What has been happening over Winter?

Things have been a little quiet over the last few months. We’ve had our usual regular monitoring tasks, tracking cover crop development with the Canopeo app and soil nitrate levels with the Nitrate Quick Test protocol, Nitrachek device and our conversions to kg/ha. Now we are focusing on getting ready for our summer crop – food quality maize with Nicolle Maize.

We fully discuss the winter cover crop in an earlier post, but in essence, triticale and vetch took off more strongly than annual ryegrass but were overtaken in mid-July after aerating through fill cover and as the triticale was affected by rust. Generally, we are happy with the covers but think growth may be a little less than previous winters. The vetch this year was a standout success after a few years of disappointment.

The free nitrate in the soil has been very low all winter. The chart below tracks the nitrate in the top 30 cm of soil since cover crop establishment. Note this is twice the standard sampling depth.

After being the lowest treatment from mid-April to mid-June, the Regenerative triticale and vetch plots showed a jump and have remained higher (although still very low) than the Conventional and Hybrid ryegrass plots. Is there a link with the canopy cover levels? If the vetch starting to release free nitrate from the nodules?

No fertiliser was added at planting, so the increase in April is assumed to be the result of mineralisation after the butternut crop was harvested and the plots disced and planted. As the cover crops established, they appear to have taken up nitrate although significant rain from 18-21 April may have had some influence.

Soil moisture measured by Hydrosense or oven drying shows no differences between any of the treatments.

Outreach

We had a few opportunities to talk about the Carbon Positive trial over winter. Notable events were taking part in Lincoln University’s State of the Land Event “Regenerative Agriculture in NZ Landscapes: From Practice to Evidence” at which Dan presented the mid-project soil carbon results and use of AI to develop a model to explain changes in and within the various carbon pools. Notably, the emerging science around photosynthates as a key driver of soil carbon suggests the significant fallow and low ground cover typical of an intensive vegetable growing programme is a major block to nett carbon sequestration.

What can we do about that? We think strip-spraying and strip-tillage is one approach. Not only does it retain actively growing (photosynthesising) plants as long as possible, strip-till also minimises tillage – a major cause of carbon burn-off. Several LandWISE Conference presentations addressed this, and the videos have been uploaded to the website.

Another technique would be getting a cover crop growing within the main crop, so that after harvest, it is already growing an “catching some rays”. This however might be a little trickier. Numerous attempts have been made by numerous groups in numerous places and results have been varied. But our Operations Advisory Group is keen that we have a goo. So, we are looking at establishing some legumes in the maize this summer, but leaving sowing until as late as possible to minimise the risk and scale of competition with the money earning maize.

Dan was also asked to present to the annual ICD Group conference. He introduced LandWISE and our history from our roots in wind erosion minimisation, through strip-till, autosteer, precision ag and various nitrate minimisation projects. It was a good opportunity to reflect on 25 or so years on LandWISE activity. While immensely varied, the focus throughout has been on sustainable production through technology and system choice. We have a large legacy of work in soil health, optimal nutrient management and making the best possible use of scare water resources. If you haven’t already, have a look at the various tools and calculators and the online learning courses on our website.

By the time our summer crop butternuts were removed from the Carbon Positive plots, the vines had dried to rope. We disced and direct drilled cover crop seed but couldn’t run an aerator through without massive tangling.

On 26 March, annual ryegrass was sown in both the Conventional and Hybrid plots, and a Triticale/Vetch mix in the Regenerative plots. With very dry, rubbly soil, we irrigated after sowing to help germination.

Because we’ve been disappointed by vetch in recent crops, Olivia ran a germination trial, placing 100 seeds in a tray of plot soil and leaving it outside. This showed 88% germination under field conditions, which we were happy about.

Triticale was first to emerge in drilled plots, with significant numbers by 1 April. Ryegrass and vetch were slower, but well underway by 7 April.

Triticale and Vetch

Annual Ryegrass

By early May, the triticale was well established with roots down at least 20 cm. The vetch roots were also reaching down and had good nodulation.

The ground cover under each cover crop is shown in the chart below. After a lag at initial germination, the ryegrass plots grew at the same rate as the triticale and vetch but did not catch up. The drop at the beginning of June followed an attempt to aerate the soil through a full cover crop once the butternut vine had sufficiently rotted. However, there was some crop damage and the average cover dropped. The regenerative triticale and vetch plots did not return to the previous full ground cover. While the triticale was recovering, around mid-July a leaf rust began spreading through the plots. Even as growth in the Conventional and Hybrid ryegrass plots continued lifting in August, the triticale weakened.

Examples of canopy images taken on 17 August show the ground is well covered, although there are more gaps in the Regenerative image and the presence of rust is apparent.

Conventional Annual Ryegrass

Hybrid Annual Ryegrass

Regenerative Triticale & Vetch

In mid-August we planned to start ground preparation by broadcast spraying the Conventional plots with glyphosate and Torus, and strip-spray the Hybrid and Regenerative plots with glufosinate and Torus. We took above-ground biomass samples on 8 August taking two 0.25 m² subsamples in each of four sub-plots per plot. The charts below show there is no difference in dry matter percentage between treatments. Despite the lower ground cover in the Regenerative plots as assessed by Canopeo, there is a significant difference in above-ground dry biomass compared to the other two which are the same.

Weather has impacted our plans to spray out the cover crops. Our next summer crop will be food quality maize, and the planting date is flexible so we can delay somewhat. But we do want to get next year’s cover crops in while the autumn is still warm, so we don’t want to wait too long.

We plan a public field walk at the MicroFarm on Carbon Positive Field Walk at 1:00 pm on Wednesday 16 September.

Our 2026 LandWISE Conference Opening Speaker, James Hunter, is a farmer with a surprising number of decades under his belt.

Rangitoto Station, farmed by Hunters since 1854, is named a local the Pa site that dates to some of the earliest times of NZ occupation. These attachments, mixed with time working for the Rural Bank in the 1980’s when government schemes (namely the Land Development Encouragement Loan) focused on clearing bush and wetlands – now described as biodiversity, and travel through South and Central America seeing first hand some of Natures wonders struggle with so-called progress reinforced for James that the little things that we have around us must be part of our future. He set out to lift farm performance while protecting all remnant native bush/scrub areas, creating wetlands and improving the quality of water leaving Rangitoto.

Time on QEII and NZ Farm Environment Trust boards strengthened the ethos that farming and looking after things natural are rewarding companions. James is currently questioning whether the “regenerative farming” description fully accounts for so much on Rangitoto Station “that is a buzz”. 

Photo from RNZ – see the full article

“http://www.rnz.co.nz/news/business/570243/disaster-waiting-to-happen-fears-carbon-farming-increases-risk-of-wild-fire.

Remember to sign up to LandWISE to get updates!

Dr. Charlie White is a faculty member at Penn State University, specializing in soil nutrient behavior and management.

He has taught various courses, including Soil Nutrient Behavior and Management, Internship, Independent Studies, Thesis Research, and Supervised Experience in College Teaching.

His research focuses on sustainable agricultural systems, biogeochemical cycles, and nutrient management to promote productive and efficient nutrient use in cropping systems.

In this presentation, Charlie will share some of the key insights into managing cover crops for nutrient management and soil health that he has learned through twenty years of research, much of it conducted in partnership with farmers in the temperate, humid climate of the Mid-Atlantic USA.

These lessons include the importance of measuring and managing cover crop and soil organic matter carbon, nitrogen, and C:N ratios to balance nitrogen retention and supply; that a little bit of grass in a cover crop mixture goes a long way to reducing N leaching; and that a cover crop mixture with balanced species proportions will be the most multifunctional, but achieving evenness in the biomass is easier said than done.

Finally, Charlie will return to his roots in reflecting on the importance of mycorrhizal fungi to the phosphorus nutrition of crops, and why P stratification in no-till system may not be as much of a problem as we think because of these symbiotic organisms.

Making sense of carbon movements. History of strip-till.

Co-founder and manager of LandWISE since 1999, Dan’s career is diverse, with a constant theme of sustainable use of land and water resources. His post-graduate studies included an MScTech in innovation Management and adoption in the primary sector, and a PhD investigating the potential of ultra-low energy electric weeding.  He brings experience across fresh and process vegetable growing, kiwifruit and arable production, to complement expertise in extension, soil health and efficient water management.

Dan is the architect of the Carbon Positive project. At LandWISE 2026, he will present data from soil carbon monitoring in the Carbon Positive project and introduce the use of AI to help understand changes in soil carbon pools.  Powerful, yes. But trustworthy?

Later, he will dive back in history to recall pioneering research into the adoption of strip tillage to minimise soil erosion and soil health impacts. That work saw the formation of LandWISE, ultimately as a stand-alone organisation promoting sustainable production through leadership, support and research. Dan remains a strong advocate for strip-till done right, having seen first-hand its contribution to better soil health, minimised fuel requirements, and financial advantages.

Sponsored by

Dr Sally Anderson is the Scientific Services Manager for Market Access Solutionz Ltd and is based in Wellington. Sally has over 15 years’ experience designing, managing, and implementing science research programmes for New Zealand’s horticultural sector. This includes co-ordinating the Vegetable Research & Innovation Board, managing Summerfruit, Citrus and Onions R&D programmes.

Sally has a science background and holds a and PhD from the University of Auckland, with over 10 years of research experience in environmental ecology, molecular biology, and microbial ecology, with prior roles at NIWA (now Earth Sciences NZ) and the Wellington School of Medicine.

Leading the science services portfolio at MAS, Sally works to support clients with technical advice in plant health research, biosecurity, crop protection, export market access.

As the Vegetable Research & Innovation Board co-ordinator, Sally worked alongside industry stakeholders to secure funding from MPI NIWE fund to support the vegetable, fruit and arable sectors to carry out monitoring post-Cyclone Gabrielle to better understand how highly productive land recovers from these extreme weather events. These learnings and those from other agencies were showcased at the Cyclone Gabrielle Research Symposium, held on the 19-20^th November 2025. Sally will summarise the symposium and its findings.

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.

Strip-till and under-sowing cover crops in maize

Rene Van Tilburg is the Senior Maize Researcher at FAR, leading the development of the maize research strategy and overseeing a range of trials. He focuses on identifying the constraints that limit yield and productivity, with a particular interest in moving beyond simple comparisons to understanding the mechanisms that drive system performance. His work emphasises understanding how and why systems respond, creating opportunities to better manipulate them to a grower’s advantage. This approach underpins the current research strategy and trial programme, which reflects a shift toward mechanism-driven research to improve on-farm outcomes. Rene will discuss his observations from trial work with strip-till and with establishing cover crops into standing maize.

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The winter cover crops in the Carbon Positive trial plots are well underway now. The last dull, wet, cold week slowed them down a little, but they still made good progress. The preparation and planting was covered in an earlier post that you can see here>

To the left of the central irrigator strip, the Regenerative plot triticale and vetch established fastest and by April 20 had reached 28% ground cover as measured using Canopeo, a brilliant free app that we use for all our weekly assessments regardless of crop (or fallow!). By contract, the ryegrass was slower to get started and on April 20 the Conventional plots averaged 5% ground cover, and the Hybrid plots a little more at about 8% cover as seen in the chart below. As well as getting underway quicker, the triticale and vetch is accelerating away. We had expected the ryegrass to be fastest, as that was what we observed in previous winter cover mixes, but a higher sowing rate of vetch and the triticale seems to be a good option at this stage.

There is some banding in the plots that seems to be an artefact of planting, but we’re not sure why. It lines up exactly on the planter but may relate to the discing and rolling that happened prior.

We continue our weekly monitoring, and assume that by next week, the Regenerative plots will have crossed the magical, but arbitrary, 30% ground cover faction. How long before the ryegrass plots reach that milestone?