Assessment of Airborne Transport of Potential Contaminants in a Wind Tunnel

The reuse of treated wastewater (TWW) for sprinkler irrigation could potentially diffuse pathogen-containing droplets off the application area. Wind and other unfavorable climatic factors enhance irrigation drift and bioaerosol dispersion, exposing humans to potentially severe health risks including the spread of diseases. Few studies have quantified bioaerosols during both spraying and airborne transport phases. Studies of effective sampling strategies to better qualify the dispersion process are also required. This paper presents experiments conducted in a wind tunnel for a deeper understanding of the effects of wind and temperature on pathogen or contaminant airborne dispersal and transport. It is the first time that passive collectors [polyvinyl chloride (PVC) lines] and active samplers (AGI-4 impinger) have been compared under analogous wind conditions using a fluorescent tracer. Droplet-size distribution was also investigated at 12 m from the boom with a NanoMoudi 122-NR cascade impactor in increasing wind conditions from 1 to 3 ms−1. PVC lines return a detailed evolution of the sprayed volume within a short range from the boom and for concentrated fluxes. Transport assessment of PVC lines indicates that transport and permanently airborne condition of the spray notably grow with increasing wind, resulting in a more compact and concentrated plume; mean transport increases from 0.13 to 1.18 Lh−1 m−2 at 7.7 m from the nozzle as the wind velocity increases from 1 to 3 ms−1. AGI-4 appears more suitable to assess finely aerosolized conditions because of its greater sensitivity compared to PVC lines as shown for sample values less than 1 Lh−1 m−2. The comparison between the AGI-4 and PVC lines shows higher values of recovery for the active samplers compared to the PVC lines. The total volume collected by the impingers was 2.93% of the sprayed volume, approximately twice that collected by PVC lines under analogous conditions, even though their sampling surface was only 1.54% that of PVC lines. Droplet-size distributions from the cascade impactor denote a median volume diameter from 1.1 to 2 μm, for the nozzle type used, and a relevant reduction in recovery at stronger wind velocities. An empirical relation time of flight is proposed as a first step in developing decision models that can be used to make sprinkler irrigation safe and to define standards for TWW reuse in agricultural practices (e.g., safe distance of application depending upon wind conditions and droplet-size distribution)

Assessment of spray drift potential reduction for hollow-cone nozzles: Part 1. Classification using indirect methods

Spray drift is one of the main pollution sources identified when pesticides are sprayed on crops. In this work, in order to simplify the evaluation of hollow-cone nozzles according to their drift potential reduction, several models commonly used were tested by three indirect methods: phase Doppler particle analyser (PDPA) and two different wind tunnels. The main aim of this study is then to classify for the first time these hollow-cone nozzle models all of them used in tree crop spraying (3D crops). A comparison between these indirect methods to assess their suitability and to provide guidelines for a spray drift classification of hollow-cone nozzles was carried out. The results show that, in general terms, all methods allow hollow-cone nozzle classifications according to their drift potential reduction (DPR) with a similar trend. Among all the parameters determined with the PDPA, the V100 parameter performed best in differentiating the tested nozzles among drift reduction classes. In the wind tunnel, similar values were obtained for both sedimenting and airborne drift depositions. The V100 parameter displayed a high correlation (up to R2 = 0.948) with the drift potential tested with the wind tunnel. It is concluded that in general, the evaluated indirect methods provide equivalent classification results. Additional studies with a greater variety of nozzle types are required to achieve a proposal of harmonized methodology for testing hollow-cone nozzles.This work was partly funded by the Secretaria d'Universitats i Recerca del Departament d'Empresa i Coneixement de la Generalitat de Catalunya, the Spanish Ministry of Economy and Competitiveness and the European Regional Development Fund (ERDF) under Grants 2017 SGR 646, AGL2007-66093-C04-03, AGL2010-22304-04-C03-03, and AGL2013-48297-C2-2-R. The authors also wish to thank Mr. Antonio Checa (Randex Iberica, S.L.) for giving us free Albuz nozzles for the spray tests. Universitat de Lleida is also thanked for Mr. X. Torrent's pre-doctoral fellowship

Des pièges améliorés et connectés

La start-up Agriodor développe le piégeage de la bruche de la féverole au moyen de mélanges attractifs mimant les odeurs de différents organes de la féverole. Problème : ces mélanges doivent être utilisés à des moments différents en fonction de l’état de la culture et du stade de développement de la bruche. Comment éviter que le déploiement de cette méthode ne soit pénalisé par une lourdeur de gestion au champ ? Pour répondre à cette question, les équipes d’INRAE et d’Agriodor collaborent dans le projet EffiTraps qui vise à révolutionner la façon d’utiliser les mélanges d’odeur au champ. L’innovation visée utilisera des diffuseurs actifs d’odeurs, commandés à distance, là où les technologies précédentes consistaient en une diffusion passive continue nécessitant plus de quantités d’odeurs. D’autre part, la diffusion active sera synchronisée entre les pièges disposés au champ et s’appuiera sur les dernières avancées en matière de micro-fluidique pour délivrer un signal olfactif optimisé en fonction des conditions microclimatiques. Grâce à une plus faible consommation de substances, à une baisse du nombre de pièges nécessaires et à une limitation des interventions au terrain, cette nouvelle technique de piégeage sera accessible au plus grand nombre. Si les résultats seront d’abord spécifiques à la lutte contre la bruche de la féverole, ils pourront par la suite être généralisés à d’autres kairomones ou phéromones.EffiTrap

Chapitre 21 - Quelles technologies pour le déploiement du biocontrôle ? Les agroéquipements, la robotique et le numérique pour optimiser l’utilisation du biocontrôle

peer reviewe

Émission des pesticides vers l'atmosphère

Émission des pesticides vers l'atmosphère. Agriculture et Qualité de l'Ai

Conception et réalisation d'un dispositif d'imagerie multispectrale embarqué (du capteur aux traitements pour la détection d'adventices)

La détection des adventices (mauvaises herbes) est un des enjeux clefs d'une agriculture propre et productive. Nous proposons dans ce mémoire une nouvelle méthode de détection basée sur des images aériennes acquises à l'aide d'un avion radiocommandé. Nous utilisons un capteur d'images multispectrales basé sur une caméra CCD et une roue de filtres. Ce capteur est suffisamment compact pour être embarqué dans un avion radiocommandé. Des images aériennes sont ainsi obtenues pour un coût trés bas. Un recalage géométrique des images est effectué afin de pouvoir utiliser les informations spectrométriques. Les informations spectrales obtenues sont ensuite utilisées pour créer trois classes dans ces images : le sol, les cultures et les adventices. La classification est décomposée en deux étapes. Dans un premier temps, un algorithme non supervisé permet de séparer la végétation du sol. Puis, des algorithmes supervisés sont mis en oeuvre pour séparer les cultures des adventices. Nous proposons une comparaison de différents algorithmes entre eux. Une méthode de détection des lignes de semis basée sur le filtre de Gabor est ensuite présentée. Cette information permet de séparer les cultures des adventices indépendamment de leurs caractéristiquesspectrales. Une méthode originale d'accélération des temps de calcul basée sur les paquets d'ondelettes est exposée. Les deux approches ayant des sources d'erreur différentes, nous proposons de les fusionner à l'aide d'une approximation de la théorie bayesienne. Enfin, un algorithme de croissance de région permet de lever les dernières incertitudes. La méthode est testée sur des parcelles d'essais.Weed detection is one of the most important issues for a non-polluting and productive agriculture. In this PhD we present a new method based on aerial images acquired with a remote controlled aircraft. We use a multispectral image sensor based on a CCD camera and a wheel of filters. This sensor is compact enough to be shipped in a remote controlled aircraft. An image mosaicing is done in order to be able to use spectrometric information. Later, spectral information is used to establish three classes : soil, crops and weeds. Classification is split in two steps. First, a non-supervised algorithm allows the separation between soil and plants. Second, supervised methods are used to distinguish crops and weeds. These various algorithms are compared to each other. A crop row detection method based on Gabor filter is developed. This information allows weeds/crop separation regardless of their spectral characteristics. An original method for computing time acceleration based on wavelet packets is detailed. These two methods having different error sources, we suggest to merge them using a Bayesian approach. Finally, a region growing algorithm achieves the classification. Experimental results obtained in test fields are provided to assess the quality of the classification.DIJON-BU Sciences Economie (212312102) / SudocSudocFranceF

Herbicide site specific spraying: use of simulations to study the impact of section width

National audienc

Simulation-aided study of herbicide patch spraying: Influence of spraying features and weed spatial distributions

International audiencePatch spraying is a technological way to reduce herbicide amounts required to control weeds by triggering spraying only where weeds lie. Nevertheless, the adoption rate of this technology by farmers is still low and there is a lack of efficient tools to assess patch herbicide applications depending on spraying features and weed spatial distributions. To avoid unrealistic in-field experiments, a virtual patch sprayer is designed and computer simulations are carried out to quantify herbicide reduction possibilities and assess the ability to apply the right rate on weed patches to ensure herbicide efficiency. The spray application simulator combines the theoretical description of the sprayer using various boom section widths (from 0.5 to 24 m) with experimental data describing various nozzle spray patterns obtained from three commercial nozzles. Virtual weed infestation maps are designed using random locations of weed patches with various spatial aggregation degrees modelled by different weed coverage rates and elliptical patch sizes. Simulation results are analysed through two performance indicators: i) the herbicide reduction ratio obtained with patch spraying compared to a uniform broadcast application (on the entire field area), ii) the proportion of weed patch area on which the application rate is higher than 85% of the prescribed application rate. Computer simulations enable to estimate a simplified relationship to quantify the reduction of herbicide use as a function of the weed coverage rate, the size of weed patches and the boom section width. This demonstrates that computer simulations provide practical tools to estimate the sprayer spatial resolution required to reach a given herbicide reduction target according to the weed spatial distribution. Simulations also demonstrate that the use of narrow section widths equipped with traditional nozzles leads to a significant proportion of weed areas exposed to herbicide under-application in the case of small patches

Spot spraying is a method that can meet the objectives of reduced herbicide by maintaining a high level of weed control efficiency without lowering crop yield and harvest quality. Individual nozzle control systems show great potential for herbicide reduction. Nevertheless, this method of application also entails the risk of under-application on weed surfaces because of the lack of spray overlap and irregular dosing. Thus, nozzle control strategies need to be refined and assessed, regarding herbicide reduction and the ability to apply the prescribed dose on the target surfaces. Six control strategies were considered by activating complementary adjacent nozzles or increasing the flowrate of specific nozzles. Theoretical analyses and simulations were carried out to compare these strategies using three indicators. Considering a simplified description of the weed spatial distribution, a herbicide reduction indicator was expressed analytically for each strategy as a function of the weed coverage rate and patch width. For each strategy, numerical simulations were also carried out to compute under- and over-application indicators considering six weed coverage rates, eight patch widths and six different spray patterns. Graphs and charts were developed to provide convenient tools to help select the best technical approach for reducing chemical applied whilst keeping the prescribed dose on targets. In particular, a good compromise could consist of setting the weed detection width (associated with each nozzle) at twice the nozzle spacing and using triangular spray patterns combined with double spray overlaps.

International audienceSpot spraying is a method that can meet the objectives of reduced herbicide by maintaining a high level of weed control efficiency without lowering crop yield and harvest quality. Individual nozzle control systems show great potential for herbicide reduction. Nevertheless, this method of application also entails the risk of under-application on weed surfaces because of the lack of spray overlap and irregular dosing. Thus, nozzle control strategies need to be refined and assessed, regarding herbicide reduction and the ability to apply the prescribed dose on the target surfaces. Six control strategies were considered by activating complementary adjacent nozzles or increasing the flowrate of specific nozzles. Theoretical analyses and simulations were carried out to compare these strategies using three indicators. Considering a simplified description of the weed spatial distribution, a herbicide reduction indicator was expressed analytically for each strategy as a function of the weed coverage rate and patch width. For each strategy, numerical simulations were also carried out to compute under- and over-application indicators considering six weed coverage rates, eight patch widths and six different spray patterns. Graphs and charts were developed to provide convenient tools to help select the best technical approach for reducing chemical applied whilst keeping the prescribed dose on targets. In particular, a good compromise could consist of setting the weed detection width (associated with each nozzle) at twice the nozzle spacing and using triangular spray patterns combined with double spray overlaps