Gianpietro Venturi

Analysis of energy comparison for crops in European agricultural systems.

Abstract The energy input and output of three energy crop chains in Europe has been reviewed. The three chains are: bio-oil production from rape, soybean, or sunflower; ethanol production from cereal and sugar beet; and the use of herbaceous lignocellulosics as raw fiber biomass. The energy input measurements are taken from the literature in terms of the average, minimum, and maximum for current agricultural practice. The bio-oil and ethanol chains are well defined and use efficient and mature technology, while the herbaceous lignocellulosic chains is still under development. The yield of bioenergy is limited by land and it is not directly correlated with inputs level; for maximum gain the inputs must be minimized. There is considerable margin for improvement in many areas with low yields. While the study does not address social and economic issues, it is clear that many of the species considered are multifunctional, and the maximizing of the economic opportunity will depend also on the exploitation of co-and by-products.

Crop yield and quality parameters of four annual fibre crops (hemp, kenaf, maize and sorghum) in the North of Italy

Abstract Four fibre crops (hemp, kenaf, maize and sorghum) considered amongst the most suitable for the conditions of Northern Italy were compared in 1995 and 1997, over two irrigation regimes (rainfed conditions and restoration of 100% ETp) and in two locations (Bologna and Milano). Three harvests were carried out on each crop at different development stages. At each harvest time data on yield and yield components were collected. Sub-samples of stems of each crop and at each harvest time were analysed following the Van Soest method. On average, fibre sorghum proved to be the higher yielding crop. It produced 26.2 Mg ha−1 of total dry matter of which 18.1 Mg ha−1 was partitioned to the stems. Fibre maize produced more total dry matter than kenaf (19.0 Mg–15.7 Mg ha−1) but dry matter accumulated to stems was higher in kenaf (10.8 and 13.4 Mg ha−1). On average, fibre hemp yielded 14.0 Mg ha−1 of total dry matter and 10.9 Mg ha−1 of stems. This result was highly affected by the low hemp production in Bologna in 1995, where unfavourable conditions, in the first phases of cultivation, resulted in a stunted establishment of the crop (18.7 Mg ha−1 of total dry matter in Milano and only 8.3 Mg ha−1 of total dry matter in Bologna). On all crops, irrigation produced a slight increase in total biomass (7%) and in stem dry matter (9%) compared to the rainfed condition. In both locations, yield increase due to irrigation was larger in maize and kenaf, than in hemp while, in 1995, it caused a severe lodging on sorghum. The four species proved to be different for growth rates, patterns of development and particularly for cellulose, hemicellulose and lignin content of stems. Cellulose content varied between 56–66% of stem dry matter in hemp, 46–57% in kenaf, 35–45% in maize and 39–47% in sorghum. As harvest time was delayed, cellulose content tended to increase for hemp and kenaf while it decrease for sorghum and maize. Hemicellulose content of hemp and kenaf stems varied between 16–19%, while it varied between 26–29% in sorghum and maize. Hemicellulose content decreased with irrigation and with delay in harvest time. Lignin content in hemp stem ranged between 8 and 13%, it was 6.9% in kenaf and maize, and ca 8% in sorghum.

Comparison of the energy performance of fibre sorghum, sweet sorghum and wheat monocultures in northern Italy

Abstract Four monocultures (fibre sorghum, sweet sorghum and wheat at high and low nitrogen doses) were compared at a field-scale over 3 years (1997–1999) in terms of net energy, net energy ratio and energy use efficiency. Two nitrogen fertilisation levels were assessed for wheat (80 and 120 kg ha −1 of N) to evaluate the energy use efficiency of the applications. For all the crops, fuels, lubricants and farm inputs together formed around 92% of the total input, mainly due to nitrogen fertilisation. A year×crop significant interaction was found for all considered parameters. In fact the monoculture did not lower the biomass yield of both sorghum types, while it involved a drop in wheat yield starting from the second year (third considering that wheat was also cultivated in the same field in 1996). The average (1997–1999) net energy supplied by the monoculture of sweet sorghum was 17, 40 and 50% higher than those of fibre sorghum and wheat at high and low nitrogen doses respectively. The energy use efficiency (EUE, i.e. the energy (MJ) requirement to produce a kg of dry matter) ranged from 0.78 to 0.96 for fibre sorghum, from 0.69 to 0.85 for sweet sorghum and from 1.00 to 1.23 and 0.91 to 1.33 for wheat at low and high nitrogen levels respectively. With ethanol as the end-product of the 3-year monoculture of sweet sorghum, the production process would be a bit less favourable in term of energy balance: the net energy yield would be 90% of that obtained by dry matter gasification (with an efficiency of 50%). If straw was not processed, ethanol from wheat was generally unfavourable. On average of the two nitrogen doses, net energy ratios were 0.99, 1.05 and 0.97 in the first second and third year respectively. If bagasse was not considered also sweet sorghum had a very low net energy ratio, but always higher than wheat (1.14, 1.12 and 1.24 over the 3 years).

Plant Population Effects on Fibre Hemp Morphology and Production

Abstract This paper reports on a 4-year study into the effect of plant density on the morphology and production of fibre hemp. At high density (180-270 plants m2), strong competition for light early in the growing season promoted internode extension (primary growth) and inhibited increase of stem diameter (secondary growth). In relating plant density to fibre hemp production it can therefore be said that a high plant population favours a high yield of long bast fibres for the textile industry. Demands only for high total yield can however be satisfied by targeting 30-45 plants mr2. This is further supported by results of self-thinning, showing plant loss in 1999 was negligible at low density (30-90 plants m2), while at high density (180 and 270 plants m2) 50% and 60% of the initial stand was lost, respectively. In view of this result, and because of the fact that no significant morphological difference was found between 180 and 270 plants m2, it is also worth to note that when growing for long bast fibres 180 plants m2 should be chosen instead of 270 in order to save seed costs.

Flowering Dynamics in Monoecious and Dioecious Hemp Genotypes

ABSTRACT Flowering is a crucial phase in hemp cultivation. It influences both stem and seed yield. A uniform and short flowering duration in hemp is desirable, because it favors uniform crop development. Moreover, flowering is often taken as a reference point for harvesting, and very long durations of flowering might mislead the operator in judging the proper time for mowing. In this article, a large dataset of flowering time and duration for different monoecious and dioecious varieties was studied and the effect of sowing time and genotype on flowering duration is discussed. Minimal flowering duration was observed when the time from emergence to flowering was short. This, was related however, to low yields. Dynamics of flowering was accurately described by a bi-logistic curve that indicates the presence of two underlying logistic processes.

Internal conductance under different light conditions along the plant profile of Ethiopian mustard (Brassica carinata A. Brown.)

This study focused on the internal conductance (g(i)) along the plant profile of Ethiopian mustard under two light conditions: (i) light from the top only (I1); (ii) light from the top integrated by supplementary lateral light along the whole plant profile (I2). Lateral light strongly increased the productivity (e.g. +104% of seed oil) and net photosynthesis (A). The latter appeared more driven by g(i) (r=0.78**) than by stomatal conductance (g(s)) (r=0.51*). Importantly, irradiance also considerably shortened the time from leaf appearance to senescence, which means that corresponding leaves in I1 and I2 had different ages. Therefore, since leaf age and irradiance have counteracting effects on g(i), I1 sometimes showed higher g(i) values than I2. With respect to irradiance, leaf age had clearly higher effects on g(i), which radically declined from the top to the basal leaves, even under constant light conditions. The internal conductance caused a significant drawdown of CO(2) from the sub-stomatal cavity (C(i)) to the site of carboxylation (C(c)) that, in turn, led to a substantial underestimation of V(cmax) calculated using the A/C(i) model. Again, the trends of g(i) and g(s) were not consistent along the plant profile, and so the ratio between stomatal and internal limitations to A changed from top to bottom leaves, accordingly. This study suggests that g(i) may be a valuable trait for increasing photosynthetic capacity and productivity; nonetheless, it suggests caution in selecting leaves for high g(i), as the latter can considerably change along the plant profile due to leaf age and irradiance effects.

A simple method to improve the estimation of the relationship between rainfall and crop yield

The time-course of rainfall is commonly presented as bar, line or scatter plots, which may sometimes be chaotic, while leading to subjective and vague assertions. More objective criteria quantifying rainfall distribution may therefore be helpful, e.g. when different years are examined concurrently. Here, some practical indices are presented based on the distance between cumulative rainfall curves and the respective theoretical evenness rainfall lines, the line joining the lowest and highest cumulative rainfall values within the considered period. After an introduction to the theory and calculation of the indices, the relationships between the indices and two major crops, maize and sugar beet, are evaluated for a period of 33 years. The results show good correlations between the indices and crop yields, up to r = 0.81, especially when the evenness index was weighted on the mean daily rainfall, i.e. the slope of the evenness line. Significant correlations were also found by recalculating the indices over strategic short-term periods for maize, which indicates how the effectiveness of these indices may be increased by choosing appropriate periods for different crops. Finally, the different indices showed no correlation, indicating little redundancy and thus suggesting a profitable conjoint use of them.

Eighty Years of Studies on Industrial Hemp in the Po Valley (1930--2010)

The Department of Agroenvironmental Science and Technology (DiSTA), University of Bologna, has been studying industrial hemp since 1930s. In the pioneering studies we mostly addressed agronomic issues while most recently, fiber quality and characteristics, along with innovative fiber processes, have been mostly investigated. In general, even though significant progresses have been achieved and innovative production strategies proposed, significant bottlenecks still remain unsolved, especially for the textile uses. Most likely, the production of bio-polymers and non-textile compounds can be economically self-sustaining in a short term, while fiber processing for textile uses still needs significant improvements.

Interaction Between Agronomic and Mechanical Factors for Fiber Crops Harvesting: Italian Results–Note II. Hemp

ABSTRACT This paper considers the first steps in some of the production chains of hemp. Effects of agronomic techniques (such as crop density, sowing and harvesting period, and variety) are evaluated. Their influence on biometric characteristics of the crops is studied on the basis of harvesting and first transformation machines. Effects of the interaction between agronomic techniques and machines are considered with respect to the qualitative and quantitative characteristics of the product obtained.

Interaction Between Agronomic and Mechanical Factors for Fiber Crops Harvesting

Abstract This paper considers the first steps in some of the production chains of kenaf and fiber sorghum. Effects of agronomic techniques (such as crop density, sowing and harvesting period, and variety) are evaluated. Their influence on biometric characteristics of the crops is studied on the basis of harvesting and first transformation machines. Effects of the interaction between agronomic techniques and machines are considered with respect to the qualitative and quantitative characteristics of the product obtained.