Greenhouses climate modelling. Tests, adaptation and validation of a dynamic climate model [Modelado del clima de los invernaderos. Experimentación, adaptación y validación de un modelo climático dinámico]
Baptista F.J.,University of Évora |
Bailey B.J.,Silsoe Research Institute |
Meneses J.F.,University of Lisbon |
Navas L.M.,University of Valladolid
Spanish Journal of Agricultural Research | Year: 2010
Most greenhouse climate models are specific for a particular combination of greenhouse type, crop, region and weather conditions. Models are formulated and validated for those conditions and it is not easy to directly extrapolate them to other, different conditions. In order to use them the coefficients need to be calibrated by experimental work, followed by validation of the adapted model. The main purpose of this work was the application of a formal dynamic climate model, defined and validated for heated greenhouses in continental regions of Spain, to non heated greenhouses in a mild winter region at the coast of Portugal. The original model was tested, adapted and validated so it simulated the microclimate inside unheated greenhouses. The methodology used enabled the problems to be identified, the model to be modified in a systematic way and then re-run to determine the improved performance. The new model includes new properties for some boundary components and sub-models for ventilation and stomatal resistance applicable to this greenhouse-crop system and new expressions for the convection heat transfer coefficients. In the validation process predicted and measured variables were compared graphically to show trends in the data and by using statistical parameters to characterise model performance. The model was validated with data representing different weather, ventilation operation and tomato crop conditions. Good agreement between predicted and measured data was obtained. It has been proved that this model can be used to estimate the greenhouse climate conditions, based on the weather conditions and on the greenhouse-crop system characteristics.
Benjamin L.R.,Rothamsted Research |
Milne A.E.,Rothamsted Research |
Milne A.E.,Silsoe Research Institute |
Parsons D.J.,Cranfield University |
Lutman P.J.W.,Rothamsted Research
Crop Protection | Year: 2010
The 'within-season' module of the Weed Manager decision support system (DSS) predicts the effect of twelve UK arable weeds on winter wheat yields and profitability. The model and decision algorithm that underpin the DSS are described and their performance discussed. The model comprises: (i) seedling germination and emergence, (ii) early growth, (iii) phenological development, (iv) herbicide and cultivation effects and (v) crop yield loss. Crop and weed emergence are predicted from the timing and method of cultivation, species biology, and the weather. Wheat and weeds compete for resources, and yield losses are predicted from their relative leaf area at canopy closure. Herbicides and cultural control methods reduce weed green area index, improving crop yield. A decision algorithm identifies economically successful weed management strategies based on model output. The output of the Weed Manager model and decision algorithm was extensively validated by experts, who confirmed the predicted responses to herbicide application were sufficiently accurate for practical use. Limited independent data were also used in the validation. The development of the module required integrating novel and existing approaches for simulating weed seedling establishment, plant development and decision algorithm design. Combining these within Weed Manager created a framework suitable for commercial use. © 2010.
Earley B.,Teagasc |
Prendiville D.J.,Teagasc |
Lowe J.,Silsoe Research Institute |
Spahr C.,Innotek Inc. |
Kettlewell P.,Silsoe Research Institute
Precision Livestock Farming 2015 - Papers Presented at the 7th European Conference on Precision Livestock Farming, ECPLF 2015 | Year: 2015
The study objective was to compare three methods of measuring body temperature in the bovine. The methods used were (a) rumen bolus (b) tympanic logger and (c) rectal thermometer. Cow TempTM rumen bolus (Innotek) was used to monitor deep body temperature. The boluses were administered orally to eight Charolais × steers (mean body weight 500 (± 24) kg. The steers were housed in a slatted floor shed at a space allowance of 3 m2/head and fed silage ad libitum and 6 kg of concentrates/head daily. Telemetry transmitters (T) were inserted into the left ear of the same eight steers and temperatures were recorded during the same 5-day period. Rectal temperatures (R) were taken every hour over the same period using a digital thermometer (Jorgen Kruuse A/S. Model VT-801BWC Lot No 0701). The steers remained in their pens during the period of temperature recording. On days 1, 4 and 5 the B temperature measurements were greater than the R or T (P < 0.05). The average temperatures recorded over the 5-day period for B, R and T were 39.0 °C, 38.4 °C and 38.2 °C, respectively. There was no difference between R and T (P > 0.05). The overall correlation coefficients for B and R were 0.34, B and T 0.65 and R and T 0.80. Rumen boluses are an efficient method of transmitting body temperatures in cattle. Body temperature can be logged from the ear in cattle fitted with a telemetric tympanic membrane sensor. Both methods require further refinement of the technology to allow them to be used routinely.
Sugnaseelan S.,University of Cambridge |
Sugnaseelan S.,Silsoe Research Institute |
Prescott N.B.,Silsoe Research Institute |
Broom D.M.,University of Cambridge |
And 2 more authors.
Applied Animal Behaviour Science | Year: 2013
Visual acuity is an important component of environmental recognition in sheep, yet knowledge about it is limited in this or other herbivorous species. We tested the ability of British Friesland × Texel female lambs to discriminate black and white square-wave gratings, presented vertically or horizontally, from a grey stimulus. Animal and environmental conditions were optimised for detection of visual acuity. Sheep could rapidly learn to discriminate some gratings from a grey stimulus. There was no difference in the ability of sheep to discriminate vertical or horizontal stimuli from a grey stimulus. Visual acuity, determined at between 11.7 and 14.0. cycles/degree, was greater than that previously predicted from anatomical measurements (7-10 cycles/degree), and considerably greater than that measured for sheep by the Landoldt C ring technique (2.6-5.7 cycles/degree). It was also greater than that measured previously in most research using ungulates and other herbivores, with a variety of techniques. It is concluded that sheep visual acuity is potentially greater than hitherto realised, but that standardisation of techniques is required to make accurate comparisons with data gathered previously. Additionally, the ability to gauge an animal's awareness and its response(s) to various visual optotypes in its macro-environment will enable us to design livestock housing, handling and transport facilities that promote animal welfare. © 2013 Elsevier B.V.
PubMed | Silsoe Research Institute
Type: Journal Article | Journal: Meat science | Year: 2011
The effectiveness of current electrical stunning systems for pigs is discussed and the need for improvements in the design and construction of stunning tongs and electrodes are explored. A review of existing stunning tong electrodes for use with free standing or restrained pig is discussed. The potential problems with existing systems are highlighted as: (1) the profile of the pigs head precludes the application of existing electrodes in the correct position; (2) the small area of contact enhances carbon build-up which increases electrical impedance; (3) the electrodes are easily tarnished with few cleaning tools provided. Good tong positions that span the brain are described as between the eye and ear on each side of the head, below the ear on each side of the head or, diagonal application between the top and bottom of the head. The notional contact impedance is the major component of resistance to current flow within the stunning system. The proposed use of different electrode designs and constructional material is investigated. The effect of the introduction of the fail-safe device would be to heighten the interest in contact impedance within the plant and that could ensure that the investigation of different electrodes is explored at least at plant level.