Strategies for the optimization of the efficiency in the plant protection product applications in olive canopies

Pesticide applications are necessary to guarantee the proper development of crops and, therefore, to ensure the profitability for the farmer. However, their mismanagement in last years has led to important environmental problems, triggering the emergence of a generalized animosity towards these practices. The European Administration, by taking into account this social concern, has developed a restrictive legal framework to guarantee the sustainability of treatments through their rationalization. In the case of olive, a very important crop in Spain, this problem is especially critical because of three main reasons. First, it is very concentrated in the Guadalquivir river basin, what makes the negative impacts to be very intense in the area, Next, the lack of knowledge and training makes farmers and technicians to not to be able to properly plan the treatments, generally overdosing to ensure biological efficiency. Last, the traditional nature of this crop and their structural characteristics (big-sized trees with very irregular tree crown shapes, wide tree and row spacing, high slope conditions…) make it especially complex with respect to spray applications to the tree canopy. The objective of this thesis is to develop new strategies to increase the efficiency of pesticide applications to olive tree crowns, through the simultaneous action on three key lines: to determine the influence of the variations in the main working parameters on the application quality, to obtain a simple model to adjust the sprayed volume to the canopy characteristics and to test new solutions to adapt the spraying equipment to the canopy shape, These objectives are developed along four main chapters. In chapter II, the influence of the spray volume and the airflow rate on the efficiency, coverage, penetration and spray homogeneity is studied. The results show that it is appropriate to reduce these parameters with respect to those usually applied in the field, reducing in this way the applied volumes and the power needs in tractors. In chapter III, different manual canopy characterization methods are compared to the most accurate technology: a LiDAR scanner. It is demonstrated that manual methods are reliable and, therefore, they can be useful to farmers and technicians to make adjustments to the spray volumes to be applied. The Mean Vector method showed to be the most polyvalent for different olive plantation systems. In chapter IV, two trials were undertaken to determine the optimum specific spray volume (sprayed L per m3 canopy volume) in isolated trees. It was determined that the specific volume of 0.12 L · m-3 resulted in an optimum coverage, in addition to improve the homogeneity of deposition throughout the crown and the spray penetration. This finding can lead to an important reduction in the volumes to be applied by farmers. In chapter V, the development of three new air-assisted sprayers adapted to the particular conditions of traditional and intensive olive orchards is explained. Each one presents some particularities that make it to be more appropriate for one system or the other, but they all showed to have the potential to improve the efficiency of the conventional airblast sprayer. Coverage increases up to 61% were achieved with these new sprayers. Keywords: olive, working parameters, pesticides, spray volume, airflow rate, LiDAR, canopy characterization, dose adjustment, specific spray volume, prototype development.La aplicación de productos fitosanitarios resulta necesaria para el correcto desarrollo de los cultivos y, por tanto, para asegurar su rentabilidad. No obstante, su mala gestión en los últimos años ha llevado a la aparición de problemas medioambientales de gran calado, lo que ha propiciado que haya una animadversion generalizada contra esta práctica. La Administración europea se ha hecho eco de esta preocupación social y ha impulsado un restrictivo marco legal para garantizar la sostenibilidad de los tratamientos mediante su racionalización. El caso del olivar, un cultivo de gran importancia en España, es especialmente crítico por tres motivos: por una parte, el cultivo se halla muy concentrado en la Cuenca del río Guadalquivir, con lo que la importancia de los impactos es muy alta. En segundo lugar, la escasez de investigación y transferencia hace que los agricultores y técnicos difícilmente estén en condiciones de llevar a cabo sus tratamientos de forma segura, optando generalmente por la sobre-dosificación para garantizar su eficacia biológica. Por ultimo, su carácter tradicional y sus características estructurales (copas de gran dimensión y de forma muy irregular, amplios anchos de calle, alta pendiente…) lo hacen especialmente complejo de cara a la pulverización sobre la copa de los árboles. El objetivo de esta tesis es desarrollar nuevas estrategias para aumentar la eficiencia de las aplicaciones de fitosanitarios a la copa de los olivos, mediante la actuación simultánea sobre tres líneas clave: determinar la influencia de las variaciones en los principales parámetros de trabajo sobre la calidad de las aplicaciones, obtener un modelo simple para ajustar el volumen de caldo empleado a las características de la vegetación y ensayar nuevas soluciones para adaptar los equipos de pulverización a la forma de la copa de los árboles. Se establecen cuatro capítulos principales que desarrollan estos objetivos. En el capítulo II, se estudia la influencia del volumen de caldo y del caudal de aire en la eficiencia, cobertura, penetración y homogeneidad de la pulverización. Los resultados muestran que es deseable reducir estos parámetros respecto a los comúnmente empleados en el campo, reduciendo así los volúmenes aplicados y las necesidades de potencia en los tractores. En el capítulo III se comparan diversos métodos de caracterización del volumen de copa manuales con la tecnología más precisa disponible en la actualidad: el escáner LiDAR. Se muestra que los métodos manuales son precisos y, por tanto, pueden ser útiles a agricultores y técnicos para realizar ajustes sobre el volumen de caldo a aplicar. Se establece el método del ‘Mean Vector’ como el más polivalente para los diferentes tipos de olivar. En el capítulo IV se llevan a cabo dos ensayos para determinar el óptimo volumen de aplicación específico (L de caldo por m3 de volumen de copa) en árboles aislados. Se determina que el volumen de 0.12 L · m-3 resulta en un grado de cobertura óptimo, además de mejorar la homogeneidad en la copa y la penetración. Esto supone una importante reducción en los volúmenes a aplicar por parte de los agricultores. En el capítulo V se detalla el desarrollo de tres nuevos equipos de pulverización adaptados a las condiciones particulares del olivar tradicional e intensivo. Cada equipo presenta unas particularidades que hace que trabaje major en un sistema o en otro, pero mejoran en todo caso al equipo comercial en términos de eficiencia. Incrementos de cobertura de hasta el 61% pueden ser conseguidos con estos nuevos atomizadores

Assessment of the Accuracy of a Multi-Beam LED Scanner Sensor for Measuring Olive Canopies

MDPI. CC BYCanopy characterization has become important when trying to optimize any kind of agricultural operation in high-growing crops, such as olive. Many sensors and techniques have reported satisfactory results in these approaches and in this work a 2D laser scanner was explored for measuring canopy trees in real-time conditions. The sensor was tested in both laboratory and field conditions to check its accuracy, its cone width, and its ability to characterize olive canopies in situ. The sensor was mounted on a mast and tested in laboratory conditions to check: (i) its accuracy at different measurement distances; (ii) its measurement cone width with different reflectivity targets; and (iii) the influence of the target’s density on its accuracy. The field tests involved both isolated and hedgerow orchards, in which the measurements were taken manually and with the sensor. The canopy volume was estimated with a methodology consisting of revolving or extruding the canopy contour. The sensor showed high accuracy in the laboratory test, except for the measurements performed at 1.0 m distance, with 60 mm error (6%). Otherwise, error remained below 20 mm (1% relative error). The cone width depended on the target reflectivity. The accuracy decreased with the target density

Development of Drift-Reducing Spouts For Vineyard Pneumatic Sprayers: Measurement of Droplet Size Spectra Generated and Their Classification

Pneumatic spraying is especially sensitive to spray drift due to the production of small droplets that can be easily blown away from the treated field by the wind. Two prototypes of environmentally friendly pneumatic spouts were developed. The present work aims to check the effect of the spout modifications on the spray quality, to test the convenience of setting the liquid hose out of the spout in cannon-type and hand-type pneumatic nozzles and its effect on the droplet size, homogeneity and driftability in laboratory conditions. Laboratory trials simulating a real sprayer were conducted to test the influence of the hose insertion position (HP), including conventional (CP), alternative (AP), outer (OP) and extreme (XP), as well as the liquid flow rate (LFR) and the airflow speed (AS) on the droplet size (D50, D10 and D90), homogeneity and driftability (V100). Concurrently, the droplet size spectra obtained by the combination of aforementioned parameters (HP × LFR × AS) in both nozzles were also classified according to the ASABE S572.1. Results showed a marked reduction of AS outside the air spout, which led to droplet size increase. This hypothesis was confirmed by the droplet size spectra measured (D50, D10, D90 and V100). A clear influence of HP was found on every dependent variable, including those related with the droplet size. In both nozzles, the longer the distance to CP, the coarser the sprayed drops. Moreover, LFR and AS significantly increased and reduced droplet size, respectively. A higher heterogeneity in the generated drops was obtained in XP. This position yielded V100 values similar to those of the hydraulic low-drift nozzles, showing an effective drift reduction potential. The classification underlines that the variation of HP, alongside AS and LFR, allowed varying the spray quality from very fine to coarse/very coarse, providing farmers with a wide range of options to match the drift-reducing environmental requirements and the treatment specifications for every spray application

In-Field Estimation of Orange Number and Size by 3D Laser Scanning

The estimation of fruit load of an orchard prior to harvest is useful for planning harvest logistics and trading decisions. The manual fruit counting and the determination of the harvesting capacity of the field results are expensive and time-consuming. The automatic counting of fruits and their geometry characterization with 3D LiDAR models can be an interesting alternative. Field research has been conducted in the province of Cordoba (Southern Spain) on 24 ‘Salustiana’ variety orange trees—Citrus sinensis (L.) Osbeck—(12 were pruned and 12 unpruned). Harvest size and the number of each fruit were registered. Likewise, the unitary weight of the fruits and their diameter were determined (N = 160). The orange trees were also modelled with 3D LiDAR with colour capture for their subsequent segmentation and fruit detection by using a K-means algorithm. In the case of pruned trees, a significant regression was obtained between the real and modelled fruit number (R2 = 0.63, p = 0.01). The opposite case occurred in the unpruned ones (p = 0.18) due to a leaf occlusion problem. The mean diameters proportioned by the algorithm (72.15 ± 22.62 mm) did not present significant differences (p = 0.35) with the ones measured on fruits (72.68 ± 5.728 mm). Even though the use of 3D LiDAR scans is time-consuming, the harvest size estimation obtained in this research is very accurate

Assessment of Spray Deposit and Loss in Traditional and Intensive Olive Orchards with Conventional and Crop-Adapted Sprayers

Plant protection product (PPP) applications to isolated olive trees are commonly performed with regular air-assisted sprayers, which are not adapted to their particular characteristics. Whilst strong efforts have been undertaken over the last years to improve technical aspects like canopy detection and automated proportional dosing, nearly no efforts have been made regarding the sprayer adaption to the crop. For this reason, three prototype sprayers were developed for traditional and intensive olive cultivations systems (P1: centrifugal fan; P2: six small side axial fans; P3: two axial fans in tower structure) with the purpose to improve the application efficiency. The main goal of the present study was to check spray quality and efficiency in comparison with the conventional sprayer in both cultivation systems. The sprayers were tested in two different olive groves and properly calibrated according to the tree dimensions. The spray deposition, coverage, drift, and losses to the ground were measured in five trees per cultivation system by placing the appropriate collectors. The sprayers performed very differently in both cultivation systems. In the intensive system, the spray deposition did not present significant differences (p = 0.105). However, it did in the traditional system (p = 0.003), with P3 obtaining the best results. The spray coverage followed the same trend, with significant differences only in the traditional orchard (p = 0.011), with the prototypes leading. The conventional equipment generated the highest spray losses in both cultivation systems. Crop adapted spraying can significantly improve the spray quality and efficiency in difficult crops like olive. This topic may have a key importance to match the environmentally sustainable use of PPP

Developing strategies to reduce spray drift in pneumatic spraying in vineyards: Assessment of the parameters affecting droplet size in pneumatic spraying

Pneumatic sprayers are widely used in vineyards due to their very fine droplet size, which makes the drift risk to become an important problem to be considered. The aim of this study was to assess the effect of the spout diameter at the release point on the spray droplet size and uniformity achieved for different liquid flow rates (LFR) and air flow rates (AFR).A test bench was developed to simulate a real pneumatic sprayer under laboratory conditions, and it was empirically adjusted to match the air pressure conditions as closely as possible to real working conditions. Two positions of insertion of the liquid hose, the conventional position (CP) and an alternative position (AP), were tested for three LFRs, 1.00, 1.64, and 2.67Lmin-1, and four AFRs, 0.280, 0.312, 0.345, and 0.376m3 s-1. The air speed decrease between the two insertion points of the liquid hose was measured. A Malvern SprayTec® instrument was used to measure the droplet size, and the D50, D10, and D90 parameter values were obtained. The relative SPAN factor (RSF) was also calculated. A model to predict variations in D50 was fitted using the aforementioned parameters.The results show that variations in the diameter of the spout significantly change the droplet size, producing a mean increase of 59.45% in D50 and similar increases in D10 and D90. The model developed to predict variations in D50 has a very high degree of accuracy (R2 =0.945). The relative decrease in the air speed along the spout did not present significant differences for the different airflow rates tested. The results of the study show that the droplet size produced in pneumatic spraying can be modified easily by varying the air spout dimensions. This should be taken into account by manufacturers from a design point of view.Postprint (author's final draft

First attempts to obtain a reference drift curve for traditional olive grove's plantations following ISO 22866

The current standard for the field measurements of spray drift (ISO 22866) is the only official standard for drift measurements in field conditions for all type of crops, including bushes and trees. A series of field trials following all the requirements established in the standard were arranged in a traditional olive grove in Córdoba (south of Spain). The aims of the study were to evaluate the applicability of the current standard procedure to the particular conditions of traditional olive trees plantations, to evaluate the critical requirements for performing the tests and to obtain a specific drift curve for such as important and specific crop as olive trees in traditional plantations, considering the enormous area covered by this type of crop all around the world.The authors thank the Ministry of Economy and Competitiveness of the Spanish Government for their economic support through the pre-commercial procurement Mecaolivar project, financed with FEDER funds, and the AgVANCE project (AGL2013-48297-C2-1-R). The first author acknowledges the support of the Spanish Ministry of Education, Culture and SportPostprint (updated version

Reducing spray drift by adapting the spraying equipment to the canopy shape in olive orchards with isolated trees

The lack of specificity of the spraying equipment commonly used in olive orchards is a remarkable problem, for not allowing farmers to apply adjusted pesticide doses to their trees, making necessary to spray very high liquid volumes that increase the environmental pollution risk. In this context, three prototypes were specially developed to increase the application efficiency in olive orchards with isolated trees, which represent 98% of the olive harvested area in Spain.Postprint (published version