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Soil aggregates and associated carbon (C) and nitrogen (N) stocks are important for soil organic matter (SOM) consequences and quality. The study is meant to understand the mechanisms of how fertilization management affects Cand Nstocks. Tobacco monocropping systems with four fertilizer treatments (0, 75, and 112kg Nha−1, and 60kg Nha−1 + manure) were established in 1998. After 19 years, crop monocrop and fertilization management redetermined soil aggregates and related indicators. The results showed the large aggregates proportion (LMP) and small macroaggregates proportion (SMP) varied inversely with changing season. The LMP gradually rose after the implementation of tillage while microaggregates gradually declined. By manure fertilizer, LMP and SMP were significantly higher than those in inorganic fertilizer treatments, while microaggregates proportion (MIP) and silt and clay proportion (SCP) were lower than in inorganic fertilizer treatments. Soil water-stable aggregate and their associated soil organic stocks are changed with growing season, and tillage practices would have potentially affected these indicators, while the proportion and soil organic stocks more quickly recovered in large aggregates by manure application. Therefore, the proper application of manure combined with chemical fertilizer would maintain soil quality in tobacco cultivation. [ABSTRACT FROM AUTHOR]

Tobacco leaves are flue-cured to create desired appearance and internal quality, but the effects of flue-curing on transformation of chemical substances in tobacco have not been fully studied. The half-leaf method and a mass balance approach were used to compare two drying methods (i.e., oven-drying and flue-curing) in terms of chemical substances in tobacco. These substances included: carbon, nitrogen, plastid pigments, and polyphenols and some important elements in tobacco leaves. Compared with oven-drying, starch content significantly decreased while saccharides (including total sugar, glucose, fructose, maltose, and sucrose) increased in flue-cured tobacco leaves. There was only numerical change in reducing-sugar content between two drying methods. Protein, total nitrogen, and nicotine content in flue-cured tobacco leaves significantly decreased compared to oven drying. Two important elements (potassium and chlorine) showed no significant change. Compared with oven-drying, four plastid pigments (lutein, chlorophyll A, chlorophyll B, β-carotene) significantly decreased and six polyphenol substances (neochlorogenic acid, chlorogenic acid, caffeic acid, chrysatropic acid, rutin, kaempferol) significantly increased. This research clarified the transformation mechanisms of chemical substances after flue-curing of tobacco leaves, which provides a reference for the transformation and an insight into the procedures to study flue-cured tobacco leaf processing. [ABSTRACT FROM AUTHOR]

The rapid and onsite detection of glyphosate in tobacco products is still a great challenge. In this study, a novel smartphone-assisted sensing platform for the detection of glyphosate has been successfully proposed through the peroxidase-like activity of Fe 3 O 4 -based nanozyme. Heptanoic acid/Prussian blue (PB) decorated Fe 3 O 4 nanoparticles (Fe 3 O 4 @C 7 /PB) could catalyze and oxidize 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS, colorless) into a steel blue colored product in the presence of hydrogen peroxide. Glyphosate could specifically inhibit the peroxidase-like activity of Fe 3 O 4 @C 7 /PB by occupying the active site, thereby the glyphosate detection could be accomplished within 10 min by monitoring the color change of ABTS. This study has developed a smartphone-based portable detection platform for online analysis of glyphosate with a detection limit of 0.1 μg mL -1 . The absorbance response curve of glyphosate showed good linearity in the concentration range of 0.125-15 μg mL -1 at 415, 647, and 730 nm. Moreover, by employing a co-precipitation technology and inhibiting the peroxidase-like activity, the glyphosate analysis would be less affected by the tobacco sample matrix. The nanosensor possesses excellent selectivity and anti-interference ability, which has application value in actual samples for onsite screening., Competing Interests: The authors declare no competing financial interest., (This journal is © The Royal Society of Chemistry.)