The shapefile provides counts and densities of livestock numbers within a hexagonal grid from data derived from the Agricultural Production Survey census final results for 2017.

I put the data into QGIS and symbolized based solely on the density of dairy cattle. The green to red color ramp goes from no dairy cattle to highest density of dairy cattle by 8 equal intervals.

We report on the use of land for primary production purposes, specifically agricultural land uses, such as beef and sheep farming and dairying, horticultural land uses, such as fruit and berry, and vegetable growing, and other land uses, such as forestry. We do this for the period 2002 to 2019.

Between 2002 and 2019:

The area of land used across New Zealand for:

• agriculture and horticulture decreased steadily with an overall decrease of 1.9 million hectares or 14 percent

• dairy farming increased 991,000 hectares (81 percent)

• sheep farming decreased 1.7 million hectares (29 percent) and beef farming decreased 1.3 million hectares (32 percent).

Boulton, A. C., Kells, N. J., Cogger, N., Johnson, C. B., O'Connor, C., Webster, J., Palmer, A., & Beausoleil, N. J. (2020). Risk factors for bobby calf mortality across the New Zealand dairy supply chain. Preventive veterinary medicine, 174, 104836. https://doi.org/10.1016/j.prevetmed.2019.104836

Surplus or unwanted dairy calves, referred to as bobby calves in New Zealand and Australia, are considered a by-product of the dairy industry. Bobby calves are defined as unweaned calves that are transported for slaughter at meat processing premises for human consumption or pet food, usually within the first week of life (Anonymous, 2015). In New Zealand, around 4 million dairy calves are born between July and September each year (Anonymous, 2017b). Approximately one quarter of these are kept as replacement dairy animals (Hickson et al., 2015), with the remainder sold as bobby calves or to be raised as beef cattle, or killed on farm (Wesselink, 1998; Stafford et al., 2001; Mellor, 2011). Thus, each year in New Zealand approximately 2.2 million bobby calves aged between four and approximately seven days are transported to slaughter.

8 things calves need in order to be fit for transport:

• Be at least four days old

• Be healthy, with no visible disease (e.g. scours), deformity, injury, blindness or disability

• Have bright eyes and upright ears

• Have the correct ear tag

• Be strong, able to rise from a lying position unassisted, move freely around the pen and bear weight on all four limbs

• Have firm hooves on which the soles show wear (indicating that they have been mobile)

• Have a dry and withered navel

• Have a full tummy – no antibiotic milk

The New Zealand Land Cover Database (LCDB) is a multi-temporal, thematic classification of New Zealand's land cover. It identifies 33 mainland land cover classes (35 classes once the offshore Chatham Islands are included). The classification was revised between versions 1, 2, and 3 but has been consistent thereafter, and always with backward compatibility maintained. Land cover features are described by a polygon boundary, a land cover code, and a land cover name at each nominal time step; summer 1996/97, summer 2001/02, summer 2008/09, summer 2012/13, and summer 2018/19. The data set is designed to complement in theme, scale and accuracy, New Zealand’s 1:50,000 topographic database https://www.linz.govt.nz/land/maps/topographic-maps/topo50-maps). LCDB is suitable for use in national and regional environment monitoring, forest and shrubland inventory, biodiversity assessment, trend analysis and infrastructure planning.

This indicator measures the numbers of farmed dairy cattle, beef cattle, deer, and sheep over time nationally, by region, and territorial authority, and approximates the density of these livestock across New Zealand.

Between 1990 and 2019:

• dairy cattle numbers increased by 82 percent nationally from 3.4 million to 6.3 million

• Canterbury dairy cattle increased tenfold (973 percent) from 113,000 to 1.2 million

• Southland dairy cattle increased sixteen-fold (1,584 percent) from 38,000 to 636,000

• beef cattle decreased by 15.3 percent nationally from 4.6 million to 3.9 million

• sheep decreased by 53.6 percent nationally from 57.9 million to 26.8 million.

Livestock farming is a widespread land use in New Zealand and a significant contributor to our economy. However, livestock adversely affects the environment, with the extent of impact dependent on the type, size, and animal density. Dairy cattle have a higher environmental impact than beef cattle, and both have a higher impact than sheep.

Livestock, particularly cattle, generate methane emissions, which contribute to climate change. Livestock can adversely affect indigenous biodiversity and soil health (for example, through erosion, habitat loss, compaction, and nutrient concentration).

Water quality can also be adversely affected, as nutrients, sediment, and bacteria from urine and faeces can leach or run off the land into rivers, lakes, and groundwaters. This can affect the health of aquatic ecosystems, as well as recreation and cultural values associated with rivers and lakes. The diminishment of water quality is of great concern to Māori and impacts mātauranga (knowledge systems), tikanga (cultural practice), whakapapa (geneology), and mahinga kai (traditional food resources) connected to water. Reduced and degraded habitats have a profound effect on Māori wellbeing and the reflection of identity in natural landscapes.

Understanding agricultural and horticultural land use can allow us to monitor changes in land use and activity in primary industries. Almost half of New Zealand’s total land area is used for agricultural and horticultural purposes. Each land use places various pressures on the land and on receiving environments such as waterways. These pressures can be both positive (for example, increased productivity) and negative (for example, impact on soil and water quality, biodiversity loss, and reduced functioning of ecosystems).

Māori agricultural and horticultural land use is expanding through the aggregation of smaller land parcels to form larger farms for primary production. To balance kaitiaki responsibilities, Māori are determined to link cultural values with commercial objectives to maintain and extend Māori community and environmental wellbeing.

Raster layer with 100m * 100m pixels, Each pixel represents the estimated nitrate-N leached in kg/ha/yr. This layer contains all nitrate leaching estimated from dairy cows.

Limitations to data analysis:

We only report on nitrate-nitrogen leaching from four types of livestock, not from fertiliser application, which was included previously. Fertiliser application is captured in Nitrogen and phosphorous in fertilisers. For this reason, and the difference in methods detailed above, values presented here are not directly comparable with previously reported values. Future research is needed to determine with greater confidence the overall magnitude of nitrate-nitrogen leaching.

The map should not be used to infer nitrate-nitrogen leaching rates for individual farms, as average farming practices were assumed and actual stock numbers per farm were not available. The spatial extent of nitrate-nitrogen leaching should be considered as an update from Environment Aotearoa 2015 and Our freshwater 2017, and should not be used for comparing time differences between information presented here and previous versions.

I clipped the TIF file down to a NZ admin boundary (downloaded from https://www.diva-gis.org/datadown), set all 0 values to transparent, and used a continuous color ramp to show low to high leaching values.

Nitrogen is an essential nutrient for plant growth. It occurs naturally, but in agricultural systems more nitrogen is commonly added to soils as fertiliser or as urine or dung from livestock. Not all the additional nitrogen can be used by plants and microorganisms, so some nitrate-nitrogen may leach (drain) from the soil. Livestock urine is the dominant source of nitrate-nitrogen leached from soil. Leached nitrate-nitrogen can enter groundwater and waterways, potentially causing ecological harm. The amount of nitrate-nitrogen leaching from the soil varies around the country as a result of different land uses, climates, and soils.

The total amount of nitrate-nitrogen leached from livestock increased from 189,000 tonnes nationwide in 1990 to 199,000 tonnes in 2017. The contributions of different regions and livestock types to national nitrate-nitrogen leaching have changed over this time.

• The amount of nitrate-nitrogen leached by dairy cattle was more than three times higher than beef cattle in 2017 (130,000 tonnes by dairy cattle in contrast to 37,000 tonnes by beef cattle).

• In 1990, nitrate-nitrogen leaching from sheep contributed 34% of national nitrate-nitrogen leaching, which decreased to 15% in 2017. In contrast, dairy cattle contributed 39% in 1990, which rose to 65% in 2017. The contribution of beef to national nitrate-nitrogen leaching has also decreased over this time period, from 26% in 1990 to 19% in 2017.

• Livestock nitrate-nitrogen leaching in Canterbury has increased 117% since 1990 (from 15,000 tonnes to 33,000 tonnes in 2017).

• 25% of all nitrate-nitrogen leached by livestock in New Zealand in 2017 was in Waikato (49,000 tonnes). Leaching in Waikato has increased 12% since 1990.

• In 2017, there were clusters of areas with higher leaching rates of nitrate-nitrogen per hectare in Waikato, Bay of Plenty, Taranaki, and Canterbury.

I recognize that code 41 Low Producing Grassland is also considered to be impacted by high agricultural grazing, but I interpret this to mean it is not currently used as grazing pastureland and is not relevant to the current topic.

Exotic sward grassland and indigenous short tussock grassland of poor pastoral quality reflecting lower soil fertility and extensive grazing management or non-agricultural use. Browntop, sweet vernal, danthonia, fescue and Yorkshire fog dominate, with indigenous short tussocks (hard tussock, blue tussock and silver tussock) common in the eastern South Island and locally elsewhere.

Land managed for the production of grapes, pip, citrus and stone fruit, nuts, olives, berries, kiwifruit, and other perennial crops. Cultivation for crop renewal is infrequent and irregular but is sometimes practiced for weed control.

Land regularly cultivated for the production of cereal, root, and seed crops, hops, vegetables, strawberries and field nurseries, often including intervening grassland, fallow land, and other covers not delineated separately.

Exotic sward grassland of good pastoral quality and vigour reflecting relatively high soil fertility and intensive grazing management. Clover species, ryegrass and cocksfoot dominate with lucerne and plantain locally important, but also including lower-producing grasses exhibiting vigour in areas of good soil moisture and fertility.

Factors associated with an increased risk of calf mortality included time in the farm of origin’s calving season, duration of travel from farm to the processor and processing slaughter schedule (same day or next day). Every additional week into the farm’s calving season increased the odds of mortality by a factor of 1.2 (95%CI 1.06, 1.35). Similarly, each additional hour of travel time increased the odds of mortality by a factor of 1.45 (95% CI 1.18, 1.76). Risk of mortality was significantly greater for calves processed at premises with a next day slaughter schedule than those processed at premises with a same day slaughter schedule (OR 3.82, 95% CI 1.51, 9.67). However, when the data set was limited to those cases that died or were condemned in the yards (i.e. excluding calves that were dead or condemned on arrival) the effect of same day slaughter was not significant. In order to reduce bobby calf mortality and morbidity, transport duration should be kept as short as possible and a same day slaughter schedule applied. While these factors can be regulated, New Zealand’s pastoral dairy system means that calves will inevitably be transported for slaughter across several months each spring. Although farm management factors did not apparently influence the risk of mortality in this study, the effect of time in farm’s calving season suggests there may be farm-management related factors that change over the season. This requires further investigation.