ABSTRACT Furrowing shank horizontal strength and working depth can be correlated with soil compaction in a no-till sowing. This study aimed to evaluate the correlation of furrowing shank strength and working depth with soil physical properties at two working speeds (1.58 and 1.87 m s-1) and four compaction levels induced by an agricultural tractor (0P, 1P, 3P, and 5P+Ballast), with four repetitions in an RBD. Thereby, we aimed to verify a potential increase in sampling density of soil compaction data. Horizontal strength at 1.58 m s-1 had Pearson correlations ranging from 0.74 to 0.73 with soil penetration resistance (SPR), and from 0.57 to 0.72 with some soil properties collected by volumetric ring. Working depth also correlated with several parameters ranging from 0.49 to 0.81. The highest correlations were verified for the speed of 1.58 m s-1, at which shanks maintained greater depth. This increased soil contact with the shank, hence sensitivity to compaction. Our findings show that furrowing shank horizontal strength and working depth can be used to monitor soil compaction.

ABSTRACT In Brazil there is a wide availability of residues, which have been used in the production of biogas and biofertilizers. The engine-generator by biogas is grid connected, and produce electricity for self-consumption and the surplus is inserted into the grid. The aim of the present study was to evaluate energetic efficiency and exhaust gas emission of two cases: two engine-generators sets of 100 kVA running on biogas, produced from residues of a poultry slaughterhouse unit (PSU) and swine fattening unit (SFU). Load variation in the engine-generator set was evaluated in the SMCP (system of protection and synchronism). There was an increase in the emission of nitrogen oxide, sulfur dioxide and exhaust gas temperature, in both cases. The elevation in the load of the engine-generator increased its global efficiency (mechanical plus electric), with levels between 6.12% with load of 10 kW and 20.91% with 70 kW. The average specific consumption of biogas in the load of 70 kW was 0.76 m3 kWh-1 in the swine fattening unit and 0.80 m3 kWh-1 in the slaughterhouse unit with load of 70 kW. The last results show an engine-generator on biogas of 100 kVA (load of 70 kW), spent an average of 1.4 m3 of biogas to produce 1.0 kWh of electricity.