Revista Engenharia na Agricultura - Reveng

Water balance estimate of beans using a dynamic systems model based on crop coefficient (Kc) variation

2021-01-07T11:23:52-03:00

The crop coefficient (Kc) is one of the most important parameters for studying the water balance, which aims to assess the relationship between growth and production dynamics and the management of water resources in irrigation systems. Thus, in this study, the effect of Kc variation on the water balance was evaluated throughout the bean crop cycle in Northeast Brazil, using a dynamic systems model. The effect of Kc variation scenarios on the water balance in the bean crop in Northeastern Brazil was simulated using the Vensim program. The soil water storage was used as state variable, input flow variable and outflow of water in the soil, and auxiliary variables that influence system flows were also considered. Thus, four simulation scenarios were performed changing values of the bean crop coefficient (Kc = 0.62; Kc = 0.72; Kc = 0.82; Kc = 0.92). The variation in soil water storage showed negative values in most phenological phases, showing significant differences between Kc conditions, depending mainly on the precipitation dynamics.

Performance of hydraulic ram built with different volumes of air chamber

2020-10-14T01:46:04-03:00

To capture surface water and groundwater, in most cases, electrical or fuel energy is required to drive a motor pump. This work aims to evaluate and compare the hydraulic characteristics of a hydraulic ram built with different volumes of PVC air chambers, according to its efficiency and economy. The study was developed at the Federal Rural University of the Amazon. Calibrated tanks and a stopwatch were used to obtain the supply flow, wasted water and repression volume. Four treatments were performed with 25% (125 L), 50% (250 L), 75% (375 L) and 100% (500 L) of raw material. For treatments with different volumes of air chambers, PVC tubes of 10, 20, 30, 40 and 50 cm in length were used. The experiment was a completely randomized design, carrying out the analysis of variance, Pearson correlation coefficient and the Tukey test for comparison among averages. There is a strong tendency to increase the repression volume and wasted when the volume of the air chamber is increased. The 0.250 L air chamber presented relevant results. In addition, it was demonstrated that with the increase in the volume of the air chamber, there was an increase in performance.

Phytoextraction and nutritional quality of forages cultivated in a constructed wetland system for wastewater treatment

2021-05-04T18:15:53-03:00

This study aimed to evaluate the effects of different concentrations of sodium on the phytoextraction of nutrients and nutritional quality of forages (P. purpureum Schum and C. dactylon Pers) grown in wetland system constructed for wastewater generated in cattle slaughterhouses (WGCS) treatment. The experiment was conducted in a randomized complete block design with three replications. The treatments were tested using 2 x 5 factorial scheme, as follows: two species of grass (P. purpureum Schum and C. dactylon Pers) and five concentrations of sodium in WGCS: 70, 100, 150, 200 and 250 mg L-1. The phytoextraction potential of nutrients and the nutritional quality of forages grown in pots simulating a wetland system constructed for WGCS with sodium concentrations were assessed in terms of the contents of the nutrients nitrogen, phosphorus, potassium, calcium, magnesium and sodium in leaf tissues. The accumulations of these nutrients in the produced forages were also evaluated. Both species presented different behaviors regarding their nutrient phytoextraction potentials. The nutritional quality was changed in the forages due to the cultivation in constructed wetlands. Forage C. dactylon Pers presented higher phytoextraction potential of sodium and potassium and P. purpureum Schum presented a higher nutritional quality.

Soybean yield in succession to single and intercropping corn and brachiaria and submitted to differents irrigation intervals

2021-01-20T08:01:14-03:00

The experiment was performed at a non-acclimatized protected screened environment. The objective of the study was to evaluate the influence predecessor crops of single and intercropping corn and brachiaria on soybean yield submitted to irrigation intervals. The experimental design adopted was in a split split-plot randomized block design with four repetitions. Two soil classes (dystroferric Red Latosol and dystrophic Red Latosol) were evaluated in the plots, three intervals between irrigations were used during the soybean flowering (each one day, two days and three days) in the subplots and three types straw in the crops autumn-winter (single corn, single brachiaria, intercropping corn and brachiaria) in the sub-subplots. The two soybean plants cultivated in polyethylene pots containing 20 liters of dystroferric Red Latosol or dystrophic Red Latosol corresponded to each repetition, according to the treatment. The irrigation intervals of three and two days, in dystroferric Red Latosol and dystrophic Red Latosol, respectively, with single brachiaria at the previous crop provided greater number and weight of pods, higher number of grains and higher soybean yield. Irrigation every three days with single corn at the previous crop in dystroferric Red Latosol and dystrophic Red Latosol, resulted in the lower soybean performance.

Can portable analyzers be reliable for biogas characterization?

2020-12-28T23:06:50-03:00

Anaerobic digestion for treatment of swine wastewater is an attractive alternative, among other aspects, for the generation of biogas. This gas is composed predominantly of methane and can be converted into electrical and thermal energy. However, the knowledge of the biogas composition is of paramount importance, especially regarding the methane content due to its energetic properties. The alternatives for this determination usually require high cost and specialized technicians. Therefore, the search for simple and low cost alternative solutions and techniques can improve the biogas use as an energy source and favor energy sustainability in pig farming. The present study aimed to compare the results of the methane composition of a portable analyzer with that of a Gasboard gas analyzer. The biogas was collected and characterized in a full cycle swine farm from January to December 2019 in the municipality of Teixeiras (MG), Brazil. The methane composition values did not differ statistically for a 5% significance level between the evaluated methods. The use of the portable kit is a simple and low cost alternative in determining the methane content in biogas and can be used reliably.

A A global overview of hydroponics: nutrient film technique

2021-04-28T22:40:15-03:00

Hydroponics is a cultivation technique without soil. There are several modalities for the system and among them is the Nutrient Film Technique (NFT), which consists of using channels to circulate nutrient solution intermittently. Due to the risks of soil and water contamination in metropolitan areas, this technique is a potential alternative to agricultural production in cities. The objective was to assess the panorama of the knowledge of the NFT system in the literature and the performance of various countries on it. For this purpose, a bibliographic survey was carried out from 2010 to 2019 on the international research bases Science Direct, Portal of Journals of the Coordination for the Improvement of Higher Education Personnel (CAPES) and Scielo, using the search terms “Hydroponics” and “Nutrient Film Technique Hydroponics”. There was an increase in the number of studies in the last four years of the analyzed period, from 2016 to 2019, thus representing an increase in interest in hydroponics, especially of the NFT type. This increase may be related to the efficiency and ease of handling of this system, productivity gains and the potential that the NFT has to reduce the carbon footprint. Thus, NFT is of great value in urban agriculture, especially in Brazil ? its biggest representative ?, with the potential to grow a lot in the future.

An approach to quality analysis, gap filling and homogeneity of monthly rainfall series

2021-04-26T21:44:20-03:00

The aim of this work was to propose a method for the consistency of climatic series of monthly rainfall using a supervised and unsupervised approach. The methodology was applied for the series (1961-2010) of rainfall from weather stations located in the State of Rio de Janeiro (RJ) and in the borders with the states of São Paulo, Minas Gerais and Espírito Santo with the State of Rio de Janeiro. The data were submitted to quality analysis (physical and climatic limit and, space-time tendency) and gap filling, based on simple linear regression analysis, associated with the prediction band (p < 0.05 or 0.01), in addition to the Z-score (3, 4 or 5). Next, homogeneity analysis was applied to the continuous series, using the method of cumulative residuals. The coefficients of determination (r²) between the assessed series and the reference series were greater than 0.70 for gap filling both for the supervised and unsupervised approaches. In the analysis of data homogeneity, supervised and unsupervised approaches were effective in selecting homogeneous series, in which five out of the nine final stations were homogeneous (p > 0.9). In the other series, the homogeneity break points were identified and the simple linear regression method was applied for their homogenization. The proposed method was effective to consist of the rainfall series and allows the use of these data in climate studies.

Effect of rainfall seasonality and land use on the water quality of the paraíba do sul river

2021-04-28T00:00:53-03:00

Monitoring water quality is important for the suitable management of water resources. Therefore, this study aims to assess the main water quality parameters and the National Sanitation Foundation-Water Quality Index (WQI_NSF) of four locations on the Paraíba do Sul River basin, in the state of Rio de Janeiro, influenced by different land use and land cover, and in the dry and rainy seasons. The following quality parameters were evaluated: total phosphorus (TP), nitrate (NO₃^-), dissolved oxygen (DO), potential of hydrogen (pH), turbidity (Turb), thermotolerant coliforms (Col), total dissolved solids (TDS), biochemical oxygen demand (BOD), water temperature (T_water) and air temperature (T_air). Statistical differences (p < 0.05) were observed between the dry and rainy seasons for the parameters: TP, Col, Turb, TDS, T_water, T_air, NO₃^-, DO, and WQI_NSF. The concentration of rainfall was effective in water quality parameters behavior. WQI_NSF was lower in the rainy season and possibly the runoff was the major cause of water quality degradation. Land use and land cover influenced the concentration of DO and Col and, consequently, WQI_NSF. Despite statistical differences, in most cases, the Paraíba do Sul River basin lies in medium water quality index according to the classification of the National Water and Sanitation Agency (ANA).

Production of eucalyptus seedlings using alternative substrates

2021-06-15T10:15:34-03:00

The efficiency of forest species production is associated with the seedlings quality. Hence, the substrate used is a determining factor in crop productivity, such as eucalyptus. Thus, the physical and chemical parameters of alternative and sustainable substrates were evaluated using coconut fiber and vermicompost in the production of Corymbia citriodora seedlings. Plants performance and quality were also evaluated by determining plant biomass and Dickson’s quality index, with or without mineral supplementation during cultivation. Results revealed that the proposed substrates obtained good physical and chemical characteristics when compared to a commercial substrate. The fertilization of seedlings showed to be essential in the production of more vigorous and better quality plants. The best quality C. citriodora seedlings was produced in the commercial substrate. However, it is worth highlighting the seedlings performance using alternative substrates such as coconut fiber and vermicompost, which represent a great potential for improvement, mainly due to its low cost and the observed result regarding the possible availability of nutrients in a gradual and constant way during the plants development.

Evaluation of the performance of covered lagoon digester in terms of the solids loading

2020-12-18T19:17:27-03:00

The use of anaerobic digesters to convert residual biomass for energy use and nutrient recovery has been increasingly indicated by the operational simplicity and added value of the treatment by-products. However, the levels of solids present in the influents to be treated directly influence the operation and management of the system. Thus, the objective of the study was to evaluate the performance of covered lagoon digesters in terms of the solids loading in the swine wastewater treatment system. The study was performed in a farm located in Zona da Mata Mineira. The monitoring took place from September 2018 to August 2019. The influent flow of waste was estimated based on the analysis of monthly water consumption on the farm. The collection and sampling took place weekly, the influents and effuents were analyzed in terms of the solids loading of total solids (TS) and volatiles solids (VS). The mean total flow distributed to the two digesters was 102.3 m³.d-1, with a mean hydraulic retention time (HRT) of 24.5 days. The results ranged from 1.14 to 2.83% for TS at the start of treatment. In most of the monitored months, anaerobic digesters were being fed with organic overload in terms of VS, which consequently affected the efficiency of the system, which were 33.6% for TS and 39.5% for VS.

Performance of two parallel covered lagoon digesters in the treatment of pig farm wastewaters

2020-12-18T19:12:00-03:00

Pig farming moves a large part of the Brazilian economy. However, due to the high polluting potential, alternatives to treat and take advantage of the effluents must be developed, being the use of digesters a possible solution. This study aimed to evaluate the performance of two parallel covered lagoon digesters (CLD) in the treatment of swine wastewater. Monitoring was performed on a farm installed in Teixeiras, Minas Gerais, Brazil, in terms of COD in the period from August 2018 to July 2019. The study demonstrated that COD removal efficiency in the CLD was 40.2 and 39.5%, which did not indicate a statistical difference at a 5% significance level. The two digesters in parallel were compatible with each other in terms of COD reduction. Furthermore, individually they did not present significant changes in their performance in the summer and winter periods.

Assessment of water availability in the period of 100 years at the head of the São Francisco river basin, based on climate change scenarios

2021-04-13T09:13:31-03:00

In the last century, changes in climate trends have been observed around the planet, which have resulted in alterations in the hydrological cycle. Studies that take into account the impact of climate change on water availability are of great importance, especially in Brazil’s case, where water from rivers, beyond being destined for human consumption, animal watering and economic activities, has a great participation in electricity generation. This fact makes its energy matrix vulnerable to variations in the climate system. In this study, a flow analysis for the head of the São Francisco river basin was performed between 2010 and 2100, considering the precipitation data of the CCSM4 climate model presented in the Fifth Assessment Report (AR5) from the Intergovernmental Panel on Climate Change (IPCC). Projections of future flow were performed for the scenarios RCP4.5 and RCP8.5, based on the SMAP rain-flow model, followed by a comparative analysis with the present climate. In general, we can observe that the decades of 2010 to 2100 will be marked by the high levels of precipitation, interspersed by long droughts, in which the recorded flow will be lower than the Long Term Average (LTA) calculated for the basin. Therefore, new management strategies must be considered to maintain the multiple uses of the basin.

Thornthwaite and mather soil water balance model adapted for estimation of real evapotranspiration of the pasture

2021-04-15T15:30:48-03:00

Determining the real water requirement for pastures is essential for the rational use of irrigation. The aim of this work was to assess the crop coefficient and performance of the Thornthwaite and Mather soil water balance (ThM) adapted to estimate the daily actual evapotranspiration (ETa) of a pasture in relation to the Bowen ratio - energy balance method (BREB). The experiment was carried out from July 2018 to June 2019 in Cachoeiras de Macacu, Rio de Janeiro State (RJ) (22º 27’S; 42º 45’W and 30 m altitude). Micrometeorological and meteorological measurements were conducted in a micrometeorological tower installed in the pasture and also in an automatic weather station, located 1 km from the pasture area. The ThM model was evaluated using linear regression between ETa determinate from BREB and the estimates from ThM using its coefficient of determination (R²) and the modified Willmott agreement index (dm). The ThM model underestimated (between 11 and 16%) the ETa for all seasons, except for spring, which overestimated by 1%. The highest precision and accuracy of the estimates were observed in autumn (R² = 0.84 and dm = 0.68) and spring (R² = 0.83 and dm = 0.82). In summer (R² = 0.56 and dm = 0.73) and winter (R² = 0.43 and dm = 0.66), the lower performance was caused by the inability of the model to represent water extraction from the soil in dry periods.

Can Digger Blades Wear Affect the Quality of Peanut Digging?

2021-02-19T11:12:59-03:00

Brazilian peanut harvests have been fully mechanized and are divided into two operations, namely digging and gathering. In both operations, losses are observed, and it is essential to avoid losses to maintain adequate machine maintenance. In this study, we aimed to quantify the interference of the harvesting period (morning, afternoon, and night) and wear of the digger-inverter mechanism (blades) on the loss indexes during the dig operation. The experiment was conducted in a commercial field using worn and new blades to dig peanuts at three different periods of the day. Losses were quantified by measuring data at 20 points, which were separated by 20 m for each treatment. The shift work did not interfere with peanut losses. However, the blade condition exhibited a strong influence on increasing the losses. Peanut growers can increase profits by up to 22% by reducing digging losses solely by periodically changing blades.

Performance of an agricultural engine using turbocharger and intercooler

2021-04-19T15:21:07-03:00

This paper aimed to evaluate the effects of air and fuel supercharging in an agricultural engine. The analyzed variables consisted of torque, power, and specific fuel consumption. Tests were carried out using a dynamometer through the power take-off of an agricultural tractor. The experiment was carried out at a laboratory in a completely randomized design arranged under a two-factorial scheme, with three replications. Six engine configurations (natural aspiration, natural aspiration + service, turbocharger, turbocharger + service, turbocharger + intercooler, and turbocharger + service + intercooler) and 10 engine speeds (1,200, 1,300, 1,400, 1,500, 1,600, 1,700, 1,800, 1,900, 2,000, and 2,100 rpm) were evaluated. The turbocharger alone did not increase engine torque and power. The increase in fuel flow enhanced engine performance for the evaluated configurations. Turbocharger + service and turbocharger + service + intercooler configurations reduced specific fuel consumption by up to 10% and increased torque and power by approximately 30% compared to the original configuration (natural aspiration).

Spatial variability of chlorophyll content in a Tifton 85 bermudagrass pasture in a tropical region

2021-05-30T10:10:47-03:00

Precision Agriculture techniques, such as the management of spatial variability of crop attributes, have been studied for several crops. However, few studies have been performed on Tifton 85 bermudagrass. Thus, this work aimed to analyse the spatial variability of chlorophyll content in a Tifton 85 bermudagrass production area, located in Seropédica, Brazil. A georeferenced grid was created to measure the chlorophyll content in two periods using a portable chlorophyll metre. Different geostatistical methods and models were evaluated in order to identify which had the best fit to analyze the spatial dependence of the chlorophyll content.The atribute was mapped based on interpolation by the ordinary kriging method. Therefore, kriging interpolation was used to create isoline maps, which were used to observe the spatial variability of the chlorophyll content. The methodology and maps generated proved to be of great value to the Tifton 85 bermudagrass producers.

Computational tool for selection and ranking of pull-type forage harvesters

2021-05-07T08:13:29-03:00

The variety of forage harvester models available in the Brazilian market demands practical tools for selecting and ranking this equipment. The present study aimed to develop an algorithm capable of providing simple and objective criteria that assist in decision-making for purchase. The communication channel of the companies was used to obtain technical specifications and the price of the equipment, which were tabulated in spreadsheets. The instructions for the manipulation of the obtained data were elaborated in the software R, with calculated ranks for the following requirements based on simulated information about a farm: price (PR), productivity and price relation (PROD.PR), fuel consumption (FC), operational comfort (OC), versatility (VERS), and overall (ALL). We obtained information from 45 models belonging to eight companies. The best machine in the overall rank (Cremasco Custom 950 C-III) was similar in the PR, PROD.PR, and FC ranks and the worst rank for OC. The algorithm established allowed the selection and ranking of the analyzed forage harvesters, providing simple, objective, and easily interpreted criteria for farmers’ use and the technicians who assist them.

Physiological quality of mechanically harvested chickpea seeds

2021-01-08T11:20:04-03:00

Our objective was to evaluate the occurrence of mechanical damage in chickpea seeds with the combination of two harvester speeds (2.5 and 3.5 km.h-1) and three adjustments for rotor rotation speeds (500, 700, and 850 rpm). Harvesting was carried out in a seed production field. Seeds were evaluated for purity, germination (G), first count (FC), germination speed index (GSI), hypochlorite, electrical conductivity, and tetrazolium tests. There was an effect of harvester speeds on seed physiological quality for the first count (FC), germination (G), germination speed index (GSI), especially when combining with high rotor rotation speed. In these cases, the speed of 2.5 km.h-1 resulted in lower values. This harvester speed also had worse results when combining with 850 rpm for purity and hypochlorite tests. The tetrazolium test was not efficient in identifying differences in seed quality. There was no significant interaction between harvester speeds and rotor rotation speeds for the conductivity test. Evaluating the harvester speed’s isolated effect (3.5 km.h-1), we identified problems in seed vigor due to the higher value of exudates in the electrical conductivity test. Low harvester speed (2.5 km.h-1) associated with high rotor rotation speeds (700 and 850 rpm) causes a reduction of the physical and physiological quality of seeds.

Modeling of technical, economic, environmental and ergonomic parameters of forestry machines in function of the quantity of days of the working scale

2021-02-18T10:02:28-03:00

Forest machine operators work on a long scale of work, which causes physical and psychological wear and consequently reduced productivity and increased fuel consumption. The objective of this research was to verify the influence of the number of days of the work schedule of harvester and forwarder operators in low-volume forest on technical, economic, environmental and ergonomic parameters. The research was performed in forest stands with an average wood volume of 0.10 m³ tree-1. In the first, second, third and fourth day of the work schedule, productivity, energy demand, production cost, carbon dioxide emission and the occurrence of fatigue in the operators were determined. The productivity values ??of harvester operators on the third and fourth days of the work schedule decreased by 2.62 and 7.74%, respectively, in relation to the average value of the first and second days. The productivity of forwarder operators was similar in the first three days of the work schedule, with a more marked reduction in the fourth day. The reduction in the number of days in the forest machine operators’ work schedule makes the operation more sustainable from a technical, economic, environmental and ergonomic point of view.

Intermittent temperatures in the conservation of ‘BRS Kampai’ peaches

2021-05-13T18:06:41-03:00

This study aimed at evaluating the quality of peaches borne by the cultivar BRS Kampai when cooled at intermittent temperatures throughout storage. They were stored at 1°C and relative humidity between 80% and 90% in a cold storage chamber. The following treatments were applied: T1 - fruit stored at 1±0.5°C; T2 - fruit stored at 1±0.5°C and increase in temperature every five days to 25°C; and T3 - fruit stored at 1±0.5°C and increase in temperature every seven days to 25°C. Fruit were submitted to increase in temperature when they were withdrawn from the cold storage chamber and kept in a heated room. Evaluations were conducted when fruit were harvested, after 10 cold storage days and 2 days of commercialization simulation at 25ºC (10+2) and after 20 cold storage days and 2 days of commercialization simulation at 25ºC (20+2). Peaches were evaluated in terms of mass loss, pulp firmness, soluble solids, titratable acidity, pH and epidermis color. T1 exhibited higher mass loss, higher soluble solid content and higher pulp firmness after 20 cold storage days, by comparison with the other treatments. T2 led to lower mass loss after 20 cold storage days than the ones of the other treatments. However, T2 also showed higher loss of pulp firmness in the same period. The use of intermittent temperatures throughout storage of ‘BRS Kampai’ peaches may be an alternative to extend their post-harvest period.

Mechanical properties of cowpea beans at different moisture contents

2021-04-19T14:08:07-03:00

Cowpea production has gained considerable ground in Brazil. Cowpea grain undergo different types of pressure and may crack and break during processing and storage, thus, there is a need to classify the mechanical properties of the beans. Therefore, this study aimed to evaluate the influence of the moisture content of cowpea beans on the maximum compressive force for fixed deformation and determine the proportional modulus of deformity under compression. The cowpea cultivars Novaera and Tumucumaque were evaluated at different moisture contents (0.12; 0.15; 0.18; 0.20; and 0.23 decimal d.b.). The experiment was arranged in completely randomized design for each moisture content and 10 deformation rates were applied (0.02; 0.04; 0.06; 0.08; 0.10; 0.12; 0.14; 0.16; 0.18; and 0.20 mm). The compression force was assessed using a universal testing machine and the proportional deformation modulus was determined. Following, hardness and elasticity of cowpea beans ??as a function of the moisture content were established. The compressive force required to deform cowpea beans decreases with increasing moisture content: between 2 and 105 N (Tumucumaque) and between 2 to 97 N (Novaera). The proportional deformation modulus of cowpea increased as the moisture content and deformation reduced, ranging from 4.9 x 107 to 31.9 x 107 Pa (Tumucumaque) and from 5.9 x 107 to 42 x 107 Pa (Novaera).

Numerical simulation applied to milk cooling

2020-09-13T23:31:50-03:00

A model is a representation of a real system that can be analysed and yield predictions under different operating conditions. The aim of this study was to model a milk cooling tank that cools milk to 4 °C to preserve its quality after milking at the farm. The model was developed and simulated using the software Ansys for finite element analysis. The results from the simulations were compared to experimental data. The model simulated milk cooling in the tank with an error lower than 2%, which is considered acceptable for numerical simulations. In other words, the model satisfactorily represents the real system. Thus, alternatives can be directly tested in the computational model to improve and optimise the milk cooling process and to better use the system without actually implementing them in the real system.

Quality of soy bean grain stored in bag silo

2020-12-10T15:16:25-03:00

Because of the rise in the use of bag silo in the last harvests due to the lack of static capacity in Brazil, the storage of grain in type of structure is currently seen as a solution to our storage deficit. Thus, the importance of maintaining the quality of grains for commercialization in these systems is considered. The objective of this experiment was to evaluate the quality of soybean grain stored in a silo bag, in the region of Dourados, State of Mato Grosso do Sul, Brazilian Central-West. The experiment was carried out in a cooperative, where soybean grain stored in silo bag are collected. The product had been received, processed at the end of the summer harvest and previously stored in metallic silos, and then transferred to the silo bags upon reception of the winter harvest. Thus, soybeans with an average water content of 11% w.b. were packed in bags composed of high-density polyethylene and hermetically sealed over a total period of 125 days, with collections of data on temperature and air relative humidity and grain sampling every 40 days. The collected samples were subjected to plant classification and analyses of water content, water activity, protein, lipids and color parameters were also performed. Na average rise of 5° C was observed in the temperature and 14% for air relative humidity which resulted in the of moldy and fermented grains after 125 days in the bags. The storage period factor was significant (p <0.05) in the variables of water content, color and oil. It was concluded that for soybeans the storage period in hermetic bags influences the quality of the grains and the internal environmental conditions in these structures are influenced by the convective microcurrents observed in the different positions inside the silo bag.

Production, chemical components, and content of bioactive compounds of strawberry cultivars

2021-05-13T18:11:05-03:00

There are only a few strawberry cultivars available in Brazil and all are imported from North America and Europe. Thus, the introduction of new materials and their evaluation under Brazilian environmental conditions is imperative. The objective of this study was to evaluate the production, chemical components, and concentration of bioactive compounds in strawberry cultivars under edaphoclimatic conditions in the municipality of Pelotas-RS. The experiment was conducted in the field with low tunnels in 2011 and 2012. The experiment in the field was arranged in a completely randomized design, with eight treatments (cultivars), four replications. Each plot consisted of nine plants. The experiment in laboratory was arranged in a completely randomized 8x3 factorial design (8 cultivars and 3 months of harvest) and 4 replications. The variables analyzed were fruit number and fruit mass per plant, production, yield, soluble solid content, titratable acidity, ascorbic acid, anthocyanins, phenolic compounds, and antioxidant activity. Cultivar and harvest month influenced acidity, and the contents of soluble solids, ascorbic acid, and bioactive compounds. Cultivar Camarosa showed higher production, and higher contents of anthocyanin, phenolic compounds, and soluble solids. Cultivars ‘Palomar and ‘Aromas’ stand out for the content of ascorbic acid.

Agronomic performance of Urochloa brizantha cv. Marandu cultivated in clayey and sandy soil submitted to water and nutritional management

2021-05-18T07:26:31-03:00

Water and nutrient supply, as well as the soil texture, are some of the challenges that affect forage yield. Therefore, the objective of this work was to evaluate the agronomic performance of Urochloa brizantha cv. Marandu cropped in clayey and sandy soil submitted to water and nutritional management, in the municipality of Rio Verde, State of Goiás. The treatments consisted of a combination of soil with two textural classes (clayey and sandy), two levels of fertilization (A1: 30; 7 and 36 and A2: 45; 10.5 and 54 NPK per Mg DM, respectively), and seven water depths (0%, 25%, 50%, 75%, 100%, 125% and 150% of the crop evapotranspiration (ETc)), in four replicates. Crop performance was evaluated using SPAD index, plant height, leaf length, leaf width, leaf/stem ratio, crude protein, neutral detergent fiber, and dry matter. The data were subjected to multivariate data analysis. The principal component analysis allowed to observe that the first principal component explained 68.94% of the data, being characterized for promoting the best crop performance in relation to leaf length and width, characteristics that reflect in the other assessed variables. Forage performed poorly in winter because of the limitation of the climatic conditions. A higher yield was observed in the dry matter submitted to depths greater than 100% of ETc, regardless of the soil texture and the level of fertilization.

Water stress in passion fruit cropping: an approach to its development

2021-05-15T16:13:41-03:00

In places with water restrictions, there is the occurrence of water stress, which compromises the entire cycle of passion fruit crop, causing damage to the vegetative and reproductive phase of the plant. Therefore, the objective of this work was to assess water stress in the passion fruit crop through an approach to its development. An experiment was carried out in May 2019 at São Paulo State University (Unesp), College of Agricultural and Technological Sciences located in the municipality of Dracena, State of São Paulo. The experimental design was completely randomized (DIC), in a 3x3 factorial arrangement, in which three passion fruit species were used: Passiflora gibertii; Passiflora foetida, and Passiflora edulis, interacting with three irrigation intervals, namely: 4, 8, and 12 days, with four replications, totaling 36 plots. It was found that the a 12-day interruption in the irrigation affects the growth of seedlings of different species of passion fruit, and the species P. gibertii has a growth rate higher than P. edulis and P. foetida. The species P. edulis showed lower contents of chlorophylls A, B, and total in relation to P. gibertii and P. foetida.

SPAD index and leaf pigments in cauliflower in different water conditions and silicon fertilization

2021-06-22T00:25:33-03:00

The measurement of leaf pigments using non-destructive methods can be influenced by water management conditions and the use of nutrients in cauliflower, not showing adequate correlations with chlorophyll contents. The objective of this study was to evaluate the correlation between the SPAD index and the pigment content in cauliflower leaves managed with different water conditions and the application of silicon (Si). The cultivation was carried out in a protected environment in the city of Maringá, Paraná State from October 2019 to March 2020. It was adopted a randomized block design, with treatments in a 3 x 4 factorial scheme, with three levels of water recharge (40; 70 and 100% of crop evapotranspiration (ETc)) and four doses of Si (0; 50; 100 and 150 kg ha-1), with four replications. Once plants showed developed inflorescence, the SPAD index was determined in the field and the levels of chlorophyll a, chlorophyll b, and carotenoids in the laboratory using leaves from the upper third. The correlation between water recharge and Si fertilization on the SPAD index was determined. The proportion of carotenoids in relation to total pigments was compared under different conditions. Correlation analysis was performed considering silicon fertilization, water recharge, leaf pigments, and the SPAD index. Silicon fertilization reduced the levels of carotenoids in addition to being related to chlorophyll a (100% of ETc) and chlorophyll b (70% of ETc). The correlation of the SPAD index with pigments is variable with the water condition of the crop, in a condition without water deficit, it is related to chlorophyll a and in a condition of 70% replacement of ETc, it is correlated with chlorophyll b.

Passion fruit production under different swine wastewater doses treated in a biodigester

2021-07-06T18:16:28-03:00

Soil fertilization using materials of animal origin, such as biofertilizers, is an important practice to maintain productive soil, as they provide beneficial effects on soil physical, chemical, and biological properties. This study aimed to evaluate the number of fruits, fruit mass, and yield of yellow passion fruits in the first year of cultivation with the application of swine wastewater (SW) treated in a biodigester. The experiment was set up at the experimental area belonging to IFCE Crato, CE, Brazil, with a spacing of 5.0 m between plants and 3.0 m between rows, using the espalier system of training and drip irrigation. The experiment was conducted in a randomized block design, with five treatments and four replications. Treatments consisted of five SW doses (D₁ = 0, D₂ = 0.50, D₃ = 1.00, D₄ = 1.50, and D₅ = 2.00 L plant^?1) applied at two phenological stages of the crop. The results were subjected to analysis of variance at a 5% significance, followed by the regression test. The increased SW doses influenced all the studied variables, following the linear and quadratic regression models, except for the mean fresh fruit mass. The highest yield was achieved with the highest studied dose, being an interesting alternative for recommendation to farmers in the region.

Development of soybean genotypes as a function of water availability and sowing seasons in Rio Verde, state of Goias

2021-04-16T10:04:13-03:00

Soybean crop yield is affected in the absence of favorable conditions for its complete development, and one of the most limiting factors is the water availability throughout the crop cycle. Therefore, the objective of this study was to evaluate the behavior of three soybean genotypes, in two sowing dates, during two harvests, in the city of Rio Verde, Stat of Goiás. Four experiments were carried out in a randomized block design, with four replicates in the 2018/2019 and 2019/2020 harvests. The variables analyzed in the experiment were plant height at maturity, days to maturity, and grain yield. The water balance in the soil considered the water storage of 46.8 mm. It was observed periods with greater water deficiency (53.5 mm) in the 2018/2019 harvest for all genotypes. In short, for genotypes with 100 to 110 days of the cycle, the sowing time that showed to be the most promising to obtain higher yields, was between October 20 and November 20, for genotypes with a cycle of 120 days. This range of adaptation becomes broader, mainly because these genotypes have a longer vegetative period, being, therefore, the period of least water requirement for the crop.

Influence of specific weight and wall friction coefficient on normal pressures in silos using the Finite Element Method

2021-05-25T16:19:38-03:00

The objective of this work was to develop models using the Finite Element Method (FEM) to assess the maximum normal pressures in the static condition in silos using different wall friction coefficient and specific weight of the stored product compared to the pressures obtained by the Eurocode 1, part 4. The geometries of the silos models were developed based on the dimensions of the experimental station at the Universidad de Leon (Spain). The material properties were obtained by Jenike shear cell tests and were used to generate the models by the MEF. 3D models were generated varying the friction coefficient (0.2, 0.4, and 0.6) and the specific weight (6; 7.5 and 9 kN / m3). It was verified that the models by FEM follow the theory of pressures in silos: normal pressures increase due to the increase in specific weight and decrease due to the increase in the friction coefficient. Moreover, the maximum normal pressure occurs at the hopper silo transition. The experimental pressures (FEM models) compared with Eurocode 1, part 4 allowed to validate the models developed, presenting trends of similar values to those found by the MEF. The experimental models demonstrated that the influence of the wall friction coefficient and specific weight significantly interferes with the pressures in slender silos.