http://repositorio.ufc.br/handle/riufc/108 2026-04-08T13:28:19Z 2026-04-08T13:28:19Z Silva, Francisco Mateus da Cunha http://repositorio.ufc.br/handle/riufc/85696 2026-04-07T18:46:23Z 2025-01-01T00:00:00Z

Título: Avaliação de fósforo em solos utilizando espectroscópia de reflectância e algoritmos quimiométricos Autor(es): Silva, Francisco Mateus da Cunha Abstract: Maintaining adequate phosphorus levels in the soil is a determining factor for plant development, influencing vital metabolic processes. Its determination through laboratory methods based on chemical extraction reagents not only generates waste but also makes these techniques costly and time-consuming, rendering their continuous and regular application unfeasible in many agricultural scenarios. This hinders the precise characterization of agricultural areas. The present study aims to evaluate the predictive potential of reflectance spectroscopy for quantifying available phosphorus content in soils, through the application of different chemometric algorithms and transformations of spectral reflectance data acquired by an optical spectroradiometer within the 350–2500 nm range, along with variable selection. For this research, 75 samples of a Neossolo quartzarenico and 75 samples of an Argissolo acinzentado were collected in the Baixo Acaraú irrigation district, and subsequently treated with 15 different concentrations of the commercial fertilizer MAP in 5 replications. For spectral data acquisition, the FieldSpec Pro FR 3 optical sensor was used. In addition to raw reflectance, spectral normalization, Savitzky-Golay filtering, and continuum removal were applied for qualitative and chemometric analyses. Available phosphorus content in the samples was determined using a UV/VIS spectrophotometer based on the Mehlich 1 extraction solution. For the calibration of the phosphorus prediction models, multiple linear regression (MLR), principal component regression (PCR), and partial least squares regression (PLSR) were employed, considering all wavelengths as predictor variables, along with variable selection via Stepwise-Forward. The results showed that spectral normalization combined with PLSR regression on the full spectrum (450–2450 nm) was the most efficient approach for predicting available phosphorus. In the combined RQO + PAcd dataset, R² = 0.95, RMSE = 12.75 mg kg⁻¹, and RPD = 4.31 were obtained; for RQO alone, R² = 0.95, RMSE = 8.30 mg kg⁻¹, and RPD = 4.66; and for PAcd, R² = 0.92, RMSE = 17.76 mg kg⁻¹, and RPD = 3.30 consistently outperforming the PCR models in all cases. Variable selection through correlation filtering and stepwise–forward reinforced the relevance of bands associated with organic matter (650–850 nm), iron oxides (850–900 nm), and 2:1 clay minerals (1400, 1900, and 2200 nm). After variable selection, model performance was heterogeneous and generally inferior to models calibrated with all wavelengths, with PCR outperforming the other regression methods and only the normalized model of the combined dataset achieving an excellent category with R² = 0.84, RMSE = 23.65 mg kg⁻¹, and RPD = 2.49. Tipo: Dissertação

2025-01-01T00:00:00Z Gomes, Israel Oliveira http://repositorio.ufc.br/handle/riufc/85695 2026-04-07T18:42:55Z 2026-01-01T00:00:00Z

Título: Impactos do descarte de efluentes da carcinicultura nas frações da matéria orgânica de solos de manguezais do semiárido Autor(es): Gomes, Israel Oliveira Abstract: Mangroves are highly important ecosystems and play a fundamental role in mitigating climate change, mainly due to their capacity to sequester carbon (C). However, the expansion of shrimp farming in estuarine areas has promoted significant changes in soil physicochemical conditions, with potential impacts on the dynamics and stability of organic matter. Therefore, this study aimed to evaluate the effects of shrimp farming effluent discharge in three impacted areas, in comparison with non-impacted sections of the same sites. Soils were analyzed to quantify total organic carbon (TOC), particulate organic carbon (POC), and mineral-associated organic carbon (MAOC), as well as to characterize the chemical composition of organic matter using diffuse reflectance infrared Fourier transform spectroscopy (FTIR-DRIFT). Recalcitrance indices and multivariate analyses were used to integrate the results and identify the main factors associated with the observed changes. The results indicate that impacted areas present lower TOC contents (21.66 g kg⁻¹) compared to non-impacted areas (23.16 g kg⁻¹), suggesting that the input of organic material and nutrients from shrimp farming enhances organic matter decomposition. However, a higher accumulation of particulate organic carbon was observed in impacted areas, especially in surface layers, confirming the input of recent and labile material. FTIR-DRIFT analyses revealed a reduction in aliphatic compounds and polysaccharides and a relative increase in aromatic and carbonyl groups, indicating faster degradation processes in impacted areas. Recalcitrance indices indicated lower carbon stability in impacted areas compared to non-impacted ones, with mean values for all combined fractions of 57.49% and 59.74%, respectively, confirming the intensification of mineralization processes associated with increased soil redox potential. It is concluded that shrimp farming alters the distribution and quality of soil organic matter in mangroves, promoting an increase in the labile carbon fraction without favoring its long-term stabilization in the soil. These results demonstrate that impacted mangroves are less efficient as carbon sinks, highlighting the need for management practices that consider not only carbon stocks but also soil conservation and ecosystem preservation. Tipo: Dissertação

2026-01-01T00:00:00Z Sousa, Bruno Eduardo Lopes http://repositorio.ufc.br/handle/riufc/85586 2026-03-31T16:37:01Z 2025-01-01T00:00:00Z

Título: Digestato de reator anaeróbio oriundo de resíduos alimentares como fonte de nutrientes Autor(es): Sousa, Bruno Eduardo Lopes Abstract: The improper disposal of food waste contributes to greenhouse gas emissions and the contamination of soil and water. One alternative to this issue is the treatment of such waste through anaerobic digestion, a process that generates biogas and a nutrient-rich by-product known as digestate, which has potential use as an organic fertilizer in agriculture. This project aims to evaluate the potential of digestate as a fertilizer for maize plants, seeking to reduce dependence on mineral fertilizers and improve soil properties. The hypothesis is that digestate derived from food waste can provide results comparable to mineral fertilization in maize cultivation. To test this hypothesis, a greenhouse experiment will be conducted at the Federal University of Ceará, using soil samples and digestate produced from food waste. The experimental design will be completely randomized, with six treatments and four replicates:T1: Control (no fertilizer), T2: 100% mineral fertilizer, T3: 75% mineral fertilizer + 25% liquid digestate, T4: 50% mineral fertilizer + 50% liquid digestate, T5: 25% mineral fertilizer + 75% liquid digestate, T6: 100% liquid digestate. Fertilizer dosages were defined based on the chemical analysis of the digestate, taking into account the availability of nitrogen, phosphorus, and potassium, and following agronomic recommendations for maize. The mineral fertilizers used were urea, triple superphosphate, and potassium chloride. Plant biometric parameters were evaluated, including height, number of leaves, and stem diameter. Dry and fresh shoot biomass were analyzed, as well as the chemical composition of macro- and micronutrients in the plants. Soil analyses included: pH, electrical conductivity (EC), phosphorus, calcium, magnesium, potassium, sodium, copper, iron, manganese, zinc, sum of bases, cation exchange capacity (CEC), exchangeable sodium percentage (ESP), sodium adsorption ratio (SAR), and potential acidity. Data were analyzed using multivariate techniques, including principal component analysis and ANOVA. Treatment means were compared using mean comparison tests, with analyses performed in SAS (Statistical Analysis System, 1995), considering a significance level of 5%. The results showed that treatments T2, T3, T4, and T5 promoted higher means for plant biometric variables, nutrient accumulation in plant biomass, and soil fertility. Treatment T4 (50% mineral fertilizer + 50% digestate) stood out by significantly increasing plant height (128.5 cm), representing an 83.57% increase compared to the control; it also promoted the largest stem diameter (21.72 mm), with a 125.78% increase compared to the control, and the highest number of leaves, with a 33.33% increase over the control. The combination of digestate with mineral fertilizers enhanced the availability of macro- and micronutrients, increasing their concentration in the soil without causing harmful sodium accumulation. Although treatment T6 (100% digestate) presented lower results compared to those with mineral fertilizer blends, it performed better than the control, suggesting its potential as a standalone fertilizer, albeit with reduced productivity. Partial replacement of mineral fertilizers with liquid digestate—especially in the 50% mineral fertilizer + 50% digestate ratio—proved effective for maize fertilization, providing agronomic results equivalent to or superior to conventional fertilization and offering environmental benefits by utilizing food waste. Tipo: Dissertação

2025-01-01T00:00:00Z Oliveira, Iana Maria de Souza http://repositorio.ufc.br/handle/riufc/85323 2026-03-13T14:02:45Z 2021-01-01T00:00:00Z

Título: Calagem e o crescimento inicial de pitaia vermelha (Hylocereus polyrhizus) propagada por sementes Autor(es): Oliveira, Iana Maria de Souza Abstract: The red pitaya (Hylocereus polyrhizus) is an epiphyte cactacea that has aroused great interest in the years due to its exotic appearance, peculiar flavor and nutraceutical qualities, in addition to the very attractive market price for rural producers. However, there are still few studies on the management carried out in the culture of pitaya. Liming is a relevant management, which should be studied since most of the Brazilian soils present an acid reaction, compromising the production of most crops. Thus, the objective of this work was to study the effects of liming on the chemical characteristics of the soil, on the morphological processes and nutritional status of red pitaya, propagated from seeds. The experiment was conducted in a protected environment and in the field, with the pots distributed according to the statistical design in randomized blocks, with five treatments (doses of limestone 0; 0.6; 1.2; 1.8; 2.5 t ha -1) and four repetitions. Each plot of the experiment consisted of two pots, for a total of 40 experimental units, one plant per pot. Throughout the period, experiments were carried out when evaluating the vegetative growth of the studied species in relation to biometric parameters. The study of contents and accumulation of nutrients in the aerial part of the plant was also carried out at the end of the experiment. The data were prepared for analysis of variance by the F test and regression analysis. Liming to increase pH and base saturation, as well as reducing aluminum saturation and adjusting the availability of nutrients. PH values between 5.5 and 6.0 and base saturation (V%) between 40 and 50% are considered adequate for the good initial development of the red pitaya. The biometric variables cladode diameter (DC), cladode thickness (EC), length of the root system (CSR), dry mass of the cladode (MSC) and dry mass of the root system (MSSR), increased positively, maximum values between the doses 1.0 t ha-1 and 1.5 t ha-1, this being the ideal range recommended to achieve the greatest growth of the plants. As for the nutrient content in the aerial part, the levels of N, P and Mg increased and Zn and Mn decreased in the plants, finding the following bands that feed the largest vegetative increments: phosphorus 9.4 - 10.0 g kg-1; magnesium 5.3 - 6.0 g kg-1; nitrogen 5.3 - 6.0 g kg-1; zinc 187.0 - 218.2 mg kg-1; manganese 162.0 - 177.0 mg kg-1. Liming contributed to the accumulation of macronutrients N, P, K, Ca and Mg and micronutrients Cu, Mn and Zn in the cladodes. Tipo: Dissertação

2021-01-01T00:00:00Z