Category Archives: Research

Agronomy, Farm Management, Nutrients, Projects, Research, Tillage, Vegetables, Workshop

Nitrogen for Asparagus Crops

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With support from the New Zealand Asparagus Council (NZAC) and funding from Our Land and Water, we undertook a rapid project to investigate best practice for nitrogen management in asparagus crops. 

One of the trial plots, set up to assess the effect of different nitrogen fertiliser rates on the yield of asparagus

It was a very difficult season for growers, with low prices, high staff shortages and the effects of the Covid pandemic. A number of growers did not harvest any crop this season. Many stopped their harvests early.

Although the project is “finished” we still have a little post-project work to do. We want to follow the crops over the next harvest to see what if any difference we can see after growers applied different rates of nitrogen fertiliser. So, with continuing support from the NZAC and growers, that’s our intention between now and Christmas. 

What did we do?

  1. We did a literature review to see what others had found
  2. We surveyed a number of growers about fertiliser and nitrate management practices. 
  3. We established five trials, two in Hawke’s Bay and one each in Mangaweka, Manawatu and Mid-Canterbury. 
  4. We offered fertiliser spreader calibrations and used the fertspread tool to complete calculations and produce reports
  5. We ran a webinar discussing on-farm trials, and interpretation of soil test results

What have we found so far?

Literature review

We reviewed literature from New Zealand, US, USA and Germany and found a reasonable agreement between the different sources. In brief: 

  • Current nitrogen fertiliser recommendations are based on limited trial work
  • Roots will grow to and extract nitrogen from at least 80 cm of soil depth
  • Nutrient deficiency symptoms are not common and careful fern and root testing are needed to see if they exist
  • While analysis of fern growth to assess nutritional status is recommended, little guidance on interpretation is given
  • Soil testing should take in the whole root depth, but there are few guidelines to establish fertiliser rates
  • Sufficient nitrogen fertiliser to grow healthy fern should be applied during the establishing years, though recommendations are few
  • Once established application, if any, should be based on replacing nutrients removed during harvest, which is about 5 kg N/tonne of spears exported
  • Research showed 75 kg-N/ha could support a crop for three years without a detectable change in fern nitrogen concentration
  • Fertiliser should be applied close to fern growth which is when uptake occurs. This will minimise leaching risk, especially on shallow or low water holding soil types

Grower Surveys

From a posted survey and detailed surveys of trial growers, we compiled some industry generalisations.

  • We found a wide range of nitrogen management practices, not indicative of a single agreed industry best practice
  • Growers follow good practice transporting and storing fertiliser
  • In general, fertiliser if any is applied at the end of harvest just before fern growth
  • Surveys showed only some growers prepare formal documented nutrient budgets, but
  • Most consider most of the relevant variables when determining how much (if any) fertiliser to apply
  • Growers do keep good fertiliser application records
  • About 60% of growers soil test annually, to 15 cm depth
  • Equipment is generally checked for accuracy, and about half are formally certified
Checking fertiliser application rate using the fertspread protocol and free online calculator

Fertiliser Trials

We need the yield data from the coming season to understand what, if any impact different rates have had on production. 

  • Limited yield data have collected so far, but what we collected and reported typical yields from our grower surveys are generally similar to those reported by Hunt et al. (2019).
  • About 12 – 13 kg N/ha is exported in the harvested crop (some with high yields are more)
  • Soil nitrate levels measured in late spring and summer were fairly consistent, but by the end of fern growth in winter, there was very little soil nitrate remaining
  • Spring and summer nitrate must be from mineralised fern residues, some decayed roots, and nitrogen fixing microorganisms, as no fertiliser had been applied

Soil nitrate levels (kg NO3-N /ha) in upper 45 cm of profile by season as determined by the Nitrate Quick Test and FAR online conversion

  • Some growers apply no fertiliser (especially this season)
  • Some growers reported applying up to 69 kg N/ha 

  • Fresh root mass was highly variable with a minimum at the end of harvest, and a maximum at the end of fern growth.
  • While roots can grow deeply, most of the soils in our trials had limitations from wetness or stones at about 45 cm.
  • The fresh root mass in summer at the end of harvest was 26,300 kg/ha, increasing to 91,700 kg/ha in winter after fern growth
  • The average concentration of NO3-N in root tissue was 1.38% of dry mass
  • At the end of fern growth (which feeds spring spear production), about 80% or more of the nitrogen in the system was found in the roots

Data we collected are generally in line with published research. 

Webinar

Covid and staff shortages left few growers able to travel to seminars. So we ran a webinar and discussed some of the key points for running on-farm fertiliser rate trials.

We are grateful to Alex Dickson for her presentation about interpreting soil tests. Taking report examples from the three main soil laboratories, Alex explained what the tests meant and how a grower can use the information. 

We recorded the webinar, so you can view the presentations:

Many thanks to the growers hosting and supporting the trials, and the NZAC and Our Land and Water for support and funding.

Agronomy, Projects, Research, Weeds

Identification of Herbicide Resistant Weeds in NZ

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Chris Buddenhagen told the folk at the 2022 LandWISE AGM Seminar in late June about research progress in the AgResearch Managing Herbicide Resistance programme,

Working with FAR, the Bragato Research Centre, and Massey University, AgResearch scientists are surveying arable farms and vineyards for presence of herbicide resistant weeds. They have collected seed from across Aotearoa including Canterbury, Otago, Marlborough, Waikato, Bay of Plenty, Gisborne, Hawke’s Bay and Wairarapa.

The first time a deliberate survey looking for examples of herbicide resistance has been conducted, the research is adding to the number of known cases in New Zealand.  As can be seen in the chart below, grasses feature prominently, some to several herbicide groups.

Chris explained that resistance results from plants with certain genes or sets of genes being preferentially selected by the management to which they are exposed. Plants constantly mutate, and a constant exposure to a certain stressor (in this case a herbicide group) means those that cope best will survive and, over time, become the dominant population. 

To identify resistance, seed has been collected from suspected survivors and from soil samples taken from the survey sites.  The seeds are germinated in a greenhouse, and sown in trays for testing.

Once established, the trays are sprayed at a defined spray rate, and plants observed for about three to six weeks. 

After a few weeks, the results of spraying become apparent. Some lines are shown to be susceptible to a particular spray, and others resistant.

Identifying resistance this way is slow and expensive. The project is also investigating other rapid testing techniques including the use of genetic markers so any plant sample can be tested virtually overnight, and at much lower cost. But that’s a story for another day.

If you want to read about the Herbicide Survey work in detail, information from the first surveys is available online as an open access publication.

See:  Buddenhagen CE, James TK, Ngow Z, Hackell DL, Rolston MP, Chynoweth RJ, Gunnarsson M, Li F, Harrington KC, Ghanizadeh H. 2021.  Resistance to post-emergent herbicides is becoming common for grass weeds on New Zealand wheat and barley farms.  Uludag A, editor. PLoS ONE. 16(10):e0258685. https://doi.org/10.1371/journal.pone.0258685

We thank Chris, Trevor James and all involved in the work for presenting it to the LandWISE Seminar participants.

Agronomy, Fertiliser, Nutrients, Projects, Research, Soil, Vegetables

Update – BMPs for Process Vegetable Crops

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Run in conjunction with McCain Foods, Heinz-Watties and Hawke’s Bay Regional Council with support from the Sustainable Food and Fibre Futures fund, this  project builds on work started under the Future Proofing Vegetable Production project.

Focusing on sweetcorn, tomatoes, beetroot and green beans, we are comparing current farm practice with either the “Nutrient Management for Vegetable Crops in New Zealand” guidelines or some alternative rate. 

Despite a late start and tricky spring, we established trials in six Hawke’s Bay paddocks, with solid support from the farmers and process companies.

Callaghan Innovation Summer Student Bram Paans deep sampling soil at sweetcorn trial establishment

Our summer intern, Bram helped considerably in getting trials established, taking many soil samples and conducting numerous Nitrate Quick Tests, supported by lab analyses completed by Eurofins. 

Nitrate Quick Test sampling supported grower decisions about fertiliser applications (or not)

We harvested five full trials; 1 green bean crop, two tomato crops and two sweetcorn crops. The data are still being analysed – results at the LandWISE AGM Seminar in June.

Picking and grading tomatoes at trial harvest

A sixth crop of beetroot  ended up with no alternative fertiliser rate after the last application was deemed not only unnecessary, but likely to result in oversize bulbs for the baby-beet specification.

Similar trials in 2022-2023 will provide information of practice and effects on the same crop selections in a different season. 

Many thanks to McCain Foods, Heinz-Watties and Hawke’s Bay Regional Council for co-funding, the farmers hosting trials, and MPI for financial support.

    

Agronomy, Fertiliser, Nutrients, Projects, Research, Vegetables

Nitrogen Best Practice for Process Crops

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This summer we began a new two year project investigating nitrate rates for process crops. Run in conjunction with McCain Foods, Heinz-Watties and Hawke’s Bay Regional Council with support from the Sustainable Food and Fibre Futures fund, this builds on work started under the Future Proofing Vegetable Production project.

Focusing on sweetcorn, tomatoes, beetroot and green beans, we are comparing current farm practice with either the “Nutrient Management for Vegetable Crops in New Zealand” guidelines or some alternative rate. 

The aim of this project is to validate the recommendations in the current best practice guide (“the book”) for one of the region’s largest industries. 

Along with comprehensive lab testing, a key tool we are using is the Nitrate Quick Test developed by the University of California – Davis and testing in New Zealand by Plant & Food Research. There’s helpful information on the FAR website. 

We have four plots of “grower practice” and four of an alternative which we are monitoring. Before any fertiliser is applied we do base measurements of the soil at three depths, covering the full root zone. Prior to side-dressing we repeat the tests to see how much nitrate is present. This takes into account any additions of fertiliser, mineralisation of organic matter and uptake by the crop. We repeat the measurements when the crop is harvested to see how much nitrate is in the crop, and how much is left in the soil. 

Many thanks to McCain Foods, Heinz-Watties and Hawke’s Bay Regional Council for co-funding, the farmers hosting trials, and MPI for financial support.

   

Agronomy, Fertiliser, Nutrients, Projects, Research

Asparagus Nitrogen Best Practice

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Together with the New Zealand Asparagus Council, we were fortunate to obtain funding from “Our Land and Water” to investigate nitrate best practice management.

We surveyed a number of growers about fertiliser and nitrate management practices. We find growers generally have good management for transport, handling and storage. We see a wide range of practices for nitrate management including rates and timing, and this is what we are trying to understand.

We have established five trials, two in Hawke’s Bay and one each in Mangaweka, Manawatu and Mid-Canterbury. We are monitoring nitrate levels in soil, roots and fern, to build a picture of how the amounts move between these pools.

As part of the project we offered fertiliser application equipment calibration, and the machines tested were doing an acceptable job. We used the fertspread tool to complete calculations and produce reports.

While a large number of samples have been sent to the Eurofins lab for analysis, we are also using the Nitrate Quick Test to assess nitrate in the soil at three depths in each plot.  When we compare the results of the quick test with lab results, we find a good agreement. The key is making sure the soil sampling is done correctly so it is representative. 

Many thanks to the growers hosting and supporting the trials, and the NZAC and Our Land and Water for support and funding.

Agronomy, AgTech, Conference, Data Analytics, Fertiliser, Innovation, New Crops, Nutrients, Orchard, Orcharding, Plant Health, Precision Agriculture, Projects, Research, Robotics, Sensing, Soil, Vegetables, viticulture, Water, Weeds

LandWISE 2021: Working Smarter

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Havelock North, 19-20 May 2021

Thanks to everyone who made LandWISE 21 such a successful Conference!

We were a touch nervous after Covid-cancelling last year, but so heartened when our sponsors jumped on-board, and delgetaes began registering earlier than usual. Perhaps there was a vacuum . . .
The speakers’ presentations are summarised in a series of blog posts, many with a short sound clip. The time put in to create the presentations is clearly huge, it is a very large gift each one makes. Thanks each and every one of you!

Topics covered:

  • Best Practice and Beyond
  • Future Proofing Vegetable Production
  • Carbon and Water
  • Smart Technologies for Permanent Crops
  • Herbicide Resistance Management
  • Agritech in NZ and Hawke’s Bay

Jump to the Conference Page for links to presentations

Agronomy, Conference, Fertiliser, Innovation, Nutrients, Research

Change on the Horizon – Jamie Blennerhassett

Dr Jamie Blennerhassett is opening LandWISE 2021 asking the questions,
“What are the future challenges to the primary industry and where might they come from?”

Jamie looked at the opportunity to get ahead of those challenges so that we not only survive as an industry but thrive.

Future environmental trends, regulations, technology threats and opportunities

Anyone with a passing interest in the news will see daily items covering the impending catastrophe of climate change and the ongoing decline of our freshwater resources. Alongside these stories, you will also likely see reporting on regulatory reform introduced to deal with these challenges as well as the resultant dissatisfaction from farmers at the scale and pace of those regulatory changes.

Should any of this have been a surprise? In short the answer is no. We have been aware of declining water quality and a changing climate from human caused greenhouse gas emissions for well over 20 years, as firstly scientists, then environmentalists and lastly the wider public sounded alarm bells and raised concerns around human caused impacts on the environment. The resulting outcome in the shape of regulatory change was inevitable as the voice of the people took effect.

So as we sit here now and reflect on the fact that the regulatory response was entirely predictable by following the science and the subsequent consumer/community desires, what are the next issues that will drive regulatory change and how do we get out in front of the change?

Topics such as indigenous biodiversity and water use efficiency are obvious places to start as they gain increasing attention from scientists and environmentalists alike. While many consumer trends come and go, particularly around things like fashion and diets, trends linked to the environment and sustainability have been consistent and growing for well over 20 years and usually follow the science. 

By looking to the science, we likely allow ourselves an early insight into the next consumer trends and a chance to get ahead of the curve in the premium end of the market by setting up our farming systems to solve for these problems. Not only will this allow us to win in the market place, it will likely have us well placed for the next wave of regulatory change that will invariably follow shortly behind those consumer demands as they then turn into the voice of the people at the ballot box.

Listen to a Summary SoundClip here:

Jamie is the Innovation Leader at Ballance AgriNutrients. He has 20 years’ experience in the fertiliser industry across a range of leadership roles from science and new product development to sales management.

Jamie has a PhD in soil science from Massey University and has a passion for finding an optimum balance between the need for efficient food production and protecting our natural environment.

Ballance AgriNutrients is a proud, and longstanding sponsor of the LandWISE Conference, the LandWISE MicroFarm and our “Future Proofing Vegetable Production” project.

Conference, Nutrients, Research, Water

Nitrogen Attenuation – Stephen Collins

Stephen Collins is a groundwater scientist for Horizons Regional Council where his job involves managing the monitoring and research aspects of the region’s groundwater resources. A particular research interest of his is understanding land use effects on water quality, which has culminated into him undertaking a PhD part-time.

Stephen’s research is on refining estimates of subsurface nitrogen attenuation. At LandWISE 2021, he discussed nitrogen attenuation and how more accurate predictions of it can help improve overall catchment management.

Abstract:

Subsurface nitrogen attenuation – a key unknown in modelling catchment-scale water quality scenarios

Collins, S.,1, 2 Singh, R.,1 Horne, D.1 & Roygard, J.2

1Massey University, Farmed Landscapes Research Centre (FLRC), Palmerston North

2Horizons Regional Council (HRC), Palmerston North

Subsurface nitrogen attenuation is a measure of how much nitrogen is removed in the subsurface environment below the farm root zone, varying from very low rates in some places, to very high rates elsewhere. In other words, some land units appear more resilient in dealing with nitrogen losses compared to others.

An effective understanding of where and when subsurface nitrogen attenuation occurs, and by how much, can have a significant impact on the way nitrogen losses to waterways are modelled and managed in a catchment, especially when water quality improvements are needed.

Where water quality improvements are required, catchment-scale water quality scenarios need to be developed that take account of attenuation dynamics. However, subsurface nitrogen attenuation appears to be spatially variable across different hydrogeological settings, leading to uncertainty in the modelling of those scenarios. Therefore, a robust method of predicting the spatial variability, and potential rate, of subsurface nitrogen attenuation across different hydrogeological settings in agricultural catchments is needed.

The primary nitrogen attenuation pathway in subsurface environments is denitrification, a microbially-facilitated biogeochemical process that reduces nitrate into predominantly ‘benign’ di-nitrogen gas. This process is governed by a range of physical, chemical and biological characteristics that influence ‘reduction-oxidation’ (redox) conditions in hydrogeological settings. Subsurface redox conditions can broadly be described as either reduced (where dissolved oxygen is low) or oxidised (where dissolved oxygen is abundant). Denitrification mainly occurs in reduced conditions.

Though the science of subsurface denitrification processes is being increasingly studied and better understood, the challenge yet remains to achieve a robust method of predicting the spatial variability, and potential rate, of subsurface nitrogen attenuation across different hydrogeological settings.

Direct measurements of denitrification is practically complex and resource intensive, and therefore not easily measurable over large spatial scales. However, the opportunity to meet this challenge potentially comes from the ability to use easily measurable groundwater quality parameters to assess groundwater redox conditions as a suitable proxy for nitrogen attenuation in subsurface environments. Further, groundwater redox conditions show a strong relationship with some landscape attributes such as soil drainage, permeability, rock type and soil texture.

To aid this research, Massey FLRC and HRC are collaboratively investigating how to refine, measure and account for subsurface nitrogen attenuation in New Zealand landscapes to inform modelling of catchment-scale water quality scenarios.

Listen to a Summary Sound Clip here:

Agronomy, AgTech, Conference, Fertiliser, Nutrients, Projects, Research, Soil, Vegetables

Making the Right Fertiliser Decision – Luke Posthuma

LandWISE Precision Agronomist, Luke Posthuma has lead our Future Proofing Vegetable Production project since arriving in 2019. He established and owns GrowMaps, a precision mapping company and has a passion for farming and horticulture.

Through the SFF Future Proofing Vegetable Production project, we have seen time and again that fertiliser savings can be made by applying the right rate of nitrogen fertiliser based on cropping goals and soil test values.

Last summer’s sweetcorn trials demonstrated that there was little value in switching to more ‘efficient’ forms of nitrogen where the application rate is already higher than required. Following on from last year’s work, this summer we set up 12 sweetcorn and 6 field tomato split-paddock trials in Gisborne and Hawke’s Bay to test two grower tools. We compared current grower fertiliser practice with a side-dressing rate determined using either the FAR Nitrate Quick Test Calculator or the HortNZ Nutrient Management Guidelines for Vegetable Crops.

Using the grower’s expected yield for a given planting, a pre-plant soil test with a potentially available N result and a Nitrate Quick test soil test collected to 90cm just prior to side-dressing, we found growers could often* (please note – not always) get away with significantly less nitrogen than they expected to apply. 

For growers facing continued environmental pressure, soil testing is a tool that can be used to justify nutrient applications. A nitrate quick test costs less than $2 plus the time taken to collect the soil sample. The Nitrate Quick Test will show whether more or less fertiliser is required, and if your current fertiliser plan is about correct.

Taking soil tests at harvest, we found that by using less nitrogen at side-dressing, we had also reduced the nitrogen in the soil profile at harvest. Minimising excess nitrogen left in the soil after harvest will reduce over-winter nitrogen leaching from a cropping paddock.

Deep Soil Sampling for Nitrate
Deep Soil Sampling for Nitrate

We want to apply sufficient nitrogen to maximise crop yield without leaving significant quantities in the soil after the crop is harvested. Following good practice means applying the right rate of fertiliser for each of your crops. The right rate will vary based on the soil test results and your expected yields.

Listen to a Summary Sound Clip here:

Agronomy, Conference, Cover crops, Fertiliser, MicroFarm, Nutrients, Orcharding, Plant Health, Research, Soil, Tillage, Vegetables, Water

Growing Soil Carbon – Phil Schofield

Phillip Schofield is a soil scientist and rural professional, working with growers and farmers, helping them improve soil function and hence profit.

He holds a B Ag Sci (hons) and a PhD, is a Certified Nutrient Management Advisor and Certified Green House Gas Advisor. Phil is a founding Board Member of the HB Future Farming Charitable Trust.

Phil provides farmers and growers with soil health advice and adapt production systems to improve farm performance and profitability in the face of increasing compliance and regulation.   

At LandWISE 21, he asked: Why is soil carbon important? How might we increase it?

Atmospheric CO2 is a greenhouse gas, responsible for global warming. The IPCC reports that soil holds two to three times as much carbon as the atmosphere, so the 4.5 billion ha of pastures and croplands are an immense source or sink.

Plants fix carbon dioxide by photosynthesis, and this provides a mechanism to move CO2 from the atmosphere to the soil. Human activities release about 9 GT C/yr. so increasing soil carbon by 0.4% would account for much of our emissions. It would also improve soil health and set us up better for climate change. Atmospheric CO2 can be sequestered. Plants exude 30% of their sugars through their roots, providing energy and raw materials for synthesis by other organisms.

Soils that contain more carbon have more humus to hold particles together, provide a better environment for root growth, hold more nutrients and hold more water. However, many of our current practices degrade soil. Regenerative practices address soil health by minimising disturbance, keeping the soil covered, always keeping living roots in the soil, increasing plant diversity and introducing grazing animals.

The HB Future Farming Trust aims to establish a series of trials partnering with industry, HBRC, CRIs and MPI. One set is a replicated trial proposed for the LandWISE MicroFarm, with further demonstration trials on orchards, vineyards, and arable and vegetable properties.

Trial sites will be heavily monitored, benchmarking soil physical, chemical and biological properties, nutrient and GHG budgets, water, energy and financial analyses of the enterprises.

Listen to a Summary Sound Clip here: