3.2. Fuel and energy consumption
The diesel fuel consumption was different in function of the
considered crop. The higher value (98.8 l ha1 per year) was
observed in the maize cultivation, the lower in the SRC (59.0 l ha1
per year), while in vSRC an intermediate value (70.5 l ha1 per year)
was registered. Concerning the produced biomass, similar values
were obtained in vSRC and maize crops (5.07 and 5.15 l Mg DM1
),
with a lower value in SRC (4.24 l Mg DM1
).The cultural operation
with higher incidence on diesel fuel consumption were the
ploughing for maize (40.5%) and the harvesting for vSRC and SRC
(41.1% and 45.2% respectively). The mineral fertilization, on the
contrary, registered the lowest incidence in all the analyzed crops
(Table 8).
The energy consumption for the poplar vSRC cultivation was
14.8 GJ ha1 per year and it was slightly inferior to SRC (15.2 GJ ha1
per year).
These values represent only the 6% of the total energy biomass
production (about 257 GJ ha1 per year, obtained from
13.9 Mg DM ha1 of biomass production).
The input energetic value for the maize was higher (26.8 GJ ha1
per year), about the 7% of the energy content of the biomass
product (about 370 GJ ha1 per year).
The output/input ratio is between 16.9 (vSRC) and 17.4 (SRC) for
the short rotation coppice and 13.8 for the maize cultivation.
The highest energy requirements were observed in the soil
fertilization, in the harvest and in the transport operations, in all
the crops (Table 9).