Mimicking indoor climate dynamics and ammonia emissions in a pig housing compartment using artificial pigs and an automatic urea spraying installation

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Assessing the Sensitivity and Uncertainty of an NH3 Emission Reduction Calculator for Dairy Cattle Barns by Means of Monte Carlo Analysis Combined with Least Square Linearization

With regard to Natura 2000, the Flemish government (Belgium) established the Programmatic Approach to Nitrogen (PAS: acronym in Flemish), with the aim of reducing environmental overload of nitrogen compounds. This approach will have substantial consequences for livestock farms located next to or within special areas of conservation and will likely result in generic measures to reduce ammonia (NH3) emissions from livestock facilities. An NH3 emission reduction calculator for dairy cattle systems (AEREC-DC) was adapted based on a mechanistic approach. Reduction coefficients estimated with this tool are used to assess the efficiency of “low NH3 emission” techniques which can be implemented in Flanders at a later stage. Field measurements will be made in the future to confirm/correct them. Emission reduction techniques combining processes such as floor scraping, flushing, manure acidification, and different types of floor were modeled. The tool comprises 36 input variables, some of which have values that are based on experimental measurements. Nevertheless, reliable information concerning other relevant variables are scarce in the literature. Hence, model sensitivity analysis is imperative. We hypothesize that the ranking of input variables in terms of their effect on the model outcome will change if different uncertainty ranges are assigned to them. Hence, this study was conducted to combine Monte Carlo Analysis associated with Least Square Linearization in order to perform sensitivity and uncertainty analyses on AEREC-DC. The sensitivity analysis was performed by assigning each input variables’ probability distribution function (PDF) with a relatively narrow variance (1% of mean value). The uncertainty analysis was carried out by gradually increasing the PDF’s variance up to what is considered realistic. The outcomes of this study will help deciding which variables urgently need to be monitored experimentally in order to improve predictions’ accuracy

Assessing airflow rates of a naturally ventilated test facility using a fast and simple algorithm supported by local air velocity measurements

The high spatial and temporal variations of airflow patterns in ventilation openings of naturally ventilated animal houses make it difficult to accurately measure the airflow rate. This paper focuses on the development of a fast assessment technique for the airflow rate of a naturally ventilated test facility through the combination of a linear algorithm and local air velocity measurements. This assessment technique was validated against detailed measurement results obtained by the measuring method of Van Overbeke et al. (2015) as a reference. The total air velocity |u-|, the normal |Y-| and tangential velocity component |x-| and the velocity vector u- measured at the meteomast were chosen as input variables for the linear algorithms. The airflow rates were split in a group where only uni-directional flows occurred at vent level (no opposite directions of |Y-| present in the airflow pattern of the opening), and a group where bi-directional flows occurred (the air goes simultaneously in and out of the opening). For airflow rates with uni-directional flows the input variables u- and |Y-| yielded the most accurate results. For this reason, it was suggested to use the |Y-| instead of |u-| in ASHRAE’s formula of Q = E × A × |u-|. For bi-directional flows a multiple linear model was suggested where input variable u- gave the best results to assess the airflow rate

Methodology for airflow rate measurements in a naturally ventilated mock-up animal building with side and ridge vents

Currently there exists no generally accepted reference technique to measure the ventilation rate through naturally ventilated (NV) vents. This has an impact on the reliability of airflow rate control techniques and emission rate measurements in NV animal houses. As an attempt to address this issue a NV test facility was built to develop new airflow rate measurement techniques for both side wall and ridge vents. Three set-ups were used that differed in vent configuration, i.e. one cross ventilated set-up and two ridge ventilated set-ups with different vent sizes. The airflow through the side vents was measured with a technique based on an automatic traverse movement of a 3D ultrasonic anemometer. In the ridge, 7 static 2D ultrasonic anemometers were installed. The methods were validated by applying the air mass conservation principle, i.e. the inflow rates must equal the outflow rates. The calculated in - and outflow rates agreed within (5 ± 8)%, (8 ± 5)% and (−9 ± 7)% for the three different set-ups respectively, over a large range of wind incidence angles. It was found that the side vent configuration was of large importance for the distribution of the airflow rates through the vents. The ridge proved to be a constant outlet, whilst side vents could change from outlet to inlet depending on the wind incidence angle. The range of wind incidence angles in which this transition occurred could be clearly visualised

Decision document on the revision of the VERA protocol on air cleaning technologies March

In the project “ICT-AGRI: Development of harmonized sampling and measurement methods for odour, ammonia and dust emissions” different subgroups have been formed focusing on either ammonia, odour or dust. In this report, the conclusions of the ammonia subgroup regarding harmonization of measurement methods for the estimation of the ammonia removal from air cleaning technologies are summarized

Insect pathogens as biological control agents: back to the future

The development and use of entomopathogens as classical, conservation and augmentative biological control agents have included a number of successes and some setbacks in the past 15 years. In this forum paper we present current information on development, use and future directions of insect-specific viruses, bacteria, fungi and nematodes as components of integrated pest management strategies for control of arthropod pests of crops, forests, urban habitats, and insects of medical and veterinary importance. Insect pathogenic viruses are a fruitful source of MCAs, particularly for the control of lepidopteran pests. Most research is focused on the baculoviruses, important pathogens of some globally important pests for which control has become difficult due to either pesticide resistance or pressure to reduce pesticide residues. Baculoviruses are accepted as safe, readily mass produced, highly pathogenic and easily formulated and applied control agents. New baculovirus products are appearing in many countries and gaining an increased market share. However, the absence of a practical in vitro mass production system, generally higher production costs, limited post application persistence, slow rate of kill and high host specificity currently contribute to restricted use in pest control. Overcoming these limitations are key research areas for which progress could open up use of insect viruses to much larger markets. A small number of entomopathogenic bacteria have been commercially developed for control of insect pests. These include several Bacillus thuringiensis sub-species, Lysinibacillus (Bacillus) sphaericus, Paenibacillus spp. and Serratia entomophila. B. thuringiensis sub-species kurstaki is the most widely used for control of pest insects of crops and forests, and B. thuringiensis sub-species israelensis and L. sphaericus are the primary pathogens used for medically important pests including dipteran vectors,. These pathogens combine the advantages of chemical pesticides and microbial control agents (MCAs): they are fast acting, easy to produce at a relatively low cost, easy to formulate, have a long shelf life and allow delivery using conventional application equipment and systemics (i.e. in transgenic plants). Unlike broad spectrum chemical pesticides, B. thuringiensis toxins are selective and negative environmental impact is very limited. Of the several commercially produced MCAs, B. thuringiensis (Bt) has more than 50% of market share. Extensive research, particularly on the molecular mode of action of Bt toxins, has been conducted over the past two decades. The Bt genes used in insect-resistant transgenic crops belong to the Cry and vegetative insecticidal protein families of toxins. Bt has been highly efficacious in pest management of corn and cotton, drastically reducing the amount of broad spectrum chemical insecticides used while being safe for consumers and non-target organisms. Despite successes, the adoption of Bt crops has not been without controversy. Although there is a lack of scientific evidence regarding their detrimental effects, this controversy has created the widespread perception in some quarters that Bt crops are dangerous for the environment. In addition to discovery of more efficacious isolates and toxins, an increase in the use of Bt products and transgenes will rely on innovations in formulation, better delivery systems and ultimately, wider public acceptance of transgenic plants expressing insect-specific Bt toxins. Fungi are ubiquitous natural entomopathogens that often cause epizootics in host insects and possess many desirable traits that favor their development as MCAs. Presently, commercialized microbial pesticides based on entomopathogenic fungi largely occupy niche markets. A variety of molecular tools and technologies have recently allowed reclassification of numerous species based on phylogeny, as well as matching anamorphs (asexual forms) and teleomorphs (sexual forms) of several entomopathogenic taxa in the Phylum Ascomycota. Although these fungi have been traditionally regarded exclusively as pathogens of arthropods, recent studies have demonstrated that they occupy a great diversity of ecological niches. Entomopathogenic fungi are now known to be plant endophytes, plant disease antagonists, rhizosphere colonizers, and plant growth promoters. These newly understood attributes provide possibilities to use fungi in multiple roles. In addition to arthropod pest control, some fungal species could simultaneously suppress plant pathogens and plant parasitic nematodes as well as promote plant growth. A greater understanding of fungal ecology is needed to define their roles in nature and evaluate their limitations in biological control. More efficient mass production, formulation and delivery systems must be devised to supply an ever increasing market. More testing under field conditions is required to identify effects of biotic and abiotic factors on efficacy and persistence. Lastly, greater attention must be paid to their use within integrated pest management programs; in particular, strategies that incorporate fungi in combination with arthropod predators and parasitoids need to be defined to ensure compatibility and maximize efficacy. Entomopathogenic nematodes (EPNs) in the genera Steinernema and Heterorhabditis are potent MCAs. Substantial progress in research and application of EPNs has been made in the past decade. The number of target pests shown to be susceptible to EPNs has continued to increase. Advancements in this regard primarily have been made in soil habitats where EPNs are shielded from environmental extremes, but progress has also been made in use of nematodes in above-ground habitats owing to the development of improved protective formulations. Progress has also resulted from advancements in nematode production technology using both in vivo and in vitro systems; novel application methods such as distribution of infected host cadavers; and nematode strain improvement via enhancement and stabilization of beneficial traits. Innovative research has also yielded insights into the fundamentals of EPN biology including major advances in genomics, nematode-bacterial symbiont interactions, ecological relationships, and foraging behavior. Additional research is needed to leverage these basic findings toward direct improvements in microbial control

Optimizing the spray application of entomopathogenic nematodes in vegetables: from spray tank to nematode deposition

Several insect pests of economic importance are encountered on vegetable crops. Being high value crops, the introduction of biological control agents such as entomopathogenic nematodes (EPN) has stimulated great interest for above and below-ground pests. However, despite promising laboratory and field trials, success with EPN in vegetables has rarely been achieved in field applications under practical conditions. Improvements in application technology for EPN that aim at minimizing losses during the transfer from the mixing tank to the target insect, increasing the competitiveness of EPN, are badly needed. Twenty years ago, the effect of application technology on EPN was underestimated. Laboratory experiments investigated the possible detrimental effects of application equipment and resulted in some rules of thumb, e.g., considering spray liquid temperature, nozzle size and pressure. Numerous succeeding studies, however, indicated that those restrictions do not prevent nematode damage. The general objective of this thesis was, therefore, to systematically screen all steps of the spray application process, from spray tank to nematode deposition, for possible detrimental or efficacy reducing effects on EPN applied in vegetables. Research started with a literature review on the effects of application technique on EPN, and on the characteristics of three important vegetable pests (cabbage maggot, onion thrips and cabbage moth) and their control with EPN. Experiments were designed to investigate two important processes of the spray system, i.e., agitation and spray formation. More practical oriented experiments were performed to study the effect of the spray application technique on nematode deposition. Finally, the effect of spray volume on nematode deposition, viability and infectivity was studied. For the application of EPN, a good agitation system is indispensable as the nematodes tend to sediment fast in a spray tank without agitation. Three agitation systems, viz. mechanical, pneumatic and hydraulic agitation were tested for their ability to keep the nematodes suspended. Hydraulic agitation was tested using a centrifugal and a diaphragm pump. Nematode damage was quantified based on viability and infectivity of the EPN. Mechanical agitation at a speed of approximately 696 revolutions min-1 did not influence the viability nor the infectivity of the nematodes. Also pneumatic agitation during 120 min was not detrimental to the EPN. Viability, nor infectivity were affected. However, the effect of hydraulic agitation differed depending on the pump type used. Hydraulic agitation using the diaphragm pump did not harm the nematodes, whereas the use of the centrifugal pump clearly affected viability. After 120 minutes of recirculation, only 19.3% of the nematodes survived; infectivity was even reduced to 0%. An additional experiment revealed that the temperature increase, from 21.7°C to 45.4°C, was responsible for the observed nematode damage. The ability of the agitation system to keep the nematodes in suspension was examined by comparing the nematode concentration observed in the samples taken at different agitation times. These measurements showed that the pneumatic agitation was unstable. Agitation during 120 minutes using the other agitation systems resulted in a significant loss of nematodes at 15 cm above the spray tank bottom. In general, the experiments prove that the agitation systems developed to agitate a chemical solution are not always suited to agitate a nematode suspension and can attribute to reduced efficacy of EPN. One of the major considerations related to the selection and use of an application system is the application distribution pattern. A completely uniform distribution of the nematodes in soil applications is not essential because the nematodes can move over short distances; however, uniform distribution is important in foliar EPN applications. The volumetric distribution pattern of EPN was tested beneath four nozzle types, i.e., a standard flat fan nozzle (TeeJet XR 110 08), an air induction flat fan nozzle (TeeJet AI 110 08), a drift reducing deflector type nozzle (TeeJet TT 110 08) and a TwinJet spray nozzle (TeeJet TJ60 110 08). A comparison with the distribution of a chemical tracer (Brilliant Sulfo Flavine, BSF) was made to reveal possible distribution problems. A significant effect of nozzle type on the distribution of EPN beneath a spray nozzle was found. The differences between the nematode distribution and the distribution of the chemical tracer were negligible for the flat fan and the TwinJet nozzle. Small differences were measured for the air induction nozzle, while a remarkable difference in EPN-BSF distribution was found for the deflector nozzle. The nematode concentration shows a sharp peak in the center of the spray fan and declines much faster toward the edges as compared with the BSF concentration. Ideally, the distribution of EPN beneath the spray boom should be uniform. A theoretical calculation of the coefficient of variation of the nematode distribution beneath a spray boom was performed and showed that the spray overlap from a spray boom decreases differences in nematode distribution. An acceptable value for the coefficient of variation was found for all nozzles, except for the TwinJet nozzle where the coefficient of variation was slightly above 7%. Effective control of insect pests using EPN requires more than a judicious choice of the nematode species. The biological agent must also be delivered in a way that enables the nematodes to infect the host. The optimization process needs to account for the particular requirements of the EPN species used, the target pest, and the crop. The effect of spray application equipment was studied on the deposition of EPN in five pest control applications, viz. cabbage maggot (Delia radicum) and cabbage moth (Mamestra brassicae) in both cauliflower (Brassica oleracea var. botrytis) and savoy cabbage (Brassica oleracea var. sabauda) and onion thrips (Thrips tabaci) in leek (Allium porrum). The nematode deposition (number of nematodes) and spray pattern (distribution of EPN in the droplets) were compared after applying a nematode suspension using a 5-nozzle spray boom equipped with flat fan (TeeJet XR 110 08), air induction flat fan (TeeJet AI 110 08) or TwinJet spray nozzles (TeeJet TJ60 110 08). Two additional spray application systems, viz. air support and row application, were evaluated on their effectiveness to deliver nematodes to their target site. Deposition of Steinernema feltiae was observed in the leek shaft (habitat of onion thrips) and at the cauliflower and savoy cabbage foot (habitat of cabbage maggot), while the deposition of S. carpocapsae was measured at the underside of cauliflower and savoy cabbage leaves (habitat of cabbage moth). Control measurements were performed using Petri dishes filled with water. Empty Petri dishes were used after spraying to measure the spray pattern. The cabbage plants were young but their foliage already sheltered the nematode spray significantly; approximately 40% of the applied nematodes did not reach the foot of the plants. Changing nozzle type did not affect the deposition results, except for the TwinJet nozzle. A spray boom equipped with these dual fan nozzles delivered significantly fewer EPN at the foot of the cauliflower as compared with the flat fan nozzle. The use of an air support system or a row application system improved nematode deposition at the foot of the savoy cabbage. These systems, however, did not significantly increase deposition at the cauliflower foot. With the standard boom spray application technique, relative nematode deposition on the bottom side of the savoy cabbage leaves was 27.2%, while only 2.6% of the applied nematodes reached the bottom side of the cauliflower leaves. Neither nozzle type nor application technique affected nematode deposition at the bottom side of the savoy cabbage or cauliflower leaves. After spraying leek with a standard boom, a low nematode deposition was measured in the leek shaft. With this technique, only 7.3 EPN cm-2 reached the transition zone in the leek shaft. Changing nozzle type or using the air support system did not significantly increase nematode deposition in the leek shaft. Overall, no differences in nematode deposition were found on Petri dishes at different sampling positions along the spray boom, thus an even nematode distribution was obtained underneath the 5-nozzle spray boom. Relative deposition on the horizontal Petri dishes, calculated based on the theoretical maximum deposition, was significantly higher for the air induction nozzle as compared to the flat fan nozzle for both nematode species. Nozzle type also affected the spray pattern of nematodes. The Petri dish surface covered with nematode containing droplets was very low and varied from 13.6% (flat fan nozzle) to 15.8% (air induction nozzle). The experiments provide evidence that EPN frequently do not reach their target sites using standard application techniques. Moreover, the nematodes reaching their target are applied in droplets that cover only a small part of the treated surface. The use of adapted spray application techniques that direct the spray to the target site are indispensable to increase chances for contact of EPN with their target and to result in a cost-effective and reliable application. Spray volume can influence the amount of free water on the leaf surface and subsequently the ability for EPN to move. Therefore, the effect of spray volume, viz. 548, 730 and 1095 L ha-1, was investigated on the deposition, viability and infectivity of EPN against Galleria mellonella on savoy cabbage, cauliflower and leek. Leaf disks and filter paper disks, placed at different angles to the spray nozzle, were exposed to a nematode spray. Increasing spray volume decreased nematode deposition on top of 7.1 cm² leek leaf disks in a 15° angle with the spray nozzle. Although the number of living nematodes observed after 240 min of incubation (24°C and 60% RH) was not significantly different between the low and the high volume application, a greater infectivity was obtained in the latter application. No significant effect of spray volume was observed on the relative deposition of S. carpocapsae on the bottom side of cauliflower and savoy cabbage leaf disks. Despite the low S. carpocapsae deposition on the bottom side of the savoy cabbage disks, high infectivity was obtained against G. mellonella. Using the lowest spray volume, infectivity decreased with increasing exposure time, while infectivity was not affected by exposure time when a spray volume of 730 L ha-1 or more was used. Based on these experiments, spray volume can be considered as an important application parameter since it can affect nematode infectivity. The results of this research confirm that the technique used for the spray application can have severe efficacy reducing effects on EPN. These effects can be observed in the different steps of the application process and vary from nematode death, loss of nematodes and problems to keep the nematodes suspended in the spray tank to difficulties to reach the target pest and covering the target site evenly. The application of chemical insecticides is known to be very inefficient since only small amounts of the applied product reaches the insect, but eventually results in acceptable pest control due to the high persistence of the chemicals. Entomopathogenic nematodes, however, have low persistence on exposed surfaces and are currently too expensive to be applied in excessive amounts. More research is therefore badly needed to develop new or adjusted spray equipment or other application techniques which can deliver nematodes more efficiently at their target site in large field applications