Session Synopsis

Growing multiple vegetable crops across a farming operation the size of Harvest Moon requires constant decision-making, careful timing and a deep understanding of what crops need at every stage of growth. In this session, Josh will walk through how Harvest Moon manages nutrient applications across more than a dozen crops using a combination of field experience, soil and sap testing, and modern data tools.

He will explain how the team schedules and calculates nutrient inputs throughout the season, how they identify inefficiencies in the system, and how these insights feed into broader Integrated Pest Management strategies. By continually measuring and refining what happens in the field, Harvest Moon is able to reduce risk, improve crop health and optimise yield.

The session offers practical, real-world insights for growers looking to sharpen their nutrient strategies, improve efficiency and get more value from the data already available in their farming systems.

Past Chair of LandWISE, John Evans will discuss his farming career at “Soil Health for Profit” in May. Over more than four decades active farming, he’s seen a number of farming systems arrive and be replaced.

John was exposed to soil improvement at a young age as his parent’s developed half of the property from Gorse Broom Blackberry and Willows into a highly productive irrigated mixed system. After returning from Lincoln College and helping with the irrigation development the farm was sold, and another larger rundown property was purchased in Dorie.

Over the next 36 years John continued his soils interest and converted the property to intensive cropping with irrigation. Pivoting the operation and taking up the opportunities that came along, he finished with a highly productive arable livestock farm with a high quality, productive specialist seed operation.

He was and is always active in his own research and hosting and supporting Foundation for Arable Research (FAR) projects. Looking back, has asks, “Have I always been a regenerative farmer?”

Minimising cultivation impacts in broadacre cropping

Simon White is a farmer and entrepreneur based in Otane, Hawke’s Bay. He and his wife, Lou, have built a diverse operation with soil health at its core. They have a mix of arable cropping and sheep and beef finishing across 1100 hectares which has been in their family for three generations. Simon and Lou won the regional supreme title at the 2025 East Coast Ballance Farm Environment Awards, which recognised their focus on sustainability and business success built on diversification and innovation.

Simon is a long-time user of direct drilling and strip tilling on his farm. He sees major benefits in time saving, fuel economy and soil health. He will describe his use of these techniques in his arable, seed production and process vegetable systems.

We were delighted to host Vicky Bloomer from Drop Consulting to present the Irrigation New Zealand Performance Assessor training course at the Centre for Land and Water this week. And what a wet week it was, so we thank them for breaking the drought in this part of the country.

The course participants were out and about visiting Drumpeel Farms to assess a centre pivot, our neighbours YummyFruit to assess drip/micro system and an Oderings nursery to look at a solid set system. At the LandWISE MicroFarm, they assessed the linear move irrigator. LandWISE Project manager Olivia Webster is one of the course participants

The performance assessment course is based on the Irrigation New Zealand Piped Irrigation System Performance Assessment Code of Practice, initially developed by Dan Bloomer at Page Bloomer Associates. The concept of irrigation performance assessment was strongly promoted by Hugh Ritchie following his Nuffield scholar experiences in the USA and he was a key player in obtaining funding support to write the New Zealand codes in the first place.

The MicroFarm Linear

The LandWISE linear machine was donated by Hugh and Sharon Ritchie. It was converted to a low energy precision application system (LEPA) by WaterForce who have been excellent with anything water related we need. The machine began life as a 460m multi-span linear at Drumpeel, and when it was due for replacement, Hugh collected the best bits and rebuilt it to fit the LandWISE MicroFarm. In its early days, it was repeatedly measured as a test case while the Code of Practice was developed! It was also used in other SFF projects assessing impacts of application intensity of soil surface redistribution and consequent soil moisture uniformity.

Quinn Elstone at WaterForce deigned the LEPA system specifically for the MicroFarm layout, centring the outlets above each 2m bed. We run two parallel header pipes along the linear span, and we can split the sprinklers between them. We can use the sprinklers as rotators doing a wide overlapping ~12m spread to maximise uniformity and minimise application intensity. Or we can run them as sprays with a 5m spread, keeping application tighter to our 12m plots. A third option is changing the nozzles to tighter 2m splash plates that water each bed individually. Or we can turn individual nozzles off.

Images of irrigator showing 12m spread rotators on left, 2m splash plates in centre and 5m sprays at right

Why LEPA?

It gives us tremendous flexibility.

In the LEPA system the nozzles are very close to the ground, so we see very little effect in windier conditions. And because we generally run the irrigation during the day to take advantage of our solar electricity system for pumping, there is often a bit more breeze than at night. We haven’t converted the machine from diesel yet – that is on a long list!

We can tailor irrigation to treatments.

In our Carbon Positive trial, we’re running 6 beds per treatment plot, and sometimes we want to do different things to different treatments. When the nozzles are running as sprays, there is very little overpal of treatments.

The WaterForce LEPA system lets us turn one treatment plot off and irrigate the other two, or irrigate only one plot. We can run nutrient solution in one header and fresh water in the other and fertigate some plots and not others, even though we have three different treatments under the irrigator at any time. For us, the Drumpeel/WaterForce machine has been life changing because without flexible high-quality irrigation, our trial work is severely impacted.

We are tremendously grateful to the Ritchies for the generous donation, and to WaterForce for their supply and installation of the components. It is this kind of community support that characterises LandWISE and has allowed it to be a success.

Validation and Practical Implementation of the Nitrachek 404

Have you tried to match soil test strip colours against the colours on the tin, and found yourself wondering if you’re seeing the right shade of purple? Those days of guesswork can be over.

The Nitrachek 404 is like having a portable lab right in your paddock. Instead of relying on visual colour matching, this electronic device reads test strips and displays precise digital readings. No more uncertainty about whether the lighting is affecting your colour judgment.

Proven Results

With funding from Te Ahikawariki, we worked with vegetable growers and agronomists to test the Nitrachek 404 across Hawke’s Bay, Manawatu, Pukekohe, and Gisborne. When comparing soil sample Quick Tests against Hill Labs analysis, we achieved 95.5% correlation with laboratory methods when proper protocols were followed.

The economics are compelling too. Laboratory tests cost ~$40 per sample, while Nitrachek strips are about $3 each. For farms requiring frequent monitoring, the device pays for itself very quickly – delivering 90% cost savings per sample.

We have conducted well over a thousand Nitrate Quick Test soil assessments over the last five years. We have identified four key sources of error: sample collection, sample preparation, reading the test strip accurately and reliably, and adjusting for soil moisture content. We have prepared resources for growers taking soil samples so check out our LandWISE Online Learning pages.

We had some major issues comparing our quick test results with those from the commercial laboratory. In some cases, the samples were badly affected by heat or wetness during transport to the lab, resulting in dubious results. But the biggest issue was properly applying the correct soil moisture. To get accurate results, we found that using the soil moisture percentage was critical. We used the online calculator that estimates soil moisture based on your soil type and whether you think the sample is wet, moist or dry. On our MicroFarm soils, this put us 30% out compared to Hill Labs – far too much for budgeting. We worked through issues with Matt Norris from BSI – Plant and Food and found that an equation using actual measured soil moisture made all the difference.

Getting the right answer

We make sure to measure actual soil moisture percentage. We either use a Hydrosense twin-prong soil moisture tester in the field, or we weigh the soil samples that we collect. After sieving the sample for the Quick Test, we dry 100 g of the left-over soil and weigh it again dry. That is easy to do and the most accurate method.

There are still a few maths steps to get from the test strip to the amount on nitrogen in your paddock! You need to calibrate the device, each batch of test strips, adjust for actual soil moisture, soil density, sample depth and, if you want maximum accuracy, add a final lab correction factor to have Quick Test results exactly match laboratory results. That is a bit of a nuisance and leaves lots of room for mistakes, so we developed an online calculator for you.

The online calculator eliminates the complexity of converting raw readings into useful field values. You enter your Nitrachek reading, correction factors, soil moisture content, and soil density, and it converts the data into the nitrate nitrogen values you need (kg/ha).

Practical Considerations

The device isn’t perfect for every situation. Some growers found the one-minute testing time slower than visual estimation for quick field checks. If you just need approximate values for immediate decisions, visual methods still work well.

However, for precise nutrient budgeting, regulatory compliance, or entering specific data into management software, the Nitrachek delivers laboratory-level accuracy at a fraction of the cost.

Getting Consistent Results

Success depends on following proper protocols. The research identified sample handling as crucial – keeping samples cool during transport and processing them promptly significantly improves accuracy. Device and strip calibrations are also essential, as each batch of test strips requires calibration due to manufacturing variations.

We found the device was accurate within the 2-75 ppm range we tested. That should cover most typical pre-planting conditions in New Zealand vegetable production. The graph below shows results from the MicroFarm and shows an average 7% difference between the quick test and lab results. You might not worry about 7%, but if you do, the online calculator lets you correct it.

For growers focused on precision agriculture and environmental compliance, this represents genuine progress – laboratory-quality soil testing that’s both affordable and immediate.

Download our full report here>

Many thanks to Te Ahikawariki for funding and supporting this work. And many thanks to the growers who took part, tested the method and the device, and gave us useful feedback. And special thanks to Matt Norris for helping us crack the puzzle and providing the “Norris Equation” that properly accounts for soil moisture levels.

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!

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 2 had a strong focus on electrification options to increase profitability and reduce emissions. New Zealand is reaching a point where solar power is the cheapest energy available – as Mike Casey noted, the cheapest form of energy ever.

Uttam Floray introduced Rewiring Aotearoa and the local chapter, Electrify Hawke’s Bay which are focused on helping promote and activate electrification. Mike Casey described the electrification of his cherry orchard and laid out a huge set of statistics and examples of ways New Zealanders can profitably swap fossil fuel machines for electric ones. Becks Smith now helps farmers work out how solar can add to their businesses having set up a solar system for irrigation pumping in Otago.

Lincoln University has chosen major investments in solar electricity to reduce emissions at the university, and Pieter-Wilem Hendriks is part of a team investigating ways to combine agricultural production with energy generation. At smaller scale, Aaron Duncan explained options for home and SME solar systems, using the Centre for Land and Water system as a case study. Boyd Benton discussed the way Ripple Tech transplants electric motors into fossil vehicles and, in a second talk, introduced micro-hydro as a viable option for sites with streams. Olivia said

“It was fantastic to hear Uttam Singh Floray, Mike Casey, Becks Smith, Pieter Hendriks, Boyd Benton, and Aaron Duncan discussing electrification and reducing emissions. You could sense their genuine passion for the topic, which made their talks even more engaging. I particularly enjoyed Mike Casey’s talk on his electric cherry farm. I found it fascinating that every piece of machinery used on the farm is electric, including the truck that transports the cherries to the packhouse. That means there are no fossil fuel carbon emissions until after the cherries have been transported from the farm.”

Horizons Regional Council Field Session

The field session on Thursday afternoon provided delegates with opportunity to get first-hand experience of some of the techniques and technologies that had been discussed. We thank “A Lighter Touch”, WaterForce, Freenergy, RippleTech, PowerSpout, Vegetables NZ, Autonabit, and Agovor for bringing their wares to demonstrate. Gadgets, machines and systems to excite, save time and money, and enable systemic changes. Olivia said

“I didn’t make it around to all the field event demonstrations, as I was demonstrating the Slakes app and the Nitrachek device. I did manage to see the smart trap, the off-grid hydro pump, the Govor robot, and the Avvy bird scaring robot. They offer so much, and we expect to see a lot more of these technologies in years to come!”

We gratefully acknowledge all our sponsors, presenters, demonstrators, and delegates!