Scielo RSS <![CDATA[Engenharia Agrícola]]> vol. 36 num. 5 lang. en <![CDATA[SciELO Logo]]> <![CDATA[Zoning of environmental conditions inside a wean-to-finish pig facility]]> ABSTRACT Using geostatistics, this study aimed to analyze environmental conditions for wean-to-finish swines at 3 pm, during the most sensitive phases to thermal stress (growth/ finishing and finishing). To this end, dry-bulb temperature, relative humidity, air speed, ammonia and carbon dioxide concentrations were measured at 81 equidistant points within the barn. Descriptive statistics was used to classify attribute variability, generating mean, median, variation coefficient, asymmetry and kurtosis, through the normality of Kolmogorov-Smirnov (KS). For that, it was used Minitab 15 software. Moreover, semivariograms were used to assess spatial dependence using the GS+ software, and through Surfer, spatial distribution maps were designed. Dry-bulb temperature and relative humidity showed a more homogeneous distribution whether compared to the other attributes. Furthermore, critical points were observed within the facility, with temperatures and low humidity, indicating the need for fogging equipment and fans to improve thermal comfort and animal welfare. <![CDATA[Clones, substrates and environments for seedlings of rubber tree rootstocks]]> ABSTRACT The objective of this study was to evaluate the growth of rubber clones GT1, PR255, RRIM600 grown on different substrates and environments for the production of rubber rootstocks. The experiment was conducted at the Universidade Estadual de Mato Grosso do Sul, Cassilândia University Unit, in Cassilândia-MS. The treatments were conducted in 3 environments: (A1): Sombrite®; (A2) Aluminet® and (A3) full sun, where the clones being tested were: GT1; PR 255 and RRIM 600, grown in substrates: pure soil; soil + cattle manure and commercial substrate usually used for forestry. The experimental design was a randomized block in a factorial 3 x 3 (three substrates x three clones), with 4 replicates with 10 seedlings of rubber trees per plot. The use of commercial substrate and soil + cattle manure in the ratio (7:1) favored the development of rubber rootstock seedlings with taller plants, more leave number, higher mass and higher quality index. For the formation of rootstocks, the variety RRIM600 was the one that showed better agronomic characteristics in the formation of rubber tree seedlings, with higher number of leaves, tallest plants, larger mass and higher quality index. The use of Sombrite® and Aluminet® screens contributed positively to the formation of rootstocks with larger root and above-ground masses. The plants produced in the Aluminet® screen showed higher number of leaves. <![CDATA[Determination of thermal comfort zone for early-stage broilers]]> ABSTRACT Environmental temperatures currently considered within comfort zone for broiler rearing may be misleading or even obsolete from actual values. Some factors such as animal genetics, nutrition and poultry management, mainly acclimatization to tropical and subtropical conditions, influence in determining the comfort zone for birds. This study aimed to evaluate the effects of five different thermal environments on animal welfare and rearing performance of broiler chickens, setting an ideal temperature range (comfort zone) for each of the first three weeks of poultry breeding. The chicks (375) were randomly placed into five climatic chambers set to distinct thermal conditions, being: one as recommended by the literature, another as stated by Cassuce and the other three at different levels of apparent cold stress (mild, moderate and severe). The findings showed that best poultry performance and ideal comfort indices (based on Black Globe Humidity and Temperature Index) were achieved within a temperature range between mild cold and Cassuce comfort temperature, rather than those previously reported in the literature. <![CDATA[Computational Fluid Dynamics (CFD) simulating heated air from wood burning inside a poultries barn]]> ABSTRACT Animal welfare is essential for livestock yield gains, which has been ethically justifiable and socially acceptable. Thus, our research aimed to test computational fluid dynamics model (CFD) to simulate heated air within a poultry barn. Data were simulated in CFD software based on Navier-Stokes equations (geometry of 3 m x 6 m, considering a symmetric mesh). As boundary conditions, a temperature of 38ºC was considered for walls where heating pipe outlets are, to the west side, besides a heat flow of zero, in symmetry to the same side. As for the sides east, south and north, walls were taken as isolated, i.e. heat flow equals to zero. The aviary heating system did not achieve a homogeneous temperature distribution, heat flow, heated air pressure and speed. Heated-air convection cells were spotted in the upper part of the building, being little used for thermal comfort by the birds. <![CDATA[Heat pump for thermal power production in dairy farm]]> ABSTRACT Besides cold for milk cooling, dairy facilities need to produce hot water for cleaning of tools and equipment. Overall, ohmic heating has been used in dairy farms, increasing power consumption and manufacturing costs. Therefore, as an alternative to reduce power consumption, this paper proposed a water-water heat pumping for simultaneous cold and heat generations. Accordingly, operational tests were performed with three heat-pump prototypes designed for dairy farms, in both laboratory and field levels. At laboratory, tests were carried out using electricity and CNG to define a coefficient of performance (COP). Biogas tests were performed in the field to measure its consumption. CNG average consumption was of 1.118 m3/ h, while biogas consume was of 2.02 m3 / h. COP averages of CNG driven pump were 0.20 for cooling, 0.39 for heating, and 0.59 for global. For electric-power driving, COP values were 1.75 for cooling, 2.25 for heating, and 4.00 for global. In addition to evaporating and compensating temperatures, engine rotation was one factor of influence on heat-pump performance. <![CDATA[Enhancing the analytical capacity for biogas development in Brazil: assessment of an original measurement system for low biogas flow rates out of agricultural biomass residues]]> ABSTRACT This study presents a comparison of two systems for measuring low-flow biogas production rates. Grass silage was used as substrate in the experiment. Measurements were made by using (a) manual readings and (b) an automated system. The automated system proved to be efficient as it allowed readings of the biogas flow rates in real time. Results were stored in a computerized system with a safe access interface to download the recorded data at any desired moment. Furthermore, the systems also minimized the error rate in comparison to the manual method. <![CDATA[Association of swine wastewater and mineral fertilization on black oat production]]> ABSTRACT Swine wastewater (SW) has high organic load, becoming an important source of macro and micronutrients to plants, promoting the improvement of soil quality and development in various cultures. However, when done without agronomic and environmental criteria, it can cause soil problems, nutrient leaching, water resource damage and plant toxicity. The objective of this study was to evaluate the soil chemical properties and the leachate in face of the association of swine wastewater and mineral fertilization (MF) in oat cultivation. An experiment in drainage lysimeter was carried out, using SW applications associated to MF or not, where treatments consisted of doses of 0, 100, 200 and 300 m3ha-1 with the absence or presence of MF, under field conditions. We concluded that swine wastewater provided significant increases in sodium, copper, zinc, and nitrite + nitrate as well as pH and calcium reductions in the soil; and in the leachate, significant increase in sodium. Moreover, the use of mineral fertilizer comprising nitrogen, phosphorus and potassium induced a significant increase in phosphorus, potassium and electrical conductivity and a significant reduction in magnesium in the soil; however, in the leachate, electrical conductivity was increased. <![CDATA[Irrigation management influence and fertilizer doses with boron on productive performance of cauliflower]]> ABSTRACT In order to provide scientific information about the irrigated cauliflower production in Northeast of Para, an experiment was installed in the Federal Rural University of Amazonia farm with the Desert hybrid under different water tensions on the ground and boron doses in the municipality of Igarapé-Açu – PA. The experimental design was a randomized block in a 4 x 4 factorial, sixteen treatments with three replications. The treatments consisted of four water tensions on the ground (15, 30, 45 and 60 kPa) as an indicative of the time to irrigate and four boron doses (0, 2, 4 and 6 kg ha-1). The irrigation was performed with drippers and irrigation management with tensiometers. Each plot, 4 m2, consisted of 8 plants located in the spacing of 1.0 m between lines and 0.5 m between plants. The hybrid is promising for cultivation in the soil and climatic conditions of the region where it was evaluated, with productivity of 17.1 t ha-1, fresh mass of the inflorescence of 0.85 kg plant-1, inflorescence diameter of 18 cm, in 38 kPa tension. The optimal dose of boron which ensured greater production of dry mass was 3 kg ha-1. <![CDATA[Degradation of sewage sludge compost disposed on the soil]]> ABSTRACT This study aimed to monitor degradation of compost from undigested sewage sludge disposed on soil surface or incorporated it. The sewage sludge was blended with wood sawdust during a 90-day composting to achieve a C/N ratio of 9. Each waste was dosed based on its total content of nitrogen and on an annual dose of 500 kg ha-1, which is broadly recommended for forage fertilization. After incorporation and surface applied (five replicates each), waste mineralization was monitored for 131 days by samplings taken from both conditions for further analyses. The samples were measured for total organic carbon (TOC); easily oxidizable carbon (OOC); total nitrogen (TN); ammonia and nitric nitrogen, and from them the total organic nitrogen (ON); volatile solids; and water content. The findings pointed to a decrease in TOC, OOC and ON contents throughout monitoring, regardless of disposal method, however, most remarkable whether incorporated to the soil, computing mineralization rates above 87%. <![CDATA[Extrapolation of regionalization equations for long-term average flow]]> ABSTRACT Knowledge about long-term average flow is essential for planning and managing water resources because it represents the potential water availability. One technique used to determine streamflow is regionalization, but because most gauge stations normally are associated with large drainage areas, the extrapolation of regionalization equations does not accurately represent the water availability; therefore, this method is not recommended. The main objective of the present paper is to propose a new method of estimating water availability that minimizes the risks of extrapolating regionalization equations for long-term average flow. The method is based on the use of a threshold value of the runoff coefficient to obtain the long-term average flow at the positions of the basin where the runoff coefficient estimated by the regionalization equation exceeds the threshold value. It was found that values of the runoff coefficient estimated average flows greater than twice those of the threshold values. The use of this method allows a reliable estimation for long-term average flows in regions of extrapolation without compromising the security of the available water supply. <![CDATA[Sowing performance by a metering mechanism of continuous flow in different slope conditions]]> ABSTRACT One of the reasons for the success of a productive culture is the correct sowing. Therefore, the seeds must be properly dosed, deposited and not damaged by the metering mechanism of the seed drill. So, the aim of this study was to evaluate in a simulator the sorghum seed deposition by a metering mechanism with continuous flow in different conditions of slope and sowing speed, and evaluate the quality of the deposited seeds assessing mechanical damage and germination. The experiment was carried out at the College of Agricultural Sciences, UNESP in Botucatu-SP, being used a simulator equipped with seed metering mechanism of helical channelled rotor type. The experimental design was randomized in a 3 x 2 factorial arrangement with six replications. The factors were three lateral slopes drill, 3%, 8% and 16%, and two sowing speed, 4 and 10 km h-1. For the damage and germination variables we added a control treatment whose seeds were evaluated without being distributed by the metering mechanism. The results indicate that increasing the lateral slope and working speed reduce the rate of seed deposition. The metering mechanism provides mechanical damage and contributes to the reduction of seed germination. <![CDATA[Fuzzy control applied to an electrical power generation system mounted on tractors for driving of agricultural implements]]> ABSTRACT The demand of the agricultural sector for more operationally efficient machines and implements motivated the development of alternatives for driving of this equipment. Aiming an electrical supply to apply in agricultural implements, this study proposes a system that uses the tractor power take off to activate a synchronous generator, using a fuzzy logic controller designed to regulate the generated voltage level. Different control architectures were tested and evaluated by simulations. In the initial stage were evaluated fuzzy PI, fuzzy PD and fuzzy PID controllers of multiple inputs and single output (MISO) and the error of the generated voltage as state variable. Subsequently, it was evaluated a fuzzy PI controller of single input and multiple outputs (SIMO) with a modified rule base for the system. In the final stage, the angular drive speed was included as state variable of the controller. The behavior of each architecture was analyzed by means of performance indexes. The results show that among the tested controllers, the modified fuzzy PI SIMO presented the best performance values while maintaining the operating variables within the established limits. <![CDATA[Yield, specific mass and coloration of azuki seeds after desiccation and storage]]> ABSTRACT Selection and dosage of desiccating herbicides may bring benefits to bean harvesting and its seed quality. This study aimed to assess yield, apparent specific mass and coloration of azuki bean seeds after pre-harvesting desiccation with different herbicides and doses and subsequent storing. In a first trial, we tested paraquat 400 (g ai ha-1), ammonium glufosinate (400 g ai ha-1), glyphosate (720 g ai ha-1), flumioxazin (30 g ai ha-1) and control. In second and third trials, we tested various doses of saflufenacil (0, 50, 75, 100, 150 and 200 g ai ha-1) and flumioxazin (0, 20, 25, 30, 35 and 40 g ai ha-1). All treatments were divided into plots and the dates of evaluation (at harvest and six months after harvest) into subplots with four replications. Even after storage, paraquat, ammonium glufosinate, glyphosate and flumioxazin had no effect on yield, specific mass or even coloration of azuki bean seeds. None of the doses of saflufenacil and flumioxazin impaired yield, specific mass and L* value of seeds, which is associated to lightness. Nevertheless, after six-month storage, the seeds desiccated with saflufenacil and flumioxazin lost color intensity and purity as function of the dose. <![CDATA[Effects of drying air temperature and grain initial moisture content on soybean quality (<em>Glycine Max (L.) Merrill</em>)]]> ABSTRACT This study aimed to evaluate the effect of air-drying temperature and initial moisture content on volume shrinkage, physical quality and oil extraction yield of soybean grains. The grains used in this experiment were harvested at two distinct moisture levels of 19 and 25%. Then, these grains were taken to dryness at three different air temperatures of 75 °C, 90 °C and 105 °C, in a forced circulation convection oven of the air. The results showed a drying time reduction with increasing air temperatures. Regarding volume shrinkage, moisture content reductions influenced grain volume and the Rahman's model was the one that best fit the data. Moreover, the higher the air temperature, the greater the effects on soybean grain shrinkage and physical quality. By grain volume reduction effected on oil yield, major impacts were observed when assessing grain initial moisture content were higher. Furthermore, the temperature of 105°C and an initial moisture content of 25% were the factors that most affected soybean grain quality, however not affecting oil extraction yield. <![CDATA[Stabilization of confined beef cattle manure: characteristics of produced fertilizers]]> ABSTRACT The growing demand for animal protein is directly related to the feedlot system of animals and their assumptions, such as the waste management. The characterization of the final products becomes an important factor in decision making by one or by other process. The objective was highlight characteristics that fertilizers present due to the used of stabilization process, by the principal component analysis. For the manure stabilization we realized three aerobic processes, composting, vermicomposting and natural decomposition, and one anaerobic, the anaerobic digestion. These processes produced the compost, the vermicompost, the decomposed manure and the biofertilizer. Fertilizers produced were analyzed by means of seventeen chemical and physic-chemical parameters. The main differences are related to stability and organic matter content. The compost is more stable fertilizer and decomposed manure is the worst. The vermicompost is presented as the best option to adsorb cadmium and lead. The biofertilizer has the lowest values of pH, CEC and adsorptive capacity of heavy metals (Cd and Pb). The decomposed manure in presence of precipitation, and the vermicompost, with significant irrigation, generates fertilizers with smaller source of potassium. <![CDATA[Use of active canopy sensors to discriminate wheat response to nitrogen fertilization under no-tillage]]> ABSTRACT Spectral reflectance sensors may be useful in discriminating biomass and nitrogen status in plants. A field experiment was carried out on a loamy Typic Hapludox under no-tillage in Ponta Grossa, Parana State, Brazil, aiming to evaluate the efficiency of active canopy sensors (GreenSeeker 505 and Crop Circle ACS-470) to discriminate wheat response to nitrogen fertilization by determining the dry mass, nitrogen status, and grain yield. A randomized complete block design was used and four treatments were replicated 12 times. The treatments consisted of nitrogen application, as urea, at the rates of 0, 50, 100, and 150 kg ha-1. The nitrogen rates were applied in topdressing at tillering of wheat crop. The readings from the sensors were sensitive to changes caused by nitrogen rates application and yet had close and significant correlations with the dry biomass production and nitrogen uptake by wheat plants. GreenSeeker 505 and Crop Circle ACS-470 sensors showed similar efficiency in discriminating biomass production and the nutritional status in the wheat crop related to nitrogen. Wheat grain yield was high and it did not follow the gains in the production of dry mass in the shoot. <![CDATA[Identification of commercial blocks of outstanding performance of sugarcane using data mining]]> ABSTRACT In order to achieve more efficient agricultural production systems, studies relating to the patterns of influence factors on commercial blocks of outstanding performance can be performed to assist management practices. The performance is considered to be the difference between the yield of a given block and the average yield of the homogeneous group that it belongs to. The methods available to identify these outstanding blocks are usually subjective. The aim of this study was to propose an objective and repeatable approach to identify outstanding performance blocks. The proposed approach consisted of performance determination, using regression trees, and the classification of these blocks by k-means clustering. This approach was illustrated using a sugarcane model. The main factors influencing the tonnes of cane per hectare (TCH) and total recoverable sugar (TRS) yields were found to be crop age and water availability during ripening, respectively. These were used to create potential yield groups, and blocks with high and low performance were identified. The proposed approach was found to be valid in the identification of outstanding sugarcane blocks, and it can be applied to different crops or in the context of precision agriculture. <![CDATA[Comparative study of energy costs in irrigation according to the new brazilian electricity tariff model]]> ABSTRACT The tariff flags on Brazil came into force in January 2015, applied to all electrical distribution agents of the national interconnected system (SIN) and all final consumers are being charged for this new model. Given this, the cost of electricity in irrigation suffered representative additions involving searches of alternatives, such as the use of diesel engines. This study aimed to analyze the costs and the total annual costs of pumping with diesel and electric operation in 3 regions of Brazil, considering the application of the tariff flags. We concluded that the Southeast region (SE) features an hourly cost of electricity above the Central-West (CO) and the Northeast (NE) regions at any adopted tariff, regardless of the time of pumping and the use of diesel engines in irrigation is feasible in terms of distances from the electrical grid that can range from 2.8 to 72.4 km, the first being the most favorable condition in the Southeast with the operation of 4 months per year with fertirrigation, in conventional tariff and red flag is the less favorable in the Northeast with 10 months/year operation with/without fertirrigation, in bohemia blue and green flag tariff. <![CDATA[The design and evaluation of travelling gun irrigation systems: enrolador software]]> ABSTRACT Travelling gun irrigation systems offer great mobility and operation flexibility with a low investment cost per unit of irrigated area. However, the drawbacks include high operating pressure, low application efficiency, and high rainfall, runoff and erosion. Many of these problems can be minimized if the design and operation of travelling gun irrigation systems are carried out carefully, taking into account several design criteria that will ensure the quality of the irrigation performed by the system. The Enrolador software was developed to meet this goal. The software designs the travelling gun irrigation system, performs its simulation and its performance evaluation. This software was experimentally applied in the Alentejo region, Portugal. The design flow rates were computed for maize and sunflower crops with the soil water balance model IrrigRotation, considering a probability of non-exceedance of 75%. Meteorological data from the Évora weather station for the years 1961 to 1990 were used. Five plots with 3, 6, 9, 12 and 15 ha were chosen for the design of the irrigation systems using the software. The Enrolador software was used to select the equipment (gun, hose and reel) and the appropriate operating parameters for each plot. This software allows for the selection of the equipment that best meets the design criteria. <![CDATA[Broadcast distribution uniformity of fertilizer with centrifugal spreaders used in variable rate application]]> ABSTRACT The quality of fertilizer distribution process is important to the success of agriculture. This research aimed to study the distribution uniformity of fertilizers with spreaders capable of performing variable rate. Evaluations were carried out in different farms, in the Southwest region of the State of Goiás, Brazil. 13 longitudinal and transversal distribution profiles with 11 centrifugal spreaders were evaluated: five with limestone, two with gypsum, two with magnesium oxide, one with monoammonium phosphate (MAP), one with super simple phosphate (SS), one with chloride potassium (KCl) and one with formulated fertilizer (02-20-20). The collectors and the form of distribution followed the ASABE S341.3 standard (2006). The broadcasted distribution by centrifugal spreaders performed unevenly over the applied area. Therefore, application evaluation, in addition to correct regulation, should be performed frequently for each type of product, even on machines with capacity in variable rate. <![CDATA[Experimental dryer design for agricultural products]]> ABSTRACT This study consisted of designing and building an experimental dryer that allows working with different temperatures and velocities of the air, aiming to perform studies on thin- and thick-layer drying of agricultural products. The project was divided into three stages: heat source designing, dryer geometric parameters, and fan selection to meet operational demand. Heating was made by a set of six electrical resistances totaling 12 kW and the drying bed in thin layer was composed of two trays with diameter of 0.20 m. Operational demands were met using a centrifugal fan with a power rating of 735.5 W. The used methodology was able to size the experimental dryers for thin- and thick-layer drying working at distinct temperatures and air velocities. <![CDATA[Erratum]]> ABSTRACT This study consisted of designing and building an experimental dryer that allows working with different temperatures and velocities of the air, aiming to perform studies on thin- and thick-layer drying of agricultural products. The project was divided into three stages: heat source designing, dryer geometric parameters, and fan selection to meet operational demand. Heating was made by a set of six electrical resistances totaling 12 kW and the drying bed in thin layer was composed of two trays with diameter of 0.20 m. Operational demands were met using a centrifugal fan with a power rating of 735.5 W. The used methodology was able to size the experimental dryers for thin- and thick-layer drying working at distinct temperatures and air velocities. <![CDATA[Erratum]]> ABSTRACT This study consisted of designing and building an experimental dryer that allows working with different temperatures and velocities of the air, aiming to perform studies on thin- and thick-layer drying of agricultural products. The project was divided into three stages: heat source designing, dryer geometric parameters, and fan selection to meet operational demand. Heating was made by a set of six electrical resistances totaling 12 kW and the drying bed in thin layer was composed of two trays with diameter of 0.20 m. Operational demands were met using a centrifugal fan with a power rating of 735.5 W. The used methodology was able to size the experimental dryers for thin- and thick-layer drying working at distinct temperatures and air velocities.