The agronomic, environmental and economic implications of a combined food and energy system.
Silvoarable systems exploit the beneficial ecological interactions that occur when
trees and crops are grown together. The combined food and energy system comprises of
strips of short rotation coppice (SRC - densely planted, fast growing hardwood trees grown
as a biofuel) planted across arable fields managed under a integrated crop management
system. Some of the potential benefits and disadvantageso f this system were assessedo ver
a three-year period (from establishment of the SRC until the first harvest) using field
experiments and an economic model.
Agronomically the impact of the system was minimal. The main effects were
localised decreases in yield and increases in crop moisture content, which occurred in the
year before the SRC was harvested. The severity and incidence of common arable crop
pests, weeds and diseases, as managed under integrated crop protection regime, were, in
general, not affected by the strips of SRC. A localised reduction in the severity of the
wheat pathogen Septoria tritici was found, whilst localised increases in slug numbers were
found in the year in which the SRC was established.
The monitoring techniques used did not identify any major effects of the SRC strips
on the distribution and diversity of polyphagous predators and earthworms in the system.
Nitrate leaching was found to be higher under the SRC strips in the first winter after
establishment than under adjacent food crops. However, in the following two winters
leaching was lower under the SRC strips than the adjacent food crops.
The system was not economically feasible as greater profits could be made from
arable cropping under current commodity prices and support regimes. This was identified
as the major barrier to adoption of the combined food and energy system. A new approach
for financial support for SRC, such as payments on an income forgone basis, were