Mitigation of GHGs Emission From Soils by a Catalyzed In-Situ Photo-Oxidative Polymerization of Soil Organic Matter

Agricultural lands under food and bio-energy crops, managed grass and permanent crops including agro-forestry, occupy about 40-50% of the Earth's land surface^1^. In 2005, agriculture accounted for an estimated emission of 5.1 to 6.1 GtCO2-eq/yr (10-12% of total global anthropogenic emissions of greenhouse gases (GHGs))^1^. However, measures to mitigate GHGs emission from agricultural soils are limited to improved cropland practices such as crop rotation, nutrient management, tillage/residue management, agroforestry, and return to natural vegetation^2^. These practices are not only far from substantially reducing GHGs emissions from soils or permanentlystabilizing soil organic matter^1-4^, but are also predicted to hardly match more than amaximum of 25% of the GHGs reductions required by the Kyoto Protocol within 2050^5^.Despite the knowledge that GHGs release from soil largely derives from biochemicaltransformations of plant litter and soil organic matter (SOM)^6-8^, no new and much wished biotechnological measures are adopted so far to augment mitigation^1^. Here we propose an innovative approach to mitigate GHGs emissions from soils based on the insitu photo-polymerization of SOM under biomimetic catalysis. Three Mediterranean soils of different physical and chemical properties were added with a synthetic watersolubleiron-porphyrin, irradiated by solar light, and subjected to 15, and 30 wetting and drying cycles. We found that the in situ catalysed photo-polymerization of SOM increased soil physical aggregation, shifted OC into larger soil aggregates, and reduced CO~2~ released by microbial respiration. Our findings suggest that "green" catalytic technologies can become viable soil management practices to enhance mitigation of GHGs emission from arable soils and contribute to match the expectations of the post-Kyoto Protocol in the agricultural sector

Decomposition of bio‑degradable plastic polymer in a real on‑farm composting process

Background: The current wide diffusion of bio-degradable plastic made up by starch-based polymeric composite has focused the attention on the allocation of bio-polymers for the direct recycling in composting processes. Actually, the acknowledged current methods to estimate the bio-degradability are mainly based on laboratory tests and measurements under controlled conditions, while scarce information are available on the effective transformation of bio-film derivatives in real composting facilities. The aim of this paper was to determine at molecular level the decomposition of specific starch-based thermoplastic mulching film for horticultural crops, in a real on-farm composting system for the attainment of mature compost for agricultural application. Results: The initial and final molecular composition of both bulk biomasses and bio-plastic composite were evaluated through 13C solid-state CPMAS-NMR spectroscopy and off-line thermochemolysis—gas chromatography–mass spectrometry. The effective decomposition of the bio-polymer was shown by mono-dimensional and pseudo-2D NMR experiments that revealed the alteration of the intermolecular linkages among the monomeric constituents, while the thermochemolysis confirmed the complete decomposition of starch components. Concomitantly, the molecular characterization of bulk compost indicated the typical selective preservation of hydrophobic components currently found in aerobic composting processes, with a significant increase (+50 %) for the yields of aromatic lignin derivatives and recalcitrant aliphatic compounds. Conclusion: In addition to the classical testing methodologies, the detailed analytical investigation represents a powerful methodology to elucidate the molecular composition and modification of plastic bio-polymers thereby providing a valuable contribution to further promote the composting process as viable way to recycle the biodegradable polymeric materials

Biomaterials and engineered microenvironments to control YAP/TAZ-dependent cell behaviour

Mechanical signals are increasingly recognized as overarching regulators of cell behaviour, controlling stemness, organoid biology, tissue development and regeneration. Moreover, aberrant mechanotransduction is a driver of disease, including cancer, fibrosis and cardiovascular defects. A central question remains how cells compute a host of biomechanical signals into meaningful biological behaviours. Biomaterials and microfabrication technologies are essential to address this issue. Here we review a large body of evidence that connects diverse biomaterial-based systems to the functions of YAP/TAZ, two highly related mechanosensitive transcriptional regulators. YAP/TAZ orchestrate the response to a suite of engineered microenviroments, emerging as a universal control system for cells in two and three dimensions, in static or dynamic fashions, over a range of elastic and viscoelastic stimuli, from solid to fluid states. This approach may guide the rational design of technological and material-based platforms with dramatically improved functionalities and inform the generation of new biomaterials for regenerative medicine applications

Optimized procedure for the determination of P species in soil by liquid-state 31 P-NMR spectroscopy

Liquid-state 31P-NMR spectroscopy becomes progressively an important role for studying phosphorus (P) dynamics in soil. Soils of different origin and organic matter content were used to optimize sample preparation and re-dissolution procedures to improve characterization of P species in soil by 31P-NMR spectroscopy. The efficiency of P extraction from an untreated fresh soil was compared to that from freeze-dried and air-dried soil samples. A freeze-drying pretreatment not only provided the greatest extraction yields of total and organic P from both farmland and forest soils but also enhanced the intensity of signals for inorganic and organic P species in 31P-NMR spectra, except for polyphosphates. Re-dissolution of freeze-dried soil extracts in relatively dilute alkaline solution and addition of a small aliquot of concentrated HCl to the NMR tube prior to analysis improved the quality of NMR spectra. Finally, the visibility of relatively weak P signals, such as for phosphorus diesters, phosphonates, polyphosphate, phospholipids, and DNA were reproducibly enhanced when 31P-NMR spectra were generated after at least 15 h of acquisition time. The optimized procedure presented here ensured the greatest detectability of inorganic and organic P species by liquid-state P-NMR spectroscopy in soil extracts

Linking organic matter chemistry with soil aggregate stability: Insight from 13C NMR spectroscopy

Soil aggregation is considered as a crucial process in agro-system sustainability due to the role in soil physical, chemical and biological dynamics. Here we tested the hypothesis that the initial chemical traits of organic matter (OM) may help to explain the variability of soil aggregation dynamics after organic amendment. We characterized ten OM types (alfalfa litter, biochar, cellulose, glucose, green compost, maize litter, manure compost, meat powder, sawdust, and solid digestate) by 13C-CPMAS NMR and elemental chemical features to investigate the effects of amendment quality on soil aggregation. In a manipulative factorial experiment, dry samples (200 g) of three soil types (S1, S2 and S3) with different texture, high pH (7\u20139), and similar OM content, were incorporated with 4 g (2% w/w) of dry, 2 mm-grounded OM, incubated in mesocosms for 300 days under controlled temperature (18 \ub1 2 \ub0C night and 24 \ub1 2 \ub0C day), and sampled at 4 dates for measuring aggregation index (AI), based on water stability of soil aggregates (WSA). We found that meat powder and alfalfa litter induced a rapid initial increase of AI, exceeding that of the controls by one to two orders of magnitude, likely acting as a C source for microbes. Biochar incorporation in soil barely affected AI, with intermediate effects with other OM types. Considering C bond types corresponding to OM 13C-CPMAS NMR spectral regions, carbonyl C was only correlated to early AI, possibly due to overlapping signals of amide structures; O-alkyl C and di-O-alkyl C (carbohydrate fraction) were positively associated to AI, indicating a promoting effect on soil structure, while aromatic C fractions showed an opposite pattern, possibly related to aggregate protection by coatings associated to water repellency, or to direct aggregate internal binding. This study demonstrates that OM chemical quality plays an important role in soil aggregation process, with the molecular composition defined by 13C-CPMAS NMR spectroscopy being more predictive of aggregation dynamics compared to classical elemental features. As such, this study provides a significant novel contribution to clarify the relationships between OM chemistry and soil aggregation

Linking organic matter chemistry with soil aggregate stability: Insight from 13C NMR spectroscopy

Soil aggregation is considered as a crucial process in agro-system sustainability due to the role in soil physical, chemical and biological dynamics. Here we tested the hypothesis that the initial chemical traits of organic matter (OM) may help to explain the variability of soil aggregation dynamics after organic amendment. We characterized ten OM types (alfalfa litter, biochar, cellulose, glucose, green compost, maize litter, manure compost, meat powder, sawdust, and solid digestate) by 13C-CPMAS NMR and elemental chemical features to investigate the effects of amendment quality on soil aggregation. In a manipulative factorial experiment, dry samples (200 g) of three soil types (S1, S2 and S3) with different texture, high pH (7\u20139), and similar OM content, were incorporated with 4 g (2% w/w) of dry, 2 mm-grounded OM, incubated in mesocosms for 300 days under controlled temperature (18 \ub1 2 \ub0C night and 24 \ub1 2 \ub0C day), and sampled at 4 dates for measuring aggregation index (AI), based on water stability of soil aggregates (WSA). We found that meat powder and alfalfa litter induced a rapid initial increase of AI, exceeding that of the controls by one to two orders of magnitude, likely acting as a C source for microbes. Biochar incorporation in soil barely affected AI, with intermediate effects with other OM types. Considering C bond types corresponding to OM 13C-CPMAS NMR spectral regions, carbonyl C was only correlated to early AI, possibly due to overlapping signals of amide structures; O-alkyl C and di-O-alkyl C (carbohydrate fraction) were positively associated to AI, indicating a promoting effect on soil structure, while aromatic C fractions showed an opposite pattern, possibly related to aggregate protection by coatings associated to water repellency, or to direct aggregate internal binding. This study demonstrates that OM chemical quality plays an important role in soil aggregation process, with the molecular composition defined by 13C-CPMAS NMR spectroscopy being more predictive of aggregation dynamics compared to classical elemental features. As such, this study provides a significant novel contribution to clarify the relationships between OM chemistry and soil aggregation

Humic substances stimulate maize nitrogen assimilation and amino acid metabolism at physiological and molecular level

The effects of a humic substance (HS) extracted from a volcanic soil on the nitrate assimilation pathway of Zea mays seedlings were thoroughly examined using physiological and molecular approaches. Plant growth, the amount of soluble proteins and amino acids, as well as the activities of the enzymes involved in nitrogen metabolism and Krebs cycle, were evaluated in response to different HS concentrations (0, 1 and 5 mg C L−1) supplied to maize seedlings for 48 h. To better understand the HS action, the transcript accumulation of selected genes encoding enzymes involved in nitrogen assimilation and Krebs cycle was additionally evaluated in seedlings grown for 2 weeks under nitrogen (N) sufficient condition and N deprivation. HS at low concentration (1 mg C L−1) positively influenced nitrate metabolism by increasing the content of soluble protein and amino acids synthesis. Furthermore, the activity and transcription of enzymes functioning in N assimilation and Krebs were significantly stimulated. HS treatment influenced the gene expression of Zea mays plants at transcriptional level and this regulation was closely dependent on the availability of nitrate in the growth medium

Combination of humic biostimulants with a microbial inoculum improves lettuce productivity, nutrient uptake, and primary and secondary metabolism

Biostimulants of natural origin represent a growing ecological strategy to increase crops productivity, especially when applied in combination with microbial bioeffectors. We studied the effect of biostimulants such as Potassium Humates (KH) from Leonardite and Compost Tea (CT) from green compost on both productivity and nutritional status of lettuce plants, as well as on the primary and secondary metabolism of treated plants, when amended either alone or in combination with a commercial microbial inoculum (M+), mainly based on arbuscular mycorrhizal fungi (Micosat TabPlus)