Sara Paliaga

Polyethylene mulching films are a major source of plastic pollution in agricultural soils especially due to improper end-use disposal. This global plastic waste problem has promoted the development of biodegradable mulching films able to fully decompose in soil after their use. This study aimed at evaluating the effect of polyethylene, Mater-Bi^® and innovative carboxymethylcellulose-, chitosan- and alginate-based biodegradable mulch films, either enriched or not with monoammonium phosphate (MAP) on soil micro-arthropods. The enrichment of the mulch film with MAP has the purposes of (i) promoting microbial breakdown at the end of the cropping cycle balancing the substrate and (ii) supplying phosphorus and ammonium as a fertilizer to the soil. Acute toxicity responses were assayed in vitro using the non-target model micro-arthropod Folsomia candida. Furthermore, outdoor mesocosms tested mulch films on micro-arthropod community using the QBS-ar approach. The assessment also included a consortium of cellulose–chitosan-degrading bacteria. Neither all the mulch films tested nor their components exhibited acute toxicity at double concentrations used in field applications. Results from mesocosms mulched with innovative bio-based mulch films are consistent with an improvement in biological soil quality. Thus, the innovative bio-based mulch films assessed in this study have the potential to boost soil communities while reducing plastic pollution in agricultural fields.

This study assessed whether long-established monospecific stands of Eucalyptus camaldulensis (EC), Eucalyptus occidentalis (EO), Pinus halepensis (PH), and Cupressus sempervirens (CS), established approximately 70 years ago, were associated with distinct patterns of soil microbial community structure and biochemical functioningin a semi-arid Mediterranean gypsiferous soil. Specifically, we examined differences in soil organic matter pools, microbial community structure, and potential enzyme activities related to C, N, and P cycling, and explored their associations with soil resource status and leaf/needle chemical traits. Mineral topsoil, leaves or needles, and litter were sampled from monospecific stands established on the same Gypsic Haploxerept near San Cataldo, Sicily. Soil chemical and biochemical properties were assessed, including microbial biomass C and N, respiration, microbial community structure, and potential enzyme activities. In addition, the elemental composition and fiber fractions of leaves and litter were analyzed. Differences among stands were assessed by one-way ANOVA, while exploratory stepwise discriminant function analyses were used to integrate soil, microbial, enzymatic, and plant-trait variables. The four stands differed markedly in soil organic matter pools, microbial community structure, and biochemical functioning. EC was associated with greater C and N availability, highest microbial biomass, respiration, and β-glucosidase activity, indicating greater potential for microbial C acquisition. PH and CS showed highest phosphatase activity consistent with greater potential for P acquisition, while their microbial profiles showed relatively greater contributions of fungal and/or actinomycete phospholipid fatty acid markers. EO showed a distinct profile, combining relatively high organic C availability with comparatively low urease and phosphatase activities. Exploratory discriminant analyses indicated that both soil resource status and residue structural traits contributed to stand separation. Long-established monospecific stands were associated with distinct soil microbial community structure and biochemical profile in this gypsiferous Mediterranean soil. Integrating enzyme activities, phospholipid fatty acid profiles, and plant-residue chemistry helped characterize these differences, which should be interpreted as associations rather than replicated causal species effects.

Basidiomycetes can colonize sweet chestnut (Castanea sativa Mill) xylem, causing white or brown rot and losses in wood quality. The aim of this study was to assess the degradative potential of five Basidiomycota strains (Armillaria mellea (Vahl) P. Kumm. (Am), Fistulina hepatica (Shaeff.) With. (Fh), and Laetiporus sulphureus (Bull.) Murrill (Ls), and two strains of Ganoderma resinaceum Boud.) on three chestnut woods differing in chemistry. The woods differed in nitrogen content (0.3%–1.0%), carbon/nitrogen (C/N) ratio (43–150), and phenolic-related traits. In a 39-day laboratory assay, the five fungal strains were inoculated on three chestnut woods and compared for colonization time, extracellular enzymatic activity, and C mineralization. Fungal colonization strongly depended on fungus × wood interaction: L. sulphureus colonized all woods within 6 days, whereas the two G. resinaceum strains required 9–33 days depending on wood type; A. mellea and F. hepatica colonized only selected woods (up to 39 days). Enzymatic screening indicated laccase activity mainly in G. resinaceum (and to a lesser extent A. mellea), while L. sulphureus expressed cellulolytic activity but no laccase. Over 39 days, total C mineralization peaked under G. resinaceum on the two Sicilian woods (up to 270–300 mg CO₂–C g⁻¹ dry wood), whereas the Tuscan wood (highest C/N and phenolic content) markedly inhibited most strains; only L. sulphureus increased mineralization in this wood (85 mg CO₂–C g⁻¹ dry wood). These findings indicate that wood chemistry, especially C/N ratio and phenolic traits, strongly modulates strain-specific decay patterns. Overall, these results highlight the need for an integrated biological–biochemical approach to evaluate fungal decay potential and to inform both the selection of more durable chestnut woods for wood products and the identification of efficient strains to accelerate lignocellulosic biomass composting.

The widespread use of conventional plastic mulch films in agriculture contributes significantly to soil pollution due to their non-biodegradable nature. This study explores the potential of novel bio-based mulch films composed of chitosan, carboxymethyl cellulose, and sodium alginate, formulated in different ratios (1:1 and 17:3), with or without enrichment with monoammonium phosphate (MAP), to serve as biodegradable films with potential nutrient-releasing functionality as alternatives to conventional plastics. A multi-analytical approach, including elemental and isotopic analysis (EA-IRMS), biodegradation assays, and pyrolysis–gas chromatography–mass spectrometry (Py-GC-MS), was employed to assess their chemical properties, degradation behavior, and environmental compatibility. The results demonstrated that the 1:1 films, both with and without MAP, achieved over 90% biodegradation within 120 days under controlled soil conditions, in agreement with international criteria for soil biodegradability. In contrast, the 17:3 films showed reduced degradation, especially without MAP enrichment, highlighting the influence of polymer composition on microbial degradation. Isotopic tracing confirmed MAP integration and revealed composition-dependent fractionation effects. Py-GC-MS provided structural fingerprints of film components and putatively annotated nitrogen-containing compounds indicative of chitosan presence. Overall, these results demonstrate that the 1:1 films can be considered viable, multifunctional, and soil-friendly alternatives to conventional plastic mulches for sustainable agriculture.

Cover crop management in vineyards under a semiarid Mediterranean environment needs strategies that enhance soil C and N status and microbial functioning without increasing disturbance. This study compared cover crops biomass incorporation (harrowing, HR; rotary tillage; RT) and non-incorporation (NI, residues left on the topsoil) into the soil in a 12-year Grecanico dorato vineyard. Traditional vineyard soil management (continuously tilled for weeds control) was also used as a control. Soil samples from 0 to 20 and 20 to 40 cm were analyzed for total organic carbon (TOC), total nitrogen (TN), microbial biomass carbon (MBC) and nitrogen (MBN), and enzyme activities. NI and HR raised TOC and TN in the topsoil versus TR, with NI frequently maintaining advantages at depth. NI also maximized MBC/MBN and reduced the metabolic quotient (qCO₂), indicating improved microbial C-use efficiency; RT showed intermediate chemistry but depressed subsoil MBC and altered MBC/MBN. Enzyme profiles reflected contrasting mechanisms: RT boosted β-glucosidase in the topsoil, TR peaked for urease and arylsulfatase but alongside lower biomass and higher specific enzyme activities, while NI supported greater overall functioning via larger biomass and lower per-C enzyme demand. The calculated geometric mean enzyme (GMea) index emphasized transient TR flush versus steadier conservation functioning. Strong vertical stratification occurred for all indices, yet NI transmitted some benefits to 20–40 cm. We conclude that residue retention or moderate incorporation promotes larger, more efficient microbial population and more balanced nutrient cycling, whereas repeated rotary tillage risks subsoil inefficiencies. In semi-arid Mediterranean vineyards, low-disturbance cover-crop incorporation (HR) or, preferably, residue retention at the topsoil (NI) offer a simple, scalable route to sustain soil quality and long-term fertility.

Bio-based polymers are a promising material with which to tackle the use of disposable and non-degradable plastics in agriculture, such as mulching films. However, their poor mechanical properties and the high cost of biomaterials have hindered their widespread application. Hence, in this study, we improved polysaccharide-based films and enriched them with plant nutrients to make them suitable for mulching and fertilizing. Films were produced combining sodium carboxymethyl cellulose (CMC), chitosan (CS), and sodium alginate (SA) at different weight ratios with glycerol and CaCl₂ as a plasticizer and crosslinker, respectively, and enriched with ammonium phosphate monobasic (NH₄H₂PO₄). A polysaccharide weight ratio of 1:1 generated a film with a more crosslinked structure and a lower expanded network than that featuring the 17:3 ratio, whereas CaCl₂ increased the films’ water resistance, thermal stability, and strength characteristics, slowing the release rates of NH₄⁺ and PO₄³⁻. Thus, composition and crosslinking proved crucial to obtaining promising films for soil mulching.

Background: Soils under organic farming systems exhibit better quality and higher biological activity than conventional systems. Manure addition, especially coupled with reduced or no tillage, significantly enhances microbial biomass and activity by improving soil physical properties and providing carbon (C) and nitrogen (N) sources. While several studies have examined the effects of transitioning from conventional to organic farming on soil chemistry and biochemistry, limited research has explored the influence of land use variations on soil fertility within long‐term organic farming systems.Aims: Therefore, the aim of this study was to assess how three different land uses—pasture, vegetable crops, and orchard—affected soil fertility under a long‐term organic farming system.Methods: Soil samples were collected from the 0 to 15 cm layer of plots used for pasture, vegetable crops and orchard, being the latter cover cropped with legumes, and analyzed to determine chemical and biochemical soil parameters.Results: Contrary to expectations, high land use intensity (vegetable crops and orchard soils) resulted in increased soil organic C and total N, compared to low intensity (pasture). Such an increase was ascribed to farmyard manure addition that counteracted the negative impact of tillage. Consequently, microbial biomass C and activity also increased. The greatest availability of organic substrates favored bacteria, particularly gram‐positive strains, shaping the microbial community. However, despite changes of microbial biomass and of the main microbial groups, microbial activity was only slightly affected, suggesting high functional redundancy of microorganisms in long‐term organic farming soil.Conclusions: Results suggested that if land use intensification provides for organic supply, its negative impact on soil fertility may be mitigated.