Files
Abstract
Sowing phases of French serradella (
Ornithopus sativus
Brot.) pasture between
extended cropping sequences in the Western Australian wheatbelt can sustain grain
production through restoring soil fertility and reducing selective herbicide use. The
objective of this article is to investigate the profitability of rotations involving this
pasture under a variety of weed management scenarios to obtain greater insight into
its value for mixed farming systems in this region. A stochastic search procedure,
compressed annealing, is used to identify profitable sets of weed management strategies
in a simulation model representing a large number of potential combinations of chemical
and non-chemical forms of weed control. In contrast to a continuous-cropping sequence,
the inclusion of a serradella phase in a rotation is profitable at high weed densities and
with increasing levels of herbicide resistance. A single year of pasture in the rotation
is optimal if resistance to Group A selective herbicides is present at the beginning of
the planning horizon, but a three-year phase is required if resistance to multiple herbicide
groups is observed. Sowing a serradella pasture twice over a two-year phase is also
shown to be economically attractive given benefits of successive high weed kills.