Abstract
The present study was conducted to evaluate the effect of lipids with different fatty acid profiles on the intake, performance, and enteric CH4 emission of Nellore steers. A total of 45 Nellore animals with an average initial BW of 419 ± 11 kg (at 15 ± 2 mo) were distributed in a completely randomized design consisting of 5 treatments and 9 replicates. The roughage feed was maize silage (600 g/kg on a DM basis) plus concentrate (400 g/kg on a DM basis). The dietary treatments were as follows: without additional fat (WF), palm oil (PO), linseed oil (LO), protected fat (PF; Lactoplus), and whole soybeans (WS). The lipid source significantly affected (P < 0.05) nutrient intake. The greatest intakes of DM, OM, and CP were observed in the animals that were fed the WF or PF diets, and the lowest intakes were observed in the animals that were fed the PO diet. Intake of NDF decreased (P < 0.05) with the addition of PO. Enteric methane emission (g/kg DMI) was reduced by an average of 30% when the animals were fed diets containing WS, LO, and PO (P < 0.05), and these diets caused a larger reduction in the energy loss in the form of methane compared to those without added fat and with added PF (3.3 vs. 4.7%). The different fatty acid profiles did not affect the backfat thickness or the loin eye area of the animals (P > 0.05). However, animals fed PO displayed lower daily weight gain (0.36 kg/d), feed efficiency (0.08 kg ADG/kg DM), HCW (245 kg), and hot yield percentage (52.6%) compared to animals that were fed the other diets. Therefore, PO compared to the other lipid sources used in this study reduces intake, performance, feed efficiency, and carcass yield. Therefore, PO is not suggested for feedlot-finished animals.

The use of swine manure (SM) as a nutrient source for pastures is increasingly common in Brazil, due to its low cost. However, this practice can cause N losses in agricultural soil, where ammonia (NH3) volatilization may be the main drawback, generating undesirable economic and environmental consequences. The objective of this study was to evaluate SM application methods that retain N within the system and determine how these methods affect forage yield and quality. The study was conducted in the municipality of Chapadinha, Maranhão, Brazil, and the following SM application methods were evaluated: (1) surface application, (2) incorporation at 5-cm soil depth, (3) incorporation at 10-cm soil depth, and (4) control when SM was not applied. Lower N losses due to NH3 volatilization and higher pasture yield and quality were found when SM was incorporated at 10-cm soil depth (83 kg N-NH3 ha-1 and 6.3 Mg DM ha-1, respectively, compared to 86 kg N-NH3 ha-1 and 1.5 Mg DM ha-1 for the control), whereas higher N-NH3 losses and lower pasture yield were observed when SM was applied to the soil surface (143 kg N-NH3 ha-1 and 2.6 Mg ha-1, respectively). Higher quality forage in terms of chemical composition was also observed when SM was incorporated at greater soil depth. Incorporating SM at 10-cm depth represents an efficient management to mitigate N-NH3 volatilization, and this application method is associated with significantly increased in DM yield and improved chemical composition.

Interpreting the geological record of Amazon biomass combustion requires comparing charcoal accumulation rates in various biomes at different time scales. Charcoal accumulation rates, a proxy for palaeofire records, were obtained in sediment cores from Amazon lakes surrounded by several vegetation types and from a reservoirs in an intense land use change region. The records presented in this study were obtained in the following areas i) a reservoirs in Alta Floresta region (northern Mato Grosso State); ii) Lago do Saci (southern Pará State), a lake close to Alta Floresta and located at the southern border of Pará State; iii) a bog in an ecotone area in the Humaitá region (southern Amazonas State); iv) lakes in lateritic iron crust of the Carajás Hills (southeastern Pará State); v) Lago Comprido, a floodplain lake close to the Amazon River and surrounded by tropical rain forest (Monte Alegre, Pará State; vi) Lagoa da Pata in the Morro dos Seis Lagos alkaline complex (São Gabriel da Cachoeira, Amazonas State) and vii) Lago Caracaranã, a secluded lake in the northern Amazon cerrado (Roraima State). The highest charcoal accumulation rates were observed for modern records related to an intense change in land use at Alta Floresta, which had no precedent during the Holocene history of the Amazon. High charcoal accumulation rates that were observed in the Carajás region during low lake level phases in the Amazon in the mid-Holocene were comparable to those at the onset of the human settlement in Alta Floresta region. An increase in charcoal accumulation rate was observed in the late Holocene when the lake level was high, suggesting an interaction between climates and human presence. Low charcoal accumulation rates are typical of modern high rainfall environments, as observed in Lagoa da Pata where the environment is not susceptible to occurrences of wildfires even during relatively drier climatic phases. Low charcoal accumulation rates also exist in the relatively dry cerrado (savanna type) biome even during relatively dry phases in the Caracaranã region where the savanna-type vegetation biomass is lower and thus generates less charcoal particles than forest ecosystems.

Genetically-modified soybean [Glycine max (L.) Merr.] resistant to glyphosate (N-phosphono-methyl-glycine) herbicide (GR) has turned out to be one of the most highly-used products of plant engineering. The impacts of the soybean, genetically transformed for glyphosate resistance, on the environment under Brazilian soil and climatic conditions are still unknown. For this purpose, two soybean genotypes, one genetically modified (GR BRS 244 RR) and a conventional isogenic genotype were grown under different weed-control methods: hand weeding and glyphosate or imazethapyr herbicide application. The study was performed in Rio Grande do Sul State with evaluations of soil microbial biomass and respiration, biological nitrogen fixation, isoflavone content in seed and glyphosate, and aminomethylphosphonic acid (AMPA) residues in seeds and soil. The use of GR did not affect soil microbial population, biological nitrogen fixation, or plant yield or isoflavone contents in seed. However, even though we used the recommended application doses, the glyphosate residues in the seeds were above levels permitted by Brazilian law. Also, AMPA residues were detected in the soil and the seeds.

The objective of this study was to investigate the application of the 15N natural abundance technique to quantify BNF inputs to different varieties of field-grown sugarcane. The experiment was planted on a low-fertility sandy soil and no N fertilizer was added. Cane yields of seven Brazilian commercial varieties at the first harvest after 18 months were similar to the mean national yields. Nitrogen accumulation of most varieties exceeded 100 kg N ha−1 yr−1 even after two ratoons. The 15N abundance values of reference weed plants at the first harvest were significantly higher than leaf sample of the cane indicating inputs of BNF between 80 and 170 kg N ha−1 during the plant crop (18 months). The hypothesis that the lower 15N abundance of the cane varieties was due to the deeper rooting habit of the cane enabling it to access mineral N of significantly lower 15N abundance than present in the rooting zone of weed reference species was discarded, as weed reference species grown in soil samples taken at seven depth intervals to 75 cm showed higher 15N abundance than samples taken from the surface 10 cm. Weeds taken from the plots of the ratoon crops did not differ significantly in 15N abundance from the sugarcane varieties which suggested insignificant contributions of BNF at this time.