<p>The CenW model developed for Waikato farms was compared against three years of eddy-covariance data from an irrigated grazed pasture in the Canterbury region. CenW was used to compare three irrigation management scenarios: no irrigation (dairy grazed), real life irrigation (dairy grazed), and sheep grazing (no irrigation or fertiliser). This initial modelling demonstrated that carbon accumulation was maximised with about 1100mm of combined rainfall and irrigation.</p>