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.

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.

The conventional treatment was broadcast sprayed with glyphosate in mid-October and cultivated in early November. It was disced, then aerated, rotary hoed and rolled. It will be planted with treated seed and 300kg/ha of Complex. After planting, 50cm strips of pre-emerge will be sprayed over the plant line.

The Hybrid treatment was strip-sprayed in mid-September, and was strip tilled at the end of October before being broadcast sprayed with Glyphosate to remove the living strips. It will be planted with treated seed coated in TrichoStart, 250kg/ha of Complex and Mycorrcin, Biostart N, and TrichoStart via liquid injection. It will get sprayed with pre-emerge over the plant line.

The Regenerative treatment was strip-sprayed at the same time as the Hybrid treatment, and before it was strip tilled, a mixture of OMYA Calciprills, Humates, Sulphur, and Boron was applied by drone. This mix has been applied every year in the Regenerative treatment in the Carbon Positive trial when the cover crop is breaking down, before planting. This mix stimulates worms and soil microbiology, which improves soil health. We used 150 kg/ha of OMYA’s Calciprills and 10 kg/ha of Boron as calcium and boron are essential for soil health and plant growth, and it is important that the correct balance is maintained.

Since our soil is naturally low in sulphur and sulphur is slowly released from organic matter decomposition, we applied 10 kg/ha of Sulphur to ensure sulphur will be available to the butternut crop. 5 kg/ha of Humates was applied as it is a microbial stimulant, it stimulates Mycorrhiza fungi, which helps plant roots access nutrients, and it also improves fertiliser efficiency.

It will be broadcast sprayed with Glyphosate to remove the living strips and any weeds that germinated from strip tilling. It will be planted with untreated seed, 150kg of Complex, 5kg/ha of Humates and Mycorrcin, Biostart N, and TrichoStart via liquid injection. It will also get two 50cm strips of pre-emerge over the plant line.

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.

We are particularly grateful to OMYA for supplying us with the Calciprills, Webster’s Lime for providing us with Boron and Sulphur, and BioStart for supplying us with Mycorrcin. We are thankful for the ongoing support of Heinz-Wattie’s, Gareth Holder from Redloh Horticulture and Hamish Thomas from NH Packing. We look forward to working with them as our butternuts are sown, grown and harvested! Carbon Positive is a partnership between LandWISE, the HB Future Farming Trust, McCain Foods, Heinz-Wattie’s and Process Vegetables NZ.

In the 2025-2026 cropping season, the fourth summer of the Carbon Positive trial, we are growing butternut pumpkins for Heinz-Wattie’s. Our planned planting date is the middle of November.

In the Conventional system, things are getting underway with a broadcast spray of glyphosate now that the sheep have been moved out. The paddock will be cultivated in early November and planted with butternuts. Fertiliser applications, including planting and side-dressing, will be at full fertiliser rates that are typical on the Heretaunga Plains.

The Hybrid system was strip-sprayed in mid-September and will be strip-tilled about three weeks before planting. Two weeks before planting, it will be broadcast-sprayed to clean up the remaining cover crop outside the strip-sprayed zone. We may spray about three days after planting if weeds or cover crop regrowth are an issue. Fertiliser applications, including planting and side-dressing, will be guided by soil results.

The Regenerative system was also strip-sprayed in September, and the plan was to avoid cultivation. However, grazing sheep have compacted the soil, so strip-tilling is our back-up plan. Two weeks before planting, it will also be broadcast-sprayed to tidy up outside the strip sprayed zones. Glyphosate will be used to knock back the ryegrass, but clovers and vetch will be left as companion crops. As with the Hybrid system, a clean-up spray may be needed three days after planting. Fertiliser rates will be set according to soil test results.

We will determine weed management tactics as we go but are anticipating that a stale seedbed approach and favourable weather may do most of the work. Our strips will allow the precision weeder to operate if necessary, and there’s a manual fallback we prefer not to think about just yet!

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.

We are particularly grateful to Heinz-Wattie’s, Gareth Holder from Redloh Horticulture and Hamish Thomas from NH Packing for their support. We look forward to working with them as our butternuts are sown, grown and harvested! Carbon Positive is a partnership between LandWISE, the HB Future Farming Trust, McCain Foods, Heinz-Wattie’s and Process Vegetables NZ.

Many thanks to our sponsors

Carbon Positive is, unsurprisingly, tracking soil carbon levels under our three different management approaches. We have two key measurements; total soil carbon and hot water extractable carbon. Hot water extractable carbon is a laboratory test measure of labile carbon, which is the ‘active’ carbon that drives soil biological processes. It is a very small portion of the total carbon, but it is doing the heavy lifting.

Starting from our November 2022 baseline of 4.1 tonnes of labile carbon per hectare, levels rose modestly to 4.6 T/ha by June 2024 following summer sweetcorn and winter cover crops. The dramatic change came after the winter cover crops that followed the process tomato crop. By November 2024, carbon stocks had jumped to 5.3 T/ha across all treatments – a 29% increase from baseline. But this peak proved temporary. Following the peas and beans double-crop, June 2025 measurements returned to 4.2 T/ha, essentially back where we started. Look at the interactive charts below.

The most striking finding is how similarly all three management approaches responded to each crop sequence. Whether under conventional, hybrid, or regenerative management, the carbon patterns were remarkably consistent: modest gains after sweetcorn, substantial peaks after tomatoes and cover crops, and return to baseline after legumes.

This suggests the biological systems under all three management approaches are equally robust and responsive. More importantly, any treatment effects are currently being swamped by much larger crop-driven fluctuations. The summer crop choice appears to matter more than tillage practices or input strategies, at least in these early years.

Process tomatoes produce a lot of biomass – not just fruit, but extensive root systems and above-ground residues that get incorporated after harvest. The charts show that at the end of the tomato crop, the labile carbon in the deeper layers was much higher. Then the November 2024 sampling captured this system at peak carbon input, just as winter cover crops were maturing and contributing even more biomass.

The subsequent return to baseline following legumes suggests that, while peas and beans fix nitrogen and benefit soil health in other ways, their carbon inputs and cycling patterns clearly differ from high-biomass crops like tomatoes.

The conventional system plants annual ryegrass and grazes it with lambs through winter, while hybrid and regenerative treatments establish ungrazed multispecies cover crop mixes. Despite these fundamentally different approaches – livestock integration versus plant-only systems – both pathways track the same carbon cycling patterns through all crop sequences.

Three years of data teaches us that patience is essential when evaluating soil carbon outcomes. The large crop-driven fluctuations mean we need several complete rotation cycles before drawing firm conclusions about management system effects. However, the consistent responses across all treatments offer important reassurance indicating that all approaches demonstrated equivalent biological function and responsiveness to crop inputs. Rather than seeing carbon “loss” in the return to baseline by 2025, we’re observing a biologically active system cycling around a stable equilibrium.

So far, our research demonstrates that soil carbon in working farm systems follows complex biological rhythms that require patient observation. The apparent “return to baseline” doesn’t represent system failure, but rather the natural cycling of a healthy, biologically active farming system responding predictably to diverse crop inputs. We’re sampling again in early November – what will we find?

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After a successful bean crop in the 2024-2025 season, the three systems were planted in cover crops for the winter. The Conventional was planted with ryegrass, the Hybrid with ryegrass, Balansa clover and crimson clover, and the Regenerative was the same as the Hybrid but with the addition of vetch.

The Canopeo phone app has been used weekly to monitor the canopy development of the cover crops. All three treatments achieved impressive canopy coverage, reaching over 90% canopy cover after just eight weeks. This rapid establishment is attributed to the ryegrass component, which typically establishes ground cover faster than other cover crop species used previously in the Carbon Positive trial.

Sheep were brought on to the Conventional plots in early July, after which they had a gradual reduction in canopy cover due to ongoing grazing, reaching its lowest point at 85% canopy cover.

The Hybrid system presented a unique challenge as it developed a significant nettle problem. This is probably an artefact of the site, rather than being caused by the Hybrid management strategy. To manage the nettles, the Hybrid was mowed in mid-July before the nettle set seed. Mowing reduced the Hybrid’s canopy cover to 65%, but the resilience of the cover crop mix was demonstrated as it quickly regrew to full canopy cover. Sheep were introduced in mid-August to reduce biomass before strip spraying.

The Regenerative treatment maintained steady canopy cover (90-100%) until sheep were introduced in mid-August to reduce biomass in preparation for strip spraying. The small fluctuations in the data are due strong shadows on bright days impacting the green percentage calculation in the app.

Cover crop biomass measurements were taken before grazing. The Conventional system produced an average of 3,987 kg/ha of dry matter from April to mid-July, compared to the Regenerative system, which produced an average of 5169 kg of dry matter per hectare from April to mid-August.

Fortnightly nitrate quick tests throughout the cover crop have provided insights into nitrogen dynamics within the different systems. Nitrate-N levels peaked approximately one month after cover crop establishment, with the Hybrid and Regenerative treatments showing higher levels than the Conventional treatment. [The Conventional Bean crop had received significantly more N fertiliser but yielded lower than the other treatments.] All treatments have shown steady decreases in nitrate-N. We haven’t seen a significant increase in nitrate-N from sheep grazing in any of the three treatments, although a slight lift in the Conventional plots may show some effect.

The Hybrid and Regenerative plots were strip sprayed on 15 September using our prototype twin-row sprayer. We wait in anticipation to see the results!