Plant Phosphorus Efficiency from Raw and Composted Agro- and Bio-Waste Anaerobic Digestates

The rising generation of organic waste (OW) can be a concern, representing at the same time a valuable opportunity for the phosphorous (P) recycling; however, yet little is known about plant-available P release from this source. In this work, two anaerobic digestates, from agro- (AWD) and bio-waste (BWD), and their respective composts (AWC and BWC), were selected to assess their P-release via sequential chemical extraction (SCE) and P species via solution 31P-NMR in NaOH+EDTA extracts. These products were also tested for the relative-P efficiency (RPEsoil) in a soil incubation (30 mg P kg−1), in comparison with a chemical-P source and a reference compost. The organic products were also compared for the ryegrass relative-P efficiency (RPEtissue) at the same P-rate (30 mg P kg−1), in a 112-day pot experiment in an Olsen-P poor soil (<3 mg kg−1), under a non-limiting N environment. The NaOH+EDTA extractions showed that inorganic P prevailed in all samples as proven by solution 31P-NMR. SCE showed very different labile-P (H2O+NaHCO3) and AW doubling BW products (84 vs. 48%); this was also confirmed by the soil incubation test in which AWD and AWC attained the best RPEsoil. Pot tests generally confirmed laboratory outcomes showing that AWD and AWC attained the best RPEtissue, from 3 to 4-folds of the BWD and BWC performance. The results showed that the feedstock mainly affects plant P availability from recycled OW and that their SCE are very informative in the description of plant-available P from this type of products to be used in rational fertilization plan

Rapid assessment of fertilizers manufacturing methods by means of a novel waveguide vector spectrometer

This study aims to test the suitability of a waveguide spectrometer, as a rapid and cheap tool to discriminate between different fertilizers according to two different manufacturing methods, such as granulation and blending. The tested instrument is a waveguide vector spectrometer, patented in 2016, that operates in the range 1.6-2.7 GHz, giving both spectral phase and gain measurements. Granulated and blended fertilizers were dehydrated and pulverized to avoid possible interferences due to the water content and the geometry of the sample. The spectral data were analysed by multivariate statistical analysis [principal component analysis (PCA) and partial least squares-discriminant analysis (PLS-DA)] in order to obtain a discrimination tool considering the whole hidden spectral information. PC1 (95% of the explained variance) and PC2 (4% of the explained variance) are shown to explain most of the spectral variability. A tendency to group samples according to the different production methods can be seen, even if the discrimination is influenced by the different chemical compositions of fertilizers. However, PLS-DA models correctly classified 100% of the samples into granulated and blended classes using spectra obtained by waveguide spectroscopy. Despite being preliminary, the tests carried out on a small number of samples show how the technique coupled with PLS-DA models could be able to discriminate between the analysed fertilizers by means of their spectral signature and according to the manufacturing method, if the chemical composition is kept constant. Further tests are necessary to validate the model, also considering the possibility of grouping fertilizers on the basis of their similar composition

Nitrogen availability in organic fertilizers from tannery and slaughterhouse by-products

Agriculture can play a primary role in the context of nutrients recovery by promoting the use of organic fertilizers (OFs). In order to use them efficiently, it is necessary to predict the nitrogen (N) bioavailability, which is a challenging matter due to the different physical-chemical characteristics of commercially available OFs. This study aims to evaluate hot-water extractable N as a rapid and cheap chemical indicator of bioavailable N. The trial was conducted on nine animal-based OFs obtained from different raw materials and treatment processes. They were fully characterized and the bioavailable N was determined by a 7-week soil incubation experiment. The results showed that hot-water extractable N underestimated bioavailable N in the case of leather meal based OFs; however, a significant linear regression fitting was achieved (R2 = 0.53). The C:N ratio was also assessed, which showed a negative correlation (−0.87) and a better linear regression fitting (R2 = 0.76) with the bioavailable N, but manifested some limitations in the prediction of leather meal based products. This experiment showed that both hot-water extractable N and C:N ratio can provide useful information for farmers in managing this class of OFs

Litter quality changes during decomposition investigated by thermal analysis

The litter decomposition process depends on the litter chemical composition, especially the ratio between more labile compounds, cellulose, and the recalcitrant lignin and waxes. Their determination is crucial to predict the process, though lignin measurement presents some limitations due to drawbacks of the different methods. Thermal analysis has been successfully applied to several organic materials in order to obtain quali-quantitative information of the chemical structure of the sample. In this work TG-DTA was used in a short-term litter decomposition study of two broadleaf forest stands of contrasting ages, and the results were compared to those obtained with a chemical method (Klason’s method) commonly used to quantify cellulose and lignin. TG-DTA was applied to the litter and to the cell walls (CW) extracted from the litter, whose cellulose and lignin content was determined using the Klason’s method. When applied to litter, thermal analysis showed a weak correlation with the Klason’s method, though it allowed the detection of the dynamics of waxes, that increased during the decomposition and could influence the later stages of the process. Contrastingly, a good correlation between cellulose and lignin determined with the two methods was found when TG-DTA was applied to the CW. In this case TG-DTA, according to NMR data, also highlighted the changes in the CW chemical structure compared with that of the litters, in particular the loss of waxes and the decreased thermostability of aromatic components. Moreover, a new concept of quality of the decomposing litter, based on the balance between the energy stored in the litter and the energy needed to release it obtained by thermal analysis, was recently introduced. Samples of the old forest litter had an initial energetic balance more favorable than those collected in the young stand. At the end of the period, the decrease in litter quality was greater in the young than in the old forest samples, due to the combined effect of the higher degradation of thermolabile substances and the accumulation of more thermostable components. Thermal analysis seems to have a good potential in litter decomposition studies, as it can link structural and energetic changes during the process

A non‑lethal method to assess element content in the endangered Pinna nobilis

The fan shell Pinna nobilis is the largest bivalve endemic to the Mediterranean and is actually a strongly endangered species. Due to the biological, ecological, and historical relevance of this species, the research of a non-lethal method to relate the element content in organism’s tissues and environment can provide information potentially useful to evaluate environmental pollution and organism physiological status. In this study, a screening on element concentration in the animal growing environment (seawater and sediments) and in four soft tissues (hepatopancreas, gills, mantle, and muscle), and two acellular tissues (calcite shell layer, and byssus) was performed. The comparison among these results was used to assess whether the no-lethal acellular tissue element concentration can be used to reveal the element presence in the environment and soft tissues. Elements, such as B, Ag, As, Mn, Mo, Pb, or Se, showed a possible relationship between their presence in the byssus and soft tissues. In the byssus Cr, Sb, Sn, and V have shown to be mostly related to the environment, more than the soft tissues, and might be used to draw a historical record of the exposure of the organism. The element concentration in the calcite shell layer did not relate with environmental element concentrations. Essential elements, like Cu, Fe, Ni, and Zn, were present in calcite shell layer and byssus and are likely related to their biological activity in the organism. The research also gave an overview on the presence of pollution and on the preferential intake route of the element. In summary, this study, performed on a limited number of specimens of this protected species, indicated that element concentration in the byssus can be applied as non-lethal method to monitor this endangered species and its interaction with the elements in the growing environment

A Modified RMCE-Compatible Rosa26 Locus for the Expression of Transgenes from Exogenous Promoters

Generation of gain-of-function transgenic mice by targeting the Rosa26 locus has been established as an alternative to classical transgenic mice produced by pronuclear microinjection. However, targeting transgenes to the endogenous Rosa26 promoter results in moderate ubiquitous expression and is not suitable for high expression levels. Therefore, we now generated a modified Rosa26 (modRosa26) locus that combines efficient targeted transgenesis using recombinase-mediated cassette exchange (RMCE) by Flipase (Flp-RMCE) or Cre recombinase (Cre-RMCE) with transgene expression from exogenous promoters. We silenced the endogenous Rosa26 promoter and characterized several ubiquitous (pCAG, EF1α and CMV) and tissue-specific (VeCad, αSMA) promoters in the modRosa26 locus in vivo. We demonstrate that the ubiquitous pCAG promoter in the modRosa26 locus now offers high transgene expression. While tissue-specific promoters were all active in their cognate tissues they additionally led to rare ectopic expression. To achieve high expression levels in a tissue-specific manner, we therefore combined Flp-RMCE for rapid ES cell targeting, the pCAG promoter for high transgene levels and Cre/LoxP conditional transgene activation using well-characterized Cre lines. Using this approach we generated a Cre/LoxP-inducible reporter mouse line with high EGFP expression levels that enables cell tracing in live cells. A second reporter line expressing luciferase permits efficient monitoring of Cre activity in live animals. Thus, targeting the modRosa26 locus by RMCE minimizes the effort required to target ES cells and generates a tool for the use exogenous promoters in combination with single-copy transgenes for predictable expression in mice