Soil organic matter humification under different tillage managements evaluated by Laser Induced Fluorescence (LIF) and C/N ratio

AbstractIn this work is presented the use of the C/N ratio and the Laser Induced Fluorescence (LIF) spectroscopy for determining the humification of soil organic matter (SOM) in an Oxisol under three different long-term tillage managements (no-tillage (NT), reduced tillage (RT) and conventional tillage (CT)). Humification of SOM was evaluated in the soil and its fractions (clay<2μm, silt 2–20μm, sand 20–1000μm). The obtained results show that lower SOM humification was observed in soil under NT, mainly at the surface (0–5cm). In CT, SOM humification values maintained constant for all investigated depths (0–5, 5–10, 10–15 and 15–20cm). Also, clay was the soil fraction that exhibited the lesser humification of SOM. Based on the obtained results it can be said that NT favors the accumulation of SOM on its surface, increasing aggregate stability and presenting samples with lower humification indexes. These results indicate a larger availability of nutrients for the plants in this management

Characterization of oil shale residue and rejects from irati formation by electron paramagnetic resonance

In this study, sedimentary organic matter of oil shale rejects, calschist, shale fine and the so called retorted shale from Irati formation was characterized. EPR was used to analyse the samples regarding loss of signal in g = 2.003 associated to the organic free radical with the calcined samples and washing with hydrogen peroxide. The radical signal was detected in all samples, however, for the calschist and shale fine samples another signal was identified at g = 2.000 which disappeared when the sample was heated at 400 ºC. Hydrogen peroxide washing was also performed and it was noted that after washing the signal appeared around g = 2.000 for all samples, including retorted shale, which might be due to the quartz E1 defect

Radiation attenuation properties based on the quantification of soil components using the Rietveld Method

We propose the use of X-ray diffraction associated with Rietveld Method (RM-XRD) for soil components quantification aiming at evaluating photon attenuation parameters (total and partial attenuation coefficients (µ), effective atomic number (Zeff), effective electron density (Nel) and cross-sections per atom (σa) and per electron (σe)). The XCOM computer code was utilized to calculate these parameters. The X-ray fluorescence spectroscopy (XRF) technique was used as reference for the quantification of soil components. Good agreement was found between XRF and RM-XRD for photons ranging from medium to high energies. Photons of low energy (<0.1 MeV) presented slight differences between these two methods. Keywords: X-ray diffraction, X-ray fluorescence spectroscopy, XCOM computer code, Mass attenuation coefficient, Cross-section

Humic substances isolated from residues of sugar cane industry as root growth promoter Substâncias húmicas isoladas de resíduos da indústria da cana-de-açúcar como promotoras de crescimento radicular

Plant growth promoting substances are widely used in modern agriculture. Several products in the market are humic substances isolated from different sources. The filter cake, a residue of sugar production, is a rich and renewable source of organic matter and these characteristics place the filter cake as a possible source of plant growth promoting substances. Humic acids (HA) from filter cake were characterized, and their effects as root growth promoters were evaluated. Chemical features of the HA were evaluated through elemental composition, acidic functional groups, E4/E6 ratio and infrared spectroscopy analyzes. The biological activity of the HA was assessed using root architecture parameters and the P-type H+-ATPase activity. The lateral root development was directly related to the stimulation of plasma membrane ATPase activity. The ability of HA to promote root development indicate that HA from filter cake can be used as environmental plant growth stimulators.<br>Substâncias promotoras do crescimento vegetal são amplamente utilizadas na agricultura moderna. Existem vários produtos no mercado, muitos dos quais são substâncias húmicas isoladas de diferentes fontes. A torta de filtro, um resíduo da produção do açúcar, é uma fonte rica e renovável de matéria orgânica e essas características a tornam uma possível fonte de substâncias promotoras do crescimento vegetal. Ácidos húmicos (AH) da torta de filtro foram caracterizados, e foi avaliado seu efeito como promotor de crescimento radicular. As características químicas dos AH foram avaliadas por meio da composição elementar, grupos funcionais ácidos, relação E4/E6 e espectroscopia de infravermelho. A atividade biológica dos AH foi acessada avaliando-se a arquitetura radicular e a atividade da H+-ATPase de membrana plasmática. O desenvolvimento de raízes laterais foi diretamente relacionado ao estímulo da atividade da H+-ATPase. A habilidade dos AH em promover o desenvolvimento radicular indica que AH extraídos da torta de filtro podem ser utilizados como estimuladores do crescimento de plantas