• Energy Research

Digestate is considered a sustainable opportunity to reduce environmental impact from fertilization, due to high content of nitrogen easily available for plants and for the low impact of its production. We tested liquid fraction of digestate from anaerobic digestion of pig slurries and urea, to assess the emissions of nitrous oxide and ammonia from soil on silage maize (Zea mays L.). Nitrogen rate was the same for both treatments (150 kg/ha) spread replacing common methods. Emissions measurements were performed immediately after fertilization using a static chamber method with a portable gas analyser. Measurements were performed daily during the first week, and twice per week until no emissions from the soil were observed. Cumulative nitrogen emissions show that digestate can be an efficient method to reduce nitrogen losses (2.87 kg N/ha/25 days and 3.76 kg N/ha/25 days for digestate and urea respectively). However, the two fertilizers emitted different kind of gases: compared to urea, digestate emitted the 23% of nitrous oxide more, on the other hand urea emitted 66% of ammonia more than digestate. Crop yield obtained under the two fertilization methods did not significantly differ in terms of dry matter (DM) (13.63 t DM/ha and 13.24 t DM/ha for digestate and urea, respectively) (significance factor α > 0.5).

Abstract Cultivation of sweet sorghum for the production of bioenergy is an attractive option to cope with the challenges of climate change and variability. In fact, on one hand it represents an interesting strategy of mitigation and, on the other, the use of drought resistant species could be considered as an opportunity of adaptation to the change of precipitation patterns. Anyway, when considering the production of agricultural feed stocks, particular attention should be addressed to the environmental sustainability of field production in order to avoid trade-offs in relation to food production, land use and pressure on the water resources. In this context, the cultivation of drought-tolerant energy crops as sweet sorghum ( Sorghum vulgare (L.) var. Saccharatum) could be an interesting option. On the bases of these considerations, the current study had the aims i) to monitor the sweet sorghum growth and productive responses to different water treatments, in order to assess the extent of tolerance to constant water stress and ii) to assess the potential for first and second-generation bioethanol production obtainable from soluble sugars and residual biomass at two different development stages, flowering and physiological maturity. Results show that the length of the growing period should be decided on the bases of the objective pursued. If the objective is just the production of bioethanol, a longer cultivation period could be more suitable, but, on the contrary, if the objective is more addressed to an optimization of water, flowering should be considered the best harvest time.

A preliminary study was conducted to analyze the sustainability of barley production through: (i) investigating sensor-based nitrogen (N) application on barley performance, compared with conventional N management (CT); (ii) assessing the potential of the Normalized Difference Vegetation Index (NDVI) at different growth stages for within-season predictions of crop parameters; and (iii) evaluating sensor-based fertilization benefits in the form of greenhouse gasses mitigation. Barley was grown under CT, sensor-based management (RF) and with no N fertilization (Control). NDVI measurements and RF fertilization were performed using a GreenSeeker™ 505 hand-held optical sensor. Gas emissions were measured using a static chamber method with a portable gas analyzer. Results showed that barley yield was not statistically different under RF and CF, while they both differed significantly from Control. Highly significant positive correlations were observed between NDVI and production parameters at harvesting from the middle of stem elongation to the medium milk stage across treatments. Our findings suggest that RF is able to decrease CO2 emission in comparison with CF. The relationship between N fertilization and CH4 emission showed high variability. These preliminary results provide an indication of the benefits achieved using a simple proximal sensing methodology to support N fertilization.

Summary During recent years, the opportunity to use energy crops for the production of biofuels aroused many interest by virtue of the potential reduction of green house gasses emissions associated to their large-scale use. Nevertheless, many studies highlight that the substitution of fossil fuels with biofuels from energy crops can lead up to serious problems related to the pressure on water resources. The present research had the aim to investigate the relations existing between biofuels production and the pressure on water resources, and how these relations are affected by climate variability. To this aim, the water footprint of maize cultivation in Tuscany (central Italy) was computed and its trend was analyzed during the last 55 years in relation to climate variability with particular attention to precipitations. The results demonstrated that the WF was affected by climate variability mainly through the effect of climate on the crop cycle. The total WF decreased over time but an increase of the blue component was found due to the change in precipitation patterns and to the rise of temperatures. Concerning the gray WF, despite a decrease in the last 55-years period mainly due to precipitation decrease, there was a reduction in N uptake by the crop and an accumulation of nitrate into the soil.

Results show that the year-to-year quality variation of wines produced in North and Central Italy depends on the large-scale climate variability, and that the wine quality improvement in the last four decades is partially due to an increase of temperature and to a decrease of precipitation in West and Central Mediterranean Europe (WME; CME). In addition, wine quality is positively correlated with air temperature throughout the entire active period of the grapevine, weakly negatively correlated with precipitation in spring, and well negatively correlated in summer and fall. The month-to-month composites of the NAO anomaly show that, in years of good quality wine, this anomaly is negative in late spring, oscillates around zero in summer, and is positive in early fall; while, in years of bad quality wine, it is positive in late spring and summer, and negative in early fall, i.e. its polarity has an opposite sign in spring and fall in good versus bad years. The composite seasonal maps show that good wines are produced when the spring jet stream over the Atlantic diverts most of the weather perturbations towards North Europe, still providing a sufficient amount of rainwater to CME; when summer warming induced by southerly winds is balanced by the cooling induced by westerly winds; and when a positive geopotential anomaly over WME shelters CME from fall Atlantic storms. Bad quality wines are produced when the jet stream favors the intrusion of the Atlantic weather perturbations into the Mediterranean. Results suggest that atmospheric pattern persistencies can be used as precursors for wine quality forecast.

In recent years, the certification of environmental sustainability has been adopted by a large number of farms. A wide range of recent literature proved consumers’ preference and willingness to pay (WTP) for certification claiming for reduced environmental impact of food production, whereas the literature on farmers’ preference for a specific scheme design is scant. This study aims at investigating the possibilities of developing an environmental certification (EC) for agricultural products that is more tailored to farmers’ expectations. Data from an original survey among 116 producers from Italy, Croatia, and Greece were used to investigate the most preferred elements of a hypothetical EC for a general agricultural product, by means of a choice experiment. Although differences emerge in relation to the nationality of respondents, the results on average suggest a clear preference and a higher WTP by farmers for a certification that may guarantee an efficient use of water resources. Furthermore, farmers are found to be more inclined toward a public certifying body and the possibility to receive technical assistance for the scheme adoption.

This study analyses the seasonal and daily dynamics of pulp temperature of olive tree (Olea europaea) fruit, measured by inserting a thermistor into the flesh of the olive to record the hourly values on a data logger. The effects of weather conditions and drupe exposures on fruit temperature are considered, as well as the relationships with thermal patterns measured by a standard agrometeorological station. A model for olive fly (Bactrocera oleae) is applied to compare insect development simulations using air and fruit temperatures as model input.