Articles publicats (Grup de Recerca en AgròTICa i Agricultura de Precisió)

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Open Access
Assessment of Recycling Tunnel Sprayers in Mediterranean Vineyards and Apple Orchards
(Elsevier, 2002) Planas de Martí, Santiago; Solanelles Batlle, Francesc; Fillat, A.
The use of air-assisted recycling tunnel sprayers in Mediterranean fruit orchards and vineyards was assessed by comparing the performance of two tunnel sprayer prototypes with an air-assisted axial flow sprayer. Field trials comprised measurements of spray deposit on the canopy, off-target spray losses and the biological efficacy of chemical applications. According to the results, no spray drift was measured during the applications with tunnel sprayers. Spray losses on the ground were localized mainly under the crop rows. However, the uniformity of the spray deposition on the canopy was worse than that obtained with the axial flow sprayer. It seems that this can be attributed to poor adjustment of the tunnel dimensions in relation to the crop size or to inadequate air-jet design. Tunnel sprayers may be an option to meet future environmental requirements for spray applications, so long as crop training systems change to smaller-size orchards and wall-shaped trellis vineyards.
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Center-pivot automatization for agrochemical use
(Elsevier, 2005) Palacín Roca, Jordi; Salse, José Antonio; Clua, Xavier; Arnó Satorra, Jaume; Blanco Ortiz, Ricardo; Zanuy, C.
This paper presents an agrochemical application system that could be incorporated into existing irrigating center-pivots. The system consisted of a hydraulic circuit with emitters, where the dose was individually controlled with variable valve timing. This paper describes the electronic control system, designed to be modular and distributed along the pivot. The main problem solved was the determination of the emitter’s absolute displacement to generate their adequate timing control. The paper ends with the test of a low-cost implementation of the complete system under real center-pivot operation.
Open Access
An Electronic Control System for Pesticide Application Proportional to the Canopy Width of Tree Crops
(Elsevier, 2006) Solanelles Batlle, Francesc; Escolà i Agustí, Alexandre; Planas de Martí, Santiago; Rosell Polo, Joan Ramon; Camp, Ferran; Gràcia, Felip
A prototype of an electronic control system based on ultrasonic sensors and proportional solenoid valves for a proportional application to the canopy width of tree crops was mounted on an air-assisted sprayer. The sprayer flow rate adjustment was based on the relationship between the actual tree width measured by the ultrasonic sensors and the maximum tree width of the orchard. The prototype was tested in olive, pear and apple orchards to assess the system performance in different crop geometries. The spray deposit distribution was measured in comparison with conventional air-assisted applications. Metal tracers were used so that spray deposits for each treatment could be measured on the same samples, reducing sampling variability. Liquid savings of 70%, 28% and 39% in comparison to a conventional application were recorded in the olive, pear and apple orchard respectively, which resulted in lower spray deposits on the canopy but a higher ratio between the total spray deposit and the liquid sprayer output (i.e. better application efficiency). A reduction of the maximum tree width parameter in the control algorithm in the apple orchard reduced spray savings but increased spray deposition, with spray savings mainly in the middle level of the outside canopy, compared to conventional air-assisted applications.
Open Access
Variable rate application of plant protection products in vineyard using ultrasonic sensors
(Elsevier, 2007) Gil Moya, Emilio; Escolà i Agustí, Alexandre; Rosell Polo, Joan Ramon; Planas de Martí, Santiago; Val, Luis
The changes in the shape and size of vines during the growing season require a continuous adjustment of the applied dose to optimize spray application efficiency. Target detection with ultrasonic sensors can be used to adapt the applied dose following the principles of the variable rate technology. A multi-nozzle air-blast sprayer was fitted with three ultrasonic sensors and three electro-valves, to modify the flow rate from the nozzles in real time, in relation to the variability of crop width. A constant application rate of 300 l ha−1 was compared with a variable rate application using the tree row volume principle at a 0.095 l m−3 canopy. The total flow rate sprayed by the nozzles was modified according to the variations of crop width measured by the ultrasonic sensors. On average 58% less liquid was applied compared to the constant rate application, with similar deposition on leaves with both treatments. A detailed analysis of savings indicates differences between the lower, middle and top part of the crop, in accordance with the leaf area distribution with crop height. No significant differences between treatments were detected in uniformity of liquid distribution and capability to reach the inner parts of the crop. This important reduction in spray volume could be followed by an equivalent reduction of plant protection products but further research work is needed to guarantee biological efficacy of a reduced dose.
Open Access
Real-time tree-foliage surface estimation using a ground laser scanner
(Institute of Electrical and Electronics Engineers (IEEE), 2007) Palacín Roca, Jordi; Pallejà Cabrè, Tomàs; Tresánchez Ribes, Marcel; Ribes Dasi, Manuel; Llorens Calveras, Jordi; Escolà i Agustí, Alexandre; Rosell Polo, Joan Ramon; Sanz Cortiella, Ricardo; Masip Vilalta, Joan; Arnó Satorra, Jaume
The optimization of most pesticide and fertilizer applications is based on overall grove conditions. In this work we measurements. Recently, Wei [9, 10] used a terrestrial propose a measurement system based on a ground laser scanner to LIDAR to measure tree height, width and volume developing estimate the volume of the trees and then extrapolate their foliage a set of experiments to evaluate the repeatability and surface in real-time. Tests with pear trees demonstrated that the accuracy of the measurements, obtaining a coefficient of relation between the volume and the foliage can be interpreted as variation of 5.4% and a relative error of 4.4% in the linear with a coefficient of correlation (R) of 0.81 and the foliar estimation of the volume but without real-time capabilities. surface can be estimated with an average error less than 5 %.
Open Access
Obtaining the three-dimensional structure of tree orchards from remote 2D terrestrial LIDAR scanning
(Elsevier, 2009) Rosell Polo, Joan Ramon; Llorens Calveras, Jordi; Sanz Cortiella, Ricardo; Arnó Satorra, Jaume; Ribes Dasi, Manuel; Masip Vilalta, Joan; Escolà i Agustí, Alexandre; Camp, Ferran; Solanelles Batlle, Francesc; Gràcia, Felip; Gil Moya, Emilio; Val, Luis; Planas de Martí, Santiago; Palacín Roca, Jordi
In recent years, LIDAR (light detection and ranging) sensors have been widely used to measure environmental parameters such as the structural characteristics of trees, crops and forests. Knowledge of the structural characteristics of plants has a high scientific value due to their influence in many biophysical processes including, photosynthesis, growth, CO2-sequestration and evapotranspiration, playing a key role in the exchange of matter and energy between plants and the atmosphere, and affecting terrestrial, above-ground, carbon storage. In this work, we report the use of a 2D LIDAR scanner in agriculture to obtain three-dimensional (3D) structural characteristics of plants. LIDAR allows fast, non-destructive measurement of the 3D structure of vegetation (geometry, size, height, cross-section, etc.). LIDAR provides a 3D cloud of points, which is easily visualized with Computer Aided Design software. Three-dimensional, high density data are uniquely valuable for the qualitative and quantitative study of the geometric parameters of plants. Results are demonstrated in fruit and citrus orchards and vineyards, leading to the conclusion that the LIDAR system is able to measure the geometric characteristics of plants with sufficient precision for most agriculture applications. The developed system made it possible to obtain 3D digitalized images of crops, from which a large amount of plant information – such as height, width, volume, leaf area index and leaf area density – could be obtained. There was a great degree of concordance between the physical dimensions, shape and global appearance of the 3D digital plant structure and the real plants, revealing the coherence of the 3D tree model obtained from the developed system with respect to the real structure. For some selected trees, the correlation coefficient obtained between manually measured volumes and those obtained from the 3D LIDAR models was as high as 0.976.
Open Access
A tractor-mounted scanning LIDAR for the non-destructive measurement of vegetative volume and surface area of tree-row plantations: a comparison with conventional destructive measurements
(Elsevier, 2009) Rosell Polo, Joan Ramon; Sanz Cortiella, Ricardo; Llorens Calveras, Jordi; Arnó Satorra, Jaume; Escolà i Agustí, Alexandre; Ribes Dasi, Manuel; Masip Vilalta, Joan; Camp, Ferran; Gràcia, Felip; Solanelles Batlle, Francesc; Pallejà Cabrè, Tomàs; Val, Luis; Planas de Martí, Santiago; Gil Moya, Emilio; Palacín Roca, Jordi
The use of a low-cost tractor-mounted scanning Light Detection and Ranging (LIDAR) system for capable of making non-destructive recordings of tree-row structure in orchards and vineyards is described. Field tests consisted of several LIDAR measurements on both sides of the crop row, before and after defoliation of selected trees. Summary parameters describing the tree-row volume and the total crop surface area viewed by the LIDAR (expressed as a ratio with ground surface area) were derived using a suitable numerical algorithm. The results for apple and pear orchards and a wine producing vineyard were shown to be in reasonable agreement with the results derived from a destructive leaf sampling method. Also, good correlation was found between manual and sensor-based measurements of the vegetative volume of tree-row plantations. The Tree Area Index parameter, TAI, gave the best correlation between destructive and non-destructive (i.e. LIDAR-based) determinants of crop leaf area. The LIDAR system proved to be a powerful technique for low cost, prompt and non-destructive estimates of the volume and leaf-area characteristics of plants.
Open Access
Design of a decision support method to determine volume rate for vineyard spraying
(American Society of Agricultural and Biological Engineers, 2009) Gil Moya, Emilio; Escolà i Agustí, Alexandre
Dose determination in crops such as grapevine, which develops a large canopy within a relatively short period of time, becomes a key factor on the final success of plant protection product (PPP) application. Efficacy of PPP applications depends on many factors. Based on multiple data obtained over several years in real working conditions using different types of sprayers in vineyards, and by adding a complete data base about crop characteristics (structure, crop stage, leaf area, LAI, etc.), the objective of this work has been to develop an easy and useful tool, DOSAVIÑA, able to determine the optimal volume rate in spray applications in vineyards. DOSAVIÑA, based on a spreadsheet (Microsoft Excel ), allows quantifying all the parameters involved in the application process (sprayer type, crop characteristics, working conditions, weather, etc.), and to determine the efficiency of the application. By selecting and choosing the different options for each parameter (crop, pesticide, working conditions, weather conditions, sprayer, and droplet characteristics) the program calculates the theoretical volume rate (L ha‐1) based on two different methods, the Optimal Coverage Method and the Tree‐Row‐Volume method. Results obtained with DOSAVIÑA allow reducing the recommended volume rate in comparison with traditional application rate selection managed for farmers. In order to make a complete and useful tool, the program includes the possibility to calculate the final working parameters (pressure, nozzle type, and size) according to the recommendations on volume rate (L ha‐1) obtained.
Open Access
Review. Precision viticulture. Research topics, challenges and opportunities in site-specific vineyard management
(Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (Espanya), 2009) Arnó Satorra, Jaume; Martínez Casasnovas, José Antonio; Ribes Dasi, Manuel; Rosell Polo, Joan Ramon
Precision Viticulture (PV) is a concept that is beginning to have an impact on the wine-growing sector. Its practical implementation is dependant on various technological developments: crop sensors and yield monitors, local and remote sensors, Global Positioning Systems (GPS), VRA (Variable-Rate Application) equipment and machinery, Geographic Information Systems (GIS) and systems for data analysis and interpretation. This paper reviews a number of research lines related to PV. These areas of research have focused on four very specific fields: 1) quantification and evaluation of within-field variability, 2) delineation of zones of differential treatment at parcel level, based on the analysis and interpretation of this variability, 3) development of Variable-Rate Technologies (VRT) and, finally, 4) evaluation of the opportunities for site-specific vineyard management. Research in these fields should allow winegrowers and enologists to know and understand why yield variability exists within the same parcel, what the causes of this variability are, how the yield and its quality are interrelated and, if spatial variability exists, whether site-specific vineyard management is justifiable on a technical and economic basis.
Open Access
Deposición transversal de líquido de las boquillas de doble abanico TTJ60-11004 y TTJ60-11002 en distintas condiciones operacionales
(Sociedade Brasileira da Ciência das Plantas Daninhas, 2009) Viana, R.G.; Ferreira, L.R.; Rosell Polo, Joan Ramon; Solanelles Batlle, Francesc; Machado, M.S.; Machado, A.F.L.
El objetivo de este trabajo fue el de evaluar la deposición transversal de caldo de las boquillas pulverizadoras de doble abanico TTJ60-11004 y TTJ60-11002 en distintas condiciones operacionales. Se utilizaron 5 muestras de cada boquilla pulverizadora siendo considerada cada unidad, una repetición. La distribución de caldo fue evaluada por medio de una mesa de evaluación de distribución construida de acuerdo con la norma ISO 56821. Se evaluó el perfil de distribución individual, la distribución volumétrica simulada de la superposición de los chorros por medio del coeficiente de variación (CV%) de los volúmenes colectados, el caudal y el ángulo de abertura de los chorros. Las condiciones operacionales fueron: presión de trabajo de 200, 300 y 400 Kpa, altura de 30, 40 y 50 cm en relación al blanco y espaciamiento entre boquillas simulados en Software (Microsoft Excel) entre 45 y 100 cm. Las boquillas presentaron perfil individual descontinuo con la mayor deposición de líquido en la región central y reducción del volumen gradual en dirección a las extremidades. El aumento de la presión promovió alargamiento del perfil y de la franja de aplicación. Las boquillas proporcionaron perfil uniforme que dependió del espaciamiento entre las boquillas, con valores menores con reducción en el espaciamiento y en presiones mayores. El caudal y el ángulo del chorro aumentaron con el incremento en la presión.
Open Access
Applying precision feeding techniques in growing-finishing pig operations
(Sociedade Brasileira de Zootecnia, 2009) Pomar, Càndido; Hauschild, Luciano; Zhang, Guo-Hua; Pomar Gomà, Jesús; Lovatto, Paolo Alberto
The high cost of feed ingredients, the use of non-renewable sources of phosphate and the dramatic increase in the environmental load resulting from the excessive land application of manure are major challenges for the livestock industry. Precision feeding is proposed as an essential approach to improve the utilization of dietary nitrogen, phosphorus and other nutrients and thus reduce feeding costs and nutrient excretion. Precision feeding requires accurate knowledge of the nutritional value of feedstuffs and animal nutrient requirements, the formulation of diets in accordance with environmental constraints, and the gradual adjustment of the dietary nutrient supply to match the requirements of the animals. After the nutritional potential of feed ingredients has been precisely determined and has been improved by the addition of enzymes (e.g. phytases) or feed treatments, the addition of environmental objectives to the traditional feed formulation algorithms can promote the sustainability of the swine industry by reducing nutrient excretion in swine operations with small increases in feeding costs. Increasing the number of feeding phases can also contribute to significant reductions in nutrient excretion and feeding costs. However, the use of precision feeding techniques in which pigs are fed individually with daily tailored diets can further improve the efficiency with which pigs utilize dietary nutrients. Precision feeding involves the use of feeding techniques that allow the provision of the right amount of feed with the right composition at the right time to each pig in the herd. Using this approach, it has been estimated that feeding costs can be reduced by more than 4.6%, and nitrogen and phosphorus excretion can both be reduced by more than 38%. Moreover, the integration of precision feeding techniques into large-group production systems can provide real-time off-farm monitoring of feed and animals for optimal slaughter and production strategies, thus improving the environmental sustainability of pork production, animal well-being and meat-product quality.
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Sensitivity of tree volume measurement to trajectory errors from a terrestrial LIDAR scanner
(Elsevier, 2010) Pallejà Cabrè, Tomàs; Tresánchez Ribes, Marcel; Teixidó Cairol, Mercè; Sanz Cortiella, Ricardo; Rosell Polo, Joan Ramon; Palacín Roca, Jordi
The use of terrestrial LIDARs in agriculture enables the measurement of structural parameters of the orchards such as the volume of the trees. The sequence of two-dimensional scans performed with a LIDAR attached to a tractor can be interpreted as the three-dimensional silhouette of the trees of the grove and used to estimate their volume. In this work, the sensitivity of the tree volume estimates relative to different error sources in the estimated spatial trajectory of the LIDAR is analyzed. Tests with pear trees have demonstrated that the estimation of the volume is very sensitive to errors in the determination of the distance from the LIDAR to the center of the trees (with errors up to 30% for an error of 50 mm) and in the determination of the angle of orientation of the LIDAR (with errors up to 30% for misalignments of 2◦). Therefore, any experimental procedure for tree volume estimate based on a motorized terrestrial LIDAR scanner must include additional devices or procedures to control or estimate and correct these error sources.
Open Access
Distribuição de líquido da ponta de pulverização com indução de ar e jato excêntrico AIUB 8502 sob diferentes condições
(Sociedade Brasileira da Ciência das Plantas Daninhas, 2010) Viana, R.G.; Ferreira, L.R.; Rosell Polo, Joan Ramon; Solanelles Batlle, Francesc; Filat, A.; Machado, M.S.; Machado, A.F.L.; Silva, M.C.C.
Objetivou-se com este trabalho avaliar a distribuição de líquido da ponta de pulverização com indução de ar e jato excêntrico AIUB 8502 sob diferentes condições operacionais. Foram avaliados perfil individual, vazão, ângulo de abertura do jato, faixa de aplicação e distribuição volumétrica simulada de duas pontas AIUB 8502 nas pressões de trabalho de 200, 300, 400 e 500 kPa, altura de 30, 40 e 50 cm em relação ao alvo e espaçamento entre pontas de 30 a 100 cm. Todas as análises foram realizadas seguindo a norma ISSO 5682-1, com algumas adaptações. A ponta apresentou distribuição de líquido excêntrica com um lado descontínuo e extremidade oposta excêntrica, com queda abrupta do volume de líquido. À medida que se aumentou a altura da barra e a pressão de trabalho, alongou-se o perfil do jato. O maior número de configurações uniformes foi obtido na altura de 50 cm, decrescendo nas alturas de 40 e 30 cm. A vazão e o ângulo do jato excêntrico aumentaram com o incremento na pressão, não havendo diferença entre o ângulo do jato descontínuo e o total entre as pressões de 400 e 500 kPa e de 200 e 300 kPa.
Open Access
Protocolo para la zonificación intraparcelaria de la viña para vendimia selectiva a partir de imágenes multiespectratrales
(Asociación Española de Teledetección, 2010) Martínez Casasnovas, José Antonio; Agelet Fernández, J.; Arnó Satorra, Jaume; Bordes Aymerich, Xavier; Ramos Martín, Ma. C. (Ma. Concepción)
En este trabajo se presenta un protocolo para la zonificación intraparcelaria de la viña con la finalidad de vendimia selectiva. Se basa en la adquisición de una imagen multiespectral detallada en el momento del envero, a partir de la cual se obtiene el índice de vegetación de la diferencia normalizada (NDVI). Este índice se clasifica en áreas de vigor alto y bajo mediante un proceso de clasificación no supervisada (algoritmo ISODATA). Las zonas resultantes se generalizan y se transfieren al monitor de cosecha de una máquina vendimiadora para realizar la recolección selectiva. La uva recolectada según este protocolo en parcelas control ha mostrado diferenciación en cuanto a parámetros de calidad como el pH, la acidez total, el contenido de polifenoles y el color. La imagen multiespectral utilizada fue adquirida por el satélite Quickbird-2. Los datos de calidad de la uva fueron muestreados según una malla regular de 5 filas por 10 cepas, procediendo a un test estadístico de rangos múltiples para analizar la separación de medias de las variables analizadas en cada zona de NDVI.
Open Access
Distribuição volumétrica e espectro de gotas de pontas de pulverização de baixa deriva
(Sociedade Brasileira da Ciência das Plantas Daninhas, 2010) Viana, R.G.; Ferreira, L.R.; Ferreira, M.C.; Teixeira, M.M.; Rosell Polo, Joan Ramon; Tuffi Santos, L.D.; Machado, A.F.L.
Objetivou-se neste trabalho avaliar a distribuição volumétrica e o espectro de gotas das pontas de pulverização de baixa deriva TTI110015, AI110015 e AVI11001 sob diferentes condições operacionais. A distribuição volumétrica foi determinada em bancada de ensaios padronizada analisando o coeficiente de variação (CV%) de uma barra simulada em computador, utilizando pressões de 200, 300 e 400 kPa, altura de 30, 40 e 50 cm em relação à bancada e espaçamento entre pontas de 40 a 100 cm. O espectro de gotas foi produzido utilizando-se apenas água como calda em um analisador de partículas em meio aquoso, nas pressões de 200, 300 e 400 kPa. Foram avaliados o DMV, a porcentagem de gotas com diâmetro inferior a 100 µm (%100 µm) e a amplitude relativa (AR). As pontas proporcionaram perfil descontínuo nas pressões de 300 e 400 kPa e uniforme a 200 kPa. Na pressão de 200 kPa, as pontas foram adequadas apenas para aplicação em faixa, e a 300 e 400 kPa, apenas para área total. Ocorreu menor CV (abaixo de 7%) com a maior pressão de trabalho e menor espaçamento entre pontas. À medida que se aumentou a pressão de trabalho, reduziu-se o DMV. As pontas TTI110015 e AI110015 em todas as pressões e a ponta AVI11001 na pressão de 200 kPa produziram gotas extremamente grossas e gotas grossas nas pressões de 300 e 400 kPa apenas para a ponta AVI11001. As pontas proporcionaram baixos valores de amplitude relativa (AR) e gotas de tamanho uniforme, bem como produziram baixa porcentagem de gotas menores que 100 µm, principalmente TTI110015 e AI110015, com menor risco de deriva.
Open Access
Variable rate dosing in precision viticulture: Use of electronic devices to improve application efficiency
(Elsevier, 2010-03) Llorens Calveras, Jordi; Gil Moya, Emilio; Llop, Jordi; Escolà i Agustí, Alexandre
Two different spray application methods were compared in three vine varieties at different crop stages. A conventional spray application with a constant volume rate per unit ground area (1 ha(-1)) was compared with a variable rate application method designed to compensate electronically for measured variations in canopy dimensions. An air-blast sprayer with individual multi-nozzle spouts was fitted with three Ultrasonic sensors and three electro valves on one side, in order to modify the emitted flow rate of the nozzles according to the variability of canopy dimensions in real time. The Purpose of this prototype was to precisely apply the required amount of spray liquid and avoid over dosing. On average, a 58% saving in application volume was achieved with the variable rate method, obtaining similar or even better leaf deposits.
Open Access
Clustering of grape yield maps to delineate site-specific management zones
(Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (Espanya), 2011) Arnó Satorra, Jaume; Martínez Casasnovas, José Antonio; Ribes Dasi, Manuel; Rosell Polo, Joan Ramon
Zonal management in vineyards requires the prior delineation of stable yield zones within the parcel. Among the different methodologies used for zone delineation, cluster analysis of yield data from several years is one of the possibilities cited in scientific literature. However, there exist reasonable doubts concerning the cluster algorithm to be used and the number of zones that have to be delineated within a field. In this paper two different cluster algorithms have been compared (k-means and fuzzy c-means) using the grape yield data corresponding to three successive years (2002, 2003 and 2004), for a ‘Pinot Noir’ vineyard parcel. Final choice of the most recommendable algorithm has been linked to obtaining a stable pattern of spatial yield distribution and to allowing for the delineation of compact and average sized areas. The general recommendation is to use reclassified maps of two clusters or yield classes (low yield zone and high yield zone) and, consequently, the site-specific vineyard management should be based on the prior delineation of just two different zones or sub-parcels. The two tested algorithms are good options for this purpose. However, the fuzzy c-means algorithm allows for a better zoning of the parcel, forming more compact areas and with more equilibrated zonal differences over time.
Open Access
Evaluation of peach tree growth characteristics under different irrigation strategies by LIDAR system: preliminary results
(International Society for Horticultural Science (ISHS), 2011) Pascual Roca, Miquel; Villar Mir, Josep Ma.; Rufat i Lamarca, Josep; Rosell Polo, Joan Ramon; Sanz Cortiella, Ricardo; Arnó Satorra, Jaume
In a four-year experiment on peach (Prunus persica L. Batsch ‘Andross’) for fruit processing, canopy volume and tree shape were evaluated by scanning trees with a Light Detection and Ranging (LIDAR) system: a non-destructive system based on low cost laser technology. A relationship was obtained between the measured LIDAR tree volume and yield and fruit weight, suggesting that LIDAR offered a good way to evaluate fruit tree production capacity. The tree volume estimation system performed well when it was used as a component in the statistical analysis of the effects of irrigation strategy on productivity.
Open Access
Ultrasonic and LIDAR sensors for electronic canopy characterization in vineyards: advances to improve pesticide application methods
(Molecular Diversity Preservation International (MDPI), 2011) Llorens Calveras, Jordi; Gil Moya, Emilio; Llop, Jordi; Escolà i Agustí, Alexandre
Canopy characterization is a key factor to improve pesticide application methods in tree crops and vineyards. Development of quick, easy and efficient methods to determine the fundamental parameters used to characterize canopy structure is thus an important need. In this research the use of ultrasonic and LIDAR sensors have been compared with the traditional manual and destructive canopy measurement procedure. For both methods the values of key parameters such as crop height, crop width, crop volume or leaf area have been compared. Obtained results indicate that an ultrasonic sensor is an appropriate tool to determine the average canopy characteristics, while a LIDAR sensor provides more accuracy and detailed information about the canopy. Good correlations have been obtained between crop volume (CVU) values measured with ultrasonic sensors and leaf area index, LAI (R2 = 0.51). A good correlation has also been obtained between the canopy volume measured with ultrasonic and LIDAR sensors (R2 = 0.52). Laser measurements of crop height (CHL) allow one to accurately predict the canopy volume. The proposed new technologies seems very appropriate as complementary tools to improve the efficiency of pesticide applications, although further improvements are still needed.
Open Access
Weed discrimination using ultrasonic sensors
(John Wiley & Sons, 2011) Andújar, Dionisio; Escolà i Agustí, Alexandre; Dorado, José; Fernández-Quintanilla, César
A new approach is described for automatic discrimination between grasses and broad-leaved weeds, based on their heights. An ultrasonic sensor was mounted on the front of a tractor, pointing vertically down in the inter-row area, with a control system georeferencing and registering the echoes reflected by the ground or by the various leaf layers. Static measurements were taken at locations with different densities of grasses (Sorghum halepense) and broad-leaved weeds (Xanthium strumarium and Datura spp.). The sensor readings permitted the discrimination of pure stands of grasses (up to 81% success) and pure stands of broad-leaved weeds (up to 99% success). Moreover, canonical discriminant analysis revealed that the ultrasonic data could separate three groups of assemblages: pure stands of broad-leaved weeds (lower height), pure stands of grasses (higher height) and mixed stands of broad-leaved and grass weeds (medium height). Dynamic measurements confirmed the potential of this system to detect weed infestations. This technique offers significant promise for the development of real-time spatially selective weed control techniques, either as the sole weed detection system or in combination with other detection tools.