Lessons for the management of highly productive land

Two years after Cyclone Gabrielle devastated the Hawke’s Bay and Tairawhiti regions, what have we learned about recovery?

Cyclone Gabrielle struck New Zealand in February 2023, causing widespread flooding that affected Hawke’s Bay, Gisborne/Tairawhiti, and Northland. In Hawke’s Bay and Tairawhiti, Cyclone Gabrielle was characterised by the enormous amount of sediment that was deposited on some of the county’s most highly productive land.

It was an extraordinarily difficult year characterised not by a single catastrophic event but by cumulative impacts from severe storms and several additional weather events including Cyclone Hale in January, Cyclone Gabrielle and Son of Gabrielle in February, and others that followed particularly in the Wairoa and Tairawhiti areas.

In November 2025, we co-hosted with FAR and Vegetable Research and Innovation, a symposium for researchers to share and compare findings from studies of Cyclone Gabrielle and recovery. Around 60 people gathered in Havelock North for two days. Thank you to all the organisations that sponsored the symposium, allowing it to be run with no fees for the participants.

A great deal of semi-coordinated activity followed in the wake of Cyclone Gabrielle. However, there was much incomplete work that would add value by helping enrich our understanding of the longer-term effects of different management responses in different scenarios. The symposium brought together those who investigated Cyclone Gabrielle’s impacts on highly productive land. They presented and discussed findings and observations to draw out lessons to aid land managers and policy makers in future events.

Among the questions were:

1. What are the lessons to pass on to those impacted by future events?
2. What are the lessons for policy makers?
3. What are the economic outcomes from different approaches?
4. How have sites responded to different management of cropping soils, given different sediment types and depths?
5. How have sites responded to the removal of sediment and any subsequent soil amelioration efforts?
6. Have permanent crops responded differently to different approaches applied in similar scenarios?
7. Are all soils recovering quickly? Will they return to previous productivity levels?

Twenty presentations covered historic storm events of note, the weather conditions before and during the cyclone, geological influences, immediate responses, food safety, and longer-term trials seeking to understand how best to return high value land to best production. We thank all the presenters for telling their stories, and all delegates for their contributions to the discussion.

At the end of the symposium, Dirk Wallace led a feedback session in which all delegates responded to a set of questions:

1. What elements aided recovery and what lessons can inform policy and sector planning?
2. What surprises and challenges emerged during recovery?
3. What key takeaways should guide future preparedness?
4. What information is still missing?

Across questions, several themes consistently emerged.

• Communication and collaboration were identified as critically important.
• Data and research surfaced as both a strength and a challenge.
• Infrastructure and preparedness were recurring concerns.
• On the technical front, soil and crop recovery exceeded expectations, with yields rebounding faster than anticipated.
• Finally, human and social dimensions were central to recovery success. Mental health support, patience, and direct communication with experienced peers were repeatedly stressed.

Participants agreed on several priority actions:

1. Establish a central information hub with regional portals to provide consistent, accessible guidance and data.
2. Commission targeted research on rainfall patterns, soil microbiology, contamination risks, and crop-specific recovery timelines, delivered in decision-ready formats.
3. Strengthen pre-event coordination through drills, contact lists, and local decision-making authority, alongside investment in backup infrastructure.
4. Embed human-first supports, including mental health services, peer advisory panels, and tailored financial relief for vulnerable growers.
5. Integrate disaster risk reduction and nature-based solutions (e.g., wetlands, “room for rivers”) into long-term land-use planning.

The symposium captured invaluable knowledge that will help communities and policymakers prepare for and respond to future events. Visit the Cyclone Gabrielle Research Symposium page to access all presentations, with videos coming soon.

Thanks everyone! Sally Anderson, Dirk Wallace and Dan Bloomer – Symposium Convenors

One of the new strips, which is located under the irrigator wire, includes alyssum, calendula, and native ground covers. The other strip which is along a fenceline has the A Lighter Touch annual flower strip mix, which includes alyssum, buckwheat, calendula, cornflower, and marigolds. We also added in a few sunflowers.

The first half of the strip under the irrigator wire has established really well, and both the alyssum and calendula are starting to flower. At the other end of the strip, it is a bit patchy and doesn’t have the same ground cover. Some of the native ground covers amongst the strip have dried out or have been eaten by rabbits, while others are thriving.

The strip along the fenceline consists mainly of buckwheat and sunflowers at the moment, as they were the first to germinate. However, there are patches where alyssum, marigolds, cornflower, and calendulas have also started to establish.

The two biostrips planted in 2024 were made up of 9 different flower mixes, first planted in spring and the second in the summer.

The spring 2024 sowings flowered in the summer but were taken over by grass and clover in the winter. We have mown the strip a couple of times to manage the grass and give the flowers a chance to grow. The alyssum, poppies, borage, and phacelia seemed to do the best in spring 2025 after being mown. Now the strip is mainly grass, clover and alyssum. We have mown it back down again and will track what happens.

The strip planted in summer 2024 and has continued to flower since it was established. Alyssum is the main flower species that has taken over and provided ground cover, but there are areas where there are still cornflowers and calendulas flowering.

There are plenty of insects in the strips and within our butternut crop, but we wanted to understand what insects are actually there and how far they are moving into the crop. To do this, we have set up sticky traps within the biostrips and at various distances into the crop. We will continue to monitor the sticky traps and will try to identify what insects are on them.

We will be holding a grower biodiversity event at the MicroFarm on March 19th. If you are interested in attending, please register here: https://a-lighter-touch.co.nz/biodiversity-grower-group-field-walks/

The Operation Advisory Group has met weekly to observe how the butternuts are growing and to make management decisions for the upcoming week. The main decisions have been about what fungicides to spray, if the Regenerative treatment needs a foliar application, and if a bactericide needs to be applied. Rob Nichol from Horticentre has played a key role in the decision making prosess, helping us identify angular leaf spot in the paddock and providing us with product recommendations.

The first fungicide application went on about a month after planting. Since then, all treatments have had a fungicide and bactericide sprayed each fortnight. With the varying temperatures and rain we have had, it has created the perfect conditions for angular leaf spot, and we have started seeing patches of it within the butternuts.

Table: Fungicide and Bactericide applications to all three treatments in the Carbon Positive Trial.

The Regenerative treatment also had an application of Bio Marinus during the first fungicide application, and a Megafol application the day before the third fungicide.

EIQ is a tool available online through Cornell University, which can be used to determine the environmental impact of specific agrichemicals. The Field Use EIQ is a score based on how toxic the product’s active ingredients are and how much has been used per hectare. The Field Use EIQ Score for each product has been low (around 10). This is why all three treatments have received the same spray applications. For comparison, when the paddocks were broadcast-sprayed with Glyphosate at the beginning of the season, the Field Use EIQ Score was 60.

We will continue to monitor disease pressure and will determine if we can use an alternative product in the Regenerative and Hybrid treatments later in the season.

Throughout the rest of the season, the Operations Advisory Group will continue to meet weekly to make management decisions.

A big thank you to all the Operation Advisory Group members who have attended our weekly field walks.

Carbon Positive is a partnership between LandWISE, the HB Future Farming Trust, McCain Foods, Heinz-Wattie’s and Process Vegetables NZ.

The butternuts in the Carbon Positive trial were planted on the 15th of November. Before the butternuts emerged, there was a high weed pressure in the conventional treatment. Therefore, it was sprayed with Buster, while the other two treatments were not.

Emergence

When the butternuts started to emerge, we noticed there was cutworm damage and found cutworms. Cutworms are one of the main insect pests in butternut crops. They chew through the butternut’s stem at ground level, killing the plant. Once we identified the problem, we sprayed Bestseller before the cutworms did too much damage.

Side Dressing

Before sidedressing, our fortnightly soil nitrate testing showed there was 80 kg N/ha in the Conventional treatment, 71 kg N/ha in the Hybrid, and 62 kg N/ha in the Regenerative treatment.

At sidedressing, the Conventional treatment received the ‘standard’ rate of YaraBela CAN (150 kg/ha). For the Hybrid treatment, the goal was to apply a half rate of YaraBela CAN (75 kg/ha), but the lowest the side dressing machine could be calibrated to was 113 kg/ha, so that is the rate we used. The Hybrid treatment also received a foliar application of seaweed. The Regenerative treatment only received a foliar application of seaweed, Megafol, and fulvic acid, as the soil nitrate results showed there was a sufficient level of Nitrate-N in the soil.

Weed Management

Standard weed management would use an inter-row cultivator before the butternuts start running. We felt there wasn’t a high enough weed pressure to do this, and that it could cause a weed strike if we disturb the uncultivated areas in the Hybrid and Regenerative treatments. All treatments were hand-weeded with a push hoe to remove any weeds before the butternuts started to run.

Operation Advisory Group

The Operation Avisory Group has met weekly, and they are happy with how the butternuts are growing, the low weed pressure and the disease pressure.

A big thank you to Andy for taking the time to side-dress our butternuts.

Carbon Positive is a partnership between LandWISE, the HB Future Farming Trust, McCain Foods, Heinz-Wattie’s and Process Vegetables NZ.

During the tomato crop (26/10/2023 – 6/3/2024), the Regenerative treatment had significantly lower nitrate levels than the Conventional and Hybrid treatments, despite all three receiving similar amounts of nitrogen. This lower nitrate level was likely due to the breakdown of the cover crop. Approximately 12 t/ha of cover crop, mainly oats, was incorporated into the soil two days before planting, which would have tied up nitrogen.

Since then, different amounts of nitrogen have been applied across treatments, and there has been no significant difference in soil nitrate levels, except during the period when the Conventional and Hybrid treatments were in peas, while the Regenerative treatment remained in cover crop.

Amount of Nitrogen applied during each crop, by treatment.

Butternuts

Our pre-season soil tests showed that there was 110 kg of potentially available nitrogen in the Conventional, 93. 3 in the Hybrid and 97.3 in the Regenerative treatment.

Two days before the butternuts were planted, there were 32 kg Nitrate-N/ha in the Conventional, 39 in the Hybrid, and 46 in the Regenerative treatment.

At planting, the Conventional and Hybrid treatments received 300 kg of Complex, whereas the Regenerative treatment received 150 kg of Complex. This increased the kg of Nitrate-N in the Conventional to 80, the Hybrid to 71, and the Regenerative to 63.

At side dressing, the Conventional treatment got 150 kg/ha of CAN. The Hybrid got 113 kg/ha of CAN and a foliar application of seaweed. The Regenerative treatment got a foliar application of seaweed, Megafol, and fulvic acid.

When testing for nitrate after side dressing, we avoided the area where the fertiliser was applied. The nitrate test showed similar results to last time. There is 74 Kg of Nitrate-N in the Conventional, 73 in the Hybrid and 65 in the Regenerative treatment. We can assume the conventional is 18 kg higher and the Hybrid is 13.6 kg higher, as this is how much nitrogen was applied at side dressing.

Our aim is to push the limits of regenerative cropping to understand how much nitrogen input can be reduced. Based on potentially available nitrogen and fortnightly soil nitrate results, the Operations Advisory Group decided not to apply granular fertiliser to the Regenerative treatment at side-dressing.

A similar approach was taken last season in beans, where no granular fertiliser was applied at side-dressing and a foliar approach was used instead. Soil nitrate levels remained similar across all treatments, and the Regenerative treatment produced the highest bean yield.

We will continue to monitor nitrate levels fortnightly, and we will do leaf testing during fruit set.

In November, we co-hosted a research symposium with Vegetable Research and Innovation and the Foundation for Arable Research. The symposium brought together those who had investigated Cyclone Gabrielle’s impacts on highly productive land to present and discuss findings and observations, and draw out lessons to aid land managers and policy makers in future events.

A great deal of semi-coordinated activity followed in the wake of Cyclone Gabrielle. However, there was much incomplete work that would add value by helping enrich our understanding of the longer-term effects of different management responses in different scenarios.

The symposium brought together researchers, advisors, farmers/growers and others involved in observing the impacts on productive land and the effects of different responses in the cases of Cyclone Gabrielle and previous similar events. More than 20 presentations covered historic events, the broader climate context of Cyclone Gabrielle, a range of land use types and many areas of research.

The convenors (Sally Anderson, Dirk Wallace and Dan Bloomer) are now in the process of collating the proceedings and preparing to load material on the conference web page. We’ll do posts as items are loaded with abstracts, summaries and presentation videos. From the outset, the response to the calamity that was Cyclone Gabrielle has been one of high support and collegiality from many, many quarters. The symposium was our attempt to get the best from all the work that was done and find the lessons for those impacted by future events.

We are most grateful for the support and enthusiastic involvement of all the presenters and delegates and the organisations that funded the event.

It is an annual competition that involves classifying different soil profiles through understanding and interpreting geology, landforms, and morphology of the soil and its surrounding landscape. Soil descriptions can then be used to determine best land use. I have competed in Marlborough, Darwin, Rotorua, and most recently Armidale, NSW. Soil judging has taught me the importance of how landscape influences soil capability, and has given me skills, learning, and connections that cannot be gained inside a classroom. Soil judging has introduced me to a community of passionate individuals who all appreciate soil as a valuable and vulnerable resource that needs to be looked after.

From my internship at LandWISE I look forward to meeting new people and learning more about horticultural systems unique to this beautiful region! What excites me about the Carbon Positive project is its comparison of different cropping systems from both an environmental and financial lens. The intersection between environmental and financial sustainability was a key idea that initially sparked my passion to pursue a career in agricultural science.

So far, I have been involved in weekly data collection to monitor soil moisture and canopy development, alongside fortnightly soil sampling to undertake nitrate quick testing across the plots. I have completed one round of soil infiltration rate testing using disc permeameters. The permeameters measure the rate at which water infiltrates the soil under different water tensions, which gives an indication into soil hydraulic conductivity and pore size distribution. This can indicate how soil structure and compaction vary between treatments.

By measuring at multiple tensions, you can determine how much flow occurs through large structural pores versus the fine-textured soil matrix. This reveals critical information about soil structure and preferential flow pathways. Different pores sizes provide different benefits:

• Macropores: > 0.075-0.1 mm – drainage, aeration, rapid flow
• Mesopores: 0.03-0.075 mm – intermediate drainage and retention
• Micropores: < 0.03 mm – water retention, slow flow (requires tensions < -100 cm)

Disc permeameters measure flow through macropores and larger mesopores only. They cannot assess micropores, which require different methods such as pressure plate apparatus or water retention curves. The practical tension limit for disc permeameters is about -15 to -20 cm due to air entry through membranes and extremely slow infiltration rates at more negative tensions.

We have a comprehensive guide that explains the permeameters and processes in more detail and a Frequently asked question page to help out.

If you want to try understanding your soil this way, contact us. The equipment is not readily available and it does take effort to learn to use if correctly.

The Conventional treatment was planted with treated seed and 300kg/ha of Complex fertiliser.

The Hybrid treatment was planted with treated seed, coated in TrichoStart and 300kg/ha of Complex fertiliser. Mycorrcin, Biostart N and TrichoStart were applied at planting via liquid injection.

The Regenerative treatment was planted with untreated seed, and 5kg/ha of humates mixed with 150kg of Complex fertiliser. As with the hybrid treatment, mycorrcin, Biostart N, and TrichoStart were applied via liquid injection.

After planting, all treatments received Ironmax slug bait before two 50cm strips of pre-emergeence herbicide, Frontier-P and Magister, were strip-sprayed over the plant lines.

Throughout the season, the Operations Advisory Group and Heinz-Wattie’s agronomists will meet weekly to track how the butternuts are growing. Together, they’ll make the calls on crop protection, weeding, fungicide and insecticide use, and adjust management decisions as the season unfolds.

A big thank you to Gareth Holder from Redloh Horticulture for taking the time to plant our butternuts.

Carbon Positive is a partnership between LandWISE, the HB Future Farming Trust, McCain Foods, Heinz-Wattie’s and Process Vegetables NZ.

On Day 3, I took a cruise through the stunning Queen Charlotte Sound, with a stop at historic Meretoto/Ship Cove. It is one of the places Captain Cook visited on several of his voyages and where he traded with the local iwi. Along the shoreline, we were shown flakes of argillite rock left behind from traditional toolmaking. The stones are not naturally found in that part of New Zealand, and their worked shapes make it clear they were taken there by Māori generations ago.

One of the real highlights of this day was watching dolphins swim alongside the boat as we travelled back through the sounds.