Agriculture Reference
In-Depth Information
planting, weeding and crop protection (when applied) are the same for all
production systems, while inputs for fertilisation and harvesting differ. The
energy requirements for irrigation are huge. In production systems that are
not irrigated, fertilisation and harvest are the largest energy users. The term
'fertilisation' includes the indirect energy in nitrogen and the direct energy
required to distribute the nitrogen over the area. The indirect energy is
about 10 times as high as the direct energy.
The main reason for the low energy requirements of the low-input
systems is that most of the nitrogen used is free of costs. The crops “grow”
on the nitrogen deposition, so that no fossil energy is required for the
production of artificial nitrogen and none for the application of it. To
produce 25 kg N costs 1.8 GJ. This amount is quite small in comparison
with the total fossil energy inputs of high-input production systems (15 to
85 GJ/ha/y), but large in comparison with the inputs in low-input systems
(4 GJ/ha/y).
When inputs are recalculated to inputs per output (resource use/ton
biomass, Table 6.3), a different
picture is obtained. The differences
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