28 April 2022
Dr Terrence Loomis
[FYI request #18989 email]
Tēnā koe Dr Loomis
Official Information Act (OIA) request: Clarification of synthetic fertiliser (nitrogen)
use in New Zealand
Thank you for your email dated 28 March 2022 requesting under the Official Information Act
1982 (the Act) clarification on Stats NZ’s Indicator for Fertilisers – nitrogen and phosphorus.
Before addressing your questions, I would like to provide some explanation of the data:
Graph 1 (Nitrogen in fertiliser sold in New Zealand, 1991-2019) and Graph 2 (Urea
fertiliser applied by dominant farm type, 2002-2019) are derived from separate data,
each with their own strengths and limitations, that do not ful y reconcile.
Data in Graph 1 is from the Fertiliser Association of New Zealand and is derived from
sales records. It is likely to capture additional fertiliser use not shown in Graph 2, and
also provides a close estimate of the nitrogen and phosphorous content in fertilisers
sold (not provided in Graph 2). But as we cannot be certain that al fertiliser sold in a
given year is used in that year (or at al ), the figures provided in Graph 1 could lead to
yearly totals of fertiliser use on land being overestimated.
Data in Graph 2 is sourced from the Agricultural Production Survey and provides
information about fertiliser actual y applied to the land. The limitation with this data is
that it does not include al agricultural land, because only farms that are GST
registered and earn more than $60,000 were included in the survey (and not al farms
wil complete the survey). This means that while Graph 2 may provide a more
accurate annual figure for total fertiliser applied to the land than Graph 1, it wil
undercount the true New Zealand total.
In addition, the data in Graph 2 does not al ow us to calculate al nitrogen and
phosphorus levels (as these are not captured separately in the survey).
Question 1: How much fertiliser of all types was applied to agricultural land in 2019?
Adding together al four fertilisers applied to agricultural land (urea, diammonium phosphate,
ammonium sulphate and superphosphate) gives a total of 1,699,040 tonnes.
Looking at Graph 2 (Urea fertiliser applied by farm type, 2002-2019) you can view this figure
by selecting compare ‘over time’ and then selecting ‘al farm types’ (under ‘dominant farm
type’).
You can then switch between the different fertilisers (in the drop-down list under ‘Fertiliser
name’) and hover over the 2019 data point. Adding the results together gives you the overal
total.
Question 2: How much nitrogen (urea) fertiliser was applied to all agricultural land in
2019?
Graph 2 shows (under the view compare ‘over time’ and ‘for al farm types’) that 606,951
tonnes of urea fertiliser, and 279,197.5 tonnes of nitrogen from urea fertiliser, were applied
to al agricultural land in 2019.
The total amount of nitrogen across al fertiliser types, applied to al agricultural land adds up
to 334,992 tonnes. This figure can be reached by adding up the nitrogen totals for each
fertiliser (urea, diammonium phosphate, ammonium sulphate) under Graph 2, using the
drop-down list under ‘Fertiliser name’.
Question 3: How much nitrogen (urea) fertiliser was applied to predominantly dairy
land in 2019?
For context, the statistics in Graph 2 use an economic measure of farm type – farms that are
“dominantly dairy” as shown in Graph 2 make their income predominantly from dairying, but
this won't necessarily mean they are “predominantly dairy land”.
Graph 2 shows that 427,325 tonnes of urea fertiliser, and 196,569 tonnes of nitrogen from
urea fertiliser, were applied to dominantly dairy farms in 2019.
The total amount of nitrogen across al fertiliser types applied to dominantly dairy farms (from
urea, diammonium phosphate, ammonium sulphate) was 223,000 tonnes. (Note that adding
up totals from individual farm types gives a slightly different total of 225, 591 tonnes – this is
due to techniques used to maintain confidentiality).
If you are not satisfied with this response, you have the right to seek an investigation and
review by the Ombudsman. Information about how to make a complaint is available at
www.ombudsman.parliament.nz or 0800 802 602.
It is our policy to proactively release our responses to official information requests where
possible. This letter, with your personal details removed, wil be published on the Stats NZ
website. Publishing responses creates greater openness and transparency of government
decision-making, and helps better inform public understanding of the reasons for decisions.
Ngā mihi nui
Kate Satterthwaite
Senior Manager, Executive and Government Relations
Office of the Chief Executive
Stats NZ
