RESUMO O tráfego intenso das máquinas nos solos cultivados aplica diferentes tensões que combinadas com altos valores de umidade desses

RESUMO:Os sistemas de preparo do solo afetam a quantidade de resíduo vegetal sobre a superfície do solo e, consequentemente, sua umidade e temperatura. Objetivou-se avaliar a temperatura e a umidade do Argissolo Amarelo em estádios de desenvolvimento da cultura do milho sob sistemas de preparo mecanizado. O experimento foi conduzido no delineamento em blocos inteiramente casualizados, com quatro repetições, em Petrolina -PE. Os sistemas de preparo do solo foram: sem preparo primário, grade off-set de discos de 0,56 m, grade off-set de discos de 0,61 m, escarificador e arado de aivecas. As leituras de umidade e temperatura foram realizadas ao longo do dia, nos horários de 6; 9; 12; 15 e 18 h, nos estádios de desenvolvimento V3, V8, R3 e R6 do milho. A umidade do solo foi avaliada na camada de 0,00-0,05 m utilizando-se do método gravimétrico, e a temperatura do solo na superfície, utilizando-se de termômetro infravermelho. Os sistemas de preparo do solo e os horários de leitura influenciaram na umidade e na temperatura do solo. Os maiores valores de umidade ocorreram no período da manhã, enquanto a maior temperatura do solo ocorreu na parte da tarde. PALAVRAS-CHAVE:mecanização agrícola, Semiárido Nordestino, variação térmica. SOIL MOISTURE CONTENT AND SURFACE TEMPERATURE IN TILLAGE SYSTEMS AND STAGES OF DEVELOPMENT OF MAIZE CROP ABSTRACT:The tillage systems affect the amount of crop residue on the soil surface, and hence its temperature and moisture content. To evaluate the variation of moisture content and soil temperature in systems of tillage on maize growth stages, an experiment was conducted in Ultisol.The experiment was conducted with randomized complete block with four replications in Petrolina -PE, Brazil. The treatments consisted of five tillage systems applied to the plots -unprepared primary, off-set disc harrow of 0.56 m, off-set disc harrow of 0.61 m, chisel plow and moldboard plow. The soil moisture and temperature readings were taken at 6, 9, 12, 15 and 18 h for the different maize stages V3, V8, R3 and R6. Soil moisture was measured in the layer between 0.00-0.05 m by means of deformed samples by using gravimetric method and soil temperature at the surface with infrared thermometer. Systems of soil tillage and hours of reading influenced the moisture and soil temperature. The highest values of soil moisture content occur in the morning, while the highest temperature of the soil in the afternoon.

The continuous use of tillage equipment without variation of the work depth can lead to soil compression problems. This study aimed to evaluate the spatial variability of soil resistance to penetration (RP) in a yellow ultisol profile in different tillage systems and tractor-equipment speeds. The experiment was carried out at the Agricultural Sciences Campus – UNIVASF, Petrolina- PE, Brazil, in randomized blocks with split plot with four repetitions. The treatments consisted of five tillage systems applied to the plots: without the first soil preparation, tandem grid and moldboard plow, 0.56 m off-set grid discs, 0.61 m off-set grid disc plus tandem grid and chisel plow. For the subplots, the speeds of the tractor-equipment used were: 2.45 km h‑1 (L1), 3.88 km h-1 (L2), 5.72 km h-1 (L3) and 6.50 km h-1 (H1). For the soil data collection and the RP determination, an electronic penetrometer was used, determining the sample profile moisture. Data analysis was carried out based on geostatistics and isoline maps. It can be verified the operationarea of the active organs of the equipment, the zoning of compacted areas (RP) and the RP levels of the studied profile. The lower RP was obtained when the tandem grid plus the chisel plow was used.

Plant cocktails used as cover crop present a significant multifunctional resource compared to monoculture, which may increase functional diversity within crop rotation and is particularly effective for designing mixtures with characteristics that increase the multifunctionality and sustainability of the agroecosystem. The objective was to evaluate sustainable agroecosystems models that improve the efficiency of nutrient cycling for crops. The treatments were arranged in four blocks in a split-plot design with two soil management (tillage and no-till) systems and three cropping systems (2 plant cocktails [PCs] and 1 natural vegetation [NV]). C/N ratio, lignin content, dry biomass (DB) production and decomposition, nutrients accumulation and mineralization by PCs and NV were evaluated. Decomposition and release of nutrients were monitored by the litterbag-method. PCs had a DB production twice higher than NV, essential for the adoption of no-tillage systems. The order of nutrient release was K> N> Ca> P> Mg. PCs as cover crops and green manure, with or without predominance of legumes and use of a no-tillage system, could be a technological strategy in agroecosystems for nutrients cycling in semi-arid regions.

Agriculture is a vulnerable sector to the climate changes, and Brazil is one of the major contributor of greenhouse gases (GHSs). Thus, the implementation of effective strategies for both mitigation and adaptation to climate change for agriculture is very important for development and also to infer sustainability to the Brazilian agricultural sector. The "low-carbon agriculture" aims to develop processes and technologies that promote mitigation of GHG emissions in agriculture and enable the adaptation of the agricultural sector to climate change. Thus, in Brazilian semiarid region, developing technologies with no-tillage systems concomitant with green manure and agrosilvopastoral systems are adapted to climatic conditions to infer sustainability in the livestock and agricultural sectors.

RESUMO:O trabalho objetivou avaliar o desempenho do trator agrícola em função dos sistemas de preparo do solo e velocidades de deslocamento. O experimento foi conduzido no Campus de Ciências Agrárias da UNIVASF, em Argissolo Amarelo num delineamento em blocos ao acaso com parcelas subdivididas e quatro repetições (blocos); constituído por quatro sistemas de preparo do solo aplicados nas parcelas -grade tandem mais arado de aiveca, grade off-set de discos com 0,56 m, grade off-set de discos com 0,61 m e grade tandem mais escarificador, enquanto que nas subparcelas aplicou-se quatro velocidades de deslocamento na mobilização do solo: 2,45 km h-1; 3,88 km h-1; 5,72 km h-1 e 6,50 km h-1. Avaliaram-se: largura e profundidade efetiva de trabalho, ruído no posto do operador, capacidades de campo, rendimento de campo teórico, variação da velocidade de trabalho e força de tração e potência estimadas. Os valores de ruídos estiveram acima do limite estabelecido pela legislação para todos os sistemas de preparo do solo. A maior largura de trabalho ocorreu para os sistemas de preparo de menor profundidade de trabalho, no caso as grades, que apresentaram maior capacidade de campo, como força de tração e potência estimados. O aumento de velocidade proporcionou incremento na capacidade de campo efetiva e operacional, na variação da velocidade, como na força de tração e potência estimados, mas reduziu o rendimento de campo teórico. PALAVRAS-CHAVE: capacidade de campo, manejo de solo, mecanização agrícola. PERFORMANCE OF THE TRACTOR IN FUNCTION SOIL TILLAGE SYSTEMS AND FORWARD SPEEDABSTRACT: The purpose of this study was to evaluate performance of the tractor in function soil tillage systems and forward speed. The experiment was conducted at the Campus Agricultural Sciences of the UNIVASF, under Vertisol in randomized blocks with split plots and four replications (blocks); consisting of four tillage systems applied to the plots -disc harrow tandem more moldboard plow, harrow disc off-set of 0.56 m, harrow disc off-set of 0.61 m and disc harrow tandem more chisel plow, while the plots were applied four forward speeds in tillage: 2.45 km h-1, 3.88 km h-1, 5.72 km h-1 and 6.50 km h-1. It was evaluated: width and effective depth of work, noise at the operator, field skills, theoretical yield, change in working speed and traction force and power estimates. The noise level were above the limit established for all tillage systems. The larger working width occurred for tillage depth of less work, if the grids, which had a higher field capacity, as traction force and drawbar pull estimates. The fastest speed provided an increase in the effective field capacity and operational, the speed variation, as the traction force and drawbar pull, but reduced the theoretical yield.

RESUMO:A modernização da agricultura por meio da utilização de máquinas agrícolas tornou-se essencial para algumas atividades agrícolas; entretanto, trouxe consigo desvantagens relacionadas com o desempenho das máquinas e a ergonomia dos seus operadores. Objetivou-se com o trabalho avaliar a patinagem dos rodados, a opacidade da fumaça e os níveis de ruído emitidos por três tratores agrícolas sem lastragem líquida. O trabalho foi conduzido no Campus de Ciências Agrárias -UNIVASF num delineamento inteiramente casualizado avaliando os parâmetros: patinagem em fatorial de dois fatores (trator e método de avaliação da patinagem) com três repetições, opacidade da fumaça em três tratores com sete repetições, e ruído em fatorial de três fatores (trator, posição de leitura e rotação do motor) com três repetições. Os dados foram analisados por meio de análise de variância e teste de Tukey a 5% de probabilidade. Diferentes métodos de avaliação da patinagem apresentaram valores distintos para a variável. A opacidade da fumaça não depende do tempo de uso do trator e da potência do motor, mas da manutenção do sistema de alimentação. Os tratores de menor potência apresentaram maiores valores de ruído. Na rotação de trabalho todos os tratores apresentaram níveis de ruído acima do permitido pela legislação brasileira para exposição sem proteção auricular. PALAVRAS-CHAVE:Ergonomia, máquinas agrícolas, mecanização agrícola. WHEEL SLIPPAGE, SMOKE OPACITY AND NOISE LEVEL OF THREE FARM TRACTORS OF TIRES ABSTRACT:The modernization of agriculture through the use of agricultural machinery has become essential for agricultural activities. The objective of this research was to evaluate the wheel slippage, smoke opacity, and the noise levels emitted by three tractors (4x2 with 40.5 kW of engine power and 2780 h; 4x2 TDA with 55.2 kW of engine power and 5638 h; and 4x2 TDA with 4.,0 kW of engine power and 367,8 h) without liquid ballast. The field trials were conducted at the Campus Agricultural Sciences -UNIVASF in a completely randomized design. The parameters evaluated were: wheel slippage in combination of two-factor (3 tractors and 2 evaluation method of sliding) with three replications, smoke opacity in three tractors with seven replicates, and noise level in combination of three factors (3 tractors, 2 reading position, and 3 engine speed) with three replications. Data were analyzed by variance analysis and Tukey test at 5% probability. The wheel slippage was significantly different according to evaluation methods, being higher using the method of the number of laps tire. The tractor with 40.5 kW of engine power showed higher smoke opacity. This result does not depend on the time of tractor and engine power use, but on the maintenance of the power system. Tractors with lower power showed higher noise level. Job rotation in all tractors showed noise levels higher noise levels than those permitted by Brazilian legislation for exposure without hearing protection.

This study evaluates the effect of a low-cost biodegradable coating formulated with potato starch, rice starch, cassava starch, and gelatin on the postharvest quality of ‘Tommy Atkins’ mango. The experimental design was completely randomized, arranged in a 7x6 factorial scheme with four replications per treatment. The data were subjected to analysis of variance using the Tukey test at 5% probability. After coating, the fruits were stored under ambient conditions (25 ± 3 ºC and 65 ± 5% RH) for 10 days, with analysis every two days. The variables analyzed were: fruit firmness, weight loss, total soluble solids, total titratable acidity, total soluble solids/titratable acidity ratio, delta absorbance (DA) index, colorimetric analysis of the peel and pulp, and ascorbic acid content. The application of biodegradable coatings did not extend the shelf life of ‘Tommy Atkins’ mango during storage.