Resumo em Inglês:

ABSTRACT The composting of waste from a broiler chicken production chain (BCPC) promotes the mitigation of environmental impacts and allows the commercialization of compost as an agricultural input. Both the characteristics and the potential for use of the final compost depends on the operational conditions during composting. The objective of this study was to evaluate the use of organic compounds generated from composting BCPC residues and the pruning debris of urban trees in the germination and initial growth of lettuce seedlings. Six organic substrates obtained under different coverage conditions (presence and absence) and number of turns (8, 12, and 16) were evaluated using the germination index (IG) and Dickson quality index (DQI) for the production of seedlings in trays and compared with a commercial substrate. Principal component analysis demonstrated that the IG is not related to the DQI. The compounds produced without coverage showed lower levels of electrical conductivity (p < 0.05) and potassium (p < 0.05) due to the leaching of soluble salts during composting. These substrates did not inhibit seed germination (IG ≥ 75%), but resulted in less robust seedlings, mainly in relation to the aerial portion. BCPC residues were viable for composting treatment and the DQI of the organic compounds (0.0125) used as substrates for the initial growth of lettuce seedlings were, on average, 14% higher than that obtained from the commercial substrate (0.090), indicating that the organic compounds were of better quality.

Resumo em Inglês:

ABSTRACT The environment control of broiler houses must be done adequately to provide good thermal conditions to broilers without wasting energy. The objective of this study was to characterize the thermal environment in two mechanically ventilated broiler houses with a negative pressure ventilation system, one with a cellulose pad evaporative cooling system and the other with misting nozzles for evaporative cooling. The experiment was conducted in Ervália-MG during winter, spring, and summer. The thermal environment was characterized based on the relationship between the temperature observed inside the broiler houses and the temperatures recommended for the thermal comfort of birds of different ages. The recorded data were evaluated using descriptive statistics, and the spatial variation of the average temperature data recorded during the growth phase in both broiler houses was evaluated graphically using contour graphs. During the brooding phase, the temperatures recorded in both broiler houses were above the recommended values (27-30 °C; 24-27 °C; and 21-24 °C, for the 1st; 2nd and 3rd weeks of bird life respectively) during the entire evaluation period. In the growout phase, it was found that during winter and spring, the interior temperature was within the recommended range (15–27 °C), however, in summer, there were periods when the interior temperature was above the comfort range of birds.

Resumo em Inglês:

ABSTRACT Ornamental pepper plants produced in containers under protected environments have high added value. We carried out research with an aim to evaluate the growth and development of ornamental pepper in containers of different colors under two protected environments, both with thermal-reflective screens under a polyethylene film: one with 18–22 % shading and the other with 42–50 % in colored containers (brown, blue, black, and red). The treatments formed by a 2 × 4 factorial (environments × container colors) were arranged in a completely random pattern with 4 replications and 5 plants per plot, and a joint analysis of experiments was used to compare environments. The protected environment covered with low-density polyethylene film having 42–50 % of shading promoted higher initial growth of pepper plants, including early maturity, compared to the protected environment with 18–22 % of shading. The colored containers, namely, the brown container in a protected environment with 42–50 % shading and red container with 18–22 % shading formed plants with better growth and yield characteristics compared to the black container. The seedlings in the blue container had delayed flowering.

Resumo em Inglês:

ABSTRACT To improve the conveying efficiency and working stability of a screw conveyor, the feeding methods, running conditions and flow characteristics of materials were studied by theoretical analysis and experiments. The theoretical analysis results show that the screw conveyor runs more stably when the helix angle of the screw blade is equal to the moving helical angle. A new spring-finger was designed by us and was used in the experiment. The experimental results show prove that the spring-finger feeder can help homogeneously and continuously to feed the screw conveyor and to improve the working stability of the screw conveyor. The movement state of materials along a pitch was videotaped by a high-speed camera with different filling rates and rotation speeds. The photographs and videos reveal that the characteristics of the materials and rotational speed affect the conveying performance and provide the basis for selecting the best operating parameters for screw conveyors.

Resumo em Inglês:

ABSTRACT Pesticide environmental risks and increased weed resistance have encouraged studies for alternatives to herbicides. Among these are weed thermal control methods by controlled heat application machines. Thus, this study aimed to test a prototype of heat-applicator machine as a function of changes in gas pressure, travel speed, and tire traffic effect on plants. Then, three experimental factors were tested: gas pressure (98, 196, and 245 kPa), travel speed (0.56, 0.78, and 1.17 m s−1), and tire traffic effect on plants (with and without traffic). The results showed that tire traffic effect on plants and subsequent heat application had no effect on control rate. Weed control rates reached levels considered satisfactory using a heat application speed of 0.56 m s−1 associated with gas pressures of 245 or 196 kPa, as well as a heat application speed of 0.78 m s−1 associated with a gas pressure of 245 kPa. A total between 60.9 and 84.9 kg ha−1 liquefied petroleum gas was required for weed control of around 80%.

Resumo em Inglês:

ABSTRACT Recently, Brazilian agriculture and the mechanization process have been improved and developed, particularly in sugarcane cultivation. The developed processes should adopt suitable management practices in terms of the technical, economic, and operational logistical aspects. As a management tool, the present study aimed to measure the impact of the accumulated use of harvesters (life in h) and agricultural productivity (Mg · ha−1) on the harvesting operational capacity (HOC). Mathematical modeling was performed on data obtained from eight sugarcane production units, and equations corresponding to the HOC as a function of the harvester's life and the crop agricultural productivity were developed. The equation that best represented the phenomenon was selected. The values of the HOC depend on operational conditions and range from (17 to 44) Mg · h−1, thereby demonstrating significant operational and economic discrepancies. When the mean life of the harvester was 10,000 h and the mean productivity of the cane field was 80.0 Mg · ha−1, an HOC of 31.7 Mg · h−1 was obtained. It was found that agricultural productivity is directly proportional to the HOC, whereas the harvester's life is inversely proportional to the HOC; the parameters are not linear in both cases.

Resumo em Inglês:

ABSTRACT Soil compaction in agricultural areas has greatly increased in recent decades due to intensive farming practices, including short-cycle crops and machinery intensification. This study aimed to evaluate the impacts of management systems on the physical quality of a dystrophic Yellow Oxisol, in the Cerrado region of Brazil. Treatments consisted of five soil management systems, with five replications (native forest [control], slash-and-burn agriculture, pasture, no-tillage, and conventional tillage). Data analysis was performed using a completely randomized experimental design. All systems were analyzed for soil density, macroporosity, microporosity, total porosity, hydraulic conductivity, infiltration, water retention curve, penetration resistance, and soil quality index (S index). The systems had significant effects on soil structure, and the evaluated properties responded well to changes promoted by them. No-tillage implementation raised soil resistance in the area previously damaged by intensive farming. Moreover, soils under pasture and slash-and-burn systems presented higher water retention in field capacity and higher S indexes, thus having a better structural quality.

Resumo em Inglês:

ABSTRACT The technological innovation in agriculture seeks to improve the performance of mechanized assemblies and, currently, rubber half-tracks are a valuable solution for agricultural tractors, combining traction performance and less soil compaction. The objective of the experiment was to evaluate the operational and energy performance of double wheeled versus rubber half-tracked agricultural tractors in the soybean sowing. The experiment was conducted in a strip-plot design with a double factorial arrangement (2×3). The first factor consisted of a tractor with double wheels on the front and rear axles versus a tractor with single wheels on the front axle and rubber half-tracks on the rear axle, while the second factor consisted of three different gears, with five replications, totaling 30 experimental units. The collected data were subjected to analysis of variance and, when significant, to the Tukey test. The sowing operation carried out with the half-tracked tractor was the most efficient in most of the analyzed parameters, allowing higher operational and energy efficiency in the soybean sowing.

Resumo em Inglês:

ABSTRACT Numerous factors are related to the individual sensory perception of consumers, which makes it impossible to adapt a model that explains their behavior. In this context and given the scarcity of statistical indexes that evaluate preferences for specialty coffees, new statistical methods should be studied. To this end, our study aimed to create an index that measures the acceptance of specialty coffees. The index was built considering the fit of regression models as a function of principal component scores. Validation was done by significance tests, whose probabilities were obtained by bootstrapping, considering the main measures used in diagnosing outliers as weights, with application to real data from different consumer groups. The coffee varieties Acaia and Bourbon were discriminated in relation to altitude. In conclusion, the index was adequate for the analysis and characterization of specialty coffees grown at different altitudes.

Resumo em Inglês:

ABSTRACT Land-use changes promote significant variations in streamflow regimes, and hydrological models allow studying their impacts. Based on this approach, this study aimed to assess the applicability of the SWAT model for different land-use scenarios and their respective impacts on the flow regime of the Mucuri River. The average monthly and daily water balance was generated after the calibration and validation of the SWAT model in the basin. Three land-use scenarios were analyzed in relation to the current land use, as follows: replacement of the agricultural area by the eucalyptus crop, replacement of the native forest area by the sugarcane crop, and replacement of pasture by exposed soil. The results showed that the SWAT model is adequate to simulate the land-use change and its impact on the flow regime of the Mucuri River; the replacement of agriculture by eucalyptus in the basin led to a decrease in the average and minimum reference streamflows; and the replacement of the forest cover by sugarcane and pasture by exposed soil provided an increase in the average and minimum reference streamflows.

Resumo em Inglês:

ABSTRACT The common bean is widely cultivated in Brazil. In the 2016–2017 growing season, an experiment was carried out in a Typic Quartzipsamment (or Neossolo Quartzarênico) soil in the municipality of Cassilândia, MS, Brazil, with the aim of characterizing specific aspects of soil management, using a linear and spatial correlation between the irrigated yield of common beans and the chemical properties of the soil. Soil samples were collected from layers at depths 0.00–0.10 and 0.10–0.20 m, within a grid of 117 georeferenced points. A data analysis was carried out using statistical and geostatistical techniques. A multiple regression analysis showed that about 31% of the grain yield variability of the irrigated common bean crop could be attributed to the spatial variability in the chemical properties of the soil. These properties have a spatial dependence that is classified as moderate and strong, with a predominantly Gaussian-type semivariogram model. Soil properties such as pH(1), pH(2), S(2) and V%(2) can be considered potential indicators of the grain yield of an irrigated common bean crop when cultivated in a sandy soil under a no-tillage system.