High-resolution monitoring of diffuse (sheet or interrill) erosion using structure-from-motion

Sheet erosion is common on agricultural lands, and understanding the dynamics of the erosive process as well as the quantification of soil loss is important for both soil scientists and managers. However, measuring rates of soil loss from sheet erosion has proved difficult due to requiring the detection of relatively small surface changes over extended areas. Consequently, such measurements have relied on the use of erosion plots, which have limited spatial coverage and have high operating costs. For measuring the larger erosion rates characteristic of rill and gully erosion, structure-from-motion (SfM) photogrammetry has been demonstrated to be a valuable tool. Here, we demonstrate the first direct validation of UAV-SfM measurements of sheet erosion using sediment collection data collected from erosion plots. Three erosion plots (12 m × 4 m) located at Lavras, Brazil, with bare soil exposed to natural rainfall from which event sediment and runoff was monitored, were mapped during two hydrological years (2016 and 2017), using a UAV equipped with a RGB camera. DEMs of difference (DoD) were calculated to detect spatial changes in the soil surface topography over time and to quantify the volumes of sediments lost or gained. Precision maps were generated to enable precision estimates for both DEMs to be propagated into the DoD as spatially variable vertical uncertainties. The point clouds generated from SfM gave mean errors of ~2.4 mm horizontally (xy) and ~1.9 mm vertically (z) on control and independent check points, and the level of detection (LoD) along the plots ranged from 1.4 mm to 7.4 mm. The soil loss values obtained by SfM were significantly (p < 0.001) correlated (r 2 = 95.55%) with those derived from the sediment collection. These results open up the possibility to use SfM for erosion studies where channelized erosion is not the principal mechanism, offering a cost-effective method for gaining new insights into sheet, and interrill, erosion processes

Chemical Characterization, Antioxidant, Insecticidal and Anti-Cholinesterase Activity of Essential Oils Extracted from <i>Cinnamomum verum</i> L.

This study is aimed at evaluating the potential of the essential oil of Cinnamomum verum (EOCV) as an antioxidant, as an insecticide against Callosobruchus maculatus and for its anti-acetylcholinesterase activity. To this end, EOCV was extracted via hydrodistillation from this plant, and the identification of the phytochemicals was performed using gas chromatography–mass spectrometry (GC–MS). The antioxidant power was determined via in vitro tests, the insecticidal ability was tested via exposing C. maculatus to EOCV, and molecular docking was used to evaluate the anti-cholinesterase ability. The results of these GC–MS analyses show that the main composition of EOCV comprises Cinnamaldehyde dimethyl acetal (64.50%), cinnamicaldehyde (35.04%) and α-Copaene (0.11%). The insecticidal potential of the studied OEs, determined by using the inhalation test, and expressed as the concentration of EOs required for the death of 50% of the insects (LC50) and that required the death of 95% of adults (LC95) after 96 h of exposure, was 3.99 ± 0.40 and 14.91 ± 0.10 μL/L of air, respectively. In the contact test, 96 h of exposure gave an LC50 and LC95 of 3.17 ± 0.28 and 8.09 ± 0.05 μL/L of air, respectively. A comparison of the antioxidant activity of EOCV to that of ascorbic acid via DPPH free radical scavenging ability and Ferric Reducing Antioxidant Power (FRAP) revealed the IC50 and EC50 values of EOCV to be much higher than that obtained for ascorbic acid, and the molecular docking simulation revealed Coumarin, Piperonal, Cinnamaldehyde dimethyl and alpha-Copaene as possessing potential inhibitory activities against human acetylcholinesterase. However, further experimental validation is needed to enhance the prospects of this study