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No-tillage farming combined with temporary cattle grazing is becoming a common practice in parts of South America. We quantified the effects of no-tillage and winter grazing of annual ryegrass (Lolium multiflorum Lam.) on soil carbon and nitrogen stock, stratification ratio (concentration in 0-5 to 10-20-cm layer) and lability (based on particulate organic matter, POM), relative to conventional tillage or ungrazed ryegrass. A 9-year-old experiment was conducted in a southern Brazilian Ferralsol. Soil under no-tillage accumulated 1.11 Mg C ha −1 year −1 and 0.10 Mg N ha −1 year −1 to 100-cm depth relative to conventional tillage when ryegrass was not grazed, and also increased the stratification ratio of carbon (1.48 vs. 1.11) and nitrogen (1.66 vs. 1.17). The carbon and nitrogen lability was also greater in no-tillage soil, as carbon and nitrogen stocks increased proportionally more in sand-POM than in silt or clay size fractions (carbon lability index = 1.57 vs. 1.00; nitrogen lability index = 1.57 vs. 1.00). Semiquinone concentrations in physical fractions were 4-28% smaller in no-tillage, suggesting less organic matter aromaticity in this treatment. Grazing, however, caused no further improvement of stocks of carbon and nitrogen in the 0-100-cm layer of notillage soil (e.g., 209 vs. 212 Mg C ha −1 , ns), or enhancement of stratification or lability of those elements, relative to ungrazed ryegrass. Overall, no-tillage effectively promoted soil carbon and nitrogen accumulation and lability in this subtropical Ferralsol, whereas grazing did not compromise the gains of no-tillage. Highlights • Capacity of no-tillage and grazing to enhance stocks, stratification and lability of soil C and N. • C sequestration with no-tillage is being debated, and little is known when combined with grazing. • No-tillage accumulated 1.11 Mg C ha −1 year −1 but grazing promoted no further C accumulation. • No-tillage effectively accumulated C in soil and grazing did not compromise such gain of no-tillage.

Most cases involving soil in criminal investigations in Brazil have focused on the chemical and mineralogical analyses of soil fractions without including the organic matter. The organic fraction contains plant-wax markers which may be useful to “fingerprint” forensic soils due to their chemical diversity, relative longevity and resistant nature. The aim of this study was to test the long- (kilometre), medium- (metre) and short- (centimetre) scale variability of plant-wax biomarkers in a forensic context in anthropised urban soils and soils developed under subtropical conditions. Two areas from the Curitiba municipality and two areas from the Colombo municipality, Paraná State, South Brazil, were selected. Soil colour analysis was carried out to obtain reflectance data over the 360–740 nm wavelength range. Furthermore, plant-wax marker compounds (n-alkanes and fatty-alcohols) were assessed by extraction and separation into different classes and an analysis of the compounds by gas chromatography (GC/MS). The compositions of the wax-marker profiles were different in samples collected side-by-side, showing sensitivity to local variations under subtropical conditions and in areas under intense human urban disturbance. Under these conditions, biomarkers may be used in real crime scenes, even on a micrometric scale of variation.

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