Grain and seed crops harvested in the Selwyn District, New Zealand

Farm: For the purposes of this census a farm is one or more blocks of land, managed as a single operation, that is engaged in agricultural activity. This includes farming of livestock, horticulture, viticulture, nurseries, forestry, growing grain and seed crops, and land that could be used for these purposes.

Grain and seed crops: Arable crops grown including for example, wheat grain, barley grain, oat grain, maize grain, other cereal grain, seed or field peas, other pulses, herbage and vegetable seeds.

Figures may not add to the totals due to rounding.
Area outside territorial authority is included in the North Island total.

http://www.stats.govt.nz/browse_for_stats/industry_sectors/agriculture-horticulture-forestry/AgriculturalProduction_final_HOTPJun12final/Data%20Quality.aspx

The compulsory registration level for GST is $60,000 so there is a partial and unquantifiable coverage of units below this level.

The Agricultural Production Surveys and Census include all units identified on Statistics New Zealand's Business Frame as having agricultural activity. The Business Frame is a list of businesses in New Zealand, based on their registration for goods and services tax (GST) with Inland Revenue. In the case of agriculture the Business Frame includes the following units: - those units registered for GST (and filing a non-zero GST return) that have indicated involvement in agricultural activity (as defined above) - those businesses with more than $200,000 of GST sales or purchases, or that are an employer, whose main activity is not agriculture but have indicated some secondary agricultural activity.

At URL provided, select 'Grain and seed crops by territorial authority, during the year ended 30 June 2012'.