All posts by LandWISE Admin

Nitrogen for Asparagus Crops

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.

Identification of Herbicide Resistant Weeds in NZ

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.

Non-Herbicide Weed Management

Dr Charles ‘Merf’ Merfield is running an updated version of his non-chemical weed management workshop. Merf is an international researcher on non-chemical weed management. He has 30 years practical and research experience in non-chemical weed management including inventing a range of weeding machinery.

Topics covered include: the context of weed management; essential weed biology and ecology; integrated weed management; plus detailed coverage of field operations and machinery. It will also cover the significant advances in electrothermal weeders that are a substitute for glyphosate, as well as robotic weeding which has been advancing at incredible speed.

The workshop will be at the Agrodome in Rotorua on Tuesday 26 July, from 9am to 5pm. Cost is NZ$450.00 excl. GST.

For more information including how to register, please click here>.

 

Update – BMPs for Process Vegetable 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  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.

    

LandWISE Conference 2022

CONFERENCE CANCELLED

Once again we are regrettably cancelling the LandWISE Conference.  The Board determined that too many organisations are struggling to keep teams operating with Covid and that encouraging people to gather is not wise. Some of our most loyal supporters suggested they would not want staff to attend this year.

Our strongest hope is that we can gather again in 2023. In the meantime, we are investigating another podcast/webinar series. If you have a topic you’d like explored, contact us!

Many thanks to our sponsors and supporters who had offered to provide assistance again in 2022. Hopefully, we’ll have and event in 2023.

 

Nitrogen Best Practice for Process Crops

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.

   

Asparagus Nitrogen Best Practice

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.

Bram, our 2022 Summer Intern

With support from Callaghan Innovation, we were delighted to welcome Bram Paans to LandWISE for the summer season. Bram has just completed a B Hort Sci and Massey University, and is returning to undertake Master of Horticultural Science studies in 2022.

Bram spent much of the summer sampling the asparagus and process crops we are researching, and doing many, many Nitrate Quick Tests. Here he is taking soil samples from a squash paddock as part of the Sustainable Vegetable Systems project being run by Vegetables Research and Innovation, Potatoes NZ and Agrilink. 

We were delighted to host Bram this season, and to show him some of the farming systems we work with and research methods we use. 

Many thanks to Bram, and Callaghan Innovation for support via the R&D Experience grants programme. 

Smart Tools for Orchard Drainage Field Walks

Project Wrap-up and Trial Results

Come and see how land shaping rows can be used to minimise rutting in your orchard.

Gisborne, 9th June 2:00 – 4:00pm 
Illawarra Orchard, 635 Awapuni Road.  

Hastings, 10th June, 1:00 – 2:30pm.
Bostock Red Barn Orchard, 247 Lawn Rd. 

Riwaka,14th June,1:00 – 2:30pm
T&G Riwaka Site, 657 Main Rd, Riwaka 

**Covered shoes, HiVis, No agrichemicals at Red Barn please**

RSVP info@landwise.org.nz or by text to Luke 022 479 6805

Future Proofing Vegetable Production Workshops

Gisborne

9 June 2021 10:00am – 12:00 noon
Bushmere Arms, 673 Matawai Rd, Gisborne

  • Key Lessons from “Future Proofing Vegetable Production”
  • Results from Summer Nitrogen Side-Dressing Trials
  • Review of Tools to Simplify your FEP Compliance
  • Wrapping up your Farm Environment Plan

Levin

15 June 2021 1:00 – 3:00 pm
The Mahi Space, 10 Bath St, Levin

  • Key Lessons from “Future Proofing Vegetable Production”
  • Results from Summer Nitrogen Side-Dressing Trials
  • Cover Crops for Intensive Vegetable Rotations

All are invited to attend these FREE workshops

Please RVSP your attendance to info@landwise.org.nz or by text to Luke on 022 479 6805