Soil Biochemical Indicators to Monitor the Impact of Microplastics on Soil Functionality in Terrestrial Ecosystems.

The present paper introduces soil as a complex system, so a multidisciplinary approach is needed to study not only the composition, abundance, and transport of microplastics (MPs) in terrestrial ecosystems but also soil properties and processes involved in their degradation and/or interaction with soil polyphasic matrix. Despite many researchers focusing their studies on the impact of MPs on the terrestrial ecosystem over the past years, little has been done about the use of biochemical indicators to study their effect on soil functionality.

Impact of Soil Fertilization with Pig Slurry on Antibiotic Residues and Resistance Genes: A Longitudinal Study.

The impact of soil fertilization with animal manure on the spread and persistence of antibiotic resistance in the environment is far from being fully understood. To add knowledge about persistence and correlations between antibiotic residues and antibiotic resistance genes (ARGs) in fertilized soil, a longitudinal soil mesocosm study was conducted. Soil samples were collected from the mesocosms immediately before spreading and then afterward at fifteen time points during a 320-day observation period. Eight ARGs (ermB, sul1, tetA, tetG, tetM, cfr, fexA, and optrA) and the class 1 integron-integrase gene, intI1, were determined in both pig slurry and soil, as well as residues of 36 antibiotics. Soil chemical and biochemical parameters were also measured. Twelve antibiotics were detected in the slurry in the range of 3 µg kg-1-3605 µg kg-1, with doxycycline, lincomycin, and tiamulin being the most abundant, whereas ermB, sul1, and tetM were the predominant ARGs. Before spreading, neither antibiotic residues nor ARGs were detectable in the soil; afterwards, their concentrations mirrored those in the slurry, with a gradual decline over the duration of the experiment. After about three months, the effect of the amendment was almost over, and no further evolution was observed.

Hybrid solid anaerobic digestion batch: biomethane production and mass recovery from the organic fraction of solid waste.

An experimental apparatus was constructed to perform hybrid solid anaerobic digestion batch processing of the organic fraction of municipal solid waste. The preliminary process was carried out with a high total solids concentration of about 33% w w(-1) and with an initial organic load of about 340 kg VS kg(-1). The fresh organic fraction to inoculum ratio used to enhance the anaerobic process start-up was 0.910 kg VS kg VS(-1). The process was conducted by spreading the percolate on top of the mixture. The percolate was stored in a separate section of the apparatus with a mean hydraulic retention time of about 1 day. During the process, acetate, butyrate and propionate in the percolate reached concentrations ranging from 3000 to 11 000 mg L(-1). In spite of these high concentrations, the biomethane produced from both the solid and the percolate was quite high, at about 210 NL kg VS(-1). The digestate obtained at the end of the run showed rather good features for being classified as an organic fertilizer according to Italian law. However, a residual phytotoxicity level was detected by a standardized test showing a germination index of about 50%.

Longitudinal study on antibiotic susceptibility in commensal E. coli from geese raised in free-range production systems.

The transmission of antimicrobial resistance bacteria from animals to humans has become an important concern. The extended-spectrum beta-lactamase (ESBL) -AmpC- producing Escherichia coli (ESBL-AmpC EC) and quinolones resistant E. coli are of particular interest. The present study aimed to evaluate the load and prevalence of antibiotic-resistant commensal E. coli along the goose production cycle on 2 free-range farms in central Italy. On A farm, oxytetracycline was administered, while the B farm did not use antibiotics during the geese productive cycle. One hundred geese of 1-day-old from the same batch were divided into the two farms. At hatching, the animals showed an average of E. coli loads was 6.83 ± 0.48 log CFU/g, and 0.28 ± 0.28, 0, 5.12 ± 0.54 log CFU/g for E. coli resistant to nalidixic acid (E. colinal), to cefotaxime (E. colicef) and to tetracyclines (E. colitet), respectively. The loads of E. coli, E. colinal, E. colicef and E. colitet on 224 environmental faecal pools were determined at 8 time points. Antimicrobial susceptibility and molecular characterization of E. colicef isolates were performed. The ANOVA was used to assess the difference in bacterial loads between the two farms. We described more than 50% of resistances for tetracyclines in both farms, and sulphonamides and cephazolin in the A farm. The loads of E. coli and E. colinal in faeces were estimated at approximately 6-7 log (CFU/g) and 5-6 log (CFU/g) in the two farms, respectively. The average load of extended-spectrum beta-lactamase Escherichia coli (ESBL EC) in goose faeces varied broadly along the production cycle: in the first weeks, a sharp increase was observed in both farms, while later on A farm, the burden of ESBL EC remained steady until the end of the production cycle and on B farm the load dramatically decreased from 6 wk of age onward. An increase in the proportion of E. colinal was observed on A farm shortly after the antibiotic administration. Our study shows that the dynamics of antibiotic-resistant E. coli in farmed geese are similar to the ones observed in broilers. However, the risk of the emergence of antibiotic-resistant commensal E. coli, might be mitigated by the adoption of good management practices, including prudent use of antibiotics.

Data on soil physicochemical properties and biodiversity from conventional, organic and organic mulch-based cropping systems.

The data presented here are related to the article entitled "Soil functions are affected by transition from conventional to organic mulch-based cropping system"[1]. Data were collected in 2016 in a processing tomato field located near Perugia, Italy. In details, data were collected in three differently managed processing tomato cropping systems: conventional integrated (INT); traditional organic with cover crops and conventional tillage (ORG); and organic coupled with conservation agriculture, with mulch-based cover crop and no-tillage (ORG+). We report data on the impact of each cropping system on crop biomass and yield, soil physicochemical properties, size and structure of soil microbial community, soil invertebrate biodiversity and habitat provision (predator-prey trophic interactions).

Geese Reared in Vineyard: Soil, Grass and Animals Interaction.

Agroforestry systems aim at increasing the productivity and the environmental sustainability of both crop and animal productions. The integration of small animals such as geese in the vineyard could represent an opportunity to improve farm income and reduce land use for grazing. The main objective of this work was to study the impact of geese rearing in an organic vineyard on the chemical and biochemical properties of the soil and the effect of Copper (Cu) supplied with the fungicide treatments. Furthermore, the amount of Cu in the animal tissues was also investigated. Three experimental areas within the vineyard were selected: High Geese Density (HGD-240 geese ha-1), Low Geese Density (LGD-120 geese ha-1) and Without Geese used as control soil (WG). The results indicated that both HGD and LGD did not affect the main chemical properties of the vineyard soils. LGD increased the amount and the efficiency of the microbial biomass in the upper soil horizons. Moreover, geese through the grazing activity reduced the Cu content in the vineyard soils, accumulating this element in their liver. However, the content of Cu in the breast and drumstick of vineyard geese did not show any significant difference in respect the meat of the control ones.

Multi-approach characterization of organic sediment produced by an anaerobic digestion plant fed with pig slurry and stored for a long term in a lagoon.

This study combined different approaches to characterize organic sediments produced by an anaerobic digestion plant feed with pig slurry, and accumulated for many years in a lagoon. The results of all analyses identified a certain homogeneity of the sediments. As a consequence of the pig diet, the sediment contained an high concentration of Zn (about 4gkg-1) and Cu (about 1.2gkg-1), which were mostly associated to the particles with a size ranging from 2 to 53µm. The sediment was made of large amount of organic matter, mostly cellulose and recalcitrant molecules, and 30-40% mineral fraction. XANES and XES spectroscopies indicated the presence of zinc phosphate (38%), zinc sulfide (32%), zinc carbonate (19%), and zinc oxide (11%). The presence in the sediment of forms characterized by a very scarce solubility, as also confirmed by the Zn and Cu chemical speciation, indicated a low bioavailability of these metals. However, although their low mobility, the high concentrations of Zn and Cu allowed to consider the sediment not suitable to use as a fertiliser due to the potential risk of metal interaction with the food chain.

Long Term Amendment with Fresh and Composted Solid Olive Mill Waste on Olive Grove Affects Carbon Sequestration by Prunings, Fruits, and Soil.

The soil amendment with organic wastes represents a way to increase the soil fertility and the organic carbon (C) stored in the agro-ecosystems. Among the organic waste materials produced by agricultural and industrial activities, olive mill wastes derived from the olive oil extraction process may represent a suitable soil amendment. The aim of the study was to evaluate the effect of fresh (SOMW) or composted mixture of SOMW and shredded olive tree prunings (C-SOMW+P) on the vegetative and productive activities of olive trees, on the C stored in the tree non-permanent structures (prunings and fruits) and in the soil. The plots treated with SOMW or C-SOMW+P showed higher vegetative and productive activities than the untreated plots, and this was attributed to the higher total N and availability of P and K supplied by the amendments. Consequently, treatments increased the C sequestered in the tree non-permanent structures than in the control trees. However, no significant different effect between SOMW and C-SOMW+P treatments was found for the C stored in prunings and fruits, whereas it was evident a stronger influence of C-SOMW+P than SOMW on soil C sequestration. Indeed, about 50% the C supplied by the treatment with C-SOMW+P was sequestered in the olive grove system, with more than 90% of the sequestered C stored into the soil. The low amount of C sequestered in the soil following the addition of SOMW was attributed to its richness of moisture and easily degradable compounds that triggered the mineralization processes controlled by the soil microbial community. Although the 8 years of amendment produced a higher fruit yields than the control, no difference occurred between the characteristics and the oil content of the olive fruits. Only the total phenol content for the oil obtained from the SOMW-treated plots was significantly higher. The other considered fruit characteristics did not show significant differences.

Co-treatment of fruit and vegetable waste in sludge digesters: Chemical and spectroscopic investigation by fluorescence and Fourier transform infrared spectroscopy.

In a previous work co-digestion of food waste and sewage sludge was performed in a pilot apparatus reproducing operating conditions of an existing full scale digester and processing waste mixed sludge (WMS) and fruit and vegetable waste (FVW) at different organic loading rates. An analysis of the relationship among bio-methane generation, process stability and digestate phytotoxicity was conducted. In this paper we considered humification parameters and spectroscopic analysis. Humification parameters indicated a higher not humified fraction (NH) and a lower degree of humification (DH) of FVW with respect to WMS (NH=19.22 and 5.10%; DH=36.65 and 61.94% for FVW and WMS, respectively) associated with their different chemical compositions and with the stabilization process previously undergone by sludge. FVW additions seemed to be favourable from an agronomical point of view since a lower percentage of organic carbon was lost. Fourier transform infrared spectra suggested consumption of aliphatics associated with rising in bio-methane generation followed by accumulation of aliphatics and carboxylic acids when the biogas production dropped. The trend of peaks ratios can be used as an indicator of the process efficiency. Fluorescence intensity of peak B associated with tryptophan-like substances and peak D associated with humic-like substances observed on tridimensional Excitation Emission Matrix maps increased up to sample corresponding to the highest rate of biogas production. Overall spectroscopic results provided evidence of different chemical pathways of anaerobic digestion associated with increasing amount of FVW which led to different levels of biogas production.

Co-treatment of fruit and vegetable waste in sludge digesters. An analysis of the relationship among bio-methane generation, process stability and digestate phytotoxicity.

The co-digestion of a variable amount of fruit and vegetable waste in a waste mixed sludge digester was investigated using a pilot scale apparatus. The organic loading rate (OLR) was increased from 1.46 kg VS/m(3) day to 2.8 kg VS/m(3) day. The hydraulic retention time was reduced from 14 days to about 10 days. Specific bio-methane production increased from about 90 NL/kg VS to the maximum value of about 430 NL/kg VS when OLR was increased from 1.46 kg VS/m(3) day to 2.1 kg VS/m(3) day. A higher OLR caused an excessive reduction in the hydraulic retention time, enhancing microorganism wash out. Process stability evaluated by the total volatile fatty acids concentration (mg/l) to the alkalinity buffer capacity (eq. mg/l CaCO3) ratio (i.e. FOS/TAC) criterion was <0.1 indicating high stability for OLR <2.46 kg VS/m(3 )day. For higher OLR, FOS/TAC increased rapidly. Residual phytotoxicty of the digestate evaluated by the germination index (GI) (%) was quite constant for OLR<2.46 kg VS/m(3)day, which is lower than the 60% limit, indicating an acceptable toxicity level for crops. For OLR>2.46 kg VS/m(3) day, GI decreased rapidly. This corresponding trend between FOS/TAC and GI was further investigated by the definition of the GI ratio (GIR) parameter. Comparison between GIR and FOS/TAC suggests that GI could be a suitable criterion for evaluating process stability.