Revista Engenharia na Agricultura - REVENG

Kinetics of drying in a Mentha crispa foam layer and adjustment of mathematical models

2023-01-05T10:35:12-03:00

Mentha crispa is a plant commonly used in folk medicine to treat illnesses and has wide industrial application. Dehydration has been used for several types of plants in order to reduce the levels of water content and water activity, so that it would allow na adequate storage due to the conservation of the active principles. The objective of this work is to investigate the process of drying mint in a foam layer. The foam was physically characterized in terms of density, expansion percentage, air incorporation capacity and stability. Drying was carried out according to a factorial experimental design, in which the input variables were: temperature (50, 60 and 70 °C), concentration of foaming agent (3, 5 and 7 %) and stirring time (3, 5 and 7 min); and the output variables were: drying time and water content (Xbs) of the product. The physical properties of the foam depended only on the foaming concentration. The rise in the temperature significantly reduced the drying time and the water content of the foam. The Page, Henderson & Pabis, Newton and Modified Page mathematical models were adjusted to the experimental data and Page’s model was the one that showed to be the most adequate to represent the drying phenomenon.

Interannual rainfall variability and soybean yields in Mata Roma municipality, Maranhão

2022-12-30T09:52:03-03:00

Among the activities affected by rainfall variability, agriculture is one of the most vulnerable. In this sense, this work aimed to relate the interannual rainfall variability with the soybean yields variability in Mata Roma municipality, Maranhão, considering dry and rainy events. For this, for the period from 2003 to 2019, data on average soybean yield and rainfall in this producing region, which is one of the main ones in the State, were analyzed. Monthly rainfall data for the period 1985-2019 were also analyzed and the dry and rainy events were identified in these two meteorological data series. The results showed that rainfall from January to May explains about 99%, on average, of the interannual variation of yields and that occurrence of dry and very humid periods disfavor the soybean crop, causing, in most cases, yields and productions far below the average for the study region. Based on the regression analysis, it was found that maximum average yield of 2942.52 kg×ha^?1 was reached with an average rainfall of 1709 mm.

Application for evaluation of the uniformity of systems of pressurized irrigation

2023-03-27T08:14:23-03:00

The evaluation and monitoring of the performance of irrigation systems are crucial in maintaining water efficiency and conservation of water and energy resources. Therefore, the objective of this study was to develop and validate an application for the coefficient of uniformity coordinators of pressurized irrigation systems. So, the UniIrrig® application was developed, using the integrated development environment Android Studio10 version 4.0.1, in JAVA language, with applicability in devices with the Android operating system. For quantitative verification, the same input values in the UniIrrig^® application were also inserted in Microsoft^® Excel 2010, in all uniformity conductors used in the application. For the qualitative analysis, together with the experience of the user, 68 students of the Agronomy course at the Federal University of Ceará (UFC) participated in tests in order to evaluate the perception of usability, design, usefulness, and general satisfaction of the tool. To validate the application in the field, a uniformity test was carried out on a center pivot in the municipality of Cascavel, Ceará state, with the aid of collectors (Kit Fabrimar) to deliver the applied depth and the consequent result of the distribution uniformity coefficient (DUC), of Hart (HDC) and weighted mean depth analysis. These values were compared to the results obtained in Microsoft^® Excel 2010. The dynamic analysis of the data evolved in “r”= 1, thus providing perfect adaptation between the results obtained by the application and by Microsoft^® Excel, finding an error equal to zero. In the qualitative assessment, 84.1% consider the application a good tool for coefficient determination. It is concluded that the UniIrrig^® application, designed for the Android operating system, can be used to quantify the assessed irrigation uniformity coefficients.

Evaluation of the antioxidant activity and total phenolic compounds of lychee pulp by different dehydration methods

2023-02-24T10:03:48-03:00

Fruits and vegetables are major sources of bioactive compounds included in human diet. The objective of the study was to evaluate the antioxidant activity and total phenolic compound content of lychee pulp. Hydroalcoholic extracts were obtained from the pulp (fresh, dried and freeze-dried), and analyzed by in vitro Folin-Ciocalteu, Fast Blue, ABTS⁺, Beta Carotene and Phosphomolybdenum Complex assays. The color and water activity of the pulp submitted to each dehydration treatment were also evaluated. The results obtained in the determination of total phenolic content did not differ statistically (p>0.05) between dried and freeze-dried pulp. The values obtained for the antioxidant activity by the ABTS⁺ method and by the phosphomolybdenum complex had a statistically significant difference. The data regarding the percentage of protection by the ?-Carotene/Linoleic Acid method showed that the dried pulp did not differ statistically from the fresh and freeze-dried pulp. However, the freeze-dried pulp presented higher antioxidant activity by the ABTS⁺ and Phosphomolybdenum Complex assays when compared to the other treatments (fresh and dried pulps).

Potassium adsorption on substrates formulated with vermiculite and peat

2023-03-30T08:16:23-03:00

The substrates composition can take place from different raw materials, being an influencer of the water and nutrient retention capacity, an important dynamic in the management of the cultivation in containers due to the possibility of nutrient leaching. It was aimed to quantify the Potassium adsorption to substrates with different proportions of vermiculite and peat, in addition to determining adsorption isotherms which would best fit the observed adsorption data, for contact periods of one and seven days. We carried out batch adsorption essays, using as an adsorbent media substrate prepared with different proportion of vermiculate and peat, and as adsorbate, solutions with concentrations of 0, 25, 50, 75 and 100 mg/L of K. The substrate that showed the highest adsorption capacity, then less leaching potential, was the one constituted with the largest amount of peat. The Freündlich’s isotherm best represents the K adsorption phenomenon in all the studied treatments.

Influence of maturity and harvest region on the chemical composition and physicochemical properties of oils derived from macauba fruits

2022-12-06T23:26:02-03:00

Macauba (Acrocomia aculeata) is a good source of vegetable oil in tropical America. Its fruits are highly suitable for biodiesel, cosmetics and food production owing to the high quality of its oil. However, the influence of maturity and harvest region on the quality of oils is not known. Thus, the chemical composition and physicochemical properties oils extracted from the macauba palm fruit at two regions of Minas Gerais and different maturity stage were investigated. C16:0 and C18:1 were the most abundant fatty acids in the mesocarp oil. C12:0, C14:0, C16:0, and C18:1 prevailed in the kernel oil. The High-Resolution Gas Chromatography analysis revealed triacylglycerols (TGs) with equivalent carbon numbers (CN) ranging between 28 and 54. TGs composed of long-chain fatty acids prevailed in the mesocarp oil (CN52 and CN54). On the other hand, the kernel showed a more complex lipid profile, containing TGs with CN between 30 and 54. The lipid content in the oils increased significantly with the ripening of the fruit and the harvest regions. Furthermore, changes in physicochemical properties were observed for both oils depending on the stage of maturity and harvest point. Macauba oils can be used in several industries, such as food and cosmetics. Thus, for its best use, the physicochemical properties of greatest interest should be evaluated in order to identify the ideal cultivation region and maturity stage.

Response of vegetative performance in soybean cultivars submitted to deficit irrigation

2023-04-10T16:17:55-03:00

Agricultural crops present phenological stages of less susceptibility to soil water deficit, in which the deficit irrigation management strategy can be used. In this context, the objective was to evaluate the influence of deficit irrigation management during different stages of development in three soybean cultivars in the edaphoclimatic conditions of the southern cerrado of Piauí. The research was conducted from September 2020 to January 2021, in the municipality of Uruçuí-PI (with geographic coordinates of 07º 13’ 46” S, 44º 33’ 22” W), under an experimental design of randomized blocks, in a split-plot scheme, where the treatments, composed in the plots, were defined according to the time of induction of the water deficit of 50% of the crop’s potential evapotranspiration - ETpc, via climate, in three soybean phenological stages (vegetative, flowering and production formation), and the subplots, were composed of three cultivars (FT 4191; FT 3181 and BG 478 IPRO), with three replications. In order to verify the effects of the imposed treatments, the following variables were evaluated: plant height, number of leaves and total dry mass of the aerial part. Variables were maintained for statistical analysis by Tukey’s test (cultivars) and Scott-Knott’s test (deficient irrigation treatments). The vegetative characteristics of the investigated soybean cultivars (plant height, number of leaves and shoot dry mass production) are drastically affected when the imposition of water deficit (50% of ETpc) is induced throughout the production cycle. Under such water conditions, the FT 4181 and 3191 IPRO cultivars stood out among the investigated cultivars, thus being identified as the most tolerant to reduced water availability in their different phenological stages.

Evaluation of soil and water loss under different soil covers

2023-03-09T10:55:36-03:00

The current hegemonic agricultural model, which is based on the green revolution, is intrinsically related to environmental and social impacts, such as erosion, desertification, and abandonment of agricultural areas. Thus, the objective of this study was to evaluate the loss of soil and water through runoff during a simulated rainfall event, testing the efficiency of different types of coverings on beds with watermelon crops, inferring that in relation to soil loss, this was greater in uncovered soil. Therefore, it should be observed that this work has applicability in the choice of efficient soil management techniques, to minimize the effects of erosion and, consequently, the environmental impacts as a result of agricultural activities. The results obtained showed a loss equivalent to 72.72% of the total for bare soil, which means a greater sedimentation of the soil, while for soils covered with corn straw and the biodegradable blanket, a loss of 19.70% and 7.58% of the total were observed, respectively. Surface water runoff, with the use of corn straw and the biodegradable blanket, was reduced by 81.22% and 67.42%, respectively. It was concluded that soil cover is effective in controlling water erosion.The current hegemonic agricultural model, which is based on the green revolution, is intrinsically related to environmental and social impacts, such as erosion, desertification, and abandonment of agricultural areas. Thus, the objective of this study was to evaluate the loss of soil and water through runoff during a simulated rainfall event, testing the efficiency of different types of coverings on beds with watermelon crops, inferring that in relation to soil loss, this was greater in uncovered soil. Therefore, it should be observed that this work has applicability in the choice of efficient soil management techniques, to minimize the effects of erosion and, consequently, the environmental impacts as a result of agricultural activities. The results obtained showed a loss equivalent to 72.72% of the total for bare soil, which means a greater sedimentation of the soil, while for soils covered with corn straw and the biodegradable blanket, a loss of 19.70% and 7.58% of the total were observed, respectively. Surface water runoff, with the use of corn straw and the biodegradable blanket, was reduced by 81.22% and 67.42%, respectively. It was concluded that soil cover is effective in controlling water erosion.

Classification of soybean pods using the deep learning techniques

2023-04-20T15:04:20-03:00

Crop productivity estimate aims at the economic definitions about crop, agricultural management, and land use, among others. However, it is common to observe the use of visual methods to estimate the productivity of the soybean crop through the classification of pods, resulting in a slow, costly method besides being susceptible to human errors. Thus, the objective of this work was to carry out the training of two deep learning methods to classify soybean pods according to the number of grains based on images obtained using a smartphone. Data collection was carried out at the Federal University of Viçosa (UFV). Data consisted of capturing images from a smartphone and training two deep learning models: Mask R-CNN and YOLOv4. To capture the images, the soybean pods were pulled from the plants and placed in a white-bottom container. This procedure occurred for each plant collected. Both models tended towards a better classification for the two- and three-grain pods, reaching a value of 90% for the F1 score metric. This fact may have occurred because of the greater amount of these two types of pods present in the chosen cultivars. Finally, the potential of using deep learning to classify soybean pods based on the number of grains was observed.

Effect of sodium chloride on germination and vigor of Cajanus cajan (l.) millspaugh seeds

2023-02-24T10:05:26-03:00

Cajanus cajan is used as fertilizer or as food for human and animal. Since salinization of soils is a worldwide problem, it is necessary to look for resistant species. Thus, this study aimed to evaluate the effect of NaCl on germination, emergence and vigor of C. cajan. Therefore, seeds of the pintadinho cultivar and five concentrations of NaCl (1.5; 3.0; 4.5; 6.0; and 7.5 dSm-¹) and control were used. A completely randomized design was performed with four repetitions of 50 seeds for each treatment. Data were submitted to analysis of variance, using the F test to compare mean squares, and the polynomial regression analysis for quantitative effects. The progressive addition of salt had no significant effect on germination and emergence of C. cajan seedlings, however it reduced its vigor.

Development and validation of cfd model for compost barn with artificial ventilation

2023-04-17T16:33:25-03:00

Computer simulation can provide reliable information about fluid flow behavior, including ventilation, in animal production systems. The ventilation system is essential for thermal conditioning, as it favors animal comfort and enhance productivity. The objective of this study was to develop and validate a CFD (Computational Fluid Dynamics) model to analyze the ventilation system in a compost barn. A mesh with greater refinement was used near the air inlet and outlet and the floor, that is, in these regions the mesh number of cells was larger, which makes a denser mesh. For the validation, data on air velocity were collected in the barn to compare with the results of the simulation. Dead zones of ventilation were identified in the barn, there was an increase in the average air velocity at the air outlet, and temperatures and air velocity were found below the optimal recommended by the literature. However, the adjusted model showed good fit with the values measured, indicating that is a good tool to predict the behavior of air velocity. In addition, the detection of ventilation dead zones inside the barn demonstrates the need for a supplementary ventilation system.

Esp8266 module use in animal production: a review

2023-04-04T14:58:54-03:00

The thermal environment in livestock buildings affects the productive and reproductive performance of animals. Therefore, monitoring thermal environment variables is necessary. This study reviewed the applicability of the electronic device ESP8266 module to monitoring animal production. The ESP8266 module is a microcontroller that enables the collection, storage and transmission of data that influence livestock production. The data collected are transferred to cloud computing systems allowing the development of supervisory systems that can be accessed by smartphones, tablets or computers. With this type of microprocessor, it is possible to develop autonomous management systems for animal production. Connected devices using the internet of things, artificial intelligence, machine learning and blockchain will facilitate the analysis of data from the production chain and the appropriate decision-making. Managers of livestock production systems will be in charge of following up and monitoring the processes.

Spatial variability of soil physical attributes under conservation management systems for sugarcane cultivation

2023-05-10T07:14:43-03:00

Conservation systems for soil management are increasing for sugarcane cultivation. However, there is still little information about the effects of this management on soil physical quality at different scales, fundamental to agricultural activity sustainability. The objective was to evaluate the variability and spatial dependence of Oxisol physical attributes under no-tillage and reduced-tillage in sugarcane cultivation. Undeformed soil samples were collected 45 days after sugarcane planting, using a regular mesh with intervals of 7.5 m, totaling 32 points in each tillage system. Soil density, resistance to penetration, total porosity, macroporosity, and microporosity were determined in two depths (0-0.10 and 0.10-0.20 m). Using geostatistical methods was verified in both tillage systems that spatial dependence in the two depths, prevailing in the layer 0.00-0.10 m, in no-tillage, strong dependence with the adjusted spherical model reduced preparation, moderate dependence, with exponential adjustment. In the 0.10-0.20 m layer, spatial dependence was an inversion and adjusted model, i.e., in no-tillage, there was moderate dependence, exponential adjustment, reduced preparation, strong dependence, and spherical adjustment. Linear correlations demonstrate how much soil physical attributes are related to management conditions and present behaviors like isoline cartogram.

Disease detection in citrus crops using optical and thermal remote sensing: a literature review

2023-05-17T11:09:37-03:00

Brazil stands out in the international citrus trade, especially due to its oranges, having produced around 16 million tons in 2021. However, productivity could be increased with greater control of diseases such as greening, which has spread around the world and leads to the total loss of affected trees. Given this scenario, it is necessary to perform fast and accurate detections in order to better manage actions and inputs. Since remote sensing is a pillar of digital agriculture, a literature review was carried out to analyze the use of optical and thermal sensors for the detection of diseases that affect citrus groves. For this purpose, the international databases Scopus and Web of Science were used to select references published between 2012 and 2022, resulting in twelve studies — most from China or the United States of America. The results showed a prevalence of methodologies that combine bands and spectral indices obtained through the use of multispectral and hyperspectral sensors, predominantly on board unmanned aircrafts (UAVs). Machine learning (ML) and deep learning (DL) classification algorithms produced good results in the detection of citrus groves affected by diseases, mainly greening. These results are affected by the stage of the infection, the presence or absence of symptoms, and the spectral and spatial resolutions of the sensors: the Red-Edge band and data with higher spatial detail result in more accurate classification models. However, the analyzed literature is still inconclusive regarding the early detection of infected plants.