  John Hodgson 《Agroforestry Systems》2007,69(3):199-213

Traditionally, poplar (Populus spp.) have been planted to control erosion on New Zealand’s hill-slopes because of their capacity to dry out and bind together the soil. Two systems: (1) widely spaced, planted poplar for soil conservation, and (2) non-eroded open pasture were compared to determine the relative effect of the poplar–pasture system on the production, nutritive value and species composition of the pasture, and on the water balance. Measurements were made at three sites with mature poplar (>29 years and 37–40 stems ha⁻¹) and at a replicated experiment with young poplar (5 years, 50–100 stems ha⁻¹). Soil water relations did not suggest strong competition for water between poplar and pasture. Pasture accumulation under mature poplar was 40% less than in the open pasture, but under young poplar was similar to that in the open pasture. Chemical composition of pasture suggested that feed quality of pasture in the open was better than under the poplar canopy, except during spring, when most chemical components were similar. At the most, in vitro digestibility of pasture dry matter was 8.9% lower and metabolisable energy of pasture dry matter was 1.5 MJ kg lower under the poplar canopy than in the open pasture. Shade tolerant species were not dominant in the plant community under the poplar canopy with grasses such as browntop (Agrostis capillaris, L.) and ryegrass (Lolium perenne, L.) being a high proportion of the plant community. Differences in chemical composition were related to differences in the botanical composition between the open pasture and the poplar understorey. It was concluded that the greatest effect of poplar was on pasture production due to shading, and that management of this silvopastoral system needs to focus on control of the tree canopy to lessen the decrease in pasture production.  相似文献   

Bacterial air pollution from an activated sludge tank     

Senator C. Raygor  Kenneth P. Mackay 《Water, air, and soil pollution》1975,5(1):47-52

Concentrations of air-borne coliforms and ‘other’ bacteria (defined as total bacteria minus coliforms) were measured. downwind of a sewage treatment plant activated sludge tank. The Gaussian plume diffusion equation adequately predicts concentrations of the ‘other’ bacteria; the diffusion equation must be modified by an extinction coefficient, equivalent to a half-life of about 7.4 s, to predict coliform concentrations. Coliform concentrations downwind of this tank did not present a significant health hazard, but the method is applicable to treatment plants of higher capacity and possibly greater emissions.  相似文献   

Effect of the non-steroidal anti-inflammatory drug, carprofen, on weaned sheep following non-surgical mulesing by intradermal injection of cetrimide     

IG Colditz  JB Lloyd  DR Paull  C Lee  A Giraudo  C Pizzato  AD Fisher 《Australian veterinary journal》2009,87(1-2):19-26

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Citronellol: geraniol ratios and temperature in geranium (Pelargonium hybrid)     

Luigino Doimo  Darren C. Mackay  Gavin B. Rintoul  Bruce R. D’Arcy  Robert J. Fletcher 《The Journal of Horticultural Science and Biotechnology》2013,88(4):528-530

Summary

Concentrations of citronellol and geraniol in essential oil from rose geranium (Pelargonium hybrid) were monitored monthly over four years using gas chromatography-mass spectrometry. Geraniol concentrations fell in winter and citronellol concentrations increased in spring. The citronellol/geraniol (C:G) ratio was a more sensitive indicator of change in oil composition than the concentration of either alcohol in isolation. C:G ratios rose sharply if the minimum air temperature (T_min) fell below 5.58C for any time during the 5 d prior to monthly harvesting. A nonlinear model is proposed to predict the C:G ratio at any T_min. High C:G ratios indicated cold stress in geranium plants.  相似文献   

Vegetation development over four years on two green roofs in the UK     

Adam J. Bates  Jon P. Sadler  Rae Mackay 《Urban Forestry & Urban Greening》2013,12(1):98-108

Carefully designed green roofs have the potential to be used as mitigation for habitats lost at ground level. The development of plant assemblages on two green roofs designed to emulate diverse brownfield habitats (brown roofs), by using recycled demolition aggregate as part of a low-fertility growth substrate, were studied over the first four years of their development. The cover-abundance of flowering plants and habitat structural components (e.g. bare ground, moss) were measured on the Domin-Krajina scale within all identified microhabitats. Drought disturbance was one of the main controlling factors on assemblage development. Annual plants were abundant and successful in the first growth season, and thereafter only re-appeared in any numbers following drought disturbances in subsequent years. Moss and Sedum acre L. increased through the study period until these plants dominated coverage. The cover-abundance of perennial wildflower species was strongly influenced by drought disturbance. The influence of drought disturbance varied between different brown roof microhabitats, with plant assemblages in coarser and less fertile microhabitats more resistant to these disturbances. Observed responses to drought were consistent with the following two hypotheses: (i) Areas of coarse substrate can act as disturbance refugia for plants during drought by helping preserve pockets of water under large clasts and within absorbent materials such as brick. (ii) The plant assemblages living in areas of more fertile substrates, which grow more luxuriantly when water availability is high, are more vulnerable to drought disturbance. Green roofs should be designed to include a range of substrate types to create several microhabitats that will collectively support more species than any single microhabitat.  相似文献   

The soil invertebrate contribution to nitrogen mineralisation differs between soils under organic and conventional dairy management     

Nicole L. Schon  Alec D. Mackay  Mike J. Hedley  Maria A. Minor 《Biology and Fertility of Soils》2012,48(1):31-42

Organic management aims to promote soil biological activity. To test whether organic management stimulates soil biological activity, invertebrates (macrofauna, mesofauna and microfauna) were collected from four paired commercial organically and conventionally managed dairy farms on different soil types (Allophanic, Pallic, Recent and flooded Recent). Food webs were constructed and rates of invertebrate-mediated N mineralisation calculated. The organic dairy operations used fewer nutrient inputs and had lower stocking rates than their paired conventional farms. This translated into lower calculated pasture production and less available plant litter entering the soil food web. Despite the lower plant litter inputs into the organic system, earthworm biomass was higher (particularly in the Recent and flooded Recent soils), suggesting that under conventional management the physical condition of the soil, as influenced by stock treading pressures, was more important for invertebrate activity and their influence on N mineralisation than was food supply. Nitrogen mineralisation was higher in organic systems, with earthworms contributing the most (24–98 kg N/ha/year). As the physical loading on the soil increased under conventional management, the ability of the soil to provide soil services (i.e. N mineralisation and litter decomposition) became compromised. Organic management on four soils stimulated biological activity by reducing the treading pressure on the soil and highlights the need to consider the influence of management practices on the faunal environment (food availability and physical condition) to understand the impacts of organic management and the role of fauna in N mineralisation.  相似文献   

Focused identification of germplasm strategy (FIGS) detects wheat stem rust resistance linked to environmental variables     

Abdallah Bari  Kenneth Street  Michael Mackay  Dag Terje Filip Endresen  Eddy De Pauw  Ahmed Amri 《Genetic Resources and Crop Evolution》2012,59(7):1465-1481

Recent studies have shown that novel genetic variation for resistance to pests and diseases can be detected in plant genetic resources originating from locations with an environmental profile similar to the collection sites of a reference set of accessions with known resistance, based on the Focused Identification of Germplasm Strategy (FIGS) approach. FIGS combines both the development of a priori information based on the quantification of the trait-environment relationship and the use of this information to define a best bet subset of accessions with a higher probability of containing new variation for the sought after trait(s). The present study investigates the development strategy of the a priori information using different modeling techniques including learning-based techniques as a follow up to previous work where parametric approaches were used to quantify the stem rust resistance and climate variables relationship. The results show that the predictive power, derived from the accuracy parameters and cross-validation, varies depending on whether the models are based on linear or non-linear approaches. The prediction based on learning techniques are relatively higher indicating that the non-linear approaches, in particular support vector machine and neural networks, outperform both principal component logistic regression and generalized partial least squares. Overall there are indications that the trait distribution of resistance to stem rust is confined to certain environments or areas, whereas the susceptible types appear to be limited to other areas with some degree of overlapping of the two classes. The results also point to a number of issues to consider for improving the predictive performance of the models.  相似文献