In 2018, The Agribusiness Group was approached by Environment Canterbury to assist in the Omnibus for future plan changes within the Land and Water Regional Plan (LWRP), focusing on the environmental impact of commercial vegetable growing. In particular, there was a requirement to determine the nitrogen losses from horticulture properties on a per Nutrient Allocation Zone basis, giving an understanding of commercial vegetable growers environmental impact over the whole Canterbury catchment.
Working alongside a number of commercial vegetable growers and HortNZ, The Agribusiness Group’s Stuart Ford and Amelia Wood, collected a number of Overseer nutrient budget’s and crop information (including yields, fertiliser and irrigation inputs). Maps determined the scale and concentration of commercial vegetable growers in the various LWRP nutrient allocation zones.
Using this information four crop rotations were created to represent green vegetables, root vegetables, intensive market gardening and market gardening with increased fallow periods. Each crop rotation was modelled over three climate zones and three soil types. The losses from these models were calculated over the number of commercial vegetable growers, their primary crops and locations, to estimate the total nitrogen loading within nutrient allocation zones from commercial growers.
The Agribusiness Group’s knowledge and experience in Overseer modelling, farm systems and policies led to increased confidence in the way the nutrient budgets were modelled, the farms they represented and the advice and thoughts given in the various meetings held for the Omnibus. Being part of the policy creation and the implementation means that we can give better informed advice to either those creating the policies and those who are implementing them i.e. farmers.