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

2026-05-05T16:33:28Z

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

Crédito rural e mitigação climática: evidências do Programa ABC no Brasil

2026-08-12T19:32:38Z

Título: Crédito rural e mitigação climática: evidências do Programa ABC no Brasil Autor(es): Bezerra, Filomena Nádia Rodrigues; Lemos, José de Jesus Sousa; Silva, Vitor Hugo Miro Couto; Campos, Kilmer Coelho; Mendes, Fernando Antônio Teixeira Abstract: Traditional agricultural systems are challenged to reconcile productivity gains with multiple dimensions of sustainability, bringing to the forefront the effects of climate change. In this context, this article aims to measure the impact of the Low-Carbon Agriculture Program (Programa ABC) on the gross agricultural production value per greenhouse gas emission in Brazil. Additionally, it seeks to examine the level of credit distribution provided by this instrument across different Brazilian regions. The synthetic control method was employed for this purpose. The results showed that the impact of the ABC Program, measured by the gap between the treated unit (Brazil) and its synthetic control (Argentina, Australia, Canada, China, the United States, India, Indonesia, Mexico, and Thailand), during the intervention period (2010–2019), exhibited a positive effect on the analyzed indicator. It is evident that there was a concentration of rural credit allocation in the Center-West and Southeast regions, which received around 31.37% and 29.65%, respectively. In summary, climate policy design should prioritize farmers’ technical training and the dissemination of conservation, mitigation, and adaptation practices in regions that are most vulnerable to climate impacts. Tipo: Artigo de Periódico

Modelagem hidrológica da intermitência fluvial e do escoamento superficial em bacias da Amazônia Boliviana e dos Andes Equatorianos

2026-08-12T10:54:51Z

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

Governança de uma política pública emergente: um estudo avaliativo da estratégia nacional de economia de impacto (ENIMPACTO)

2026-08-05T15:38:17Z

Título: Governança de uma política pública emergente: um estudo avaliativo da estratégia nacional de economia de impacto (ENIMPACTO) Autor(es): Souza, Michelle Lima Ribeiro Moreira de Abstract: The impact economy has gained prominence as a new public agenda aimed at promoting solutions to social and environmental challenges through the articulation of the state, the market, and civil society. In Brazil, the National Strategy for the Impact Economy (Enimpacto) represents the main federal initiative oriented toward consolidating this field as an intersectoral public policy. Its trajectory, however, reveals both potentialities and fragilities, marked by institutional inequalities, difficulties in federative coordination, the absence of a unified legal framework, and disputes over the meaning of the term “impact.” This research aims to understand the political, institutional, and symbolic factors that shape the governance of Enimpacto, as well as the meanings attributed to the policy by different actors and the lessons derived from its trajectory. A qualitative and explanatory approach was adopted, based on content analysis of official documents and interviews with actors involved in the formulation, implementation, and monitoring of the policy. The findings indicate that the governance of Enimpacto still operates with low political and normative density, strong dependence on technical staff, and fragilities in federative coordination. They also reveal a mismatch between the discursive broadening of the policy and the persistence of recognition criteria anchored in business-oriented parameters, which restricts the access and legitimacy of peripheral, community-based, and territorially rooted initiatives. At the same time, the research shows that Northeastern states, especially Ceará, Rio Grande do Norte, and Alagoas, have played a relevant role in the territorial activation of the policy, functioning as spaces of institutional learning and federative innovation. It is concluded that strengthening Enimpacto depends on greater normative stability, broader social and territorial participation, revision of recognition criteria, and the construction of participatory and territorialized evaluation mechanisms. Tipo: Dissertação