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.

So far we have calculators for:

• Centre Pivots
• Linear Moves
• Travelling Irrigation
• Solid Set Irrigation
• In-depth Pressure & Energy Analysis

We sent Dan off to keep working on calculators for:

• Multiple Spraylines
• Drip/Micro Irrigation
• a few other ideas!
• and we haven’t seen him for a while

These calculators are based on the 2005 Irrigation Code of Practice for System Evaluation. Its methods have been very well tested over the years and we a proud to have been involved from the start.

The calculators do not store any of your data. The calculations are done in the webpage on your computer and are deleted when you refresh or close the page. That means only you have your data, but if you want to redo things, you’ll have to start again.

Please give us feedback. We are thinking of adapting the Fertiliser Application calculator to this format as well if we get good reviews. And if people want to save their work, we can look into that too.

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.

With funding from Te Ahikawariki, we teamed up with regional agronomists to ask a number of growers about cover cropping. We wanted to learn what the barriers were to new entrants, and what the ongoing headaches were for those who do use cover crops.

Three-quarters of the 32 growers surveyed have been using cover crops for an average of 23 years. These aren’t beginners struggling with basics—these are people who’ve figured out how to make cover crops profitable, and their insights challenge everything we think we know about adoption barriers.

We were perhaps not too surprised to find the barriers everyone assumes matter most actually don’t. Equipment access scored just 1.2 out of 4 as a barrier—the lowest of everything measured. Information gaps scored only 1.6. These experienced growers have moved way beyond those basic issues.

So what are the real barriers? Three big ones that actually matter:

1. Nitrogen Tie-Up (The Technical Killer)

Cover crops locking up nutrients when your cash crop desperately needs them. This scored 2.7 out of 4—the highest barrier measured. It’s not about getting cover crops established; it’s about managing what happens to your nitrogen afterward.

2. Weed Management Gone Wrong

Getting effective suppression without creating new problems. Too often, cover crops become part of the weed problem themselves rather than solving it.

3. Operational Flexibility (The Hidden Killer)

This one was not even in our list of questions but came through loud and clear in grower comments. As a Hawke’s Bay grower put it:

“Once land is cover cropped it ties it up for a period of time and if it’s a wet season then it reduces options and we can fall behind in our planting programme.”

It’s about losing the ability to adapt when weather doesn’t cooperate. That’s a fundamental farming system challenge, not a technical problem you can solve with research.

Why Three-Quarters of These Growers Persist

Despite the barriers, 75% of surveyed growers use cover crops. What’s driving them?

Soil structure improvement absolutely dominates. It scored 3.4 out of 4, with 87% rating it as highly important. Half called it “make-or-break” for their decision.

One Pukekohe grower explained: “The difference in soil workability after a few years of cover crops is dramatic—better water infiltration, easier cultivation, improved root penetration.”

Interestingly, environmental benefits come second. Biodiversity enhancement, soil moisture management, input reduction—they all scored well, but practical farming benefits drive adoption more than environmental ideals. These growers are businesspeople first.

Species That Work (And the Ones to Run From)

After 23 years of collective experience, some clear winners and losers have emerged:

The Champions:

• Oats: Top the list for reliable establishment, easy termination, good biomass production
• Annual ryegrass: Consistent cover, works with livestock
• Vetch: Nitrogen fixation benefits

The Problem Children:

Multiple growers warned about rye—”potential to become a weed” and “difficult to remove.” Brassicas got harsh verdicts too, especially near seed crops. One grower’s blunt assessment: “Radish is a strict no no” because of contamination risks.

And those complex multi-species mixes everyone talks about? “Hard to manage and control weeds” was the verdict. The experienced growers say start simple, learn the basics, then add complexity gradually. Seed crop contamination is huge here because of our export industry. You can’t afford volunteers in the wrong places.

Land tenure creates headaches too. Landlords want to graze cover crops for income while growers want maximum biomass for soil benefits. As one frustrated grower explained:

“When cover crops are grazed we see little benefit especially over a wet period as we need more cultivation and have worse soil structure.”

These aren’t technical problems you can research your way out of—they’re structural issues that need policy solutions.

We’re Not Alone in This

The good news? Remarkably similar patterns show up internationally. US research confirms soil health is the primary driver globally—87% internationally versus our 87.5%. The same technical challenges around nitrogen management and termination timing appear everywhere. We’re not unique in our barriers, which means we can learn from solutions developed overseas.

Getting Started: Advice from the Trenches

What’s the advice for growers considering cover crops? Start simple. Pick one reliable species like oats. Begin on less critical paddocks. Most importantly, plan your termination method before you plant—that’s where many beginners fail. Expect a learning curve. One Canterbury grower with 15 years’ experience captured it perfectly:

“The first year taught me what not to do. The second year taught me what might work. By the third year, I started to see why everyone talks about soil structure benefits.”

At the bottom of this post you can download a link to a report by Charles “Merf” Merfield. We asked him to put his experience and thoughts on paper for all to see. It’s well worth your time to read. In brief, Merf says:

Simply put, cover crops are plants you grow for reasons other than selling them. Think of them as your farm’s support crew—they’re not the stars of the show, but they make everything else work better. That’s why they’re increasingly called “service crops” overseas, which honestly makes a lot more sense when you think about it. These aren’t exotic plants we’re talking about. Most cover crops use the same species you already know well—oats, ryecorn, mustards, clovers, and annual ryegrass. The difference is how and why you’re using them.

Cover crops aren’t a one-size-fits-all solution—they’re more like a Swiss Army knife with different tools for different jobs. Green manures are all about fixing nitrogen from the air using legumes. Catch crops are your nutrient insurance policy. Mulch crops suppress weeds better than most herbicides. Smother crops actually smother established problem weeds, think of them as your biological bulldozer. Then there are the conservation biocontrol crops—plants that support beneficial insects to keep pest populations in check.

The Cost Reality

Seed costs are real—they scored 2.5 out of 4 as a barrier. But the bigger challenge is demonstrating long-term value. One grower captured the economic puzzle: “How to put a value/dollar on them, especially longer term benefits.” The benefits take 2-3 years to become obvious, so you need patience and persistence.

Thanks to Daniel Sutton for initiating this research, and the regional agronomists who helped interview growers; Andrew Luxmoore in Pukekohe, Chris Lambert in Gisborne, Dan in Hawke’s Bay, Karen Coleman in Manawatu/Levin and Charles Merfield in Canterbury. And thanks, as always to the growers who gave time to share their experiences and knowledge.

Download the Full Cover Crops Survey Report

Download a supplementary report by Charles Merfield

We think it is important that our LandWISE membership is up to date on regulations and are pleased to include this post on our website and in our newsletter. Many farm dams are excluded from the new regulations, but there are many that are covered. Farmers sometimes make big ponds, and we are aware of a few “home-builds” that were actually large dams with significant safety significance! Have a look and check your backyard (and the regulations) if you think you might be included.

Dam Safety Regulations are in force

The Building (Dam Safety) Regulations 2022 commenced on 13 May 2024.

The regulations have been made to improve the resilience and maintenance of Aotearoa New Zealand’s dams, protecting people, property and the environment from the potential impacts of dam failures.

Only classifiable dams are impacted by the regulations. Dams are classifiable if they are 4 or more metres in height and store 20,000 or more cubic metres volume of water, or other fluid.

Background to the Regulations
The Regulations were made by the Government in May 2022 and provide a nationally consistent approach to dam safety. Having a dam safety framework brings Aotearoa New Zealand in line with most other countries in the Organisation for Economic Co-operation and Development (OECD).

Since May 2022, the Ministry of Business, Innovation and Employment (MBIE) has been working with industry groups and regional authorities to ensure dam owners are aware of the Regulations and provide them with information and resources to support them to meet their responsibilities when the Regulations came into effect.

What do the Regulations mean for you?
If you are the owner of a water retention structure, firstly you need to determine if your structure meets the definition of a classifiable dam (that is, if it meets the height and volume thresholds).

• If you determine that your dam is classifiable, you will then need to determine your dam’s potential impact classification (PIC). If you do not have a classifiable dam, no further action is required under these Regulations.
• Once the PIC has been determined, you will need to then have the PIC audited and certified by a Recognised Engineer, who will work with the dam owner to complete a dam classification certificate.
• Dam classification certificates need to be submitted to the relevant regional authority.
• Owners of dams with a medium or high PIC have further actions they need to take.
• The only additional requirement for owners of dams with a low PIC is to review their dam’s PIC within five years of the regional authority approving it.
• If you own a dam and fail to meet your responsibilities under the law (the Building Act 2004 Regulations), then you may be liable for a fine.

Resources to help you
You can read more about the definitions, regulations, and find resources to support you, on MBIE’s Building Performance website: www.building.govt.nz/managing-buildings/dam-safety/

Included in these resources is the Measuring and calculating the height and volume of agricultural dams resource. This is designed to help horticultural or agricultural dam owners calculate the volume of their dam and understand if they are impacted by the Regulations.

MBIE has also published another resource, the Potential Impact Classification checklist, which is a checklist to support dam owners to identify and collate information for a PIC assessment.