The first question is ‘Does the model simulate yields
realistically ? Simulations of experiments grown
each year with and without irrigation at Broom’s
Barn are shown in comparison to observed values in
Fig. 2. The simulations used the real sowing and
harvest dates, and the simulations agree reasonably
well with the observations. The simulated sugar yields
accounted for 0.88 of the variation in the observed
sugar yields and the calculated root mean square error
was 1.18. Over the same period, the yields in the experiments
have tended to increase at a rate of 0.181
and 0.147 t/ha per year for irrigated and rain-fed
crops, respectively.