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Litter decomposition provides a continuous flow of organic carbon and nutrients that affects plant development and the structure of decomposer communities. Aim of this study was to distinguish the feeding preferences of microbes and plants in relation to litter chemistry. We characterized 36 litter types by 13C-CPMAS NMR spectroscopy and tested these materials on 6 bacteria, 6 fungi, and 14 target plants. Undecomposed litter acted as a carbon source for most of the saprophytic microbes, although with a large variability across litter types, severely inhibiting root growth. An opposite response was found for aged litter that largely inhibited microbial growth, but had neutral or stimulatory effects on root proliferation. 13C-CPMAS NMR revealed that restricted resonance intervals within the alkyl C, methoxyl C, O-alkyl C and di-O-alkyl C spectral regions are crucial for understanding litter effects. Root growth, in contrast to microbes, was negatively affected by labile C sources but positively associated with signals related to plant tissue lignification. Our study showed that plant litter has specific and contrasting effects on bacteria, fungi and higher plants, highlighting that, in order to understand the effects of plant detritus on ecosystem structure and functionality, different microbial food web components should be simultaneously investigated.

Biochar is nowadays largely used as a soil amendment and is commercialized worldwide. However, in temperate agro-ecosystems the beneficial effect of biochar on crop productivity is limited, with several studies reporting negative crop responses. In this work, we studied the effect of 10 biochar and 9 not pyrogenic organic amendments (NPOA), using pure and in all possible combinations on lettuce growth (Lactuca sativa). Organic materials were characterized by 13C-CPMAS NMR spectroscopy and elemental analysis (pH, EC, C, N, C/N and H/C ratios). Pure biochars and NPOAs have variable effects, ranging from inhibition to strong stimulation on lettuce growth. For NPOAs, major inhibitory effects were found with N poor materials characterized by high C/N and H/C ratio. Among pure biochars, instead, those having a low H/C ratio seem to be the best for promoting plant growth. When biochars and organic amendments were mixed, non-additive interactions, either synergistic or antagonistic, were prevalent. However, the mixture effect on plant growth was mainly dependent on the chemical quality of NPOAs, while biochar chemistry played a secondary role. Synergisms were prevalent when N rich and lignin poor materials were mixed with biochar. On the contrary, antagonistic interactions occurred when leaf litter or woody materials were mixed with biochar. Further research is needed to identify the mechanisms behind the observed non-additive effects and to develop biochar-organic amendment combinations that maximize plant productivity in different agricultural systems.

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Fusarium head blight (FHB) is a multifaceted disease caused by some species of Fusarium spp. A huge production of mycotoxins, mostly trichothecenes, often accompanied this disease. Amongst these toxic compounds, deoxynivalenol (DON) and its derivatives represent a major issue for human as well as for animal health and farming. Common and durum wheat are amongst the hosts of trichothecene-producing Fusaria. Differences in susceptibility to fungal infection and toxin accumulation occur in wheat cultivars. Recently, increasing incidence and severity of Fusarium infection and a higher DON accumulation in durum wheat were observed in Italy, especially in Northern regions. In this study, we analyzed wheat yield, technological parameters, the incidence of Fusarium infection and DON content in kernel samples of durum wheat coming from three locations of Southern Italy with different climatic conditions and grown during two seasons, with two methods of cultivation. Four different durum wheat cultivars prevalently cultivated in Southern Italian areas were chosen for this study. Our analysis showed the effects of environment and cultivar types on wheat productivity and key technological parameters for the quality level of the end-product, namely pasta. Notably, although a low rate of mycotoxin contamination in all study sites was assessed, an inverse relation emerged between fungal infection/DON production and durum wheat yield. Further, our study pinpoints the importance of environment conditions on several quality traits of durum wheat grown under Mediterranean climate. The environmental conditions at local level (microscale) and soil management practices may drive FHB outbreak and mycotoxin contamination even in growing area suitable for cropping this wheat species.