Phasing out synthetic nitrogen fertiliser deserves careful scrutiny

At a time when food security is a growing challenge in New Zealand, and too many people are not eating enough fruit and vegetables, the Green Party’s proposal to phase out synthetic nitrogen fertiliser deserves careful scrutiny.

A blanket restriction would inevitably constrain vegetable supply, increase prices for New Zealanders, and have direct consequences for health outcomes.

More than 80 percent of vegetables produced in this country are grown for the domestic market. New Zealand growers produce around 90 per cent of all fresh vegetables consumed here, making a productive vegetable sector fundamental to feeding the nation.

Nitrogen is an essential plant nutrient, and fertiliser is critical to delivering the quantity, reliability, and timing required to grow horticultural crops, particularly vegetables, at the scale New Zealanders need.

It is not a “nice to have” or an “easy option” for growers. There is currently no practical alternative that can produce sufficient volumes at scale. To meet New Zealand’s food security needs, we need a rigorous but pragmatic approach to synthetic nitrogen use.

The focus should be on responsible nutrient management, backed by robust industry assurance programmes and continuous improvement, not on removing one of the fundamental tools required to grow healthy food.

There is a significant body of research highlighting the importance of keeping vegetables affordable and accessible for New Zealanders, as well as the potential consequences when costs rise.

A 2020 University of Otago study, The health and health system cost impacts of increasing vegetable prices over time, estimated that increases in vegetable prices could impose health system costs of between $490 million and $610 million through reduced vegetable consumption.

In 2024, NZIER research, Making the economic case for vegetable production in New Zealand, warned that constraints on commercial vegetable production could severely affect supply.

The research indicated that a 20 per cent reduction in production could increase vegetable prices by at least 20 per cent, and potentially by more than 100 per cent. One example cited was broccoli reaching $27 per kilogram, or about $9 a head.

Vegetables that New Zealanders have long regarded as dietary staples should not become luxury items. Robust measures are already in place to manage fertiliser use.

Modern horticultural production relies on precision nutrient management. Practices such as soil testing, nitrogen budgeting, split applications, crop-specific nutrient recommendations, and decision-support tools help growers closely match nitrogen use to crop demand.

Growers are committed to managing risks to freshwater, including the risk of nitrogen loss. Audited and certified Good Agricultural Practice (GAP) systems are in place, and approximately Around 75 per cent of vegetable growing land is covered by the NZGAP Environment Management System (EMS) module for farm environment plans.

The sector is focused on continuous improvement. HortNZ has updated a suite of environmental codes of practice, and NZGAP is refreshing the EMS module to meet freshwater farm plan requirements.

New Zealand’s growers help put food on the plates of every New Zealander. They do this while managing significant risks, including droughts, floods, and soaring costs. It is getting harder for them to keep doing this essential work, especially where the returns for doing so are diminishing.

Every political party and relevant agency should look at the horticulture sector as a whole and genuinely understand how its many interconnected parts work together.

It is time to recognise that freshwater and climate planning must treat food production as a national priority, not an afterthought. New Zealand needs a National Direction for Commercial Vegetable Production.

I do not believe those proposing a blanket restriction on essential fertilisers want to place further heavy burdens on an already stretched grower community.

I do not believe they want to hobble vegetable production or push healthy produce out of reach for many shoppers.

However, that would very likely be the consequence of what they are calling for.

At HortNZ, our door is always open to discuss the realities of growing fruit and vegetables in New Zealand and the work being done to protect the land, protect waterways, and protect Kiwis’ access to affordable, healthy produce.

Greater knowledge and understanding of fruit and vegetable growing would help ensure this critically important sector remains resilient, productive, and sustainable into the future, for the benefit and wellbeing of all New Zealanders.