Giant reed (Arundo donax L.) as energy crop in Central Italy: A review

In the European Union energy security have been driving the search for economically viable and environmentally sustainable renewable energy sources since the 90’s. Energy crops could represent a good opportunity to combine the energy goals with the conservation of farmer incomes and the global climate change control. Giant reed (Arundo donax L.) is a perennial rhizomatous grass particularly attractive for energy production because of a high yield potential, a generally positive environmental impact and a good attitude to energy conversion. Long-term studies carried out in Central Italy confirmed its high production level, in both fertile and marginal lands (aboveground yields from 38 to 20 t ha–1 year–1). In addition, the crop highlighted a high growth rate at the beginning of the growing season, progressively decreasing in summer when high temperature and low water availability occurred. Giant reed nutrient requirements were generally low and part of nutrient stocks were remobilized from the rhizome to the aboveground biomass over the spring, with the opposite flow occurring in autumn. From an environmental point of view giant reed showed a positive energy balance with a high-energy efficiency. Compared to other energy crops, giant reed showed the lowest GHG emissions per unit of energy and the best performance in terms of cost per ton of dry biomass or per unit of energy. To improve knowledge on giant reed and to favour the diffusion of energy crops in Italian cropping systems, further studies are needed to analyze the long-term effects of giant reed on soil fertility and the optimal soil management after its cultivation. In our researches the environmental impacts of giant reed and its production costs were referred to the production phase. Therefore, there is the need to extend the research activity to the whole energy chain and to identify the most sustainable conversion technologies (e.g. biogas, 2nd generation bioethanol, etc.) for the different environments

Seasonal nutrient dynamics and biomass quality of giant reed (Arundo donax L.) and miscanthus (Miscanthus x giganteus Greef et Deuter) as energy crops

The importance of energy crops in displacing fossil fuels within the energy sector in Europe is growing. Among energy crops, the use of perennial rhizomatous grasses (PRGs) seems promising owing to their high productivity and their nutrient recycling that occurs during senescence. In particular, nutrient requirements and biomass quality have a fundamental relevance to biomass systems efficiency. The objective of our study was to compare giant reed (Arundo donax L.) and miscanthus (Miscanthus × giganteus Greef et Deuter) in terms of nutrient requirements and cellulose, hemicelluloses and lignin content. This aim was to identify, in the Mediterranean environment, the optimal harvest time that may combine, beside a high biomass yield, high nutrient use efficiency and a good biomass quality for second generation biofuel production. The research was carried out in 2009, in San Piero a Grado, Pisa (Central Italy; latitude 43°41' N, longitude 10°21' E), on seven-year-old crops in a loam soil characterised by good water availability. Maximum above-ground nutrient contents were generally found in summer. Subsequently, a decrease was recorded; this suggested a nutrient remobilisation from above-ground biomass to rhizomes. In addition, miscanthus showed the highest N, P, and K use efficiency, probably related to its higher yield and its C4 pathway. Regarding biomass quality, stable values of cellulose (38%), hemicelluloses (25%) and lignin (8%) were reported from July onwards in both crops. Hence, these components appear not to be discriminative parameters in the choice of the harvest time in the Mediterranean environment. In conclusion, our results highlighted that, in our environment, a broad harvest period (from late autumn to winter) seems suitable for these PRGs. However, further research is required to evaluate the role of rhizomes in nutrient storage and supply during the growing season, as well as ecological and productive performances in marginal lands, in particular those where water availability may be a limiting factor

Double row spacing and drip irrigation as technical options in energy sorghum management

The effect of two row spacing configurations and four water supply levels was investigated on sweet and fibre sorghum in Central Italy for two consecutive years. Results highlighted the influence of both irrigation and row spatial configuration on crop productivity. Indeed, several studies have pointed out the positive response of sorghum to irrigation in Mediterranean climate, as in this environment water stress represents one of the main limiting factors on crop productivity. On the other hand, few attempts have been made to explore the role of row spacing on energy sorghum productivity. Results outlined an average increase in sorghum dry biomass yield ranging from +23% to +79% at variable rates of water supply as compared to rainfed control. The positive effect of irrigation was also observed on leaf area index and radiation use efficiency. Moreover, we observed a crop yield increase, from 9% to 20%, under double row spacing compared to the standard planting pattern ( i.e. single row spacing). Finally, it was confirmed the efficient use of water by sorghum and the great ability of sorghum to increase its biomass yield in response to increasing volumes of water supplied. Therefore, this work suggests how row spacing configuration and drip irrigation could be feasible technical options to increase sorghum biomass yields in Mediterranean environments. These techniques should be experienced by farmers towards a sustainable intensification of current cropping systems

Productivity of giant reed (Arundo donax L.) and miscanthus (Miscanthus x giganteus Greef et Deuter) as energy crops: growth analysis

The growing interest in bioenergy crops is leading to the development of new research aims. In fact, there is a lack of knowledge of most of these crops in terms of suitability to specific environmental conditions and of biotic and abiotic influences. The objective of our study was to compare giant reed ( Arundo donax L.) and miscanthus ( Miscanthus × giganteus Greef et Deuter), two promising lignocellulosic energy crops in Southern Europe, in terms of productivity, through growth analysis, in order to understand environmental and/or management constraints to crop development. Our research was carried out in 2009, in San Piero a Grado, Pisa (Central Italy; latitude 43°41' N, longitude 10°21' E), on a seven-year-old crop, in loam soil characterised by good nutrient and water availability. Results confirmed high yields in both species, about 40 t/ha/yr in miscanthus and 30 t/ha/yr in giant reed, achieved in the second half of October. Different growth strategies were noted as miscanthus developed a greater number of stems per square meter and higher stems, although it showed minor basal stem diameter and leaf area changes. In addition, the physiological difference between crop pathways (C3 in giant reed vs C4 in miscanthus) in a non-limiting environment allowed miscanthus to perform better. As a result, the choice of the proper crop has to be made in order to obtain maximum yield levels, minimising external inputs and optimising the land use

LIFE+IPNOA mobile prototype for the monitoring of soil N2O emissions from arable crops: First-year results on durum wheat

Agricultural activities are co-responsible for the emission of the most important greenhouse gases: carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O). Development of methodologies to improve monitoring techniques for N2O are still needful. The LIFE+IPNOA project aims to improve the emissions monitoring of nitrous oxide from agricultural soils and to identify the agricultural practices that can limit N2O production. In order to achieve this objective, both a mobile and a stationary instrument were developed and validated. Several experimental field trials were set up in two different sites investigating the most representative crops of Tuscany (CentralItaly), namely durum wheat, maize, sunflower, tomato and faba bean. The field trials were realized in order to test the effect on N2O emissions of key factors: tillage intensity, nitrogen fertiliser rate and irrigation. The field trial on durum wheat was set up in 2013 to test the effect of tillage intensity (minimum and conventional tillage) and nitrogen fertilisation rate (0, 110, 170 kg N ha–1) on soil N2O flux. Monitoring was carried out using the IPNOA mobile prototype. Preliminary results on N2O emissions for the durum wheat growing season showed that mean daily N2O fluxes ranged from –0.13 to 6.43 mg m–2 day–1 and cumulative N2O-N emissions over the period ranged from 827 to 2340 g N2O-N ha–1. Tillage did not affect N2O flux while increasing nitrogen fertilisation rate resulted to significantly increase N2O emissions. The IPNOA mobile prototype performed well during this first year of monitoring, allowing to catch both very low fluxes and peaks on N2O emissions after nitrogen supply, showing a good suitability to the field conditions

Produttivita' di colture poliennali dedicate ad uso energetico: il caso della canna comune (Arundo donax L.) e del miscanto (Miscanthus x giganteus Greef et Deuter)

Il crescente interesse verso la coltivazione di specie dedicate per la produzione di energia rinnovabile pone nuovi obiettivi da raggiungere. Tali colture, infatti, risultano poco conosciute sia in termini di adattamento a specifici ambienti di coltivazione, che di risposte a diversi livelli di intensificazione colturale. Allo stesso tempo, la valutazione della qualità della biomassa riveste un ruolo di fondamentale importanza che, a sua volta, incide notevolmente sulla destinazione d’uso della stessa e sull’efficienza dell’intera filiera. A tal proposito, il presente lavoro di tesi si pone come obiettivo quello di confrontare i principali aspetti legati alla produzione di due specie erbacee perenni a destinazione energetica particolarmente promettenti per l’areale mediterraneo, quali la canna comune (Arundo donax L.) ed il miscanto (Miscanthus x giganteus Greef et Deuter). Durante la stagione 2009, le due colture, entrambe al settimo anno d’impianto, sono state paragonate: (i) in termini di produttività, attraverso lo studio delle dinamiche di accrescimento per comprendere le eventuali limitazioni di carattere ambientale e/o di tecnica colturale che influiscono sullo sviluppo della coltura; (ii) in merito alle necessità nutritive, per meglio comprendere le esigenze durante la stagione di crescita e la loro capacità di ottimizzare l’uso dei nutrienti; (iii) andando ad investigare le eventuali variazioni della qualità della biomassa in diversi momenti dell’anno, in funzione di un impiego della biomassa prodotta per la produzione di biocarburanti di seconda generazione. L’attività sperimentale, svolta presso il Centro Interdipartimentale di Ricerche Agro-Ambientali “E. Avanzi” (Italia centrale), ha confermato le elevate capacità produttive di entrambe le specie, con valori massimi di resa in sostanza secca pari a circa 40 t/ha/anno per il miscanto e 30 t/ha/anno per la canna comune, raggiunti nella seconda metà di ottobre. Lo studio dell’analisi di crescita ha messo in evidenza le diverse strategie di sviluppo delle due colture, in cui la resa più elevata del miscanto è prevalentemente dovuta ad un maggior numero di culmi per unità di superficie, caratterizzati però da minori dimensioni, sia in termini di diametro basale che in termini di superficie fogliare. Lo studio della dinamica dei nutrienti ha fatto registrare valori massimi di asportazioni, riferiti alla parte aerea delle piante, pari a circa 130 kg/ha di azoto, a 40 kg/ha di fosforo e a 350 kg/ha di potassio, con fenomeni di traslocazione dei nutrienti verso l’apparato rizomatoso che si verificano a partire dalla prima metà di agosto per entrambe le colture. Infine, l’analisi della qualità della biomassa ha messo in evidenza come, da luglio ad ottobre il contenuto in cellulosa, emicellulosa e lignina si sia mantenuto pressoché stabile con valori per entrambe le colture mediamente pari a 38%, 25%, e 8%. In conclusione, in un ambiente caratterizzato sia da buone disponibilità idriche che da terreni mediamente fertili, il miscanto e la canna comune mostrano una buona attitudine al loro inserimento in sistemi colturali per la produzione di energia. Infatti nonostante esse siano caratterizzate da strategie di accumulo della biomassa diverse, entrambe rivelano similitudini in termini di esigenze nutrizionali e attitudine alla produzione di biocarburanti di seconda generazione. Ulteriori studi sono comunque necessari per valutare le performance produttive ed ecologiche in aree marginali, in particolare in quelle in cui la disponibilità idrica può rappresentare un fattore limitante

Influence of soil texture and crop management on the productivity of miscanthus (Miscanthus × giganteus Greef et Deu.) in the Mediterranean

Biomass productivity is the main favorable trait of candidate bioenergy crops. Miscanthus 9 giganteus is a prom- ising species, due to its high-yield potential and positive traits including low nutrient requirements and poten- tial for C sequestration in soils. However, miscanthus productivity appears to be mostly related to water availability in the soil. This is important, particularly in Mediterranean regions where the risk of summer droughts is high. To date, there have been no studies on miscanthus responses under different soil conditions, while only a few have investigated the role of different crop managements, such as irrigation and nitrogen fertilization, in the Mediterranean. Therefore, the effects of contrasting soil textures (i.e. silty-clay-loam vs. sandy-loam) and alternative agricultural intensification regimes (i.e. rainfed vs. irrigated and 0, 50, 100 kg ha␣1 nitrogen fertilization), on miscanthus productivity were evaluated at three different harvest times for two con- secutive years. Our results confirmed the importance of water availability in determining satisfactory yields in Mediterranean environments, and how soil and site characteristics strongly affect biomass production. We found that the aboveground dry yields varied between 5 Mg ha␣1 up to 29 Mg ha␣1. Conversely, nitrogen fertilization played only a minor role on crop productivity, and high fertilization levels were relatively inefficient. Finally, a marked decrease, of up to ␣40%, in the aboveground yield occurred when the harvest time was delayed from autumn to winter. Overall, our results highlighted the importance of determining crop responses on a site- by-site basis, and that decisions on the optimal harvest time should be driven by the biomass end use and other long-term considerations, such as yield stability and the maintenance of soil fertility