REVISTA ENGENHARIA NA AGRICULTURA - REVENG

MINIMUM NUMBER OF POINTS FOR A RELIABLE SOIL WATER RETENTION CURVE USING RICHARDS’ PRESSURE CHAMBER

2020-08-03T10:49:23-03:00

The soil hydro-physical characteristics are very important for studies about soil water dynamics. The soil water retention curve it is a soil characteristic sometimes expensive and time consuming to be done and could be a problem for farmers. The numbers of points and its tension evaluated are normally choose arbitrarily. This study aimed to define the fewest pairs of soil moisture and water soil potential points which result in a reliable water retention curve in two different soils (sandy and clay). Using different tensions by suction table and Richards’ pressure chamber, nine replications were adjusted by van Genuchten's equation. Curves with 4, 5, 7, 8, 9, 10 and 13 points were studied and the curve with 13 points was adopted as standard. The obtained parameters for different pairs of soil moisture and their corresponding soil water potential were compared to the equivalent standard curve and submitted to analysis of variance (F test), and their values were compared by the Scott-Knott test (5% of probability). The curve with 7 points, using the tensions of 0; 40; 100; 300; 1,000; 5,000 e 15,000 hPa, was the lower number of points that did not showed statistical difference in any parameters of the model and the point with 15,000 hPa shown to be important and should be used on the combination of points to obtain a good adjustment.

MORPHOLOGY OF PARDO RIVER WATERSHED AT THE BORDER OF THE STATES OF BAHIA AND MINAS GERAIS

2020-10-08T14:46:46-03:00

ABSTRACT

The spatial analysis of watersheds, as well as the evaluation off the changes occurring in their catchment area along the time are essential for the qualification of environmental changes. This study aims to characterize morphometrically the Pardo river watershed, as well as to evaluate the changes in soil use and occupation occurring between 2001 and 2016. The morphometric analysis consisted of the determination of the geometric parameters, relief information and drainage network using Geographic Information Systems. The land use and occupation information was collected through data from the online mapping platform of the Brazilian Mapping and Land Use Mapping (MapBiomas). According to the results, morphometry indicated that the watershed has low propensity to flood occurrence and tendency to conservation; great part of its area is between 600 and 1000 m of altitude, with predominance of undulating and soft-undulating slopes. The analysis of land use and occupation showed that the area devoted to agricultural activities increased during the period evaluated and occupies most of the basin, while the area of ??forests was reduced, the second in size, and these two classes occupy more than 96 % of catchment area.

ANALYSIS OF THE USE OF CONSTRUCTION WASTE AS SOIL ACIDITY CORRECTIVE

2020-08-03T10:38:36-03:00

The construction and demolition waste (CDW) can be used as soil acidity corrective, which allow its final destination as an input of agricultural and environmental interest, beyond pollution control. This alternative of final destination makes possible the reduction on the amount of solid waste disposed in landfills, which will reduce the environmental impact and increase the useful life of the landfills. Therefore, the objective of this study was to evaluate the use of the construction waste to correct the pH of an acidic soil, typical of the southeastern region of Brazil. The CDWs used were collected in static buckets positioned next to building sites in Belo Horizonte, MG; sifted at less than 0.297 mm diameter and incorporated into an oxisol (red yellow latosol) collected on an exposed slope at Federal University of Minas Gerais (UFMG). Then, an incubation curve (after 21 days of incorporation of the waste to the soil) was performed varying the dose of the construction waste to the soil, aiming to obtain a pH x dose curve. Using logarithmic regression, the equation pH = 0.5454 ln(Dose) + 6.9646 was defined as ideal to describe this relationship. Thus, for the agricultural use it will be necessary a dose of 1,71 t ha-1, while, for pollution control, it will be necessary a dose of 46,28 t ha-1.

MODELING OF WATER EROSION IN A SUB-BASIN IN RIO GRANDE DO SUL USING THE RUSLE MODEL

2020-05-05T19:03:22-03:00

The intense use of farming land has caused many consequences to the environment, among them, water erosion. The scale study of river basins through modeling allows the identification and estimation of soil losses, aiming at the conservationist planning of the site. The objective of this work was to predict soil loss in the Micaela sub-basin, with an area of ??37 km2 located in the municipality of Pelotas, Rio Grande do Sul. For the prediction of soil loss, the Revised Universal Soil Loss Equation (RUSLE) was used. Erosivity was obtained from data from the literature and erodibility was estimated by means of the inherent soil attributes and the topographic factor calculated according to the accumulated flow and declivity in each pixel. For the cover factor, data from the literature were used, according to use recommendation and existing soil cover. The study area shows a strong erosivity, which ranged from 8,045 to 8,833 MJ mm ha-1 h-1 year-1. The Argissolos occupy 81.31% of the sub-basin and present high erodibility, varying from 0.0369 to 0.0422 Mg ha h ha-1 MJ-1 mm -1. The sites with the largest vegetation cover were those with the lowest soil losses. However, in more than 36% of the area, the soil losses are above the tolerable therehsold, indicating that they are more prone to degradation and, therefore, the systems of land use and adopted management should be reviewed.

IRRIGATION FREQUENCIES FOR Eucalyptus grandis SEEDLINGS

2020-09-09T12:22:11-03:00

One of the bottlenecks in relation to the production of forest seedlings is irrigation, especially in lower-tech nurseries. The small volumes of substrate, where the seedlings develop, lead to low water storage. This can cause water deficit and significant losses in seedlings production, even leading to plant mortality. The objective of this study was to determine the best irrigation frequencies for Eucalyptus grandis seedling production in lower-tech nurseries. The experiment was conducted between 04/08/2013 and 07/23/2013 (106 days) in Chapadão do Sul, Mato Grosso do Sul, Brazil. The experiment was installed in a split plot scheme, with the irrigation frequencies in the plots and seven evaluations (15, 30, 45, 61, 76, 91 and 106 days after sowing) in the subplots, in a randomized complete block design, with five replicates. Four irrigation frequencies were tested: IF1 (one daily irrigation - 11:00 a.m.), IF2 (two daily irrigations - 11:00 a.m. and 7:00 p.m.), IF3 (three daily irrigations - 07:00 a.m., 11:00 a.m. and 7:00 p.m.) and IF4 (four daily irrigations - 07:00 a.m., 11:00 a.m., 3:00 p.m. and 7:00 p.m.). The sample units were composed of eight seedlings in 50 cm3 containers with conical shape, filled with soil and vermiculite in a volume ratio of 1:1. The irrigation depth was estimated by reference evapotranspiration (Penman-Monteith) multiplied by a crop coefficient equal to two. Plant height, number of true leaves, shoot dry mass, root dry mass, total dry mass, seedling quality index, survival and water use efficiency of Eucalyptus grandis seedlings were evaluated. The average daily irrigation depth in the experimental period was 5.2 mm. Based on the results, for Eucalyptus grandis seedling producers, in lower-tech nursery, irrigation management with twice-a-day frequency (11:00 a.m. and 7:00 p.m.) is recommended.

SEWAGE PHOSPHORUS REMOVAL USING HEN EGGSHELLS THROUGH DIFFERENT CONTACT SYSTEMS

2020-10-09T16:46:26-03:00

Hen eggshell is a waste with high phosphorus (P) removal capacity from synthetic solutions. However, there is a lack of knowledge about how to use this material on P removal from real wastewater. The present study proposed to evaluate two types of system for P removal from wastewater using eggshells. On the first system, eggshells grinded, sieved in 0.425 mm, and contained in coffee filters, were fixed to baffles using calico cloth bags. On the second, the eggshells in the same conditions were attached to vertical wooden rods and distributed at different heights. For both systems, P concentration was daily monitored for four weeks, with and without medium acidification and hydraulic retention time of one day. The baffles system was more efficient, reaching a maximum removal of 15.93% in wastewater with pH 4.73. P removals did not differ significantly over the weeks; however, there is a tendency to vary the efficiencies according to the change in pH. The baffled tank, for presenting higher performance in P removal, is the most suitable for use in a domestic wastewater treatment system.

SALINE STRESS AND EXOGENOUS APPLICATION OF PROLINE IN CASHEW ROOTSTCK

2020-08-11T10:18:53-03:00

The scarcity of good quality water and the occurrence of long dry periods are limiting factors for irrigated agriculture, especially in semiarid regions, which induces the use of saline water and technologies that enable its use in agriculture. In this context, the objective of the present study was to evaluate the influence of exogenous application of proline on growth and phytomass of BRS 226 Planalto precocious dwarf cashew rootstock irrigated with water of different levels of salinity. The study was performed in a greenhouse, in the municipality of Pombal - PB, in a protected environment, using a randomized block design in a 5 x 4 factorial scheme. The treatments consisted of different levels of electrical conductivities of irrigation water – ECw (0.3; 1.0; 1.7; 2.4 and 3.1 dS m-1) associated with foliar application of proline - P (0, 4, 8 and 12 mM), with three repetitions and two plants per plot. The irrigation with saline water of up to 0.85 dS m-1 can be used for the production of BRS 266 cashew rootstck. Proline concentration of 8 mM promoted largest dry phytomass of the BRS 226 Planalto cashew rootstock. The increase in proline concentration up to 12 mM applied via leaf does not attenuate the deleterious effects of salinity on the absolute growth rate of plant height and on the fresh and dry leaf phytomass of the BRS 226 Planalto cashew rootstock.

APPLICATION OF THE CONSTRUCTION WASTE AS A REDUCING AGENT IN THE SOLUBILITY OF IRON TAILING METALS

2020-07-02T12:33:16-03:00

Iron ore tailings has acid pH and high content of metals, such as iron, aluminum and manganese. Regarding the environment, these metals poses a risk of contaminating the soil and underground water. Yet, construction residues usually have high pH and because of this, they can be used to neutralize soil acidity and to reduce metal availability in mining tailing piles. The objective of this study was to evaluate the aplicabilith of CW to promote neutralization of the acidity in iron ore tailings aiming at decreasing the solubility and mobilith of metal found in them. Thus, a sample of construction waste was collected and characterized which was later incorporated at different doses into a sample of iron mining tailing collected in the Iron Quadrangle (Minas Gerais – Brazil). The construction waste raised the pH of the tailing sample from 5.58 to 8.22. Moreover, the incorporation of the waste incorporation decreased the manganese solubility in at least 80%. Despite the lack of national legislations and policies on the use of construction waste for this purpose, the results show that it is a promising technological alternative.

MODELS FOR ESTIMATING POTASSIUM AND NITRATE TO CHANGES OF ION CONCENTRATION IN SOIL SOLUTION

2020-07-13T10:03:13-03:00

The adequate fertigation use bases on the application of nutrients by water according to crop needs throughout its cycle. The evaluation of nutrients in the soil solution may be faster if based upon soil electric conductivity and moisture by using parametric models. The objective of this study was to evaluate the sensitivity of two parametric models for estimating nitrate and potassium concentration in the soil solution under changes of ion concentration during a crop cycle. One model was that from Vogeler et al. (1996) in which ion concentration is a function of soil moisture and electrical conductivity; the other was the potential in which the concentration is a function of the electrical conductivity of the soil solution. The potential model presented a better performance compared to that of adapted from Vogeler, as for estimation of ion concentrations as for the sensitivity of this model to changes in concentration of this ion in the soil solution. The models showed greater sensitivity when fitted to data corresponding to all possible occurrences in the soil during the crop cycle. The model should consider a range of concentrations with the possible values of the soil solution along crop cycle.

DEVELOPMENT OF Tabebuia aurea AND Anadenanthera macrocarpa UNDER DIFFERENT LEVELS OF SHADING

2020-09-01T10:55:42-03:00

The efficiency in the initial growth of trees can be related to the ability of the seedlings in adapting to different light intensites in the enviroment. The objective of this work was to evaluate the influence of different levels of shading in the initial growth of Tabebuia aurea and Angico (Anadenanthera macrocarpa) in the nursery phase. The experiment was conducted at the Federal Rural University of Semiárido located in Mossoró-RN. The seeds of A. macrocarpa and T. aurea were collected from parent trees and donated by the Caatinga/ UFERSA / Petrobras Project, where, afterwards, they were processed. The composting used in the experiment was coconut fiber, after the substrate was placed in 55-cm³ tubes and organized in plastic supports. The seedlings were submitted to three levels of shade, full sun (absence of shade), shade of 50% and 80%. For the different levels of shading, mean values of the height/diameter ratio of the neck were obtained of 3.74 (A. macrocarpa) and 1.57 (T. aurea) for cultivation in full sun, 0% of shading, indicating that the growth of this cropt may have better results under these conditions. The highest values of the Dickson Quality Index (DQI) were observed in seedlings grown under a lower shade level of 0.03454 and 0.11719. The species T. aurea shows little tolerance when subjected to high levels of shading, showing that the luminosity interfere in the initial growth of the species. A. macrocarpa, also acquired a better development in full sun, showing less progress at higher levels of shading.

POTASSIUM FERTIRRIGATION ON ICEBERG LETTUCE

2020-07-13T09:55:02-03:00

The aim of this work was to evaluate the influence of potassium doses, being applied in fertigation on iceberg lettuce cultivar “Lucy Brown” in Typic Hapludox. The experimental design was in randomized blocks, consisting of six doses of K2O (0; 15, 30, 45, 60, 75 kg ha-1) and four blocks. The treatments were applied in six periods: 15, 21, 28, 34, 39, and 43 days after transplantation seedlings, using potassium chloride as a source of K2O. The variables analyzed were: total fresh mass, fresh head mass, head circumference, number of inner leaves, number of outer leaves, total number of leaves, total yield and commercial yield. Data were subjected to analysis of variance and means compared by regression models. Thus, we can conclude that the K2O doses that provides the highest value of the variables is 75 kg ha-1, with the exception of the number of internal leaves that do not have a significant effect.

PRODUCTION AND POST HARVEST OF ‘KENT’ MANGO UNDER DIFFERENT IRRIGATION SYSTEMS

2020-10-08T14:41:20-03:00

Facing the fruit market’s search for more efficient production systems, this research aimed to identify an arrangement of efficient irrigation systems for the productive and postharvest characteristics of ‘Kent’ mango fruits, under the conditions of the Brazilian semiarid. The research was performed in an agricultural property in the municipality of Petrolina-PE, with the soil classified in Quartzarenic Neosol. Four irrigation system arrangements were tested: a micro sprinkler below the canopy; a micro sprinkler between plants; two lateral dripper lines per row of plant; and a ring-shaped drip strip around the plant in a randomized block design with five repetitions. The productive characteristics were evaluated, such as number and average weight of fruits and productivity; and qualitative parameters (evaluated by plant quadrant): volume, density, firmness, soluble solids content and titratable acidity. A micro sprinkler between plants provided a greater number of fruits and productivity, as well as greater firmness and titratable acidity for mangoes of the South and West quadrants; these characteristics associated with the lowest soluble solids content of the pulp, at the time of harvest, was also obtained with a micro sprinkler between plants and induce a longer post harvest time to the fruits.

SPATIAL CORRELATION BETWEEN THE CHEMICAL ATTRIBUTES OF A RED LATOSOL AND THE GRAIN YIELD OF COMMON BEAN

2020-09-25T10:59:17-03:00

In recent years, common bean in Brazil has become interesting to precede the growing of off-season cotton due to its short cycle. This study was carried out in a Red Latosol in Chapadão do Sul, MS and aimed to select among the attributes of the evaluated soils, those with the best linear and spatial correlation, to explain the variability of grain yield of common bean in the soil layers of 0 - 0.10 m (layer 1) and 0.10 - 0.20 m (layer 2), sampled in a grid of 121 georeferenced points (spacing of 5 meters between points). The soil chemical attributes were determined: pH, carbon (C), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), aluminum (Al), and the sum of bases (SB). The analysis of these data was carried out using statistical and geostatistical techniques that made it possible to verify that for the grain yield of common bean, the multiple regression analysis indicates that approximately 20% of its variation is attributed to the variation in the chemical attributes of the soil presented in the present study. The chemical attributes pH1, pH2, C1, Ca1, Ca2, Mg1a, Mg2, Al2, SB1, and SB2 have spatial dependence classified mostly as moderate. Both linearly and spatially, C1 stood out as a potential indicator of common bean grain yield when grown under no-tillage.

ESTIMATE OF THE INTENSITY-DURATION-FREQUENCY PARAMETERS OF INTENSE RAINFALL FOR THE STATE OF ALAGOAS, BRAZIL

2020-09-01T23:48:31-03:00

The study of the rainfall characteristics is of fundamental importance since the frequency of floods has increased in several parts of Brazil due to anthropic impacts of climatic changes. Thus, this study aimed to determine the parameters of the intense rainfall equation (K, a, b, c) for 52 municipalities in the State of Alagoas using data from 164 rain gauges ta available from the National Water Agency (ANA). The data series were subjected to consistency analysis and further desegregation of maximum daily rainfall to durations of the 5; 10; 15; 20; 25; 30; 60; 360; 480; 600; 720 and 1,440 minutes and return period of 5; 10; 25; 50 and 100 years according to different probabilistic models. The adjustment of the parameters was carried out by means of non-linear regression, with R² greater than 0.949 for all the stations, considering for this purpose one station per municipality, totaling 51 municipalities of study. It was obtained that the maximum rainfall intensity predicted increases with the increase in the return period and decreases with the increase of the duration of the rain. The greater intensities were detected in the mesoregion of Eastern Alagoano and the lowest intensities in the mesoregion of Sertão Alagoano.

DERIVATIVE SPECTROPHOTOMETRY FOR NO3- DETERMINATION IN SANITARY SEWAGES

2020-12-11T19:43:45-02:00

The objective of this study was to observe the feasibility of using the UV spectrophotometric method of the second derivative in the determination of nitrogen in the form of nitrate in sanitary sewers, since this method is indicated for water with low content of organic matter. Therefore, the results obtained in that method were compared with the salicylate methodology. The Mann-Whitney test showed a significant difference (? = 5%) between the results obtained in both methods. However, when compared, the difference between them was less than 0.25 mg L-1 in half of the observations. Despite this significant difference, the use of the second derivative method for sanitary sewage samples showed satisfactory performance.

INFLUENCE OF SOIL COMPACTION LEVELS ON COWPEA PRODUCTION

2020-02-03T16:11:49-02:00

Cowpea, a short-cycle legume with large production in the North and Northeast regions, has its productive potential limited by edaphic characteristics and degradation processes of soil physical quality, such as compaction. This process may interfere with plant development and productivity by restricting root system growth, aeration, water and nutrient availability. The objective of this work was to analyze the interference of different levels of compaction in the soil physical characteristics, root growth, development of the aerial part and productivity of cowpea. The experiment was conducted in a greenhouse following a completely randomized design with a control (control) and four levels of soil compaction, with four replications. Each experimental unit was composed of PVC tubes composed of a 0.05-m layer of gravel, cotton fabric and a 0.04-m layer of soil. The different levels of compaction were obtained using a proctor socket and a wooden base. Based on the value of penetration resistance (PR) of 1.00 MPa, soil reached the macroporosity considered as critical theresohold for soil aeration. Results indicate that the higher the PR of the soil, the lower the development of the root system and the aerial part. The productive aspects of cowpea presented better results in plants grown in soils with a level of resistance to penetration close to 0.8 MPa.

GROWTH AND DEVELOPMENT OF MOMBASSA GRASS GROWN IN FULL SUN AND SHADE UNDER NITROGEN LEVELS

2020-02-03T16:12:17-02:00

The objective of this work was to evaluate the effects promoted by full sun and natural shading (25%) enviroemnts , under the productive components of Panicum maximum cv. Mombasa grown in diferent levels of nitrogen (0, 25, 50, 100 kg ha-1 cycle-1 ). Urea was used as nitrogen source, applied on the surface. This study evaluated the following variables: number of total leaves (NTL), number of green leaves (NGL), number of dead leaves (NDL), leaf lifespan (LLS), sheath length (SL), stem elongation rate (SER), Phyllochron (PHYL), leaf appearance rate (LApR), leaf elongation rate (LElR), leaf senescence rate (LSR), average length of leaf blade (ALLB), leaf area index (LAI) and tiller population density (TPP). The shaded environment provided better conditions for sheath length and leaf elongation rate, however in full sun the tiller density was higher.

GREEN WATER FOOTPRINT AND SUSTAINABILITY FOR ESPIRITO SANTO STATE

2020-02-03T16:12:49-02:00

Water footprint is a relatively new concept of freshwater appropriation that considers its direct and indirect use by a consumer or producer and used as a comprehensive indicator of the appropriation of water resources. The objective of this study was to estimate the green water footprint and evaluate its sustainability in the state of Espírito Santo, using the land use information and indicators of water scarcity. The total green water footprint was estimated by the sum of the green water footprints of pasture, forest, coffee cultivation, forestry, and other agricultural uses. The state’s total green footprint estimated was 47.5 billion m³/year, and the pasture class represented 48.5% of this total, followed by forest (29.8%), coffee cultivation (10.1%), forestry (6.4%), and other crops (5.2%). The ratio between the mean annual total volume of precipitated water and the green WF in the state was 80%. The environmental sustainability assessment shows that the green footprint was unsustainable for most of the year, on average, mainly in the May to September.

TEMPORAL ANALYSIS OF SOIL OCCUPATION IN MUCURI WATERSHED BETWEEN 1989 AND 2015

2020-02-03T16:18:05-02:00

Anthropogenic action has caused intense changes in land use and cover over the decades. Identifying and knowing these changes makes it possible to measure the impacts that can be generated as well as to identify patterns of the development of a particular region and the relationship between society and land use. Thus, it is intended to identify the changes made in the land use and occupation of the Mucuri river basin between 1989 and 2015. So, this study used remote sensing techniques and tools besides aerial photographs to map the region and to identify surface behavior. Within the Mucuri basin, the soil had been mostly occupied by classes of forest and agricultural area, consistent with the social and economic reality of the region over the last decades. The changes that have occurred indicate a reduction in water availability, growth in urban occupation and, in many cases, soil and vegetation cover deterioration.

PROBABLE RAINFALL OF DIVINÓPOLIS CITY, MINAS GERAIS STATE, BRAZIL

2020-02-05T16:12:23-02:00

The aim of this paper was to analyze the behavior of non-parametric statistical distributions on the prediction of probable monthly and total annual rainfall as well as to determine the monthly and annual probable rainfall with different levels of probability for Divinópolis, Minas Gerais State, Brazil. The analysis consisted in adjusting the theoretical probability distribution to a data series of 66 years of monthly and annual rainfall. The data were obtained from the Hidroweb service, controlled by the National Water Agency (ANA, in Portuguese). The frequency distributions of Gumbel for Maximus, Fréchet and Gamma were adjusted to the observed series, where the adherence of these models to the data were tested by the Kolmogorov-Smirnov and Chi-Squared test, both with 5% of probability. The model that best represented, in most cases, the frequency distributions of the series of total monthly precipitation was Gumbel for Maximus, while the Fréchet model had the worst result, not fitting to the data of the historical series for both tests performed in the study. The probable monthly maximum precipitation for Divinópolis is 527 mm, associated with a probability of 5% and for January, while the lowest one is 0.0042 mm, with probability of 95% in July.

MONITORING XYLEM SAP IN SUGARCANE THROUGH TDR

2020-02-06T17:39:32-02:00

The TDR can be used to measure water content and nutrients in several media with a potential to monitor the xylem sap flow in plants. The objective of this study was to determine whether there is a correlation between the xylem sap content and water available in the soil for sugarcane cultivation using TDR. The study was conducted in a protected environment with eight boxes (500 L). The boxes were divided into two treatments with different water application rates (1.6 and 3.4 L h-1) through subsurface irrigation. In each box TDR probes were inserted in the medium part of sugarcane stalk, totaling three probes per box to monitoring the sap flow. The soil water content was monitored using 20 net-placed probes. Therefore, the simultaneous monitoring of xylem sap and soil water content occurred for five months. As a result, it was obtained that the xylem content monitoring through TDR is moderately related to soil moisture, with a response to the absorption and translocation of the solution in the stem of sugarcane plants as a consequence of irrigation applications and/or fertirrigation. Thus, it was concluded that there is a weak relations between water contents in the soil and plant, especially for the treatment that used the highest flow rate (3.4 L h-1).

PYRACLOSTROBIN PRESERVES PHOTOSYNTHESIS IN ARABICA COFFEE PLANTS SUBJECTED TO WATER DEFICIT

2020-02-07T17:35:31-02:00

The objective of this study was to investigate the effect of pyraclostrobin on the photosynthetic performance of rabica coffee plants subjected or not to a water deficit, using the parameter of gas exchange (net CO2 assimilation, stomatal conductance, transpiration rate, and internal CO2 concentration and nocturnal respiration), chlorophyll fluorescence a parameters (minimum fluorescence, maximum fluorescence, maximum quantum yield of photosystem II, effective quantum yield of PSII, quantum yield of regulated energy dissipation and quantum yield dissipation non-regulated) as well as the concentrations of chloroplast pigments. In the plants maintained without water deficit, pyraclostrobin did not cause any alteration on the parameters of chlorophyll a fluorescence; however, it contributed to an increase in the level of chlorophyll a + b, CO2 assimilation and CO2 influx for the carboxylation sites of the stroma. Decreases in nocturnal respiration in plants treated with pyraclostrobin, submitted or not to water deficit seems to be a common strategy in reducing energy waste in the maintenance metabolism. Under water deficit, pyraclostrobin contributed to increase the photochemical yield, enabling plants to effectively prevent the capture, use and dissipation of light energy.

A MODEL FOR HYDRAULIC DESIGN OF IRRIGATION LATERAL LINES

2020-02-18T17:49:36-03:00

There are several models for hydraulic designs and optimization of lateral lines depending on the existing pressure head profile and flow which allows designing longer lateral lines, therefore decreasing the cost of the system implementation. A model has been developed to calculate the pressure head and required flow rate at the inlet of lateral line using the back step method. A set of equations was implemented in an algorithm in the R language. For the calculations, the following variables must be provided: pressure head at the end of the lateral line (Hend), coefficients K and x of the characteristic equation (flow-pressure) of the emitter, pipe diameter (D), emitter spacing (Se) and number of emitters (Ne). For the evaluation of the model, the pressure head at the end of the lateral line, the pipe diameter and the number of emitters were varied within the established limits. Relationships between these variables were established by regression analysis using the least-squares method. The model shown in the study was suitable for the calculation of the pressure head and flow rate profile along the lateral line. The power, plateau, exponential and linear equations were adjusted to describe these relationships. These equations can help in the design of irrigation systems by simplifying the procedures in order to meet the design criteria. Also, the proposed equations allow evaluation of the systems still in the design phase.

TEMPORAL PERSISTENCE OF SOIL WATER STORAGE TO IDENTIFY LOCAL SITES FOR ADEQUATED MONITORING OF SOIL WATER

2020-06-03T11:31:29-03:00

The water layer stored in the soil in a vegetated area presents spatial-temporal variation, which establishes uncertainties regarding the region to be monitored for irrigation control purposes. Assuming that its spatial pattern of distribution is persistent over time, one can identify the region that systematically presents mean values representative of the entire area, using temporal stability analyses. However, this regional temporal persistence is always associated with a variability around the overall mean, which led to the proposition of a temporal consistency indicator (TCI). For the execution of this work, Urochloa decumbens was grown in an experimental, very clayey soil, over two annual cycles. In each cycle, measurements were made of the water stored in the soil (ARM) during soil drying cycles. The use of geostatistical techniques associated with the temporal stability analysis were performed. The results show that it is possible to characterize TCI as an adequate and convenient indicator to support decision making in questions related to soil water monitoring in irrigated agricultural systems.

FIXED CONVENTIONAL SPRINKLER IRRIGATION SYSTEM: COMPONENTS OF COST AND ECONOMY OF SCALE

2020-09-23T12:02:22-03:00

The costs involved in the implementation and operation of irrigation systems are of paramount importance for the economic planning of irrigated agriculture. Therefore, the objective of this work was to determine the implantation, fixed and annual variables costs, and the occurrence of economies of scale for a fixed conventional sprinkler irrigation system for different area sizes and slope in the impulsion line. Thus, irrigation projects were developed for areas of 1, 3, 5, 10, 15, 20 and 25 ha and slopes in the pumping pipe of 7 and 15%. Also, this work evaluated the implementation, annual fixed and variable costs and their components and the occurrence of economy of scale. The implementation, fixed and variable costs increased as the size of the area increased, but for the fixed and implementation costs, an increase was observed due to the exponential cost of the pipes and their greater participation in the total cost and the variable cost was because the maintenance follows the implementation cost. Therefore, the cost with the pipelines has greater participation in the implementation of the system. The cost of implementation and the total fixed and variable costs raised with the increases in the size of the irrigated area. The variable cost of energy is constant as area size is increased and the raise is by approximately 5.2%, as the slope increases from 7 to 15%. The increasing in the size of the irrigated area provides diseconomies of scale.

COLOURING OF COFFEE GRAINS RELATED TO DIFFERENT RELATIVE HUMIDITY OF THE DRYING AIR AFTER PARTIAL DRYING

2020-07-23T09:26:47-03:00

Changes in color of coffee grains are indications of occurrence of oxidative processes and biochemical changes, which can alter the taste and aroma precursors of the grains, resulting in lower beverage quality. Thus, the aim of this study was to evaluate the color characteristics of peeled coffee grains subjected to different relative humidity of the drying air after partial drying. Coffee (Coffea arabica) fruits were harvested in the cherry stage and were wet processed. The treatments were the results of the combination of three dry bulb temperatures and three dew point temperatures. The control of dew point temperature was performed only after the grains reach the partial drying. Considering the Tbd of 40 °C - 40 °C, the reduction of the Tpd (2.6 °C) increased the grains bleaching, while the increase of Tpd (16.2 °C) resulted in a more yellowish-red. Tbd of 40 °C - 35 °C and 35 °C - 35 °C are indicated for bluish-green color formation, associated with higher sensory quality. The Color Saturation (C*) of the coffee grains are highly correlated with the b* color parameter, while the tonality (Hue) is negatively correlated with the a* color parameter.

APPLICATION OF DOSES OF FREEZE-DRIED EXTRACT FROM MORINGA OLEIFERA SEEDS IN WATER TREATMENT

2020-12-14T23:01:47-02:00

Despite the proven performance and cost-effectiveness of chemical coagulants, natural coagulants are being studied. Among them, Moringa oleifera has been investigated more intensively as it contains proteins that are efficient in the alternative treatment of water for human consumption. The objective of the research was to use water with pH, turbidity and apparent color with levels above that allowed by Brazilian legislation and to treat it with freeze-dried extract of moringa seeds in different doses, selecting the best one for each parameter studied. The study was conducted at the Laboratory for Processing and Storing of Agricultural Products, at the Federal University of Campina Grande, Campina Grande, PB, Brazil. The extract was obtained as a result of the freeze-drying method. Three water quality parameters were evaluated: pH, turbidity and apparent color. Doses of 12, 16, 18 and 24 g/500 mL of freeze-dried extract of moringa seeds were used. Jar tests were performed at 160 rpm. The application of different doses of the freeze-dried extract resulted in pH according to the limits required by Brazilian legislation for drinking water. Based on the best efficiencies in pH, reduction of turbidity and color, doses of 24 g/500 mL were selected for pH and turbidity and 16 g/500 mL g for the apparent color.

PHYSIOLOGICAL CHANGES IN WHEAT SEEDS DURING THE ARTIFICIAL DRYING PROCESS

2020-07-21T23:05:34-03:00

The desiccation tolerance presented by orthodox species is a characteristic that allows the loss of water keeping the seed viable. However, the reduction of the moisture content by drying, has a critical limit, and a loss beyond this limit results in a reduction in the physiological quality of the seeds, TBIO Sossego cultivar. The objective of this study was to evaluate the physiological changes resulting from the reduction of moisture percentage in the artificial drying process of wheat seeds. The seeds used were of the cultivar TBIO Sossego with initial water content of 14.7%. The seeds were dried at 40 ± 2 °C until reaching 12, 10 and 8% moisture. The evaluated variables were germination, seedling length, electrical conductivity, field emergence, shoot length and root length. Drying of wheat seeds can be performed up to 8% moisture without affecting the physiological quality of the seeds.

DRYING KINETICS OF PEELED COFFEE SUBMITTED TO DIFFERENT TEMPERATURES AND RELATIVE HUMIDITY OF THE AIR OF DRYING AFTER PARTIAL DRYING

2020-07-13T10:14:22-03:00

The mathematical modelling is fundamental for the understanding of the related processes the drying, that influences the quality of the coffee drink. The objective of this study was to evaluate the influence of different relative humidity of the drying air after partial drying on drying kinetics of peeled coffees. Coffee fruits were harvested in the cherry stage and processed by wet, resulting in the portion of peeled coffee. Eleven treatments of drying were accomplished, being nine results of the combination of three dry bulb temperatures and three dew point temperatures, more two treatments without the control of the dew point temperatures. The control of the relative humidity by the dew point temperature was made after the grains reached the partial drying. Among the studied models, those of Diffusion Approximation and Modified Midilli were the most adequate for describing the drying process of the first and second part of drying respectively. The effective diffusivity coefficient of water in coffee grains ranged from 0.81 x 10-11 to 1.84 x 10-11 m² .s-1 during the first part of the drying and ranged from 1.49 x 10-11 to 3.29 x 10-11 m² .s-1 during the second part of the drying, increasing significantly with the reduction of the dew point temperature and increase of the dry bulb temperature.

MOISTURE ADSORPTION ISOTHERMS AND DRYING KINETIC OF PERSIAN CLOVER (Trifolium resupinatum L.) AND ARROWLEAF CLOVER (Trifolium vesiculosum) SEEDS

2020-12-10T15:12:46-02:00

The aim of this work was to obtain adsorption isotherms and to study the drying kinetics of persian clover (Trifolium resupinatum L.) and arrowleaf clover (Trifolium vesiculosum) seeds. The equilibrium moisture content and the moisture adsorption behavior were found by isotherms curves at 40, 45 and 50 ºC, and the Peleg model was the most suitable. The drying kinetics was determined by thin layer assays in an air parallel flow dryer at all three temperatures. In addition, the predominance of the falling drying rate period for the two species of seeds was observed, and the critical moisture content values were approximately of 0.20 and 0.25 g_waterg_{dry matter}^-1 for persian clover and arrowleaf clover seeds, respectively. The effective diffusivity values were estimated in ranges of values of 3.61×10^-11 – 6.81×10^-11 m² s^-1 for persian clover and 6.76×10^-11 – 1.15×10^-10m²s^-1 for arrowleaf clover seeds and the temperature effect was expressed by an Arrhenius relation. Thus, drying kinetics confirmed the greater difficulty in moisture removal from the arrowleaf clover seeds, compared to the persian clover seeds drying, in agreement with the results obtained through adsorption isotherms.

AUTOMATIC SYSTEM FOR PSYCHROMETRIC CALCULATIONS

2020-05-21T17:55:49-03:00

Air psychrometric properties are important in several areas of agricultural engineering, such as calculation of evaluation of the animal environment and air control in grain storage units. Due to their relevance and the complexity and the uncertainties in the use of psychrometric charts, the objective of this paper was to develop the software, PsyCalculator, which stands out for the automated function that allows presenting the data acquired through sensors and the respective psychrometric properties of the air, either in graph or tables. The automatic data acquisition system consists of a microcontroller that performs readings of sensors that measure the dry bulb temperature and another variable, which may be: wet bulb temperature, relative air humidity or dew point temperature. Then, the values are sent to the PsyCalculator software system. In addition to the values ??of dry bulb temperature, the software system presents wet bulb temperature and dew point temperature, values ??of saturation vapor pressure, vapor pressure, mixing ratio, specific volume, enthalpy and degree of saturation. Among the psychometric variables analyzed, the software developed in the study presented a maximum error of 2.14% for the calculation of dew point temperature. The developed software allows the automation of systems that depend on the psychrometric parameters in a friendly and precise fashion.

QUALITY OF NAPOLI CV. EGGPLANT COATED WITH CARNAUBA WAX

2020-02-19T15:28:34-03:00

The objective of this study was to evaluate the quality of eggplant Napoli cv. coated with Carnauba wax and stored for seven days at room temperature. Treatments consisted of immersion of fruits in two concentrations of two types of commercial wax, totaling four treatments: Meghwax ECF 124 to 9% concentrations (Megh 9%); Meghwax ECF 124 to 18% (Megh 18%), Arua BR 18% (Pomacea canaliculata) Tropical 9% (Arua 9%), and Arua BR 18% Tropical 18% (Arua 18%). The control treatment consisted of fruit without coating with wax and immersed in water. Fruits were analyzed at 0, 3, 6, and 7 days for the outer appearance, weight loss, turgor pressure, titratable acidity (TA), soluble solids (SS), SS/TA ratio, ascorbic acid, and pH. The waxes were effective in reducing weight loss. The turgor pressure showed a decrease during storage, which was more pronounced in the control treatment. The treatments did not differ among themselves for the levels of soluble solids. Fruits immersed in Arua wax at 18% concentration showed higher titratable acidity. The levels were reduced during storage. The control fruits showed higher pH. The ascorbic acid contents decreased by 15.0%, 16.4%, 16.5%, 16.9%, and 34%, considering the control treatments. Fruits subjected to Arua wax at 18% had longer shelf-life; the control fruits showed shorter shelf-life. Thus, it is concluded that 18% Aruá wax was the most effective to increase the shelf life of eggplants when stored at room temperature.

QUALITY OF CORN SEEDS STORED IN DIFFERENT TYPES OF PACKAGING AND STRESS CONDITIONS

2020-06-25T17:32:06-03:00

Corn (Zea mays) is one of the most cultivated poaceae in the world with high agricultural potential. It is propagated through seeds, which sometimes remain stored until the sowing period. Among the various forms of storage, some aspects related to the environment and the type of material that constitutes the packaging may compromise the viability and vigor of these seeds. Therefore, the objective of this study was to evaluate the physiological quality of corn seeds stored in different types of packaging and subjected to conditions of high temperature and relative humidity throughout storage. For this purpose, water content, germination and vigor were evaluated through the cold test. A completely randomized design in a 4 x 4 factorial scheme (packaging x evaluation times) with four replications was used. Data were subjected to analysis of variance and regression, and the means were compared by Tukey test at 5% probability, using the Sisvar 5.3 statistical software. It was concluded that, in 45 days of storage, the water content in corn seeds reached values of up to 13.62%, which resulted in a reduction in the vigor due to high respiration caused by the storage temperature.

SENSORY AND PHYSICOCHEMICAL EVALUATION OF TRADITIONAL POWDER COFFEE

2020-07-13T09:40:31-03:00

Coffee is one of the most important products for the Brazilian economy. Due to this fact, its sensory acceptance is extremely important for both the consumer and the producer. The objective of this study was to evaluate the acceptance of six brands of traditional roasted coffee in the southern region of Minas Gerais. The samples were evaluated by 124 consumers through the following tests: acceptance for appearance, aroma, taste, texture and overall impression, ideal for bitter taste and body and, finally, purchase intention. In addition, colorimetric and soluble solids analyses were performed. According to the results obtained, sample D had the highest frequency of positive purchase intention, while sample A had the highest frequency of negative purchase intention. Sample F had the closest ideal bitter taste and, in relation to the body of the drink, sample C was considered the closest to the ideal. Sample F presented the highest acceptance for all attributes evaluated in the acceptance test.

REFERENCE EVAPOTRANSPIRATION THROUGH HARGREAVES METHOD USING THE SOLAR RADIATION ESTIMATION FOR GOIÁS STATE, BRAZIL

2020-06-24T17:14:17-03:00

This study evaluated the Hargreaves model (HG) with seasonal adjustments of the calibration coefficient (Krs) of the radiation equation to estimate the reference evapotranspiration (ETo) in 23 weather stations in Goiás State, Brazil, in comparison to the Penman-Monteith FAO (PM-FAO) standard method. The models were evaluated using Pearson’s correlation coefficient, Willmott’s agreement index, relative error, absolute mean error and root mean square error. The Krs values ranged from 0.146 to 0.189 ° C-0.5, while ETo PM-FAO ranged from 3.68 to 4.79 mm d-1; ETo HG from 3.99 to 5.16 mm d-1 and ETo HG-Krs from 4.15 to 5.02 mm d-1 in the annual period. Seasonal adjustments resulted in values of 0.144 to 0.205 ° C-0.5 for the dry period, from April to September, and 0.144 to 0.146 ° C-0.5 for the rainy period, from October to March. The first quarter (summer), presented Krs values from 0.150 to 0.175 ° C-0.5; the second quarter (autumn), from 0.154 to 0.218 ° C-0.5; the third quarter (winter), from 0.139 to 0.206 ° C-0.5; and, finally, the fourth quarter (spring) of 0.141 to 0.166 ° C-0.5. Thus, the use of the seasonally adjusted model proved to be viable for the estimation of ETo, in view of the simplicity and its good adherence to the standard method.

DEVELOPMENT OF AN AUTOMATED SYSTEM FOR WEATHER DATA COLLECTION AND FORECASTING CLIMATE EVENTS BY MEANS OF RADIO FREQUENCY

2020-08-11T10:03:53-03:00

The weather forecasting method is based on the analysis of data collected to support decision-making. This paper describes the development of a weather station (prototype) to assist in monitoring plantations and forecasting extreme weather events. The strategy adopted is to use a set of stations connected via radiofrequency forming a communications network to better understand and anticipate such events. The weather forecasting method is based on analysis of data collected to support decision making. The laboratory tests were successful, but field tests had several difficulties and unforeseen events that will be described at the end of this paper.

EQUATIONS OF INTENSITY, DURATION AND FREQUENCY FOR THE PERUÍPE, ITANHÉM AND JUCURUÇU RIVER BASINS

2020-12-03T15:11:07-02:00

The intense rainfall equations present a great technical interest for hydraulic works projects. In the State of Bahia, there are only 19 equations of intensity, duration and frequency modeling, requiring a greater number of equations for the State. The most recent ones are almost 15 years old, with only two in the Peruípe, Itanhém and Jucuruçu river basins. Thus, the objective of this work was to determine the parameters of the equations of intensity, duration and frequency (IDF) of the rainfall stations for different locations of the basins of the Peruípe, Itanhém and Jucuruçu rivers, located in the far southern Bahia State. Initially, 59 stations were selected, out of which only those with over 20 year-old data and records from 1980 onwards. Rainfall disaggregation was carried out using the method proposed by Cetesb (Environmental Company of the State of São Paulo, Brazil) and the parameters (K, a, b and c) were adjusted through nonlinear multiple regression using the nonlinear-generalized reduced gradient interaction method, where adjustment was evaluated by the coefficient of determination (R2). In the end, 29 equations were adjusted, with coefficient of determination greater than 0.99, therefore, improving the perspective of planning hydraulic works in the region. This correlation could also be observed by the regression equation of the observed data with the adjusted ones, where the slope coefficient of the line was close to 1.0 for all rainfall stations.

COMPARISON BETWEEN ESTIMATION METHODS OF REFERENCE EVAPOTRANSPIRATION IN BOM JESUS ??DA LAPA, BA

2020-02-21T10:46:08-03:00

Among the reference evapotranspiration (ETo) equations, the FAO-56 Penman-Monteith (PM FAO-56) model is considered the most accurate, but this model requires a greater amount of meteorological data. On the other hand, there are other methods that require fewer variables and have shown good precision according to the location. The objective of this work was to evaluate the efficiency of four methods for estimation of daily ETo, comparing them with FAO-56 PM equation in Bom Jesus da Lapa, Bahia, Brazil. To do so, a dataset from 2010 to 2017, acquired at the National Institute of Meteorology (INMET), was used. The models were analyzed by means of statistical indicators: Willmott’s concordance index, root mean square error (RMSE), mean bias error (BIAS), coefficient of determination “R²”, correlation coefficient “r” and coefficient of confidence “c”, in addition to the classification of the coefficient of confidence. The results obtained show that Hargreaves and Samani equation was the only method classified as “good” and is recommended. While the models of Camargo, Priestley and Taylor and Benevides and Lopes are not recommended to calculate ETo in the municipality.

INFLUENCE OF TEMPERATURE AND ALTITUDE ON THE EXPANSION OF COFFEE CROPS IN MATAS DE MINAS, BRAZIL

2020-02-20T10:35:43-03:00

Coffee is among the most significant products in Brazil. Minas Gerais is the largest state producer of Arabica coffee. Coffee activity has excellent growth potential, which justifies the identification of new areas for expansion of the culture. This study aimed to determine factors that affect the spatial distribution of coffee plantations the most, as well as to identify areas with a greater aptitude for its expansion in the region of the Matas de Minas (63 municipalities). The MaxEnt software was used to elaborate a model capable of describing the area with the highest potential for estimating the probability of coffee adequacy. The elaboration of the model considered the records of occurrence, climatic and topographic variables of Matas de Minas, the second largest state producing region. The area under the curve (AUC), the omission rate and the Jackknife test were used for validation and analysis of the model. The model was accurate with an AUC of 0.816 and omission rate of 0.54% for the ‘test’. It was identified that the potential distribution of coffee in Matas de Minas is determined by changes in the annual maximum temperature, although it did not generate a significant gain when omitted, accounting for a considerable loss in the model. However, the most influential variables on the delineation of distribution were, the altitude and the annual average temperature. The most favorable areas for expansion of coffee culture in the Matas de Minas were found in the vicinity of the region of Alto Caparaó.
Abbreviations used: A1 (altitude); A2 (maximum annual temperature); A3 (annual minimum temperature); BIO 1 (annual average temperature 1); BIO 4 (temperature seasonality), BIO 12 (annual precipitation); BIO 15 (precipitation seasonality); csv (comma-separated values); AUC (area under the curve).

ERGONOMIC EVALUATION OF AGRICULTURAL TRACTORS USED IN FORESTRY OPERATIONS

2020-09-26T17:30:39-03:00

The objective of this work was to evaluate farming machines adapted to forestry work and to verify if their characteristics meet the safety, ergonomics and working conditions necessary to maintain the health and safety of the operators. Thus, three farming tractors were selected, with a closed cabin and a minimum power of 73.5 kW, a widely used specification in the forestry sector. The following ergonomic parameters were considered: acess to the cab, cab dimensions, visibility, seat, controls and operation, work posture, cabin air conditioning, noise, lighting and maintenance aspects. The evaluations were based on the guidelines contained in the “Ergonomic Guidelines for Forest Machines” of the Swedish Forestry Research Institute, developed for forestry machines. The results showed that all the evaluated machines presented ergonomic standards below those indicated in all evaluated aspects, particularly related to access to the work station and difficulties during mechanical maintenance, besides the necessity of adopting forced postures during the working day due to operator’s seats. It was concluded that the farming machines adapted for work in forest processes presented significant gaps in relation to the ergonomic aspects, which represents high and imminent risks of development of occupational diseases in their operators, as well as the predisposition to work accidents.

ANALYSIS OF THE LONGITUDINAL DISTRIBUTION OF TOMATO SEEDLINGS TRANSPLANTED AS A FUNCTION OF OPERATIONAL SPEED

2020-06-12T13:41:48-03:00

The semi-mechanized transplanting of industrial tomato seedlings has become a viable alternative for the farmers. The aim of this work was to evaluate the influence of operating speed in the transplanting process of tomato seedlings. The work was conducted in a commercial area with 58 ha irrigated by a center pivot. The operating speeds evaluated were of 1.62; 3.15 and 4.00 km h^-1, being the measurement of the distribution and the number of transplanted seedlings carried out after the passage of the mechanized set. The means of the distances between seedlings determined at each operating speed, before and after the passing on, were analyzed by Tukey test at 5% probability. For lower operating speeds of transplanting, it was observed a greater distance between the seedlings.

INFLUENCE OF TIME OF GLYPHOSATE APPLICATION IN THE CONTROL OF BRACHIARIA

2020-10-28T15:30:34-03:00

In the no-tillage system, the burndown of brachiaria is usually performed with the application of systemic herbicides, such as glyphosate. As a result of environmental conditions (temperature, relative humidity and winds), the timing of spraying can directly interfere in the control efficiency. Therefore, the objective was to study different times of application of glyphosate in the control efficiency of Urochloa brizantha cv. Marandu. The glyphosate was applied in the morning, afternoon and evening, at doses of 0; 360; 720; 1080; 1440 and 2160 g a.e. ha-1. Water-sensitive papers were placed randomly on the plants at each time of application, in order to check the quality of spraying. To analyse the efficiency of U. brizantha burndown, the control was evaluated at 21 days after application. At 42 after application a mowing was done and 90 days after mowing, the dry matter accumulation and the Leaf Area Index of regrowth were determined. The best control results of Urochloa brizantha cv. Marandu were obtained in the applications of glyphosate during the morning and afternoon. Evening applications of glyphosate should be avoided.

QUALITY CONTROL OF PNEUMATIC SPRAYING IN TOMATO

2020-08-11T10:14:32-03:00

Tomato is a vegetable of great importance on the national scene. One of the problems of this culture is the great susceptibility to attack by pests and diseases. Thus, one of the most used practices is chemical control with phytosanitary products. The objective of this study was to evaluate the technical parameters of pneumatic spraying in tomato culture, through the study of the volumetric index and the population of spray droplets, aiming to reduce the spray volume, obtain the best efficiency and the social and environmental safety of the applications. The study of the droplet population was performed using water-sensitive paper labels. These labels were placed in the canopies of the tomato plants at three different heights and two positions. The sprays were made using a pneumatic backpack sprayer. After applying the syrup (dye + water), the water-sensitive paper labels were collected and subjected to the coverage and droplet density analyses by the computer program “CIR” version 1.5. The pneumatic sprayer proved to be efficient for the application of phytosanitary products in the tomato. The percentage of the target covered area ranged from 2.1 to 8.3% for volumetric indices as a function of thirds and positions, whereas the density of droplets ranged from 145.4 to 690.1 drops cm-2 for thirds and positions of the tomato plants evaluated. Finally, the volumetric index of 5 mL m-3, with a consequent spray volume of 50 L ha-1, met the parameters of a quality spray.

DEVELOPMENT OF A LASER PROFILOMETER FOR THE GENERATION OF 3D- MODELS TO MEASURE THE VOLUME OF FERTILIZER APPLIED BY FERTILIZER SOWERS

2020-09-01T10:52:20-03:00

Laser profilometry based on triangulation is a method for measuring depth of points in space that uses a laser beam to scan the object. The image of a laser-line projected onto a surface of an object is captured and treated in image-analysis software, which calculates its profile. The union of a sequence of profiles allows the construction of the 3D-digital models of objects. The objective of this work was to develop a methodology and to build a prototype of a threedimensional scanner based on laser triangulation. A prototype was built, with a gantry structure containing a car on which are a laser diode and a camera. This car is driven by an endless shaft driven by an electric motor with variable speed. When moving the car, the laser module produces a line on the surface of the object that is filmed by a camera fixed at a known angle, obtaining the necessary information to generate the 3D model of the object. Tests were made on regular objects: hubcaps, pyramids and cobblestones and the results showed that the 3D-models produced had the same dimensions. Tests were also made on irregular objects such as soil surface and fruit. The prototype proved to be solid for generating 3D models of objects.

INFORMATIONAL PHASE OF THE DEVELOPMENT OF EQUIPMENT FOR ANALYSIS OF DIRECT SHEAR AND PRE-COMPACTION OF THE SOIL

2020-09-04T07:58:51-03:00

Given the real need for advances in studies such as the relationship of soil-machine dynamics, it is clear that there are almost no innovative systems developed to attend this demand. The design of agricultural machinery and equipment can be facilitated by having information and mechanisms that allow the prediction of the mechanized-set behavior in real work situation, especially regarding the traction effort demanded by the tractor, due to the energy demand of the equipment that interact directly with the soil. Obtaining this information usually requires high-cost imported laboratory equipment. Thus, the objective of this work was to obtain the design specifications for the development of a direct shear and soil pre-compaction analysis equipment with low manufacturing cost. The Phases Methodology was used to obtain the necessary parameters, in the informational phase of the desirable aspects for each design requirement. Through a step-by-step analysis, it was possible to obtain customers’ needs, together with the establishment of the desired criteria, and the design requirements for the new product development was generated. The use of the Phases Model allowed the transformation of customers’ requirements into the design requirements, enabling hierarchization by degree of importance and thus enabling the execution of future steps.

OPERATIONAL PERFORMANCE AND COSTS OF MECHANIZED STUMP EXTRACTION SETS

2020-09-29T15:48:21-03:00

Stump extraction can be carried out in different ways, among which the mechanized removal is the most usual in the forestry sector. Information regarding the operation with cutting implements is important in the context of decision taking, operational and economic optimization of the activity. The objective of this work was to evaluate the operational performance and mechanized costs of different stump extractors implements in an eucalyptus harvested area. The work was carried out in an Eucalyptus urograndis clones harvested area where the treatments adopted for removal were the following: agricultural tractor + shredder head (T1), excavator + shovel bucket (T2); excavator + shredder head (T3), excavator + stump shear (T4) and bulldozer mat + stump pullers (5). The experimental design was the completely randomized, with four replications per treatment, where it was evaluated the operational efficiency (Ef), operational field capacity (Ofc), extraction productivity (Ps), hourly fuel consumption (Fch), hourly cost (HC), operational (OC) and by extracted stump (SC). For the conditions of the work, the T5 was the one with the highest Ef, Ofc, and Ps, lowest OC and SC.

SPECTRAL CURVES FOR IDENTIFICATION OF WEEDS IN WHEAT CROP

2020-02-03T16:17:33-02:00

The principal weeds in wheat cultivation are black oats and ryegrass and their control is generally performed without considering the spatial variability of the density of weed infestation. One way to identify weed species is by analyzing spectral curves of the targets. The objective of this work was to evaluate the spectral curves of wheat, black oats and ryegrass to identify which wavelengths are able to distinguish these species. The experiment was set using the species: black oats, ryegrass and wheat. Each species was sown in individual experimental plots in a completely randomized design with nine replications. HandHeld 2, ASD® spectroradiometer with 325-1075 nm spectral range was used to perform readings at full bloom stage. Then, the reflectance spectral data were grouped into eight spectral bands: violet, blue, green, yellow, orange, red, red edge and near infrared. Descriptive statistics of reflectance of the targets as well as analysis of variance (p<0.05) and test of Tukey for comparison of the means (p<0.01) were performed using the reflectance measurement of each spectral band. The results showed that the yellow and orange spectral bands obtained higher capacities of differentiation of the species under study. It can be concluded that the analysis of spectral curves of target of black oat and ryegrass weeds and wheat crop makes it possible to differentiate species in full bloom stage.

ECONOMIC FEASIBILITY OF THE USE OF TRACTOR/AGRICULTURAL IMPLEMENTS FOR BUILDING TERRACES

2020-06-02T11:36:14-03:00

The objective of this work was to analyze the operational costs of agricultural mechanization in the construction of terraces as well as its purchase economic feasibility. This experiment was conducted in the city of Montes Claros, Minas Gerais. It evaluated the operating costs considering the availability of implanting three terraces: Manghum, Nichols and Wide Base terraces. A three-fixed-disc plow was adopted for the Manghum type, a three-reversible-disc plow was used for the Nichols type and a drag-plow was used for the Wide Base. Even with higher hourly-costs (R$ h-1), the drag-plow provided a lower total cost (R$ terrace-1) and consequently more terraces were built per hour due to its higher efficiency. The Leveling Point has shown that for the Manghum terrace, to purchase the tractor and the fixed disc plow is feasible if the number of worked-hours exceeds 219.3 hours per year; for the Nichols terrace type, to purchase the tractor and the reversible disc plow is only possible when the number of hours is higher than 247.7 hours per year and, for the Wide Base terrace, to purchase the tractor and the drag-plow is viable with a number of hours exceeding 167.8 hours per y

SISFLOR: A COMPUTATIONAL SYSTEM TO DETERMINE THE OPTIMAL TREE BUCKING

2020-06-29T14:44:34-03:00

Um mercado florestal cada vez mais competitivo e atrelado às demandas por multiprodutos da madeira favorecem o estudo e o desenvolvimento de aplicações que busquem aumentar a receita dos empreendimentos florestais. Durante a colheita, o padrão de corte (sortimento) no qual as árvores são traçadas é determinado tradicionalmente pela experiência do motosserista, sem o emprego de qualquer técnica de otimização, o que pode acarretar em perdas financeiras em relação aos produtos comercializados. Normalmente, existem inúmeros sortimentos distintos passíveis de escolha e dificilmente processados por um algoritmo de força bruta. Trata-se do problema do sortimento florestal em nível de árvore individual com o objetivo de maximizar o valor comercial das árvores abatidas. A Programação Dinâmica (PD) apresenta-se como uma técnica de otimização eficiente para determinar os sortimentos ótimos das árvores, pois permite reduzir significantemente o número de cálculos a serem feitos. Nesse sentido, o objetivo desse trabalho foi desenvolver um sistema computacional moderno e intuitivo capaz de encontrar os sortimentos ótimos via PD a fim de auxiliar as empresas durante o traçamento dos fustes, caracterizando-se assim, como uma ferramenta de apoio à tomada de decisão. Após a execução do sistema, o sortimento ótimo é exibido detalhando-se sequencialmente todos os produtos que devem ser retirados do fuste analisado, assim como seus respectivos volumes e receita.

SOIL DENSITY AND OPTIMUM MOISTURE FOR SOIL COMPACTION IN FIVE SOIL CLASSES IN WESTERN BAHIA STATE

2020-08-31T09:41:25-03:00

The transformation of natural ecosystems into agricultural environments modifies the soil structure and it may result in its compaction. Therefore, the objective of this work was to determine the optimum moisture for soil compaction (wot) and maximum soil compaction density (Ds_max) in different soil classes in western Bahia State. The samples were collected in five sites covering different soil classes: Orthic Quartzarenic Neosol (RQ), Orthic Ebanic Vertisol (VEo), Haplic Cambisol (CX) and two Red-Yellow Latosol, one already cropped (LVA) and another with native forest (LVA1). Wot and Ds_max were determined according to ABNT NBR 7182 (1986) standards. Data were submitted to a regression analysis and also to the analysis of the principal components (PCA). Wot presented a decreasing order: VEo> LVA> LVA1> CX> RQo, ranging between 8.20 and 15.00% and Ds_max showed the following order RQo> LVA> LVA1> CX> VE, ranging between 1.34 and 1,92 Mg.m^-3. The wot was directly proportional to the clay content and the organic carbon and inversely proportional to the soil sand content. For Ds_max, the influence of the clay was inversely proportional whereas in wot, this variable promoted the growth.

NUTRITIONAL STATUS OF CORN PLANTS ESTIMATED THROUGH DIFFERENT VEGETATION INDICES IN THE GROWTH STAGES

2020-10-08T16:09:44-03:00

Several vegetation indices (VIs) have been proposed in the literature with the objective of exploring the spectral properties of the vegetation as they are usually related to biophysical parameters of the plants. The objective of this study was to evaluate the relationship between VIs, obtained in two different RPAS platforms (Remotely-piloted spacecraft system) and proximity system at different corm growth stages with the nitrogen (N) nutritional status in the plant. Five treatments with different nitrogen fertilizer rates (20, 60, 120, 180 and 240 kg ha-1) were studied in order to generate the variability of nitrogen uptake by the plant in four blocks with five replicates each. Reading of the following VIs were performed: NDRE and NDVI (proximity sensing, Optrix sensor) and NDRE, NDVI, EVI2 and GNDVI (RPAS platform, MicaSense Parrot Sequoia sensor) at the phenological stages V5, V6, V7, V9, V11 and V12. Corn plants were collected to evaluate N content in the aerial part of the plant. The N content was higher in V7 growth stage and lower in V12 stage. The VIs obtained through the RPAS platform presented higher relationship with the corn nutritional status when compared to the proximity sensors. The V12 corn growth stage had higher relationship of VIs and plant N content in comparison to the proximity sensor.

EFFECT OF FOLIAR-APPLIED TANNERY SLUDGE ON GROWTH AND PHYSIOLOGY OF PASSIFLORA EDULIS SEEDLINGS

2020-10-07T23:03:10-03:00

Today, industries are increasingly concerned about the disposal of their waste. One of the proposed solutions to deal with certain wastes is through agriculture in the form of fertilizers. Thus, the objective of this study was to evaluate the effect of liquid tannery sludge as foliar fertilizer on the growth and physiology of passion fruit seedlings. The experiment was conducted in a greenhouse, in a randomized block design with six replications. Six treatments were applied to leaves: tannery sludge diluted in water (132, 263, 395 and 527 mL L-1); only water (control); and the conventional treatment. The following growth characteristics were evaluated: leaf production, plant height, crown diameter, stem diameter, total fresh matter and dry matter of the plants. The physiological characteristics evaluated were the indices chlorophyll, nitrogen balance, flavonoids, anthocyanins, and plant color. The flavonoid index increased in plants that received foliar application of 527 mL L-1 without compromising the other characteristics evaluated. The doses 263, 395 and 527 mL L-1 showed the best results for the growth characteristics, equaling those of the conventional treatments. Foliar application of tannery sludge can be recommended for yellow passion fruit seedlings.

OPTIMIZATION OF CANOLA AGRONOMIC YIELD SUBMITTED TO DIFFERENT DOSES OF POTASSIUM IN FLOWERING

2020-08-11T10:25:53-03:00

Providing nutrients in quantities and at the right time is of paramount importance to obtain high yields in canola culture. The objective of this work was to evaluate the agronomic performance of the Hyola 433 hybrid, submitted to potassium fertilization during flowering, during the 2016/2017 harvest. A randomized block design with four repetitions was used, in a 2x5 factorial scheme, with two canola phenological stages (F1 and F2) and five potassium doses in coverage (0, 15, 30, 60 and 120 kg ha-1). The following phenometric variables were evaluated: emergence at the beginning of flowering (EIF), flowering duration (DFL), maturation duration (DFL) and cycle; as well as agronomic variables: number of silicas per plant (NSP), number of grains per silicas (NGS), plant height (ESP), mass of a thousand grains (MMG), productivity (PRO) and oil content. There was no interaction between application times and potassium doses for MMG, PRO and oil content. The dose of 60 kg ha-1 increased the DFL and the cycle. The maximum number of 309 silicas per plant was obtained with the dose of 120 kg ha-1 of K2O. The increase of potassium concentrations reduced calcium concentration in plant tissue. In general, potassium fertilization during flowering increases the expression of variables related to canola phenology and agronomic performance.

METHODOLOGY OF ECONOMIC EVALUATION OF EXTERNALITY EMISSIONS IN RELATION TO THE VALUE OF ELECTRIC POWER GENERATED BY THE BURNING OF BIOGAS IN THE RURAL ENVIRONMENT

2020-12-14T21:42:09-02:00

Brazilian cattle raising needs greater automation as a way to improve productivity and at the same time new ways to meet the growing energy demand. Thus, an alternative is to use renewable sources of electric energy such as biogas. This work proposes a methodology for economic evaluation of the externality denominated emissions, originating from the generation of electric energy through the burning of biogas from residues of Brazilian livestock. Thus, an equation was proposed and applied to obtain the value of this externality as a percentage of the value of electric energy, where greater results indicate greater potential for this externality. The results showed that the emissions, assessed as an externality and quantified on the basis of carbon credits can account for up to 69.4% of the electricity price, but if quantified in relation to the social impact of carbon, the externality in reference exceeds the value of electricity, reaching 408.4%. As a result, it is clear that the use of biogas for power generation in livestock can present other valuable products in addition to electricity and, consequently, can add value to livestock activity.

SPATIAL VARIABILITY OF PHYSICAL ATTRIBUTES, LITTER AND SOIL CARBON STOCK IN A FAMILY FARMING SYSTEM IN TOCANTINS

2020-02-03T16:13:18-02:00

The monitoring of soil attributes allows the evaluation of its ability to perform its functions within an agroecosystem. The objective of this work was to evaluate the spatial variability of soil physical attributes, litter and carbon stock in a family farming system in the Cerrado Tocantinense. The area is located in the southern region in the state in the municipality of Aliança do Tocantins. Four types of land use were diagnosed in the area: brachiaria pasture intercropped with stylosanthes, Andropogon pasture, orchard and native forest. The native forest was considered as a reference. The study area totaled 7.9 ha-1 in which it was distributed an irregular sample grid composed of 160 points. Deformed and undeformed samples were collected for each georeferenced point at depths of 0-10 and 10-20 cm, as well as samples to determine the litter and soil carbon stock. Data were submitted to exploratory analysis and geostatistical study. It was found that the conversion of native forest for different soil uses through orchard, brachiaria, andropogon and native forest caused spatial variability in physical attributes, litter and soil carbon stock at depths 0-10 and 10-20 cm. The orchard subarea stood out as a promising system in the accumulation of organic carbon due to cattle manure.

CONTROL SYSTEM FOR COMPLETE BURNING IN FURNACE USING LAMBDA PROBE

2020-02-04T12:44:04-02:00

The objective of this work was to evaluate the biomass burning process in a furnace, using chip as a raw material and an oxygen sensor (lambda probe) to monitor the percentage of oxygen in the gases exhausted during combustion, aiming to maintain the percentage of the coefficient of excess air (?) in the operating range of 1.20 to 1.25%, considered ideal for the biomass (chip) used in the study. Once the excess air is identified at the upper furnace exit, the air entrance in the system will be closed by means of a butterfly valve using a servo motor driven by a Programmable Logic Controller (PLC). The valve was opened or closed according to the oxygen level; when it was lower than 1.20%, the door remained open, and it was closed when the level reached 1.25%, finishing the cycle of the process. The open and closed states of the valve occurred by means of two reed switch magnetic key sensors installed in the air intake system. For the control, monitoring and data acquisition, a supervisory system created using the Elipse SCADA software was used so it was possible to obtain a system database, which will provide important information to maximize the efficiency of the furnace.

SYSTEMATIC BIBLIOGRAPHICAL REVIEW OF SCIENTIFIC PUBLICATIONS ON THE USE OF MILLET AND SORGHUM AS VEGETABLE COVER

2020-02-04T17:41:33-02:00

The use of alternative systems seeking unsustainability in agricultural production in Brazil, has developed strongly with the use of No-Tillage System (NTS), therefore remodeling the production system. For the production efficiency, it is necessary to use suitable crops as plant cover, depending on the region where the no-tillage system will be set, in which sorghum and millet crops were very positive. Thus, the objective of the work is to perform a systematic literature review on papers approaching the subject with the use of sorghum and millet as a vegetative cover for subsequent no-tillage. It is possible to verify a concentration of the studies after the 2000 decade, in the Southeastern and Central-Western regions of Brazil.

MINING RESIDUE IN THE COMMERCIAL LIMESTONE BLENDING AND THE CHEMICAL ATTRIBUTES OF A LATOSOL

2020-09-11T08:50:08-03:00

The limestone mining activity causes environmental impacts due to the generation of waste. However, the reuse of these residues has been investigated with the objective of improving soil fertility and acidity correction. The objective of this work was to evaluate the potential for using mining residues in the commercial limestone blending and in the chemical attributes of a dystrophic Red Yellow Latosol. The experiment was carried out in three steps: the first corresponded to the sampling and characterization of the residues in the tailings pile; the second was the combination and characterization of the new soil acidity correction agents as well as the selection of treatments based on the Neutralization Power and doses of soil acidity correction agetns (0.0; 0.5; 1.0; 2.0; 4.0 t ha^-1); in the third step, a test of the incubation and calibration of the application doses of the soil acidity correction agents was performed. It was found that even with the raise in the levels of Ca²⁺ and Mg²⁺ in the correction agents, it was not possible to provide an optimal supply of nutrients to the soil, a fact explained by the low constant solubility of CaCO₃ and MgCO₃. However, the commercial limestone blending with tailing was efficient, as it had a significant effect on raising the pH and neutralizing the soil moisture potential.

GROWTH EVALUATION OF CROSSBRED HOLSTEIN×GYR CALVES AND HEIFERS RAISED IN TROPICAL CONDITIONS

2020-12-08T09:55:15-02:00

The objective of this study was to evaluate growth and body development of crossbred Holstein×Gyr calves and heifers raised in tropical conditions. Thirty-two crossbred heifers (Holstein×Gyr) aged between 1 and 1314 days were used. For assessing the animals’ body weight, the heifers were weighed once a week with a chest tape for weighing cattle, using the specification for medium breeds recorded on the tape itself. The experiment was conducted in a completely randomized design. Body weight data were analyzed using linear regression as a function of age, using the R software. We could observe that animals less than 200 days old had a performance estimate of approximately 0.517 kg day-1, while after at 200 days of life, the estimated weight gain was 0.237 kg day-1. Heifers had a higher growth rate before 200 days of age than after this age, which can affect the age at the first calving of the herd. Thus, as the age for the first breeding is linked to the weight of the live animals, the delay in the growth of the calves becomes detrimental to the breeding.

PROFILE OF SAWMILLS IN THE UBÁ FURNITURE HUB IN THE STATE OF MINAS GERAIS

2020-10-06T08:58:59-03:00

The objective of this work was to identify, diagnose and characterize the sawmills in four municipalities in the State of Minas Gerais (Divinésia, Senador Firmino, Brás Pires and Dores do Turvo) that provide lumber for the industries in the Furniture Hub in Ubá, State of Minas Gerais. A semi-structured questionnaire with open questions, answered in loco and accompanied by a responsible person (interviewer), with information on the identification of the potentialities and fragilities of the local lumber sector as well as to know the raw material (logs), the wood split processes, the internal management, the qualification of the employees, the machinery, products, market and prospects of the sector in these municipalities. It was found that Eucalyptus wood is the most used. The diameter of the logs is shown as the factor that affects the yield in 100% of the analyzed sawmills, where cracking and variability of the logs are the main difficulties of working with the raw material. The lumber sector in the analyzed municipalities needs a greater qualification, both managerial and technical, to improve the activity. In addition, it is necessary to better organize the companies related to the lumber sector through associations and support from local entities and greater exposure of the products to the local consumers.