Carbon inputs from Miscanthus displace older soil organic carbon without inducing priming

The carbon (C) dynamics of a bioenergy system are key to correctly defining its viability as a sustainable alternative to conventional fossil fuel energy sources. Recent studies have quantified the greenhouse gas mitigation potential of these bioenergy crops, often concluding that C sequestration in soils plays a primary role in offsetting emissions through energy generation. Miscanthus is a particularly promising bioenergy crop and research has shown that soil C stocks can increase by more than 2 t C ha−1 yr−1. In this study, we use a stable isotope (13C) technique to trace the inputs and outputs from soils below a commercial Miscanthus plantation in Lincolnshire, UK, over the first 7 years of growth after conversion from a conventional arable crop. Results suggest that an unchanging total topsoil (0–30 cm) C stock is caused by Miscanthus additions displacing older soil organic matter. Further, using a comparison between bare soil plots (no new Miscanthus inputs) and undisturbed Miscanthus controls, soil respiration was seen to be unaffected through priming by fresh inputs or rhizosphere. The temperature sensitivity of old soil C was also seen to be very similar with and without the presence of live root biomass. Total soil respiration from control plots was dominated by Miscanthus-derived emissions with autotrophic respiration alone accounting for ∼50 % of CO2. Although total soil C stocks did not change significantly over time, the Miscanthus-derived soil C accumulated at a rate of 860 kg C ha−1 yr−1 over the top 30 cm. Ultimately, the results from this study indicate that soil C stocks below Miscanthus plantations do not necessarily increase during the first 7 years

Wpływ jesiennego terminu siewu na przezimowanie mieszańcowej i konwencjonalnej odmiany rzepaku ozimego

Field experiment on different sowing dates of two winter rapeseed cultivars (Brassica napus L. spp. and oleifera biennis Metzg.) was carried out in years 2009-2010 at the Experimental Station of the Aleksandras Stulginskis University (54°53’ N; 23°50’ E). The objective of the study was to evaluate the effect of winter rapeseed sowing date on the biometric parameters of rapeseed rosette: number of leaves, root collar diameter, height of apical bud, and its chemical composition: N:K ratio, amount of dry matter, total sugar in autumn before wintering, changes of chemical composition during the autumnwinter period, and overwintering. Sowing date significantly influenced all the examined indexes. According to the biometric parameters, the chemical composition of leaves, and the apical bud, winter rapeseed sown between August 30th and September 5th was best prepared for wintering and overwintered. Growth during the period of preparation for overwintering was more intensive. Changes in the chemical composition during the overwintering period were more favourable and the overwintering of winter rapeseed was better in the hybrid cultivar Kronos compared with cultivar Sunday.Doświadczenie polowe przeprowadzono w latach 2009-2010 w Stacji Doświadczalnej Litewskiego Uniwersytetu Rolniczego (54°53’ N; 23°50’ E). Zastosowano różne terminy siewu dla dwóch odmian rzepaku ozimego (Brassica napus L. spp. oleifera biennis Metzg.). Celem badań była ocena wpływu terminu siewu dwóch odmian rzepaku ozimego na wartość parametrów biometrycznych w stadium rozety, skład chemiczny jesienią przed przezimowaniem, zmiany składu chemicznego w okresie jesienno-zimowym i przezimowanie. Termin siewu znacząco wpłynął na wszystkie badane cechy. Według parametrów biometrycznych, składu chemicznego liści i pąków wierzchoł-kowych, rzepak ozimy zasiany w terminie od 30 sierpnia do 5 września był lepiej przygotowany do przezimowania i w konsekwencji przezimował najlepiej. Wzrost w okresie przygotowania do przezimowania był bardziej intensywny, zmiany składu chemicznego w ciągu zimowania były korzystniejsze oraz przezimowanie mieszańcowej odmiany rzepaku ozimego Kronos było lepsze niż tradycyjnej odmiany rzepaku ozimego Sunday

Megafloods in Europe can be anticipated from observations in hydrologically similar catchments

Megafloods that far exceed previously observed records often take citizens and experts by surprise, resulting in extremely severe damage and loss of life. Existing methods based on local and regional information rarely go beyond national borders and cannot predict these floods well because of limited data on megafloods, and because flood generation processes of extremes differ from those of smaller, more frequently observed events. Here we analyse river discharge observations from over 8,000 gauging stations across Europe and show that recent megafloods could have been anticipated from those previously observed in other places in Europe. Almost all observed megafloods (95.5%) fall within the envelope values estimated from previous floods in other similar places on the continent, implying that local surprises are not surprising at the continental scale. This holds also for older events, indicating that megafloods have not changed much in time relative to their spatial variability. The underlying concept of the study is that catchments with similar flood generation processes produce similar outliers. It is thus essential to transcend national boundaries and learn from other places across the continent to avoid surprises and save lives