I agree with Val - who did the work and funding sources - there seems to be available space on the last page.

There is a missing word in the conclusions (capitals):

A more detailed analysis of model dynamics
suggests that the somewhat surprising outcome
for the “N-cycling + soil physical” modelling
approach is DUE to the result of less favourable soil
water and nitrogen conditions for the crop due to
greater drainage. Thus, we conclude that simple
nutrient cycling models may overestimate the
benefits of greater soil carbon. This emphasises
the value of the systems modelling approach in
considering the wider effects of altering an
apparently simple crop-soil system that is actually
quite complex.

I am also wondering about the statement in the conclusion that "that simple nutrient cycling models may overestimate the benefits of greater soil carbon" Doesn't Table 2 only show an overestimation at low N levels in terms of yield (i.e. a benefit) with the extra 1% C and greater yields at high N for the complex model - the average yield increase is higher with the complex model. Similarly for N2O the increase is higher for the simple model in all cases - this is not overestimating a benefit - surely that is overestimating a negative? Maybe some word changes will clarify?
