REVISTA ENGENHARIA NA AGRICULTURA - REVENG

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.

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).

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.

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.

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.

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.

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.

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.