The feasibility of using a combination of organic fertilizer with a reduced rate of chemical nitrogen fertilizer as an alternative to conventional inorganic fertilization was tested on the growth and biomass accumulation of hemp plants and the phytochemical accumulation in their inflorescences. To achieve this goal, a field experiment was set up with the following nine treatments: F0, no fertilizer; NPK, mineral fertilizer with 100 kg ha⁻¹ nitrogen; C1, compost from solid digestate (50%) + cardoon-based spent mushroom substrate (50%); C2, compost from solid digestate (50%) + straw-based spent mushroom substrate (50%); C3, C4, C5, and C6, composts from solid digestate (50%, 67%, 75%, and 84%, respectively) and cardoon waste (50%, 33%, 25%, and 16%, respectively); SD, non-composted solid digestate. C1–C6 and SD were added to the soil, along with half the rate (50 kg ha⁻¹) of chemical nitrogen fertilizer. Taking F0 as a reference, all fertilized treatments, except C6 and SD, showed a notable increase in plant growth and biomass accumulation in the stem, inflorescence, and whole plant. Among the organic treatments, the best growth performances were detected in C1 and C5, which reached, or even exceeded, that of NPK. Compared to F0, all fertilized treatments had high phenolic acid and flavonoid yields, while high carotenoid, tocopherol, terpene, and cannabinoid (mainly CBD) yields were detected in all fertilized treatments except C6 and SD. Among the organic treatments, C1 and C5 stood out for their highest phenolic acid, flavonoid, carotenoid, and tocopherol yields, while C1, C2, and C3 stood out for their highest terpene and cannabinoid yields, which, in both cases, reached, or even exceeded, those of NPK. Overall, our findings show that 50% replacement of inorganic nitrogen fertilizer with C1 to C5 composts may represent a cost-effective and environmentally safe alternative to conventional inorganic fertilization that can sustain the growth of hemp plant and the phytochemical accumulation in its inflorescences, thus promoting the use of this crop for fiber and bioenergy production, as well as for applications in food, nutraceutical, agrochemical, and cosmetic sectors.

Mulching is one of the most recommended practices in agriculture due to its positive effects on the plant/soil system. Very few experiments have been conducted to date to investigate the effect of mulching, with both organic and inorganic materials, on tobacco. The main aim of this study was to test the synergic effect of a soil-biodegradable (according to standard EN17033) mulching film (the commercial Mater-Bi^®, Novamont SpA, Novara, Italy) and drip irrigation (M-D) compared with that of bare soil and sprinkler/drip irrigation (first/second part of the growing season; BS-SD) on a tobacco crop (Nicotiana tabacum L., flue-cured Virginia) grown in the Tiber Valley (the tobacco cultivation district of Central Italy). BS-SD represents the standard practice applied by tobacco growers in the study area. The plants grown under the M-D management system grew more and developed faster than the plants grown under BS-SD conditions. Under the M-D system, yields increased in comparison with the BS-SD conditions (+29%, on average). The gross revenue obtained via the M-D-cured products also increased (+63%, on average) thanks to higher prices assigned by expert evaluators on the basis of the extrinsic quality traits (color, structure and texture, degree of ripeness, elasticity, lamina integrity, handling defects, and vein incidence). The economic value of the cured products increased with the leaf crowns; it was the lowest in the basal (B) leaves and the highest in the middle-upper (MU) leaves. The intrinsic quality traits of the cured leaves (total N and nitrate contents, alkaloids, and reducing sugars) also confirmed that the best quality was found in the M-D-cured products, as determined by expert evaluation. Interestingly, the reducing sugar (RS) contents of tobacco obtained using the M-D management system were 2.5-, 1.1-, and 0.9-fold greater than those under the BS-SD conditions (B, M, and MU products, respectively). An additional commercial value of the cured products was thus obtained with the M-D crop management system due to RS, an intrinsic quality trait considered by manufacturing industries.

The use of peat, the standard substrate used for soilless cultivation of horticultural crops, is becoming of increasing concern as peat is a non-renewable resource and its extraction can degrade wetland ecosystems, creating a strong environmental impact. For this reason, the search for organic materials that can totally or partially replace peat has become increasingly important. In this research, three types of composts (C1, C2, C3), derived from cardoon biomass mixed in different volumes with woody and/or fruit wastes, were utilized as the constituents of growing media, at two dilution rates with peat (60:40 and 30:70 v:v), to assess their effect on the growth and quality of baby leaf lettuce in a greenhouse trial. The two cultivars Imperiale and Verde d’Inverno, belonging to the butterhead and romaine lettuce types, respectively, were employed. Plant performance and yield were unaffected or were positively affected by compost-containing growing medium compared to the control. The cultivars responded differently to the growing medium; the Imperiale showed the highest yield with C1 compost at a 60% rate while the Verde d’Inverno with the C2 was at 30%. The total chlorophyll, carotenoids, and ascorbic acid were found higher in the Verde d’Inverno than in the Imperiale variety while the total polyphenols, flavonoids, and antioxidant activity were lower. Also, the content of chlorophylls as well as of antioxidant compounds and antioxidant activity were differently affected by the growing medium, depending on the lettuce cultivar. The results obtained indicate that cultivated cardoon waste-based compost is a promising constituent of the growing media for baby leaf production. The specific varietal response observed should be considered to optimize both yield and product quality.

Tobacco (Nicotiana tabacum L.) is an industrial crop cultivated worldwide with intensive management systems that include continuous cropping, conventional tillage and high use of agrochemicals. The increasing concerns about environmental and economic sustainability call for innovative practices to maintain yield while managing weeds and enhancing soil fertility. Our research investigated the effect of green manure or cover crops coupled with minimum tillage on Kentucky tobacco production and the level of control of weeds. Six integrated management systems were tested in a four-year trial in Tuscany, Italy: (TS1) conventional farming management as defined above; (TS2) reduction in fertilizers and compost application; (TS3) rotation of tobacco–leguminous green manure and reduction in fertilizers; (TS4) rotation of tobacco–leguminous green manure and compost application without fertilizers; (TS5) rotation of tobacco–mixture of cover crops, minimum tillage before tobacco transplant, reduction in fertilizers; (TS6) as in TS5 but with a compost amendment addition. The different farming practices represented an ecological filter for the weed communities. The combination of conventional tillage, compost application and green manure was sufficient to control weed development. On the other hand, cover crop termination via roller crimper and minimum tillage did not reduce weed pressure, thereby negatively affecting tobacco production. Further studies are needed to improve the effectiveness of mulching and minimal tillage on weed levels not detrimental to tobacco development. It would be advisable to alternate different weed management strategies to prevent community specialization, mitigate negative effects on crops and enhance biodiversity at the farm scale.