The usage of biodiesel, a renewable and biodegradable fuel, is becoming increasingly popular. The objective of the study was to evaluate the operational performance-tractor forward speed, drawbar power, and fuel consumption-and smoke density of an agricultural tractor using biodiesel, diesel, and biodiesel/diesel mixtures as fuel in a tilled field. Soybean biodiesel, murumuru biodiesel, and three combinations of soybean biodiesel and murumuru were used: 90S10M (90% soybean and 10% murumuru), 80S20M (80% soybean and 20% murumuru), and 70S30M (70% soybean and 30% murumuru). The biodiesel/diesel ratios were: B0, B5, B15, B25, B50, and B100; the letter B indicates the presence of biodiesel and the number is the percentage of biodiesel in the diesel. The results showed an increase in specific fuel consumption (SFC) of 10.13%, 16.66%, 12.69%, 14.59%, and 17.42% for murumuru, soybean, 90S10M, 80S20M, and 70S30M, respectively, when comparing B100 to B0. SFC was influenced by the type of biodiesel, B100 of soybean, 90S10M, 80S20M, and 70S30M consumptions were, respectively, 7.8%, 2.9%, 5.2%, and 8.8% higher than those of murumuru. The hourly volumetric consumption (HVC) of 90S10M was 4.8% higher than soybean and murumuru. The tractor's forward speed and drawbar power did not have any significant difference. Smoke density was reduced by 51.6%, 23.04%, 30.41%, 37.8%, and 36.9% for Murumuru, Soybean, 90S10M, 80S20M, and 70S30M, respectively, when comparing B100 to B0. For Murumuru, the smoke density was 59.0%, 43.8%, 28.6%, and 30.5% lower for this variety of biodiesel when compared to soybean at 90S10M, 80S20M and 70S30M, respectively. The results demonstrate the potential usage of biodiesel as a substitution for diesel.

Biodiesel is an alternative fuel to diesel engines. This study aimed to evaluate fuel consumption and smoke density of agricultural tractors fueled by biodiesel, diesel, and biodiesel/diesel mixtures in a tilled field. Treatments consisted of distilled methyl ester (biodiesel) of babassu (Orbinya martiana) and seven combinations of it with two standard diesel fuels (B S1800 and B S50). The blending ratios were 0, 5, 15, 25, 50, and 100% biodiesel in diesel oil (B0, B5, B15, B25, B50, and B100, respectively). Regarding the results for hourly volumetric consumption, no difference was found between B0 and B100 when using B S1800, whereas an 8% increase was observed when using the S50. The weighted hourly consumption increased by 11.29 and 16.9% from B0 to B100 using B S1800 and B S50, respectively. Similarly, the specific fuel consumption increased by 11.1% and 14.3% from B0 to B100 using B S1800 and B S50, respectively. Yet, when comparing B0 and B S1800, the smoke density reduction was 68.6% and between B S50 and B100 was 58.0%. Our findings show that babassu biodiesel is a suitable substitute for diesel oil, without causing any damage to the tractor's engine.

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Given the need for new alternatives to finite source of energy from fossil fuels, testing of alternative fuels has become quite important. Studies have been carried out using sets of tractor with equipment to evaluate the operational performance together with supplying diesel and biodiesel. Biodiesel is a feasible alternative as it waives adjustments in diesel cycle engines, unlike other clean fuels such as natural gas or biogas, for example. This study aimed at to assess the operational performance and smoke density of a tractor running on diesel and biodiesel, through the parameters of fuel type and engine speed. The assessed engine speeds were 1800, 1900, 2000, 2100, 2200, 2400 and 2600 rpm and the fuel types were diesel B S1800, diesel B S500, soyabean biodiesel and murumuru biodiesel. The results showed that there was an increase in the specific consumption for all fuel types with increasing engine speed, and 1900 and 2000 rpm, mainly for the use of biodiesel speed range that least interferes with the performance. The smoke density was reduced when using soyabean and murumuru biodiesels.

RESUMO: Mesmo para culturas mais estudadas como a soja, a dúvida em relação a aplicar ou não N na semeadura ainda persiste. No caso do amendoim, com a introdução de novas cultivares de alta produtividade, há necessidade de definir se esta estratégia de manejo deve ser recomendada ou não. O