Modeling the effects of farming management practices on soil organic carbon stock under two tillage practices in a semi-arid region, Morocco.

Farming management practices are of paramount importance for soil organic carbon (SOC) sequestration in carbon (C) cycling at different scales. However, due to a lack of proper methodologies, estimating the impacts of different soil management practices on overall SOC stock remains inadequately quantified. In this paper, a process-based model, Denitrification-Decomposition (DNDC), was validated on midterm (9 years) and employed depending on the local climate, soil and management conditions, to assess the impacts of alternative management practices on SOC stock under two tillage systems, in a semi-arid region of Morocco. Validated results showed a good agreement between model simulated and observed values, based on the normalized root mean square error (RMSE) and Pearson correlation coefficient (r). This agreement indicates that the DNDC model could capture patterns and magnitudes changes across the climate zone, soil type, and management practices. Modeled results pointed out that, under no-tillage practice (NT), the SOC content increased by 30% compared to conventional tillage (CT). During the simulated period (9 years), the SOC sequestration potential (CSP) has been greatly improved with increased crop residue rate and application of farmyard manure (FY-manure). This increase ranged from 415 kg C/ha to 1787 kg C/ha under NT practice, and from 150 kg C/ha to 818 kg C/ha under CT system. In contrast, increasing fertilizer rate had low to negligible effect on SOC stock. On the other hand, CSP declined by 107-335 kg C/ha and by 177-354 kg C/ha under NT and CT practices respectively, when decreasing N-fertilizer rates. In light of these results, an increase in crop residue rate returned at surface after harvest and application of organic fertilizer, especially under NT practice, can substantially improve SOC stock in a semi-arid region.

Modeling of the distribution of heavy metals and trace elements in argan forest soil and parts of argan tree.

The transfer of heavy metals and trace elements from argan forest soil into the wood, leaves, almonds, and argan oil was studied. Analyzed metals were: chromium, cadmium, copper, zinc, lead, calcium, phosphorus, potassium, and magnesium. Correlations linking different behaviors of the studied heavy metals and trace elements observed by multidimensional analysis were attributed to partial-spatial variations. Whereas the RV-coefficient of wood, leaf, almond and oil groups was high, the soil group correlated poorly with the other groups.

Can the dietary element content of virgin argan oils really be used for adulteration detection?

Levels of eight dietary elements were assessed by ICP-AES in virgin edible and beauty argan oil samples prepared from four remote locations of the argan forest, and over a three-year period. The data showed sufficiently little variability to assess that all argan oil samples present, in terms of dietary elements, a similar composition, independently from the tree location within the argan forest. Therefore, adulteration detection by trace element analysis in edible and beauty argan oil is a method that can be generalised.

SBA-15-type organosilica with 4-mercapto-N,N-bis-(3-Si-propyl)butanamide for palladium scavenging and cross-coupling catalysis.

This work describes the synthesis of novel functional silica materials with difunctional thiol-amide substructures and featuring regular architectures on a mesoscopic level. The functional materials were synthesised by both one-pot co-condensation and post-grafting approaches. The thiol groups confined in the matrix were found to be efficient for palladium entrapment, leading to highly active and reusable heterogeneous catalysts for Sonogashira and Suzuki-Miyaura cross-coupling reactions. This work evidences the crucial role of both the thiol precursor and the condensation degree of the silica scaffold in view of the design of stable and reusable tailor-made mesoporous catalytic silica materials.

Periodic mesoporous organosilica from zwitterionic precursors.

Mesoporous hybrid silica bearing zwitterionic species were synthesized via template-directed hydrolysis-polycondensation reactions from zwitterionic ammonium sulfonate precursors. The formation of the nanostructured phases involves specific precursor-template interactions. The obtained materials are efficient heterogeneous catalysts in Biginelli reactions.

Influence of humic fractions on retention of isoproturon residues in two Moroccan soils.

The influence of different fractions of soil organic matter on the retention of the herbicide isoproturon (IPU) has been evaluated. Water and methanol extractable residues of (14)C labeled isoproturon have been determined in two Moroccan soils by beta -counting-liquid chromatography. The quantification of bound residues in soil and in different fractions of soil humic substances has been performed using pyrolysis/scintillation-detected gas-chromatography. Microbial mineralization of the herbicide and soil organic matter has been also monitored. Retention of isoproturon residues after 30-days incubation ranged from 22% to 32% (non-extractable fraction). The radioactivity extracted in an aqueous environment was from 20% to 33% of the amount used for the treatment; meanwhile, methanol was able to extract another 48%. Both soils showed quantities of bound residues into the humin fraction higher than humic and fulvic acids. The total amount of residues retained into the organic matter of the soils was about 65 % of non-extractable fraction, and this percentage did not change with incubation time; on the contrary, the sorption rate of the retention reaction is mostly influenced by the clay fraction and organic content of the soil. Only a little part of the herbicide was mineralized during the experimental time.