Roberto Cardelli

A two-year field experiment was conducted in an organic vineyard in Tuscany (Italy), to evaluate the effects of micronized biochar (0.5% v/v) applied via fertigation on soil fertility/biological quality and Vitis vinifera performance. The biochar, derived from pyrogasified mixed wood, was compared to watered controls (CTR) following a randomized plot design. Soil chemical properties, dehydrogenase (DHA) and alkaline phosphatase (APA) activities, and plant parameters (biomass, leaf area, gas exchange, chlorophyll, flavonols, and foliar nutrients) were assessed in samples collected in July and September (2021 and 2022). Biochar did not significantly alter total and dissolved organic carbon contents or nitrogen fractions but enhanced DHA and APA activities, alongside increased available phosphorous content (+37.5%) and exchangeable potassium content (+7.1 and +19.7% in September 2021 and July 2022, respectively), indicating improved microbial activity and nutrient availability. Conversely, exchangeable calcium and magnesium contents decreased, likely due to biochar adsorption properties. Plant responses included increased leaf area and dry biomass in 2022, elevated net photosynthesis rate (+14.4%) and apparent carboxylation efficiency, and transient increases in foliar nitrogen, phosphorous and potassium contents, with reduced magnesium concentration (–27%) but stable chlorophyll levels. These findings suggest that low doses of micronized biochar may enhance soil quality and vine physiology, supporting its efficient and effective use in organic vineyards.

A two-year field experiment was conducted in an organic vineyard in Tuscany (Italy), to evaluate the effects of micronized biochar (0.5% v/v) applied via fertigation on soil fertility/biological quality and Vitis vinifera performance. The biochar, derived from pyrogasified mixed wood, was compared to watered controls (CTR) following a randomized plot design. Soil chemical properties, dehydrogenase (DHA) and alkaline phosphatase (APA) activities, and plant parameters (biomass, leaf area, gas exchange, chlorophyll, flavonols, and foliar nutrients) were assessed in samples collected in July and September (2021 and 2022). Biochar did not significantly alter total and dissolved organic carbon contents or nitrogen fractions but enhanced DHA and APA activities, alongside increased available phosphorous content (+37.5%) and exchangeable potassium content (+7.1 and +19.7% in September 2021 and July 2022, respectively), indicating improved microbial activity and nutrient availability. Conversely, exchangeable calcium and magnesium contents decreased, likely due to biochar adsorption properties. Plant responses included increased leaf area and dry biomass in 2022, elevated net photosynthesis rate (+14.4%) and apparent carboxylation efficiency, and transient increases in foliar nitrogen, phosphorous and potassium contents, with reduced magnesium concentration (–27%) but stable chlorophyll levels. These findings suggest that low doses of micronized biochar may enhance soil quality and vine physiology, supporting its efficient and effective use in organic vineyards.

Biochar, produced by pyrolyzing biomass under limited oxygen, can improve soil quality while supporting long-term carbon sequestration. This study compared two wheat-straw biochars (BC) made at 450 °C (BC1) and 600 °C (BC2), with a commercial hardwood biochar produced at 1280 °C (BC3) using lettuce in a sandy, nutrient-poor soil under a carbon capture, utilization, and storage (CCUS) perspective. Higher pyrolysis temperature increased fixed carbon, ash, and alkalinity and reduced volatile matter, indicating greater carbon stability (BC2 > BC1). Germination tests showed good compatibility, with BC1 performing best, likely because moderate temperatures retain more labile organic fractions. In growth-chamber trials (0.75% w/w), biochar boosted lettuce biomass and root development mainly when combined with mineral fertilization, with BC2 (25% and 59%, respectively) and BC3 (18% and 52%, respectively) yielding the strongest gains; unfertilized plants responded little, confirming that biochar is mainly a soil conditioner rather than a nutrient source. Biochar also stimulated soil enzymes linked to C, N, and P cycling and improved leaf chlorophyll, nitrogen status, and antioxidant capacity under fertilization. The nutrient profiles differed by biochar: BC1 increased K and nitrate, while BC2/BC3 lowered nitrate and BC3 enhanced Ca, Mg, and P uptake. Overall, agronomic outcomes depend on feedstock and pyrolysis temperature: mid-temperature biochars enhance productivity and soil biological activity, whereas high-temperature biochars maximize carbon permanence.

The progressive decline in fertility in nutrient-poor sandy soils has increased interest in soil conditioners that improve nutrient availability. Rising costs and the need to restore biological fertility have shifted attention towards fertilizers that not only enhance productivity but also improve soil biological activity. This study aims to evaluate the effects of biochar (3% w/w; BC) and wood distillate (one irrigation intervention per week at 2% v/v; WD), applied individually or in combination (BC + WD), on a nutrient-poor soil, evaluating soil fertility and basil plant physiology and growth but also antioxidant responses in a pot experiment. Soil NPK content and enzymatic activity were assessed, while plant growth, macronutrient uptake, gas exchange, and antioxidant system responses were monitored after 28 and 56 days of treatment. BC treatment, followed by BC + WD treatment, increased soil P availability by 36% and 37%, respectively, after 56 days compared to untreated soil (CNT). A similar pattern was evidenced for the exchangeable K and pH of the soil. Although BC led to a reduction in soil enzymatic activity, the BC + WD treatment enhanced urease and acid phosphatase activity after 56 days by 26% and 7%, respectively, compared to CNT. Similarly, P uptake by plants was improved by BC + WD after 56 days, while potassium, K, uptake increased in both the BC and BC + WD treatments by 38% and 75% at the final sampling. BC or BC + WD resulted in improved photosynthesis and gas exchange, while WD influenced responses related to redox balance and antioxidant activity over time. Moreover, BC + WD slightly stimulated an increase in dehydroascorbate reductase (+52%), ascorbate peroxidase (+78%), and glutathione reductase (+41%) activity compared to CNT, enforcing the plant antioxidant system. Therefore, the positive antioxidant responses were primarily attributed to the use of BC rather than WD. Both BC and BC + WD proved to be effective and sustainable soil conditioners with beneficial effects on soil P and K availability, as well as certain enzymatic activities. For plants, the effects were more pronounced with BC treatment, showing antioxidant responses within the first 56 days. In general, BC improved soil fertility, and WD acted as a modulator of nutrient dynamics and plant physiological responses, especially when combined with BC.

Wood distillate (WD), also known as pyroligneous acid, is a liquid byproduct of charcoal production. It has antimicrobial and antifungal properties thanks to its combination of over 200 components, including organic acids, polyphenols, tannins and others. In this work, microcapsules containing WD coated with chitosan or chitosan and micronized biochar were developed, and their efficacy was tested against the soil-borne fungal pathogen Macrophomina phaseolina. The three products used fit into a circular economy model, and these bio-based microcapsules can be used to promote sustainable agricultural practices. The microencapsulation of WD was carried out via an ion-exchange gelation method, using sodium alginate as the polymer. WD microencapsulation and coating formation were successfully performed, resulting in microcapsules with a size between 600 and 700 µm when dried. Three types of WD microcapsules were produced: uncoated, chitosan-coated and chitosan–biochar-coated. Solubility tests were conducted by measuring the pH of each type of microcapsule in distilled water. It was observed that their solubilization trends were different depending on the type of microcapsules. In vitro growth of M. phaseolina on PDA plates was completely inhibited using WD concentrations of 3–5%. Furthermore, when WD microcapsules were added to a liquid culture medium, those coated with chitosan and biochar induced a significant reduction in M. phaseolina growth.

Biochar (Bc) and liquid vermicompost extracts (LVEs) are increasingly being used as biofertilizers in agriculture to promote soil-microbe-crop interactions. However, although both these products can potentially act synergistically due to their complementary characteristics, their co-application in different soils has not yet been investigated. Therefore, firstly, an LVE-activated biochar (B_LVE) was experimentally formulated and the persistence of LVE bacteria over a 60-day storage period was determined. The total number of LVE bacteria increased by 10-fold after 7 days and was stable throughout the entire biochar storage period. In addition, changes in the composition of the bacterial community were observed after 30 days of storage, indicating that taxa less represented in pure LVE may be advantaged upon biochar colonization. Secondly, a microcosm experiment was performed to evaluate whether the biological fertility and enzyme activities of two soils, differing in organic matter content, could be enhanced by the addition of LVE-activated biochar. In this experiment, three different doses of Bc, LVE, and B_LVE against the carbon-related biological fertility index (i.e., biological fertility index, BFI) and three enzyme activities over a 21-day incubation period were tested. The B_LVE treatment yielded the best results (i.e., BFI +32%, enzyme activities +38%). This indicates that Bc and LVEs can act synergistically to promote soil fertility, quality, and microbial activity. By integrating LVE-activated biochar into their soil management practices, farmers could achieve higher crop yields and healthier products.

Red raspberry fruit production is increasing worldwide due to the growing consumer interest in foods with high antioxidant properties. However, raspberries are very perishable fruit with a short shelf life. Chitosan applications have shown promising results in promoting the storage of different berry fruit. This work aimed at analysing the effects of chitosan applied in pre- and/or post-harvest on the quality and antioxidant properties of raspberry fruit during cold storage and room temperature conditions (i.e., 6 d at 4 °C and 3 d at 20 °C, respectively). Pre-harvest chitosan applications reduced fruit weight loss during cold storage and room temperature conditions but also reduced fruit decay at room temperature conditions. At the end of the whole storage conditions, chitosan-coated raspberries at pre-harvest were brighter than those of the uncoated control fruit. Furthermore, pre-harvest treatments with chitosan increased the total phenol and anthocyanin contents and promoted the highest total antioxidant activity compared with other treatments. After cold storage, post-harvest chitosan application drastically reduced the development of fungi that cause fruit decay, thus minimizing the potential risk of mycotoxin production. Overall, this study demonstrates that applications of chitosan in pre-harvest are sufficient to ensure the goal of maintaining and/or increasing fruit quality and antioxidant properties during cold storage and room temperature conditions.

Red raspberry fruit production is increasing worldwide due to the growing consumer interest in foods with high antioxidant properties. However, raspberries are very perishable fruit with a short shelf life. Chitosan applications have shown promising results in promoting the storage of different berry fruit. This work aimed at analysing the effects of chitosan applied in pre- and/or post-harvest on the quality and antioxidant properties of raspberry fruit during the cold storage and room temperature conditions (i.e., 6 d at 4 °C and 3 d at 20 °C, respectively). Pre-harvest chi-tosan applications reduced fruit weight loss during cold storage and room temperature condi-tions but also reduced fruit decay at room temperature conditions. Furthermore, pre-harvest treatments with chitosan increased the total phenol and anthocyanin contents and promoted the highest total antioxidant activity with respect to other treatments. Of note, after the cold storage, post-harvest chitosan application drastically reduced the development of fungi that cause fruit decay, thus minimizing the potential risk of mycotoxin production. Overall, this study demon-strates that applications of chitosan in pre-harvest are sufficient to ensure the goal of maintaining and/or increasing the quality and antioxidant properties of fruit during cold storage and room temperature conditions.

Natural products such as wood distillate (WD) are promising alternatives to xenobiotic products in conventional agriculture and are necessary in organic farming. A field study gave insight into the effectiveness of WD applied as foliar spray (F-WD), soil irrigation (S-WD), and their combination as growth promoters for field beans. The soil fertility and quality parameters, plant growth, nutrient uptake, and resource partitioning within plants were evaluated. In a pot trial, we tested the effect of S-WD on root nodule initiation and growth. S-WD increased DOC and microbial biomass by approximately 10%, prompted enzyme activities, and increased nitrate and available phosphorus in soil, without affecting the number and growth of nodules in field beans. In contrast, the F-WD slightly reduced the DOC, exerted a lower stimulation on soil enzymes, and lowered the soil effect in the combined distribution. In field beans, the F-WD reduced the stem height but increased the number of pods per stem; S-WD increased the N and P concentrations of leaves and the N concentration of the pods. Moreover, all WD treatments retarded plant senescence. The WD revealed itself to be promising as a growth promoter for grain legumes, but further research is needed to understand the interference between the combined soil and foliar applications.

The recycling of key nutrients and bioenergy from waste materials is a goal of sustainable agriculture. The co-application of biochar and a vermicompost solution (vermiwash) could enhance the positive effects of both materials on soil biomass and biological activities. Tomato plants were grown in soil amended with biochar, mixed at a rate of 2% w/w, and vermiwash, applied through fertigation at a rate of 25 mg per plant, alone (B and V) and in combination (BV). Organic C, dissolved organic C (DOC), soil biomass C, and some enzymatic activities were determined at the start (T0) and the end (T100) of the cultivation period in bulk soil and rhizosphere soil. B and V significantly increased the organic C and soil biomass contents. In addition, B retained the DOC species derived from the soil and, in the BV treatment, also the humic substance of the vermiwash. Generally, all the parameters achieved higher values in the rhizosphere than in the bulk soil. The altered soil index three (AI3) of enzyme activities suggests that applying V and B is helpful for the soil microorganisms. Synergisms between B and V were low in the bulk soil and clearly evident in the rhizosphere.