Search

The progress of a project aimed at developing a decision support system (DSS) for overall welfare assessment is described. We chose the pregnant sow as a 'case' to develop the assessment method. First, we designed and tested a very simple prototype DSS in order to examine several basic ideas as to how welfare can be assessed on a scientific basis. In this prototype welfare assessment was based on the needs of animals. The second version of the DSS, which extended the approach taken in the first, included a wider range of housing systems and an improved knowledge base. It used a rigid formal procedure to construct the model, moving directly from scientific statements into if-then rules. However, this extended version resulted in counter-intuitive scores for the seven main housing systems for pregnant sows. In the third version of the DSS the complexity of the model was reduced, if-then rules being excluded. It was based on more general biological considerations (needs and sub-needs) and produced scores which accorded better with expert opinion. Weighting was managed in a simplified, but procedural way. For improved welfare assessment we suggest that the method of 'reflective equilibrium' should be used

In the framework of the EC-funded AIR-project Objective plant quality measurement by digital image processing taking images each three weeks during more than nine months follows the development of Ficus benjamina plants. From these images a large number of features is extracted and a relation is laid between these features and the external quality by using neural networks. A segmentation procedure for classifying the pixels into object pixel (plant) and non-object pixels (background) has to be used before feature extraction. Segmentation procedures based on thresholding depend on the specific threshold that is used, especially when the transition between object and background follows a ramp instead of a step andlor the intensity of the object andlor background is not constant for the whole image. Improved versions of MAX-MIN filters for edge enhancement are less noise sensitive than other filters for edge enhancement as for example a Laplace operator. The same feature extraction procedures are applied to images with different illumination levels and that have or have not been enhanced by improved MAX-MIN filtering. The influence of image enhancement by improved MAX-MIN-filtering on the segmentation of images and consequently on the feature values will be discussed.

We investigated the hypothesis that manipulating water out-flow of a plant through the shoot environment (potential transpiration, ET0) in a glasshouse could modulate the effect of salinity/osmotic potential in the root environment upon yield of tomatoes. Contrasting root-zone salinity treatments were combined with two climate treatments –– a reference (high transpiration, HET0) and a "depressed" transpiration (low transpiration, LET0). The salinity treatments, characterised by their electrical conductivity (EC) were 6.5, 8 and 9.5 dS m-1, were always coupled with a reference treatment of EC=2 dS m-1. In another experiment, concentrated nutrients (Nutrients) and nutrients with sodium chloride (NaCl) at the same EC of 9 dS m-1 were compared. Marketable fresh-yield production efficiency decreased by 5.1 or each dS m-1 in excess of 2 dS m-1. The number of harvested fruits was not affected; yield loss resulted from reduced fruit weight (3.8 er dS m-1) and an increased fraction of unmarketable harvest. At the LET0 treatments, yield loss was only 3.4 er dS m-1 in accordance with the reduction in fruit weight. Low transpiration did increase fruit fresh yield by 8 n both NaCl and Nutrients treatments at an EC=9 dS m-1. Neither EC nor ET0 affected individual fruit dry weight. Accordingly, fruit dry matter content was significantly higher at high EC than in the reference (4 er each EC unit in excess of 2 dS m-1) and responded to ET0 to a minor extent. Control of the shoot environment in a greenhouse to manipulate the fresh weight of the product may mitigate the effects of poor quality irrigation water without affecting product quality.

De legsector heeft al veel slagen gemaakt op het gebied van maatschappelijke acceptatie. Het project Well-Fair Egg wil nog een stap verder. De ambitie van het project Well-Fair Eggs is om een welzijns- en milieuvriendelijke houderij en productie van eieren te ontwerpen, die op het vlak van eikwaliteit voldoet aan de eisen van de afnemers van eiproducten en qua kostprijs kan concurreren met kooisystemen. Door daarbij de wensen en eisen van ‘pragmatische consumenten’ (circa 35% van de Nederlanders) te gebruiken, kunnen de eieren ook verantwoord worden afgezet op de markt voor tafeleieren

An algorithmic approach to computer-aided simulation is used to optimise the design of the shed. The shed contains individual stalls (2) and a passage (3) leading to feeding troughs (4). Water troughs (5,6,7) are provided. There are automatic supplementary feeding stations (8,9,10), two of which contain milk robots (11,12). Cows can be brought in at fixed times for milking or they can themselves choose when to be milked, day or night, depending on their own biological clocks or herd instincts.

Maatschappelijk verantwoord ondernemen in de varkenshouderij

Er wordt met name ingegaan op de extra mechanisatiekosten en de extra arbeid bij agrarisch natuurbeheer

This thesis discusses automated support for operational management of greenhouse crops and proposes a knowledge-based system to support the grower in his operational management task.Operational management is defined as the day-to-day decision making processes which directly or indirectly lead to activities that influence the growth and development of the crop. To improve automated support for operational management, the growers operational decision making has been analyzed in the light of theory related to problem solving. The analysis of the task environment has resulted in a model of the decision processes within operational crop production management. This model has been based on the intelligence - design - choice cycle of Simon (1997). During the design and choice phases of this model the grower has to convert his observations at the crop and environment level into actions that can be implemented at the control level. Since this conversion is considered a complex and knowledge intensive task, a knowledge-based system is proposed to support the grower. The main idea behind the approach is to allow the grower to tell the system what objectives it must pursue and have the system deduce the required device settings at the control level. As these objectives may be situated at the crop, environment and control level, both domain knowledge as well as a suitable inference mechanism is required to realize such an approach.Analysis of the knowledge in the domain of crop production shows that this knowledge is, or can be made available. Regarding the latter, the Blossom-end Rot example shows that knowledge can be made available in a suitable format.With respect to the inference mechanism past approaches have been surveyed. Based on the results of this survey, the characteristics of the inference problem, and the attributes of the domain knowledge, it has been concluded that constraint reasoning fits the requirements best.Simulation experiments with a prototype implementation show that the constraint reasoning can indeed be used as inference mechanism, however it is argued that the amount of work needed to realize and implementation in practice is formidable.

This thesis discusses automated support for operational management of greenhouse crops and proposes a knowledge-based system to support the grower in his operational management task.Operational management is defined as the day-to-day decision making processes which directly or indirectly lead to activities that influence the growth and development of the crop. To improve automated support for operational management, the growers operational decision making has been analyzed in the light of theory related to problem solving. The analysis of the task environment has resulted in a model of the decision processes within operational crop production management. This model has been based on the intelligence - design - choice cycle of Simon (1997). During the design and choice phases of this model the grower has to convert his observations at the crop and environment level into actions that can be implemented at the control level. Since this conversion is considered a complex and knowledge intensive task, a knowledge-based system is proposed to support the grower. The main idea behind the approach is to allow the grower to tell the system what objectives it must pursue and have the system deduce the required device settings at the control level. As these objectives may be situated at the crop, environment and control level, both domain knowledge as well as a suitable inference mechanism is required to realize such an approach.Analysis of the knowledge in the domain of crop production shows that this knowledge is, or can be made available. Regarding the latter, the Blossom-end Rot example shows that knowledge can be made available in a suitable format.With respect to the inference mechanism past approaches have been surveyed. Based on the results of this survey, the characteristics of the inference problem, and the attributes of the domain knowledge, it has been concluded that constraint reasoning fits the requirements best.Simulation experiments with a prototype implementation show that the constraint reasoning can indeed be used as inference mechanism, however it is argued that the amount of work needed to realize and implementation in practice is formidable.

Theoretically, using information about crop growth would allow the extension of present greenhouse control strategies towards a truly economic optimal control strategy. A brief survey is given of developments in the scientific literature. A full solution would require to consider the long-term crop development as well as all relevant short-term dynamics of the crop, the greenhouse and the external weather. Obstacles for the acceptance of such solutions are briefly discussed. One of the key factors is the lack of reliable crop development models for the wide variety of crops encountered in practice, and the need to leave part of the decision freedom in the hands of the grower. An analysis is given of simplified approaches resulting from integrating the crop equations over a day or more. The temperature integral concept, a specific example of such approach, is gaining popularity, despite the fact that it lacks exploitation of knowledge about the fast crop responses. The discussion leads to the concept of separation of responsibilities, where the short-term effects, including photosynthesis and evapo-transpiration, are handled by an automated model-predictive optimal controller, while the long-term effects are left to the grower, with support from a flexible decision support system based on crop models whenever they become available.

Since the mid 1970s substrate growing has become popular in the greenhouse industry in The Netherlands. Because of the small rooting volumes that are used in substrate growing, such systems require an accurate fertilization, but at the same time they offer possibilities for precise control and management of the conditions in the root environment.The osmotic potential of the substrate solution in the root environment is often used for improvement of the quality of the produce. For adequate management of the osmotic potential, firstly information about the absorption of water and ions by the crop is essential. Secondly, the effect of the osmotic potential and its interaction with climatic conditions in the greenhouse on crop development must be known. Thirdly, information on the spatial distribution of water and ions in the root environment should be available, because this may strongly affect salinity effects on plants.In studies on effects of low osmotic potentials on crops, both osmotic and specific ion effects should be distinguished. The osmotic effects predominate for most crops and growing conditions. Osmotic effects can be described according to the model developed by Maas and Hoffman. This model is characterized by two parameters, the salinity threshold value and the salinity yield decrease value. In this simple model the EC caused by nutrients is not taken into account separately, though nutrients have a significant effect on the EC of the substrate solution in greenhouse cultivation. So the model needs adjustment for the contribution of nutrients to the EC. Furthermore, effects of EC variations in time and space have been described.Fruit vegetables and cut flowers were used as test crops in experiments with different EC values in the root environment. Comparisons were made between EC effects caused by NaCl and by nutrients. Yield of tomato, cucumber, and sweet pepper were reduced at increasing EC, but most fruit quality characteristics were favourably affected. Blossom-end rot, however, increased with increasing EC. For sweet pepper this was especially the case after NaCl addition. Salinity threshold values for the vegetable crops varied between 2.3 and 3.5 dS m -1and relative salinity yield decrease values between 2.3 and 7.6 % per dS m -1. The flower weigths of gerbera, carnation, rose, aster, bouvardia and lily were negatively affected by increasing EC. Salinity threshold values ranged from 1.1 to 4.3 dS m -1and salinity yield decrease values varied between 2.1 and 16.8% per dS m -1. For aster such parameters could not be obtained, because the highest EC of 4.2 dS m -1did not affect production. However, the regrowth of this crop after the first harvest was specifically strongly hindered by NaCl. Bouvardia also exhibited a specific sensitivity to NaCl. This effect was studied in more detail to obtain information about which ion, either Na or Cl, was responsible for this effect. The results showed that bouvardia was specifically sensitive to Na.The response of tomato and cucumber to an unequal distribution of nutrients and NaCl in the root environment was studied with plants grown in a split-root system. Tomato yield was determined by the EC value considered optimal for production if present in one of the rockwool cubes, despite the fact that the EC in the other cube was up to 10 dS m -1. Tomato absorbed water preferably from the root part with the lowest EC and nutrients from the root part with the highest EC. When the EC in the root parts was raised by nutrients from low to standard values, the nutrient uptake by cucumber was highest from the parts with the highest concentration. In root parts with concentrations of nutrients > 4 dS m -1the uptake decreased strongly. Nutrient uptake from one root part with high NaCl was also reduced when the NaCl concentration in the other part was low. When both root parts had high NaCl concentrations the plant was able to take up adequate amounts of nutrients. Like tomato, cucumber absorbed water preferably from the root part with the lowest EC. In case no nutrients were supplied in one root part, the water uptake from that root part was reduced.Interactions between salinity effects and climatic conditions and effects of temporal variation of salinity were studied with tomato as the test crop. High EC under low light conditions did not affect yields. In spring and summer yield reductions between 5 and 7 % per dS m -1were found. In one experiment at very high humidity the yield reduction was about 10 % per dS m -1. This was in contradiction with the nature of the interaction between salinity and climate in other studies. Obviously the calcium status of the plant had played a dominant role in this experiment. From the experiments with temporal variation of EC it could be concluded that for estimation of the yield reduction not only the lengths of the EC-intervals and the EC-level during the interval but also the light intensity during the interval has to be taken into account.The management of salinity in relation to nutrient supply was discussed. Nutrient absorption of greenhouse crops was studied by determining the total nutrient uptake and the nutrient uptake in relation to the water absorption (the so-called uptake concentrations). The widely published very low external concentrations to achieve optimal yields, are not realistic because of the high flow rate necessary to adequately supply crops with nutrients. External nutrient concentrations corresponding with 1.5 dS m -1are required for sufficient nutrient supply to greenhouse crops.Required and acceptable external concentrations were defined considering the following aspects. Required external concentrations should not exclusively be related to a sufficient supply of nutrients in order to attain maximum growth or yield, but also to quality demands of the market. Acceptable concentrations should be considered with respect to maximum accumulation of residual ions to a level that does not negatively affect crop production and quality. In this way leaching and thus environmental pollution is minimized.In the assessment of required and acceptable concentrations osmotic and specific ion effects should be clearly distinguished. When no specific ion effects occur, the "space" between the nutrient concentration required for maximal production and the required concentration with respect to the produce quality or the acceptable concentration with respect to maximum salt accumulation can be filled up with any ion available in the system. With specific ion sensitivities the accumulation is restricted by the critical non toxic level to the crop.Required and acceptable concentrations of ions strongly depend on crop and growing conditions. Under cool and humid growing conditions, use of drip irrigation, and CO 2 supply, EC-values in the substrate solution between 3 and 6 dS m -1seem to be realistic. Such conditions can be realised in greenhouses in North-West Europe from autumn until early spring. For summer conditions the EC-values suggested in this study between 1.5 and 3.0 dS m -1are more realistic. In the interpretation of EC-values more credit should be given to the consequences of spatial distribution of ions in the substrate. The stable equilibrium established between low and high concentrated spots in the systems, offers excellent possibilities for an osmotic escape by plants. The discussion is concluded with some calculations of environmental pollution as a consequence of different management strategies of irrigation and drain-off.

This work deals with the yield loss caused by saline irrigation water in greenhouse tomato cultivation, and the way climate manipulation may be used to limit damage. The hypothesis is that by "controlling" the evaporative demand of the ambient, it is possible to manipulate plant water status, in order to restore the balance distorted by high salinity (osmotic pressure) in the root environment. The scientific aim of this work is to explain the interaction between water inflow (root environment) and water outflow (shoot environment) in determining crop fresh yield.The results are presented of a series of long-term experiments with commercially-grown greenhouse tomato. A constant ratio was maintained between a "high" and a "low" potential transpiration (ET 0 ), combined with a "high" and a "low" concentration of salt in the nutrient solution (EC), in the range between 2 and 9.5 dSm -1 . Neither EC nor ET 0 had effect on the number of harvested fruits or on dry weight of individual fruits, whereas EC affected water content of fruits. Marketable fresh-yield production-efficiency decreased linearly with increasing EC of the nutrient solution. Yield decrease (5.1% per dSm -1 ) at high transpiration resulted from reduced weight of individual fruits (3.8% per dSm -1 ) and an increased fraction of unmarketable fruits (mainly caused by blossom-end rot). For the low transpiration treatment, however, yield loss was 3.4 % per dSm -1 , fully accounted for by the reduction in fruit weight. The lack of effect of either treatment upon dry matter production is explained by the observation that individual leaf area was reduced (8% per dSm -1 ) only at EC exceeding 6.5 dSm -1 ; and that the number of leaves produced by each plant was increased by EC (2% per dSm -1 ). The reduction of fruit size at high EC was mainly caused by a smaller fruit growth rate, in particular during the cell-expansion phase, and a slightly shorter duration of growth. There was no effect of transpiration on fruit growth rate at 2 dSm -1 , but a significant negative effect at higher EC. The limitation of growth by high EC was shown to be reversible in an experiment whereby the EC of the nutrient solution was lowered after a 5-month 9 dSm -1 treatment. Size of harvested fruits increased gradually, until fruits that had developed fully under the new EC condition, reached a "normal" volume. Similarly, leaves that were already expanded at the moment of lowering EC did not respond to the change in EC, but "new" leaves did.Water uptake per unit leaf area was not affected by osmotic potential of the nutrient solution. The hydraulic resistance within the plant (deduced from measurements of the water potential of the leaf and the stem) was independent of the transpiration flow and was not affected by the osmotic potential of the nutrient solution. The stem water potential was shown to react similarly to a decrease of water potential of the nutrient solution (higher salt concentration) and to an increase in water outflow (transpiration) from the leaves. Since the water potential of the fruits responded weakly to variations in both root and shoot environment, water transport into fruits was regulated mainly by the water potential of the stem.It is concluded that modern greenhouse management offers an opportunity to optimise environmental conditions in relation to root zone salinity, and that the principle of transpiration control developed here, gives a blueprint for climate control when dealing with high EC in the nutrient solution.Key words : salinity, EC, osmotic potential, soilless cultivation, potential evaporation, ET 0 , transpiration, humidity, greenhouse climate, water uptake, water potential, water relation, tomato, Lycopersicon esculentum , fruit weight, fruit size, growth rate, maturation, leaf area index (LAI), vegetative growth, yield, quality, cracking

The effects of some significant factors on the flow of fertilizers through orifices, such as orifice diameter, orifice shape, particle diameter, fertilizer type, air temperature, and air relative humidity were investigated. The effect of air temperature on the flow rate was small as the effects of the other factors were significant.

This study focuses on the environmental impact of agricultural production. The aim of the study is to identify the most important sources of greenhouse gases, acidifying and eutrophying compounds in Tomato Cultivation, Greenhouse Horticulture and Total Agriculture in The Netherlands. Within each of these three sectors we distinguish two systems. The System Agriculture (System A) includes the first-order processes of the agricultural production chain and the System Industry (System I) includes some second-order processes. Results indicate that, in general, System A emissions exceed System I emissions. However, in some cases emissions from System I are relatively high compared to System A emissions, and need to be considered when quantifying the total environmental impact of agricultural production. For example, acidifying emissions from the production of electricity and rockwool (both second-order processes) contribute almost 25% to the total acidifying emissions from System Greenhouse Horticulture A+I.

Miscanthus is a tall perennial rhizomatous grass with C4 photosynthesis which originated in East Asia. This article provides an overview of the most important results and experience gained with miscanthus in Europe over the past 10 years. Field trials have been established throughout Europe from the Mediterranean to southern Scandinavia. Most reported trials have used a vigorous sterile clone Miscanthus x giganteus, which has been propagated vegetatively either by rhizome cutting or in vitro culture. Yields in autumn have been reported in excess of 30 t ha−1 (12 t acre−1) for irrigated trials in southern Europe. Without irrigation autumn yields of 10–25 t ha−1 (dry matter) can be expected. The quality of miscanthus biomass for combustion is in some respect comparable to woody biomass and normally improves by delaying harvesting until the spring, although harvestable yields are thus reduced by 30–50% compared with autumn yields. Different technical options for establishment, harvesting and handling of miscanthus have been developed and these significantly effect production costs. Miscanthus production is characterized by low fertilizer and pesticide requirements making it a relatively benign crop environmentally. The main limitations to miscanthus production from M. x giganteus are the high establishment costs, poor over-wintering at some sites and insufficient water supply in southern regions of Europe. New agronomic techniques and new genotypes with improved characteristics are being developed and screened over the wide range of ecological conditions in Europe. Against this background of European experience the prospects for growing miscanthus in North America are discussed.

Since the mid 1970s substrate growing has become popular in the greenhouse industry in The Netherlands. Because of the small rooting volumes that are used in substrate growing, such systems require an accurate fertilization, but at the same time they offer possibilities for precise control and management of the conditions in the root environment.The osmotic potential of the substrate solution in the root environment is often used for improvement of the quality of the produce. For adequate management of the osmotic potential, firstly information about the absorption of water and ions by the crop is essential. Secondly, the effect of the osmotic potential and its interaction with climatic conditions in the greenhouse on crop development must be known. Thirdly, information on the spatial distribution of water and ions in the root environment should be available, because this may strongly affect salinity effects on plants.In studies on effects of low osmotic potentials on crops, both osmotic and specific ion effects should be distinguished. The osmotic effects predominate for most crops and growing conditions. Osmotic effects can be described according to the model developed by Maas and Hoffman. This model is characterized by two parameters, the salinity threshold value and the salinity yield decrease value. In this simple model the EC caused by nutrients is not taken into account separately, though nutrients have a significant effect on the EC of the substrate solution in greenhouse cultivation. So the model needs adjustment for the contribution of nutrients to the EC. Furthermore, effects of EC variations in time and space have been described.Fruit vegetables and cut flowers were used as test crops in experiments with different EC values in the root environment. Comparisons were made between EC effects caused by NaCl and by nutrients. Yield of tomato, cucumber, and sweet pepper were reduced at increasing EC, but most fruit quality characteristics were favourably affected. Blossom-end rot, however, increased with increasing EC. For sweet pepper this was especially the case after NaCl addition. Salinity threshold values for the vegetable crops varied between 2.3 and 3.5 dS m -1and relative salinity yield decrease values between 2.3 and 7.6 % per dS m -1. The flower weigths of gerbera, carnation, rose, aster, bouvardia and lily were negatively affected by increasing EC. Salinity threshold values ranged from 1.1 to 4.3 dS m -1and salinity yield decrease values varied between 2.1 and 16.8% per dS m -1. For aster such parameters could not be obtained, because the highest EC of 4.2 dS m -1did not affect production. However, the regrowth of this crop after the first harvest was specifically strongly hindered by NaCl. Bouvardia also exhibited a specific sensitivity to NaCl. This effect was studied in more detail to obtain information about which ion, either Na or Cl, was responsible for this effect. The results showed that bouvardia was specifically sensitive to Na.The response of tomato and cucumber to an unequal distribution of nutrients and NaCl in the root environment was studied with plants grown in a split-root system. Tomato yield was determined by the EC value considered optimal for production if present in one of the rockwool cubes, despite the fact that the EC in the other cube was up to 10 dS m -1. Tomato absorbed water preferably from the root part with the lowest EC and nutrients from the root part with the highest EC. When the EC in the root parts was raised by nutrients from low to standard values, the nutrient uptake by cucumber was highest from the parts with the highest concentration. In root parts with concentrations of nutrients > 4 dS m -1the uptake decreased strongly. Nutrient uptake from one root part with high NaCl was also reduced when the NaCl concentration in the other part was low. When both root parts had high NaCl concentrations the plant was able to take up adequate amounts of nutrients. Like tomato, cucumber absorbed water preferably from the root part with the lowest EC. In case no nutrients were supplied in one root part, the water uptake from that root part was reduced.Interactions between salinity effects and climatic conditions and effects of temporal variation of salinity were studied with tomato as the test crop. High EC under low light conditions did not affect yields. In spring and summer yield reductions between 5 and 7 % per dS m -1were found. In one experiment at very high humidity the yield reduction was about 10 % per dS m -1. This was in contradiction with the nature of the interaction between salinity and climate in other studies. Obviously the calcium status of the plant had played a dominant role in this experiment. From the experiments with temporal variation of EC it could be concluded that for estimation of the yield reduction not only the lengths of the EC-intervals and the EC-level during the interval but also the light intensity during the interval has to be taken into account.The management of salinity in relation to nutrient supply was discussed. Nutrient absorption of greenhouse crops was studied by determining the total nutrient uptake and the nutrient uptake in relation to the water absorption (the so-called uptake concentrations). The widely published very low external concentrations to achieve optimal yields, are not realistic because of the high flow rate necessary to adequately supply crops with nutrients. External nutrient concentrations corresponding with 1.5 dS m -1are required for sufficient nutrient supply to greenhouse crops.Required and acceptable external concentrations were defined considering the following aspects. Required external concentrations should not exclusively be related to a sufficient supply of nutrients in order to attain maximum growth or yield, but also to quality demands of the market. Acceptable concentrations should be considered with respect to maximum accumulation of residual ions to a level that does not negatively affect crop production and quality. In this way leaching and thus environmental pollution is minimized.In the assessment of required and acceptable concentrations osmotic and specific ion effects should be clearly distinguished. When no specific ion effects occur, the "space" between the nutrient concentration required for maximal production and the required concentration with respect to the produce quality or the acceptable concentration with respect to maximum salt accumulation can be filled up with any ion available in the system. With specific ion sensitivities the accumulation is restricted by the critical non toxic level to the crop.Required and acceptable concentrations of ions strongly depend on crop and growing conditions. Under cool and humid growing conditions, use of drip irrigation, and CO 2 supply, EC-values in the substrate solution between 3 and 6 dS m -1seem to be realistic. Such conditions can be realised in greenhouses in North-West Europe from autumn until early spring. For summer conditions the EC-values suggested in this study between 1.5 and 3.0 dS m -1are more realistic. In the interpretation of EC-values more credit should be given to the consequences of spatial distribution of ions in the substrate. The stable equilibrium established between low and high concentrated spots in the systems, offers excellent possibilities for an osmotic escape by plants. The discussion is concluded with some calculations of environmental pollution as a consequence of different management strategies of irrigation and drain-off.

This work deals with the yield loss caused by saline irrigation water in greenhouse tomato cultivation, and the way climate manipulation may be used to limit damage. The hypothesis is that by "controlling" the evaporative demand of the ambient, it is possible to manipulate plant water status, in order to restore the balance distorted by high salinity (osmotic pressure) in the root environment. The scientific aim of this work is to explain the interaction between water inflow (root environment) and water outflow (shoot environment) in determining crop fresh yield.The results are presented of a series of long-term experiments with commercially-grown greenhouse tomato. A constant ratio was maintained between a "high" and a "low" potential transpiration (ET 0 ), combined with a "high" and a "low" concentration of salt in the nutrient solution (EC), in the range between 2 and 9.5 dSm -1 . Neither EC nor ET 0 had effect on the number of harvested fruits or on dry weight of individual fruits, whereas EC affected water content of fruits. Marketable fresh-yield production-efficiency decreased linearly with increasing EC of the nutrient solution. Yield decrease (5.1% per dSm -1 ) at high transpiration resulted from reduced weight of individual fruits (3.8% per dSm -1 ) and an increased fraction of unmarketable fruits (mainly caused by blossom-end rot). For the low transpiration treatment, however, yield loss was 3.4 % per dSm -1 , fully accounted for by the reduction in fruit weight. The lack of effect of either treatment upon dry matter production is explained by the observation that individual leaf area was reduced (8% per dSm -1 ) only at EC exceeding 6.5 dSm -1 ; and that the number of leaves produced by each plant was increased by EC (2% per dSm -1 ). The reduction of fruit size at high EC was mainly caused by a smaller fruit growth rate, in particular during the cell-expansion phase, and a slightly shorter duration of growth. There was no effect of transpiration on fruit growth rate at 2 dSm -1 , but a significant negative effect at higher EC. The limitation of growth by high EC was shown to be reversible in an experiment whereby the EC of the nutrient solution was lowered after a 5-month 9 dSm -1 treatment. Size of harvested fruits increased gradually, until fruits that had developed fully under the new EC condition, reached a "normal" volume. Similarly, leaves that were already expanded at the moment of lowering EC did not respond to the change in EC, but "new" leaves did.Water uptake per unit leaf area was not affected by osmotic potential of the nutrient solution. The hydraulic resistance within the plant (deduced from measurements of the water potential of the leaf and the stem) was independent of the transpiration flow and was not affected by the osmotic potential of the nutrient solution. The stem water potential was shown to react similarly to a decrease of water potential of the nutrient solution (higher salt concentration) and to an increase in water outflow (transpiration) from the leaves. Since the water potential of the fruits responded weakly to variations in both root and shoot environment, water transport into fruits was regulated mainly by the water potential of the stem.It is concluded that modern greenhouse management offers an opportunity to optimise environmental conditions in relation to root zone salinity, and that the principle of transpiration control developed here, gives a blueprint for climate control when dealing with high EC in the nutrient solution.Key words : salinity, EC, osmotic potential, soilless cultivation, potential evaporation, ET 0 , transpiration, humidity, greenhouse climate, water uptake, water potential, water relation, tomato, Lycopersicon esculentum , fruit weight, fruit size, growth rate, maturation, leaf area index (LAI), vegetative growth, yield, quality, cracking

Bijdrage aan de KNPV-voorjaarsvergadering

Voor het welzijn van de koe zijn bepalend: aantal ligplaatsen, kwaliteit van het voer, negatieve prikkels uit de omgeving, de aard van de vloer en keuzevrijheid. Dit moeten de 5 belangrijkste kenmerken zijn van een melkveehouderijsysteem. Dat stelt de Animal Sciences Group op basis van een model dat is gebaseerd op een literatuurstudie in het kader van het LNV-project Kracht van Koeien ter stimulering van duurzame melkveehouderij

ASG ontwerpt baanbrekende houderijsystemen voor de melkveehouderij – het betreft stallen inclusief de belangrijke schakels in de keten, zoals de aanvoer van krachtvoer en kunstmest. Dit in opdracht van LNV. Het project kreeg de naam Kracht van Koeien. De onderzoekers bouwden onlangs een rekenmodel (Cowel) om de risico- of welzijnsscore van stalsystemen te bepalen

In the scientific literature several attempts have been made to systematically assess the overall welfare-status of animals in relation to housing and management. This paper reviews assessment tables and schemes that have been constructed to this end. These tables and schemes have a tabular format that allows an assessment of housing systems using a list of welfare-relevant attributes (properties of the housing system). Rather than identifying deficits, the focus of this review is on finding positive recommendations for the purpose of developing a method for overall welfare assessment (OWA) on a scientific basis. The main recommendation is to use the tabular format as representation formalism for OWA. The concept of linked tables provides the key to performing OWA on a scientific basis in an explicit and systematic way.

Several authors have concluded that scientists should not attempt to perform overall animal welfare assessment (OWA). They argue that scientists have continued to fail to make progress in this area and that value judgements are inherently involved in OWA for which science cannot provide answers. We take a more positive attitude toward OWA and argue that scientists should avoid creating a self-fulfilling prophecy. OWA is necessary for making actual moral and political decisions. Science has already accumulated much relevant information about welfare and this information should be applied in decision making. The task of OWA is to assess welfare based on knowledge of the biological needs of animals. Weighting of welfare relevant factors constitutes a problem. However, when scientists cannot provide empirical data to solve weighting issues, this does not mean that rational answers cannot be found, e.g. in the form of procedural rules. OWA is conceived as a problem of multi-criteria decision making with fuzzy information. If focuses on the descriptive aspect of welfare, i.e. on what the welfare status of the animals really is without taking an ethical stance. The welfare status of animals depends on their biology and on the way animals assess their own welfare. It does not depend on how it happens to be perceived by us. Even though OWA necessarily remains a human activity, it is not arbitrary, nor does it allow of multiple 'correct' answers. OWA is a descriptive activity that can achieve more and more accuracy as science proceeds.

Welfare concerns that matter to animals is their state of need. Satisfaction and frustration of needs are associated with emotional states, the subjective experience of which directly determines the welfare status of an animal. Because emotional states are difficult to assess, overall welfare assessment (OWA) is best approached as an assessment of needs. For actual OWA, a list of needs must be formulated. Different authors have formulated different lists. From these lists a concept need-list was constructed. For validation the needs-based approach for OWA was discussed in interviews with experts (n=21) in the field of ethology and other welfare related sciences. These experts generally used mental terminology to define welfare, but when asked to classify their definition of welfare, many preferred a definition in terms of measurable parameters or a combination of both mental terms (feelings) and measurables. Most experts believed that welfare can be assessed objectively and that the problem of OWA is indeed best approached through an assessment of needs. Experts differ as to the exact composition of the list of needs. A list of needs is formulated which we intend to use for OWA in the case of sows.

In 2004 werd de 1e fase van het project 'Houden van hennen' in Voorthuizen afgerond. Het project heeft als doel houderijsystemen voor leghennen te ontwikkelen, waarin rekening wordt gehouden met de wensen van dier, consument en pluimveehouder. Pluimveehouder Chris Borren bouwt nu als eerste een praktijkstal op de fundamenten van dit project. Het gaat om een opfok en legstal (waarvan hier dwarsdoorsnedes zijn gegeven) voor biologische leghennen

Pluimveehouders van de Scharrelclub Veluwe merkten een positieve kant op van de schadelijke piepschuimkever: bij een groeiende populatie neemt de overlast van de vogelmijt af. Zij vroegen Wageningen UR te onderzoeken hoe de piepschuimkever kan worden ingezet bij de vogelmijtbestrijding

Digital image processing (DIP) is a potential tool for measuring and classifying pot plants in various growth stages in an automatic, objective and consistent way, with a high capacity and low labour input. In this study, features of begonia cuttings which could be relevant for grading were analysed. Images of unrooted and rooted Begonia elatior [B. hiemalis] cuttings were acquired and analysed with DIP. The various parts of the cuttings were identified and measured using knowledge based image processing. These measurements were shown to be consistent and to be well correlated with the features measured in conventional ways. Experts graded the rooted cuttings into 3 classes: small, medium and large. The effect of grading unrooted cuttings and growing them with similar-sized cuttings was still apparent 4 weeks later - the rooted cuttings in graded units were more uniform than those in random units. Two models were constructed to determine the quality of the rooted cuttings based on DIP measurements, one based on multiple linear regression and one based on a neural network. Both were able to grade at least 75% of the rooted cuttings in the same class as the expert. The neural network-based model performed slightly (5%) better, especially for the classification of small and large plants. The lack of objective quality criteria is a major obstacle for the development of grading models for pot plants.