Fresh fruit from freshwater

This is the story of how growers use practices and tools on the ground, developed through research, to help achieve efficient use of freshwater for the good of the environment, their communities and their businesses.

Horticulture is New Zealand's third largest export earner in the food and fibre sector. According to the Ministry for Primary Industries,  73.5% of horticultural export value (excluding wine) came from kiwifruit, apples and pears in 2023 . Orcharding is a low-emissions industry, which makes it a key land use to help New Zealand achieve our climate mitigation goals while contributing to GDP and feeding the world.

Using the right amount of freshwater and the right nutrient inputs at the right times ensures fruit will grow to match consumer demand and sustain plant health year on year. This story shows how growers are working toward the most efficient possible use of these inputs for the good of their businesses and the environment.

The National Policy Statement for Freshwater Management 2020 (NPSFM) is driving freshwater planning across the country. The NPS directs councils to design objectives, policies, rules and limits in their regional plans to achieve long-term community aspirations for freshwater.

Part 9A of the Resource Management Amendment Act 2020 and the 2023 RMA (Freshwater Farm Plans) Regulations require horticultural operations with five or more hectares to have a certified freshwater farm plan. The plan needs to identify risks to freshwater in the context of the local catchment and manage those risks over time.

Water is one of the key ingredients needed for plants to grow. Trees and vines need enough soil moisture to ensure balanced growth and fruit quality. Too much water can have a negative impact on fruit quality and size, increase the risk of root rot or plant death, or cause nutrient leaching into the environment. Too little water inflicts stress on the plant, or even death. For all of these reasons, growers seek to use just the right amount of water to a high degree of precision.

There are varying methods of calculating irrigation requirements. Industry recommends using "trigger point irrigation" to find the irrigation target zone between soil that is too dry, when plants begin to wilt, and fully saturated, when waterlogging begins.

A target point is the ideal soil moisture content achieved with irrigation.

A trigger point is the status when any less moisture in the soil would cause damage to fruit growth or quality from water stress.

The irrigation target zone, which sits in between, is illustrated in the diagram below.

Growers use good and best management practice to ensure they are meeting industry standards. On-orchard observation is the first step to track plant health, soil profile and soil moisture. This observation can be supported by properly installed and interpreted technology. Making accurate measurements and records of soil water status, applied irrigation and rainfall helps keep the soil moisture level between the target and trigger points. Good management for irrigation means that irrigation systems are efficient and scheduled with trained operators and auditable records.

Read more:  New Zealand Apples & Pears Integrated Fruit Production manual 

Read more:  Good Management Practice  from IrrigationNZ

There is  uncertainty about changes to rainfall, drought and frost  in fruit-growing regions under climate change projections, but the sector is preparing to adapt to potential physical and social climate risks. For example, growers are adjusting to the physical risk of severe wind events by maintaining shelterbelts (tall borders of trees) and artificial crop protection structures (e.g. overhead or vertical cloth canopies) to protect their orchards.

As the ways that communities manage water allocation evolves in a changing regulatory environment, the horticultural industry is focusing on sustainable management of water resources. Dry periods combined with increased demand for freshwater from other land uses will make accessing water for irrigation more challenging over time.

For example, Zespri is investing in research to develop climate-resilient kiwifruit cultivars, including those with increased water efficiency, drought tolerance, ability to withstand waterlogging.

Read more:  Zespri Climate Adaptation Plan 

 Research by Plant and Food Research  under the Sustainable Land Management and Climate Change research programme has also looked into where perennial (orchard and berry) crops will be best suited under different climate scenarios. Similar work for other crops is now compiled under Our Land and Water's  Data Supermarket  tool. The tables below show examples of climate change impacts and adaptation strategies for selected orcharding crops, adapted from  work by Plant and Food Research .

New irrigation schemes, including water storage, are part of the industry's climate adaptation strategy. Storage allows users to capture water when there is more than enough to use when water is scarce. It gives water uses security of supply and ensures reliable water access. The next section showcases different types of water storage used by growers.

Growers manage the amount of water they use, but they also manage their impacts on water quality. The next section considers nutrient management, and how risks to freshwater are reduced on-orchard.

All nutrients in an orchard system need to be balanced and supplied at optimal levels at the right time to support production goals. Nitrogen (N) and phosphorus (P) in particular are essential nutrients for plant growth, but plants require  17 essential nutrients  to complete their life cycle.

Nitrogen is a natural part of plant growth and naturally present in soil when it is "fixed" by legumes like clover and then converted to a form that plants can use. Growers add fertiliser to get the right amount of growth at the right time, while doing their best to avoid nitrogen loss to the environment, also known as leaching.

Growers add nitrogen to their trees and vines with fertiliser and compost. Nitrogen is only one of the essential elements for plant growth, and some nitrogen inputs eventually leave the system in harvested fruit.

In horticulture, it makes good business sense to use just the right amount of water and nutrients to achieve maximum productivity and fruit quality. Too many nutrients can cause overgrowth ("vigour"), waste or loss from the orchard system.

To understand the efficiency of an orchard's nitrogen-use, industry encourages growers to calculate their nitrogen balance by subtracting their outputs from their inputs.

A perfectly efficient system would have a nitrogen balance of zero, but there is some uncertainty about the rate of mineralisation and plant nutrient uptake. This means that it's not possible to match inputs exactly. Growers also need some buffer room to make sure that if a weather event washes out fertiliser, there are still enough nutrients in the soil for fruit to reach the size required to sell, to maintain plant health and to produce enough wood for next season's fruit to grow.

Type, timing, rate and method of each nitrogen application are all important considerations for maximising vine uptake and avoiding nitrogen losses to the environment. Other factors like soil chemistry, plant health, and temperature can all affect the quantity of nutrients available to the plant and how much the plant absorbs.

Growers have site-specific knowledge that makes them the best-informed person to consider climate, soil type, root extent and similar factors. Fertiliser advisors are brought in as experts on other factors like soil chemistry and potential nutrient interactions. Making adjustments to one nutrient may require rebalancing of other nutrients too, which is one area where a professional advisor comes in handy.

The most efficient and effective nutrient management plans come from growers and their advisors working closely together and pooling their knowledge.

Industry assurance programmes require comprehensive data and record-keeping to help growers meet market and regulatory standards. Before buying their product, domestic and export markets require orchardists to use  Global G.A.P.  or  NZGAP  standards, which are benchmarked to ensure good agricultural practice for food safety, social practice and environmental rules. The horticultural sector is working to ensure that industry assurance programmes, such as the NZGAP Environmental Management System (EMS) add-on, are recognised as equivalent to regulatory Freshwater Farm Plans.

Industry product groups advise growers to keep a nutrient management plan. Industry assurance schemes can facilitate this, so long as growers keep a nutrient budget for each crop and fertiliser and compost application records. The examples below show how growers in the pipfruit and kiwifruit industries develop these plans.

Nitrogen is not the only contaminant of concern for orcharding. Sediment and phosphorus (P) also have the potential to runoff into waterways from orchards. Most P is lost in fine sediment particles, so managing sediment will manage loss of P as well.

Sediment loss is detrimental to orchards, as well as the environment, because it indicates that valuable topsoil is being lost. That is the section of the soil with the most nutrients where most helpful biological activity takes place. Sediment can worsen water quality for irrigation and clog irrigation equipment. Infilling - when sediment clogs waterways - also increases flooding risk. These factors are additional motivation for growers to care for the environment through preventing runoff.

Industry groups advise growers not to apply phosphorus during high rain periods, especially on sloping sites, to avoid runoff.

Growers are also advised to complete orchard assessments during or after heavy rainfall to check where water is leaving the orchard and whether it's taking sediment along with it. Mapping the orchard allows growers to evaluate risk factors like slope. Once the risks are known, it is more straightforward to determine which mitigation actions are needed to reduce the amount of future runoff.

Example mitigations include maintaining a dense groundcover of vegetation that keeps soil on the ground and slows surface water as it moves through the orchard. Mulch can serve the same purpose. Growers also increase organic matter in the soil to improve its water holding capacity and aerate their soil to improve its absorption. Growers can use level spreaders on steep orchards to smooth out the rivets where small water channels form when it rains. This disperses fast, concentrated flows, which allows the water to be better absorbed.

These types of mitigations are communicated to growers through Codes of Practice, which are practical on-farm guidelines written based on collaborative research between industry and the science sector. For example, the section below describes research to improve understanding and management of runoff funded by industry.

Some growers are taking on the mantle themselves to be role models for best environmental practice. The case studies below showcase how real growers are making their irrigation and nutrient management systems more efficient.

Growers can't be expected to do it all on their own, so the horticulture industry, with the help of central government funding, is facilitating adoption of freshwater farm plans.

The Growing Change project is supporting growers to develop GAP freshwater farm plans through advisor support, technical workshops, peer-to-peer learning, and a formal training program on managing freshwater risks from horticulture. The project is a partnership between HortNZ and the Ministry for the Environment, funded through the Essential Freshwater Fund.

To learn more about this project visit:   Growing Change | Horticulture New Zealand — Ahumāra Kai Aotearoa (hortnz.co.nz).  

The dashboard below shows data about the priority catchments where Growing Change is helping growers. It shows the number of growers already registered for the EMS versus the total HortNZ-registered growers and how much growing land is covered in each catchment.

Select a catchment from the drop-down list in the top right to see relevant statistics about the area.

 Click here to open the summary viewer in a new tab .

Note: LCDB growing area refers to the Land Cover Data Base. This includes short-rotation cropland (vegetable and arable crops) and perennial cropland (orchards, vineyards and other perennial crops). Since the EMS add-on is not applicable to arable crops or vineyards, EMS-registered growing area may not expect to reach 100% in some catchments.

Growers are already thinking carefully about how to manage their impacts on freshwater. Taking care of the environment is key to the long-term sustainability of their businesses, as they draw on the soil and water resources to grow the healthy kai we all eat. The environment's success is their success; they just ask for the government to trust in the good work they're already doing to continually improve.

You can learn more about the topics discussed in this StoryMap at the sources below.

•  HortNZ website 
•  Fruit product group websites 
•  Zespri website 
•  New Zealand Kiwifruit Journal  (Kiwifruit Journal articles are available to subscribers via  Canopy .)
•  IrrigationNZ 

Contact info@hortnz.co.nz for specific questions.

You can also learn about how vegetable growers manage their freshwater risk at the link below.