Agricultural activity

This section provides information about agricultural activity and its relationship to recreational water quality in Aotearoa New Zealand. 

The agricultural sector plays an important role in New Zealand’s economy. However, poorly managed livestock and agricultural production can have a major impact on the environment. 

Recreational water bodies can be contaminated with effluent from farm animals or chemical runoff of fertiliser product. Faecal bacteria from this waste can cause gastrointestinal or respiratory diseases, while chemicals such as nitrogen and phosphorus commonly used in fertilisers can contribute to the growth of toxic algae.

Overall, livestock numbers are in decline

In 2020, there were 36.9 million livestock in New Zealand, including sheep, dairy cattle, beef cattle and deer. Compared to 2019, the total number of livestock has fallen by 2.2%, equivalent to 838,000 animals.

From 2002 to 2020, the total number of livestock decreased by 27.4 percent, from 50.9 million to 36.9 million. Most of the decline is due to a drop in sheep numbers, which decreased from 39.6 million in 2002 to 26.0 million in 2020, a difference of just over one third. In contrast, the number of dairy cattle increased by 20.1%, from 5.2 million in 2002 to 6.2 million in 2020 (Figure 1).

Figure 1: Number of livestock, by type, 2002-2020

The Manawatū-Whanganui region had the greatest density of livestock in 2020

In 2020, the Manawatū-Whanganui region had the greatest livestock density (403.2 animals per km² of farmland) nationwide. The region also possessed the greatest density of sheep (328.8 animals per km²).

As for other types of livestock;

• The Taranaki region had the highest density of dairy cattle (122.8 per km²)
• The Hawke’s Bay region had the highest density of beef cattle (52.2 per km²)
• The Canterbury region had the greatest density of deer (13.1 per km²)

Figure 2: Density of livestock by region (animals per km²)

Livestock density by territorial authority

Livestock density gives an indication of the number of livestock per total land area. The measure does not account for the amount of agricultural land, so should be interpreted with caution. 

In 2017, New Zealand had an average livestock density of 144.4 animals per km² (Figure 3). Sheep were the predominant livestock type - with an average density of 103.0 animals per km². In that year, Gore District had the highest density of livestock (684.5 animals per km²), followed by Central Hawke's Bay District (391.3 animals per km²) and Masterton District (390.6 animals per km²).

Figure 3: Number of livestock per square kilometre (total land area), by type, 2017

The area of agricultural land is decreasing

Between 2007–2017, the area of land in New Zealand used for agricultural purposes decreased by 5.4%, an area equivalent to 800,490 hectares. The bulk of the decline was in the Canterbury and Otago regions, which account for 70.6% of the decline between them (with a reduction of 339,925 and 255,237 hectares respectively).

Agricultural land makes up at least 50% of the area of almost all regions (Figure 4). Consequently, New Zealand uses a little over half of its entire land area for agricultural purposes. Though most regions experienced a reduction in agricultural land between 2007–2017, farmland expanded in a few regions. Notable expansions occurred in Auckland and Bay of Plenty, where an additional 8.6% and 6.5% (respectively) of the region’s land area was converted to farmland. The largest decline was in the Otago region, where 8.2% of the region’s land was converted from farmland to other uses.

Figure 4: Agricultural land as a percentage of regional area, 2007 & 2017

Between 2007 and 2017, the area of farmland used exclusively for sheep farming decreased by an area equivalent to 29% of all farmland (Figure 5). The number of sheep farmed in New Zealand also declined by around a third during that period, suggesting sheep are not being farmed more intensely given the smaller area.  The agricultural sector’s diversification away from specialised sheep farming is indicated by the area of mixed sheep & beef farming quadrupling between 2007 and 2017.

From an environmental perspective, a given number of cattle tends to have a greater impact on their environment than an equivalent number of sheep owing to their greater mass, higher feed requirements and increased output of waste in the form of faecal matter and methane emissions.

Figure 5: Allocation of farmed area, by farm type, 2007–2017 (percentage of total farmed area)

Irrigation is increasing, but almost exclusive to the South Island

Irrigating agricultural land can place pressure on recreational water bodies by increasing the runoff of agricultural chemicals or faecal pollutants from the land into the water. Between 2002 & 2017, the area of irrigated agricultural land almost doubled from 384,152 to 746,739 hectares, an increase of 94%. Around 84% of all irrigated land is in the South Island, primarily in the Canterbury and Otago regions (Figure 7), accounting for 64% and 13% of the total area respectively.

Figure 7: Area of irrigated land, 2002 & 2017

Measured by volume, surface water (i.e. water from rivers & lakes) provides 73% of all consented freshwater takes for agricultural use (Table 1), most of which is used for irrigation. Surface water takes can affect the speed and volume of water flow in rivers from which water is taken, which in turn can affect the water quality within these waterways. River flow helps to disperse pollutants such as toxic algae and bacteria, so reduced flow can lead to build-ups of these contaminants.

Table 1: Consented annual freshwater takes for agricultural purposes, by region, 2017/18 (shown in billions of litres)

Information about the data

Livestock numbers

Source: Statistics New Zealand - New Zealand Annual Agricultural Production Surveys, and five-yearly Agricultural Production Censuses. For more information, visit the Statistics New Zealand Agricultural Production Statistics webpage. 

Agricultural land use

Source: Statistics New Zealand (2002, 2007, 2012 & 2017). Agricultural Production Census. Retrieved from https://www.stats.govt.nz/information-releases/ and http://archive.stats.govt.nz/

Irrigation

Source: Statistics New Zealand (2020). Consented freshwater takes. Retrieved from https://www.stats.govt.nz/indicators/consented-freshwater-takes