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.

A Te Ahikawariki / VICE Project

SLAKES: a cost effective measure of soil structural stability is one of two projects I have been running as a part of my Te Ahikawariki/VICE internship. A key part of the project was engaging with growers to demonstrate and support valid paddock sampling and correct use of the test methods. Our aim was for growers in each regional community to know how to use and understand results from a standardised assessment methodology consistent with SHI guidelines. As part of the Slakes project, we ran individual farm workshops with growers in Hawke’s Bay, Pukekohe, Palmerston North/Levin, and Gisborne. 

Soil aggregate stability

Soil aggregate stability is a measurement of aggregates’ ability to resist degradation and maintain structure when being affected by external forces such as rainfall, vehicle traffic, and tillage. It is correlated with soil erosion, water retention, aeration, root growth, soil microorganisms, and soil carbon. 

Soil aggregate stability is one of the three key soil health indicator tests recommended by the Soil Health Institute (SHI), alongside soil organic carbon concentration and carbon mineralization potential. The SHI recommends the Slakes method for testing aggregate stability as it is practical and cost-effective.  

The Slakes method uses a free app that was developed by the SHI and the University of Sydney, to test aggregate stability. The app is used to take images of sets of three aggregates, initially dry and again after they have been submerged in water for 10 minutes. The Slakes app takes photos, times submersion, and calculates an Aggregate Stability Index, which is the ratio of initial to final soil area. 

The Slakes Project outline was to: 

• Compare the Slakes aggregate stability index and Manaaki Whenua – Landcare Research wet sieving aggregate stability results 

• Correlate the results to a visual soil assessment (VSA) score, bulk density, and total carbon 

• Engage with growers while demonstrating valid paddock sampling and how to use the Slakes app 

Most samples collected throughout this project were taken from an uncropped and a cropped area within the same paddock. When comparing the Slakes aggregate stability index and the Manaaki Whenua Landcare Research wet sieving aggregate stability results, there was a clear trend in both methods that the uncropped areas had higher aggregate stability.  

When comparing the VSA and aggregate stability results, most of the cropped paddocks had good VSA structure scores but weak aggregate stability. This suggests that the tilth created by cultivation looks good, but it lacks the strength of true aggregates that are the basis for good soil structure.  

There was a moderately strong relationship between the Slakes aggregate stability index and the total carbon percentage in the soil (R² = 0.69), with the uncropped areas (blue dots) having higher total carbon and aggregate stability than cropped areas (brown dots). 

Throughout the Slakes project, we received positive feedback from growers about the Slakes app, as it provides a quick, simple, and affordable way to gauge the soil’s aggregate stability without needing to send samples away to a lab. However, some growers asked how they can use it to aid their management. Most are keen to know if there is an aggregate stability index threshold that indicates when poor stability will impact productivity.  They recognise the test is low cost, but some would like the option to send it to a laboratory to save time.

Many thanks to Te Ahikawariki, the Vegetable Industry Centre of Excellence, for supporting me in my internship, and for funding LandWISE to undertake the Slakes research project. And thanks also to the farmers, growers and consultants who spent time trying out the Slakes method with us and giving us their considered feedback.

Olivia

Download the Project Report

The LandWISE Conference, Getting to Carbon Positive, attracted more than 80 people who heard speakers on a wide range of topics related to ongoing sustainability.

Day 1 discussed ways to assess our emissions levels, how we can reduce our environmental impact through diverse farming techniques including regenerative practices and soil health, and new research around pest management.

Pii-Tuulia Nikula opened with an introduction to emissions accounting, which was followed by Uttam Floray outlining how Toitu certifies emissions. Ron McFetridge from WaterForce said he was asked by key clients about WaterForce’s emissions, which set them on a journey to reduce their emissions and environmental impact. Olivia’s take:

“I enjoyed listening to Ron discuss how WaterForce has been installing solar panels on their offices, putting in electric vehicle chargers, and deploying electric and hybrid vehicles for their staff. Given that they travel 4.5 million kilometres annually as a company, WaterForce saw electrification as an effective way to reduce emissions and environmental impact. By doing this, they are setting a precedent for other companies.”

Dan Bloomer presented results from the Carbon Positive trial including the 2024-2025 cropping programme and a Carbon balance for each of the treatments, which showed nitrogen fertilisers and diesel were the largest CO₂^-e contributors. The introduction of livestock added significantly to overall emissions, even if on farm for a relatively short time. Matt Norris presented results from regenerative cropping trials, including use of composts, at LeaderBrand in Gisborne, Angus McKenzie described how Wairuna Farm is applying the principles in Canterbury, the various things he had been trialing on his farm, and how they created a wetland to treat drainage water. Sam McNally addressed ways to increase soil carbon and explained fundamental changes in our understanding of soil carbon sequestration and carbon pathways. Photosynthesis feeds the whole system!    

Three speakers discussed beneficial non-crop plants. Dan talked about the lessons from growing multispecies cover crop mixes in the Carbon Positive trial. Charles Merfield provided information about cover crops for regenerative cropping and the need to ask what functions you wanted cover crops to perform. Jeff Smith presented lessons from biostrip and insectaries research through the A Lighter Touch project.

Day 1 was wrapped up with Asha Chhagan talking about new technologies to assist pest and disease management, and Bethan Shaw reporting on work done looking at earwigs recolonising orchard sites that had been devastated by Cyclone Gabrielle. Daniel Sutton and Chris Lambert reporting on trials with a camera equipped AI enabled pest trap.

Olivia’s take:

“The conference was a good opportunity for me to do my first conference presentation! I talked about the Slakes app and things we have learned from using it to assess soil aggregate strength, and I spoke about the Nitrachek device project that I have been running as a part of my Te Ahikawariki/VICE internship.”

Many thanks to all our sponsors, speakers and delegates!

Getting to Carbon Positive

Wednesday 21 – Thursday 22 May
Havelock North Function Centre

In 2025 we’re delighted to bring you a conference with focuses on regenerative crop production, carbon footprinting, and electrification. We’ll have new technologies to think about and see, we have speakers with proven track records, and we’re looking forward to catching up with old friends and new.

Do we know the footprint of our activities? How do international markets assess them and what will we need to report? We are proud to present Associate Professor Dr Pii-Tuulia Nikula to open the managing our footprints conversation. We’ve done the numbers on our Carbon Positive cropping treatments, and we’ve others talking about what they are doing to address their footprints too.

If we are going to get to Carbon Zero (or better) we need to think about both inputs and outputs from our systems. Can we soak up more than we lose? Which inputs have the greatest impact?

We will report on progress and lessons from another year of our regenerative cropping research and present some new tools for growers to assess nitrate levels and soil stability. We’ll have examples for viewing at the Horizons Regional Council Field Session. Others will update us about new technologies for pest and disease control and reintroducing insects to cyclone impacted orchards and discuss the use of bio-strips and insectaries to encourage beneficial insects.

We’ll need energy, of course, but how much can we generate on-site? Is electrification realistic now? Where to in the short to medium term? We are delighted to have Mike Casey of the Electric Cherry Orchard and CEO of Rewiring Aotearoa opening the discussion on electrification and alternative energy case studies. We’ll have electric vehicles for perusal.

Thanks to our Sponsors!

We look forward to seeing many of you again in 2025.

At LandWISE 2025 you’ll hear about regenerative cropping systems (however they be defined, or not), soil carbon and sequestration, and the use of cover crops in vegetable and arable systems. Add in the role of biology and ecology in pest and disease management, and some new systems and gadgets to monitor crop pests, soil nitrates and soil health, and the programme has much to offer!

Havelock North Function Centre
21 – 22 May 2025

We will update delegates on our Carbon Positive regenerative intensive process cropping project. Matthew Norris will describe the research completed and take-away knowledge from the Leaderbrand Regenerative Cropping project, with fascinating insights around the use of composts. And Angus Mckenzie will describe his own farming approach and that of others in Canterbury seeking to apply regenerative principles in day-to-day management. A common factor with all projects is the focus on lifting soil carbon levels, a topic that will be drilled into by Sam McNally.

Our Carbon Positive Operations Group has learnt some hard lessons with cover crops over the last three years, but we think we are now much better informed and positioned. We will present a list of questions! Also, with support from Te Ahikawariki/VICE, we’ve begun a small study of cover cropping with interviews of farmers who do and don’t use cover crops. We hope to have some preliminary findings by the conference. Charles (Merf) Merfield, one of the team interviewing will discuss cover cropping, an area he has researched and implemented for many years.

Drawing from “A Lighter Touch” research, Jeff Smith will discuss the use of bio-strips and insectaries to encourage beneficial insects to aid in pest management. Daniel Sutton will report on research using “Smart Traps” to automate collection of pest presence data. From Plant and Food Research, Asha Chhagan will talk about new technologies for pest and disease control and Bethan Shaw will discuss work reintroducing beneficial insects to orchards impacted by Cyclone Gabrielle.

Rounding out New Tools, Olivia Webster will present LandWISE work using a new soil slaking measurement app and a device to more precisely determine soil nitrate levels when using Quick Test strips.