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Desenvolvimento de equipamento óptico para avaliação nutricional em plantas: aplicação na cultura do milho

Mon, 01 Jan 2024 00:00:00 GMT

Título: Desenvolvimento de equipamento óptico para avaliação nutricional em plantas: aplicação na cultura do milho Autor(es): Nogueira, Felipe Hermínio Meireles Abstract: The search for technologies that promote more sustainable and efficient practices is an increasingly important priority on the global agricultural scene. With this in mind, the use of spectroradiometry techniques to assess nitrogen concentration in maize crops has proved to be a promising alternative for conducting precision agriculture practices. In addition, the development of new instruments with optical sensors for agricultural applications has become increasingly important given the challenges of maintaining the sustainability of production systems. With this in mind, this work sought to improve elements of the use of MSPAT (Multispectral Soil Plant Analysis Tools) to determine reflectance. The improvements involved the development of a reference plate with sintered barium sulphate, new approaches using programming techniques, electronics and 3D printing. In addition, the performance of the optical instruments used to estimate leaf nitrogen in the maize crop was also assessed. With this in mind, an experiment was carried out in the experimental area of the Agricultural Electronics and Mechanisation Laboratory (LEMA), located at the Federal University of Ceará (UFC), with AG-1051 maize planted under treatments N0, N60, N90, N120, N150 and N180 (0, 60, 90, 120, 150 and 180 kg.ha-1 of N, respectively) with four replications, in two crop cycles and a Completely Randomized Design (CRD). The assessments took place during the V5, V10 and R2 phenological stages and were carried out using the MSPAT, SPAD and FieldSpec PRO FR 3 equipment. The spectroradiometer was used under the conditions provided by the dark-room of the UFC Geoprocessing Laboratory. The samples were then prepared for nitrogen (N) determination according to the methodology proposed by Kjeldah. In addition to leaf nitrogen, morphological parameters were also assessed throughout plant development, production, biomass and dry matter. The spectral indices (NRI, Normalise Ratio Index) were then correlated with the leaf N data and the individual bands were evaluated using Pearson's coefficient (r). Linear regression was then carried out (p-value < 0.01) with the NRI's to select the models, by optical instrument, that showed the best coefficient of determination (R²) with the leaf N data sets: i) at each stage of development, for the two crop cycles and ii) with the entire data set. Cross-validation (k-fold) was then carried out to assess the error parameters RMSE, MAE and adjusted coefficient of determination (R²adj.). The results for the best predictive models reveal different patterns for the selected bands between the data sets, as well as low generalisation capacity. However, it was possible to validate relevant models with MSPAT, SPAD and FieldSpec, which showed an R²adj. of 0.7871; 0.6959; 0.7199 and RMSE of 0.0425; 4.47; 0.0214 g.kg-1; respectively. From the model that showed the best performance with MSPAT, when using the NRI with the 900 and 560nm bands, the application in an agricultural area provided an RMSE of 2.73 g.kg-1 and MAE of 2.47 g.kg-1. However, it is clear that the use of new technologies has great potential for assessing leaf N in maize crops. Tipo: Dissertação

Avaliação do sensor de umidade S12 para arduíno no monitoramento automático da umidade do solo

Thu, 01 Jan 2026 00:00:00 GMT

Título: Avaliação do sensor de umidade S12 para arduíno no monitoramento automático da umidade do solo Autor(es): Cavalcante, Ruan Santana Abstract: Water is a fundamental abiotic resource for life on Earth, present in various human activities, especially in agriculture. Population growth has led to an increase in water demand, which has necessitated the implementation of new agricultural technologies focused on controlling and using water in a sustainable and improved way, with the use of water monitoring through soil moisture sensors. Arduino systems have been gaining popularity in the market and in scientific research related to agricultural engineering due to their operational simplicity and low cost, enabling the development of automated sensor systems for soil moisture monitoring. The objective of this study is to evaluate the potential performance of the corrosion-resistant Arduino soil moisture sensor model S12 by analyzing its response time compared to the response time of a properly calibrated neutron probe. The methodology consists of evaluating the response time of the Arduino S12 moisture sensor using a calibrated neutron probe as a comparison for soil moisture measurements. The variation in moisture readings made with the Arduino S12 sensor will be observed relative to those taken with the neutron probe within a tank system with soil, where the moisture and temperature of the soil are kept under constant control. Moisture measurements will be taken from saturation to the lowest moisture limit detected by the sensor, and from these data, the calibration curve and the response time curve of the sensor will be constructed and compared with the neutron probe's response time. The calibration curve of the Arduino sensor showed consistency with its linear behavior and a positive correlation between the measured soil moisture values and time, with a coefficient of determination of 0.98, a value within the acceptable range for the equation. Moreover, the results of the analysis of variance for the variation in soil moisture measured by the sensor and time showed no significant difference between measurements taken from different soil samples, which indicates good precision of the sensor for estimating soil moisture. Tipo: Dissertação

Produtividade e desenvolvimento do sorgo granífero sob diferentes manejos hídricos, adubação nitrogenada e inoculação com Bacillus aryabhattai

Thu, 01 Jan 2026 00:00:00 GMT

Título: Produtividade e desenvolvimento do sorgo granífero sob diferentes manejos hídricos, adubação nitrogenada e inoculação com Bacillus aryabhattai Autor(es): Rocha e Silva, Wevertonn Vasconcelos Abstract: Grain sorghum exhibits high adaptation to water stress conditions, making it a viable crop for semi-arid regions. The objective of two studies was to evaluate the development and yield of grain sorghum (cv. LAS 3004 G) under different water management strategies associated with nitrogen fertilization and inoculation with Bacillus aryabhattai. Growth and yield variables, such as stem diameter, plant height, panicle mass, and panicle length, were analyzed. The experiments were conducted in a greenhouse at the Federal University of Ceará, Fortaleza, Brazil. Two experiments were carried out in a randomized block design: Experiment I followed a 5x2 factorial scheme (five irrigation depths: 40, 60, 80, 100, and 120% of crop evapotranspiration (ETc); and two nitrogen application methods: conventional and fertigation, totaling 40 experimental units); and Experiment II followed a 5x2 factorial scheme (five irrigation frequencies: 1, 2, 3, 4, and 5 days based on daily ETc; with and without inoculation, totaling 40 experimental units). In Experiment I, results indicated that the 80% ETc irrigation depth was the most efficient, promoting growth similar to higher depths with lower overall water consumption. In general, higher irrigation depths reduced the crop cycle, anticipating flowering and harvest. There was no significant difference between nitrogen application methods for yield variables. In Experiment II, inoculation with B. aryabhattai shortened the crop cycle and mitigated the effects of water deficit, increasing panicle mass by 60.76% under the highest water restriction (5-day irrigation frequency) compared to the non-inoculated treatment. Higher irrigation frequencies (F1 and F2) significantly influenced the development and yield of the sorghum crop. The crop cycle was extended under conditions of lower water supply. Inoculation with Bacillus aryabhattai promoted increases in yield variables, especially under higher water stress conditions, indicating a mitigating effect Tipo: Dissertação

Erosividade da chuva na Bacia Experimental de Aiuaba, semiárido cearense

Wed, 01 Jan 2025 00:00:00 GMT

Título: Erosividade da chuva na Bacia Experimental de Aiuaba, semiárido cearense Autor(es): Silva, Mariana Gonçalves Vieira da Abstract: The study of rainfall erosivity is of great relevance due to its impacts on soil and the environment, especially in vulnerable regions such as the semiarid. However, there is a significant scarcity of erosivity data for areas like the Caatinga. This work aims to systematize disdrometer data, estimate kinetic energy, rainfall erosivity, and the raindrop drag coefficient in the Caatinga of the semiarid region of Ceará, particularly in the Aiuaba Experimental Basin. Erosivity was estimated based on the rainfall kinetic energy and the maximum intensity in 30-minute intervals, and compared with the erosivity factor equation of Wischmeier and Smith (1978). The development of a computational program enabled detailed analysis of disdrometer data and the calculation of erosivity for each rainfall event. The raindrop drag coefficient, a parameter required for calculating terminal velocity, remains unexplored in the Caatinga region. The results indicated that the measured kinetic energy was 1.9 times higher than that estimated by models and that the average rainfall erosivity was approximately twice as high as that obtained through the conventional method, highlighting the underestimation of erosive potential by the traditional model. The calibrated parameters for the monthly erosivity equation of the Caatinga resulted in higher values than those found for the temperate region of Brazil, confirming the need for regional adjustments. The findings of this research provide specific parameters for the Caatinga and may support improvements in models and the development of soil conservation strategies in semiarid areas. Tipo: Dissertação