Area of barley harvested in 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.

Bull: An entire (ie not castrated) male cattle.
Calf: A young cattle of either sex between birth and weaning, with eight temporary teeth. Also sometimes refers to animals up to one year old.
Cow: A mature female cattle beast of any age, but usually over 30 months.
Dry cow/ewe: A female animal not carrying offspring.
Ewe: A female sheep.
Exotic timber: Timber harvested from trees which are not native to New Zealand.
Heifer: A female cattle having no more than six permanent incisors.
Hogget: A young male or female sheep having no more than two permanent incisors in wear.
Lamb: A sheep under 12 months of age, or without any permanent teeth in wear.
Ram: An adult uncastrated male sheep having more than two permanent incisors in wear.
Steer: A male cattle castrated when young. Does not develop secondary sexual characteristics (eg large shoulders) or masculine temperament.
Two-tooth: A sheep with two teeth (a one-year-old).
Wether: A castrated male sheep.
Mated gilt: A gilt pig is a female under the age of 1 year. Generally, the term refers to a pig who has not farrowed, or given birth to a litter. Once a pig has had a litter and is past her first year, she is called a sow.

Figures may not add to the totals due to rounding.
Please note that forestry data refers to the year ended 31 March 2017. The rest of the data refers to the year ended 30 June 2017.

http://datainfoplus.stats.govt.nz/Item/nz.govt.stats/6362a469-f374-412e-ac25-d76fd0962003?_ga=2.219295770.229510065.1537262179-321851374.1528776322#/nz.govt.stats/0da803f1-7e28-448d-8360-28c03a92a9a1/#

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 'Agricultural production statistics: June 2017 (final) – additional tables'.