http://repositorio.ufc.br/handle/riufc/68 2026-08-14T00:45:17Z http://repositorio.ufc.br/handle/riufc/86124 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 2024-01-01T00:00:00Z http://repositorio.ufc.br/handle/riufc/87458 Título: Modelagem hidrológica da intermitência fluvial e do escoamento superficial em bacias da Amazônia Boliviana e dos Andes Equatorianos Autor(es): Moran, Arianna Elizabeth Sotomayor Abstract: Water availability has been studied at increasingly detailed scales, especially in water-scarce regions, with less focus on humid and subhumid areas, particularly in South American countries. Andean watersheds play an essential role in regulating the regional hydrological cycle, providing water for human consumption, irrigation, hydropower generation, and ecosystem maintenance. However, limited data availability and insufficient hydrological monitoring still pose challenges to understanding runoff dynamics in these regions. In this context, the development of distributed and semi-distributed hydrological models has expanded the ability to represent the processes that control the hydrological behavior of watersheds. Among these models, the Soil and Water Assessment Tool (SWAT) stand out, as it allows for the simulation of water resource dynamics at different spatial and temporal scales, taking into account the influence of environmental characteristics and changes in the hydrological system. Thus, this dissertation uses hydrological modeling to investigate different aspects of runoff dynamics in Andean watersheds in Bolivia and Ecuador, ranging from the characterization of intermittency in small-scale sections to the representation of the hydrological response at the watershed scale. The thesis is structured into two main chapters, in which the objectives were: i) to capture and simulate flow intermittency patterns in a Bolivian Andean watershed, the Upper Rio Chico, using the modified Soil and Water Assessment Tool (SWAT-k); ii) to evaluate the SWAT model’s ability to simulate surface runoff in the Echeandia River basin (Ecuadorian Andes), with special emphasis on the representation of peak events. The results from the Upper Rio Chico indicated that the SWAT-k model was able to represent the intermittency patterns of surface runoff and the low-flow conditions observed during the study period, while also reproducing the seasonal dynamics of river runoff and medium- to low-flow conditions. Regarding SWAT’s ability to simulate surface runoff dynamics, the model systematically underestimated flow events in the Echeandia River watershed during the validation period, indicating limitations in representing rapid hydrological responses characteristic of small Andean watersheds. Tipo: Tese 2026-01-01T00:00:00Z http://repositorio.ufc.br/handle/riufc/87368 Título: Caracterização dos acidentes envolvendo máquinas, implementos e ferramentas agrícolas em assentamentos rurais no Estado do Ceará Autor(es): Maciel Neto, João Pereira Abstract: Safety in the workplace is often neglected in the cities, even occurring periodic inspections and enhanced this lack in agricultural areas, where often because of the difficult access and long distances, do not occur to the inspections. In rural settlements which are areas of agricultural production, which aims to the reorganization of land use or the search for new social standards in the organization of the agricultural production process, require such review due to provide security for activities performed. In this group of workers, seated lacks technical support and training because of the use of agricultural machinery and implements in order to avoid accidents. The objective was to characterize and quantify the accidents in the use of agricultural machinery (tractor, disintegrating forage, chainsaw, etc.) and tools: hoe, sickle, knife, among others, in rural settlements in the state of Ceará. The data collection method is through questionnaires and interviews with the settlers. The collected data will be tabulated and analyzed using the chi methods - square, descriptive analysis and contingency table. We interviewed 88 settlers in twenty-two settlements located in the cities of Caucaia, Pentecoste, Ocara, Umirim, Tururu, Canidé, Granja, Uruoca and Senador Sá. There was then a male relative frequency of 73% in agricultural work and in relation to schooling, among men and women, 20% were illiterate and 50% have not completed elementary school, which hinders the implementation of training. Of the respondents 80% have not gone through any instruction on how to operate the machines or agricultural tools, having been passed on the knowledge acquired by the most experienced of the group. Regarding the use of individually PPE protective equipment, 77% did not use it and the other did incomplete, despite being in dangerous activities. The most common accidents focused on disintegrating machine fodder (39%), followed by manual instruments. It follows, therefore, that there is need for a critical look at the agricultural work in rural settlements, which use machinery, equipment or tools, due to the occurrence of many accidents arising from lack of training and not follow in the use of the responsible agencies. Tipo: Dissertação 2015-01-01T00:00:00Z http://repositorio.ufc.br/handle/riufc/87289 Título: Reserva explotável e modelo de otimização para alocação de água em aquífero aluvial no semiárido brasileiro Autor(es): Costa, Antonia Thayna Sousa Abstract: The Northeast region of Brazil has faced long periods of drought, resulting in the depletion of surface water reserves. Given this scenario, groundwater sources, especially in alluvial aquifers, have become vital to support agricultural activities, particularly in areas with public irrigation projects, such as the Morada Nova Irrigation Project (PIMN) in the state of Ceará. In view of this problem and considering the potential risks of overexploitation of this resource, the overall objective of this study was to obtain an optimal agricultural exploitation plan for the PIMN, with the main constraint being the annual exploitable water reserve of the alluvial aquifer. Specifically, the research had the following objectives: to calculate the annual exploitable water reserve of the alluvial aquifer in the PIMN section; to perform an economic analysis of shrimp farming based on the profitability indicators of the investment analysis; to generate a linear programming model with the objective function of maximizing the net revenue of the PIMN. The model was solved using the LINDO (Linear Interactive and Discrete Optimizer) computer program, which solves systems of linear equations using the iterative “revised simplex method” algorithm. The exploitable reserve was calculated based on the variation in the potentiometric surface between the end of the dry season and the end of the rainy season, a period in which the maximum recharge of the aquifer is observed, either through rainfall and/or river-aquifer interaction. The results of the research led to the following conclusions: The groundwater reserves of the alluvial aquifer in the PIMN are quite significant, but the aquifer is overexploited due to the high-water demand of shrimp farming, an activity that has grown exponentially. Shrimp farming proved to be economically viable at a real annual interest rate of 12% and a return on invested capital in the third year, standing out as the most profitable activity and accounting for 96% of total annual net revenue. The area occupied by shrimp farming in the PIMN in 2024 already exceeded the area limit suggested by the optimal occupation plan by 13.3%. Water insecurity signals risks in the economic dimension, as a 40% reduction in water availability leads to a reduction in net revenue of nearly 50% Tipo: Dissertação 2026-01-01T00:00:00Z