Organic Amendments (OAs) has been used in agroecosystems to promote plant growth and control diseases caused by soilborne pathogens. However, the role of OAs chemistry and decomposition time on plant growth promotion and disease suppression is still poorly explored. In this work, we studied the effect of 14 OAs at four decomposition ages (3, 30, 100, and 300 days) on the plant-pathogen system Lactuca sativa-Rhizoctonia solani. OAs chemistry was characterized via 13 C-CPMAS NMR spectroscopy as well as for standard chemical (i.e. N content, pH, EC) and biological parameters (i.e. phytotoxicity and R. solani proliferation bioassay). OAs have shown variable effects, ranging from inhibition to stimulation of Lactuca sativa and Lepidium sativum growth. We recorded that N rich OAs with high decomposability were conducive in the short-term, while converting suppressive in the long term (300 days). On the other hand, cellulose-rich OAs with high C/N ratio impaired L. sativa growth but were more consistent in providing protection from damping-off, although this property has significantly shifted during decomposition time. These results, for the first time, highlight a consistent trade-off between plant growth promotion and disease control capability of OAs. Finally, we found that OAs effects on growth promotion and disease protection can be hardly predictable based on the chemical characteristic, although N content and some 13 C CPMAS NMR regions (alkyl C, methoxyl C, and carbonyl C) showed some significant correlations. Therefore, further investigations are needed to identify the mechanism(s) behind the observed suppressive and conducive effects and to identify OAs types and application timing that optimize plant productivity and disease suppression in different agroecosystems.

The urgency to reduce resource depletion and waste production is expected to lead to an economy based on renewable resources. Biofuels, for instance, are a great green alternative to fossil fuel, but they are currently derived from edible vegetable oils such as soybean, palm, and sunflower. Concerns have been raised about the social–economic implication and ecological impacts of biodiesel production. Cultivating new lands as biodiesel feedstock rather than food supply, with the consequent increase in food prices, leads to so-called indirect land-use change (ILUC). Establishing bioenergy crops with phytoremediation ability on contaminated soils offers multiple benefits such as improving soil properties and ecosystem services, decreasing soil erosion, and diminishing the dispersion of potentially toxic elements (PTEs) into the environment. Castor bean is an unpalatable, high-biomass plant, and it has been widely demonstrated to possess phytoremediation capability for several PTEs. Castor bean can grow on marginal lands not suitable for food crops, has multiple uses as a raw material, and is already used in biodiesel production. These characteristics make it perfect for sustainable biodiesel production. Linking biofuel production with environmental remediation can be considered a win–win strategy.

SummaryNitrogen (N) fertilization of Kentucky dark fire-cured tobacco can be used to increase weight of high quality cured leaves for cigar manufacture. We conducted field experiments at 11 different locations in the province of Benevento (Southern Italy) where the following four N treatments were compared: 1) unfertilized control (N0); 2) a site-specific N rate, calculated by a N fertilization plan (NFP) based on physical and chemical soil characteristics, which ranged between 113 and 145 kg N ha−1; 3) 200 kg N ha−1 (rate commonly used by farmers, N200); 4) 100 kg N ha−1 (half of the rate commonly used by farmers, N100). Yields of the following five commercial quality categories of cured leaves were measured: i) wrappers, ii) heavy filler (Fh), iii) light filler (Fl), iv) heavy shredded (Sh) and v) light shredded (Sl). Fh cured products of B1, B4, B6 and B10 locations were analyzed for: total alkaloids, reducing sugars, chlorides, total N (Kjeldahl), ammonium-N (NH4-N), nitrate-N (NO3-N), and tobacco specific nitrosamines (TSNA). Color parameters: Lightness (L), Chroma (C) and Hue (H) were determined on five cured leaves / plot of both Fh and Fl types at B1, B2, B3, B6, B8 and B10. A blind evaluation of cured leaves collected across locations was conducted by a panel test who considered the main basic characteristics of cured leaves (stalk position, leaf structure, texture, etc.). The total yield of cured products increased with fertilization across locations, up to NFP treatment, without any statistically significant increase at N200 treatment. Fertilization increased yield of wrappers at B1 up to NFP treatment (113.5 kg N ha−1), without any significant increase at N200 treatment. Yield of light filler product was positively influenced by fertilization up to the maximum dose only in 5 out of 11 locations. Total alkaloids significantly increased with increasing fertilization up to 100 kg N ha−1 without any significant changes at higher N rate. Fertilization hardly increased L and C of Fl leaves, which appeared light-brown but brilliant-colored. There was a reduction in the H value of Fh products which indicated a darker tone of those leaves with respect to Fl. Increasing N rate affected production costs more than revenues. According to agronomic results, in most locations the best results in terms of net revenues were obtained by NFP treatment. Considering that N rates above the NFP would disqualify growers from the economic aids provided by EU agrienvironmental measures, by economic point of view the NFP treatment would be recommended over the current grower standard (N200).

Tobacco cultivation is characterized by high amounts of waste biomasses whose disposal frequently represents a complex and expensive problem. A study was conducted to evaluate thepotential of pre-harvest light air-cured (Burley) and dark fire-cured (Kentucky) tobacco waste biomasses as a source of bioactive compounds (nutraceutical ingredients) such as polyphenols. Pre-harvest waste materials (topping fresh materials and residual stalks at final harvest) were collected to determine dry matter, total polyphenols content (TPC; Folin assay), and DPPH (2,2-diphenyl-1-picrylhydrazyl) and ABTS (2,20-azino-bis(3-ethylbenzothiazoline-60-sulfonic acid) diammonium salt) antioxidant capacity. Polyphenols quali-quantitative profiles obtained by Orbitrap Q Exactive of both tobacco types were also determined. Total pre-harvest waste biomass amounted to 3956.9 and 1304.4 kg d.w. ha−1 in light air-cured (Burley) and dark fire-cured (Kentucky) tobacco types, respectively. Polyphenols content, expressed as g kg−1 dry weight (d.w.), ranged between 4.6 and 15.7 g kg−1 d.w. and was generally greater in leaves than in stalks. Considering both leaves and stalks, the light air-cured (Burley) tobacco crop yielded 22.1 kg ha−1 of polyphenols, while the dark fire-cured (Kentucky) tobacco yielded 12.0 kg ha−1. DPPH and ABTS were significantly greater in leaves than in stalks waste biomass in both types of tobacco. The most abundant components were quinic and chlorogenic acids, rutin, and luteolin rutinoside.

In this work, a grass-based phytoremediation system integrated with an organic amendment and biostimulants was evaluated for remediating contaminated sites. Plant growth and biological fertility were monitored to assess the efficacy of a vegetative cap used as a safety measure to reduce sanitary and environmental risks of industrially contaminated soils and soil-washing sludges. Both matrices were potentially contaminated with Pb and Zn with an ecological risk index from low to moderate. According to potentially toxic elements (PTEs) bioaccessibility tests, the exposure to the released fine particulate matter may cause serious risks to human beings, in particular to children. The grass mixture was well adapted to both the substrates and a low PTEs mobility was detected, thus, reducing the leaching risk to ground water sources. Compost addition augmented significantly nitrogenase reductase (nifH) and ammonia monooxygenase (amoA) gene expression abundance in both substrates. Furthermore, a positive interaction between compost fertilization and a Trichoderma-based biostimulant inoculation was recorded in sludges resulting in a significant stimulation of nitrogen-fixing and ammonia-oxidizing bacteria. The application of compost and biostimulant increased soil fertility and plant growth. Furthermore, there was a slight reduction in PTE bioaccessibility, thus, improving the efficiency of the phytostabilization, limiting the resuspension and dispersion of the health-risk soil particulate.