Resumo -O objetivo deste trabalho foi mapear e avaliar a variabilidade espacial da condutividade elétrica do solo (CE), obtida por meio de sensor de contato de campo, num Latossolo Vermelho distroférrico, sob plantio direto de grãos, e relacionar a CE com os teores de argila medidos pelo método do densímetro, em amostras georreferenciadas de solo. As amostras foram coletadas numa área de 13 ha, por meio de uma grade de 40x40 m e de grades de 20x20 m, 10x10 m e 5x5 m. A continuidade espacial da CE e do teor de argila foi modelada com o uso de semivariogramas. A CE variou de 1,9 a 13,7 mS m -1 , com valor médio de 5,2 mS m -1 e coeficiente de variação de 48%. O mapa interpolado mostrou tendência de aumento da CE com o aumento dos teores de argila. Os coeficientes de determinação foram de 0,78 e 0,77 entre CE e teor de argila, camadas 0-5 e 5-10 cm, respectivamente. O mapa da CE reflete suficientemente a variação espacial dos teores de argila para uso na delimitação de zonas de manejo.Termos para indexação: geoestatística, granulometria, agricultura de precisão, sensores de campo. Electrical conductivity mapping in relation to clay of a Ferralsol under no tillage systemAbstract -The objective of this work was to map and evaluate the spatial variability of the soil electrical conductivity (EC), measured with a contact sensor in a Rhodic Ferralsol under no till grain crops. The values of soil EC were related to soil clay content, measured by the densimetric method in georreferenced samples collected at 0-5 and 5-10 cm, in a 13 ha field. Soil samples were collected using a 40x40 m grid and densed grids of 20, 10 and 5 m spacing. Spatial continuity of EC and of clay content was modeled using semivariograms. Soil EC ranged from 1.9 to 13.7 mS m -1 with an average of 5.2 mS m -1 and coefficient of variation of 48%. The kriged map of soil EC pointed out a tendency of increase where clay levels were higher. Determination coefficients between soil EC and clay content were 0.78 and 0.77, respectively for 0-5 and 5-10 cm depth. The EC map adequatly reflects the spatial variation in soil texture for establishing the limits of management zones.

O objetivo deste trabalho foi avaliar, com um sensor ótico ativo, o comportamento do índice de vegetação por diferença normalizada (NDVI - "normalized difference vegetation index"), nas culturas de trigo, triticale, cevada e milho. Cinco experimentos foram conduzidos no Paraná e São Paulo, com variação de classes de solo, doses e fontes de N, e variedades de trigo. As seguintes variáveis foram avaliadas: NDVI, teor de N foliar, matéria seca e produtividade das culturas. Análises de regressões foram realizadas entre as doses de N aplicadas e NDVI, teor de N foliar, matéria seca e produtividade. Análises de correlação entre as variáveis foram realizadas. O trigo, triticale e cevada apresentaram resposta às aplicações de doses crescentes de N, pelo aumento nas leituras do NDVI, no teor de N foliar e na produtividade. Medido pelo sensor ótico ativo utilizado, o NDVI apresenta alto potencial para manejo do N nas culturas do trigo, triticale e cevada, e baixo potencial para a cultura do milho. Há interferência das variedades de trigo nas leituras do sensor ótico ativo.

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The amount of energy required to produce a commodity or to supply a service varies from one production system to another and consequently giving rise to differing levels of environmental efficiency. Moreover, since energy prices have been continuously increasing over time, this energy amount may be a factor that has economic worth. Biomass production has a variety of end-products such as food, energy, and fiber; thus, taking into account the similarity in end-product of different crops (e.g.: sunflower, peanuts, or soybean for oil) it is possible to evaluate which crops require less energy per functional unit, such as starch, oil, and protein.This information can be used in decision-making about policies for food safety or bioenergy. In this study, 23 crops were evaluated allowing for a comparison in terms of energy embodied per functional unit. Crops were grouped as follows: starch, oil, horticultural, perennial and fiber, to provide for a deeper analysis of alternatives for the groups, and subsidize further studies comparing conventional and alternative production systems such as organic or genetically modified organisms, in terms of energy. The best energy balance observed was whole sugarcane (juice, bagasse and straw) with a surplus of 268 GJ ha −1 yr −1; palm shows the highest energy return on investment with a ratio of approximately 30:1. For carbohydrates and protein production, cassava and soybean, respectively, emerged as the crops offering the greatest energy savings in the production of these functional foods.Keywords: EROI, starch, oil, fertilizer, fiber, energy balance requirements by Brazilian agriculture is important to an evaluation of its sustainability. Based on this view, this study aimed to evaluate the energy embodied in 23 crops and assess how much energy is used in their production as well as the energy return, in order to direct subsidies in accordance with an environmental friendly and energy-saving policy that will secure the food supply in Brazil. Materials and MethodsEnergy flows of the following 23 crops were assessed: maize; wheat, cassava, potato, rice, bean, soybean (produced in two Brazilian regions: system 1 in the state of Paraná and system 2 in the state of Mato Grosso), peanut, sunflower, castor bean (comparing two systems, system 1 using low-level technology and system 2 a higher level of machinery and technology; and a third group comprising palm, lettuce, banana, onion, carrot, cucumber, bell pepper, tomato, cotton, eucalyptus, citrus, coffee and sugarcane. For this group, three scenarios of energy output flow (EOF) were developed: the first considering the production of juice only, the second juice plus bagasse, and third juice, bagasse and straw as output.From the utilisation point of view, there are basically two types of material flow: i) inputs applied directly, such as limestone, fertilizers, seeds and other chemicals used that carry with them amounts of energy for the production process and are currently in use in the fields; and ii) inputs applied indirec...

The development of low-cost miniaturized thermal cameras has expanded the use of remotely sensed surface temperature and promoted advances in applications involving proximal and aerial data acquisition. However, deriving accurate temperature readings from these cameras is often challenging due to the sensitivity of the sensor, which changes according to the internal temperature. Moreover, the photogrammetry processing required to produce orthomosaics from aerial images can also be problematic and introduce errors to the temperature readings. In this study, we assessed the performance of the FLIR Lepton 3.5 camera in both proximal and aerial conditions based on precision and accuracy indices derived from reference temperature measurements. The aerial analysis was conducted using three flight altitudes replicated along the day, exploring the effect of the distance between the camera and the target, and the blending mode configuration used to create orthomosaics. During the tests, the camera was able to deliver results within the accuracy reported by the manufacturer when using factory calibration, with a root mean square error (RMSE) of 1.08 °C for proximal condition and ≤3.18 °C during aerial missions. Results among different flight altitudes revealed that the overall precision remained stable (R² = 0.94–0.96), contrasting with the accuracy results, decreasing towards higher flight altitudes due to atmospheric attenuation, which is not accounted by factory calibration (RMSE = 2.63–3.18 °C). The blending modes tested also influenced the final accuracy, with the best results obtained with the average (RMSE = 3.14 °C) and disabled mode (RMSE = 3.08 °C). Furthermore, empirical line calibration models using ground reference targets were tested, reducing the errors on temperature measurements by up to 1.83 °C, with a final accuracy better than 2 °C. Other important results include a simplified co-registering method developed to overcome alignment issues encountered during orthomosaic creation using non-geotagged thermal images, and a set of insights and recommendations to reduce errors when deriving temperature readings from aerial thermal imaging.