Category Archives: Research

Variable Rate N Fertiliser – the Value Proposition

Adrian Hunt is a crop scientist at Plant and Food Research.

He recently completed a PhD at the University of Tasmania, investigating Pre-Harvest and Post-Harvest factor effects on the quality of onion bulbs exported to Europe for counter seasonal supply.  He now works across the vegetable and arable sectors to improve yield, profitability and environmental outcomes.

Together with colleagues Joanna Sharp, Paul Johnstone and Bruce Searle, Adrian has been investigating the value proposition for variable rate fertiliser application.

The technology to deliver variable rate fertiliser in an automated manner has advanced substantially in recent years. This has been aided by new or adapted spreading technologies coupled with location awareness using GPS (Global Positioning System). It is now technically possible to distribute fertilisers in a wide range of spatial patterns within a paddock, however the value proposition of variable rate fertiliser application is not thoroughly understood.

The Plant and Food team looked at the difference in productivity, profitability and potential environmental impact of a range of spatial management scales.

Based on a sampling grid of 105 points in a Hawke’s Bay paddock and used mineral N and a N mineralisation assay to quantify the underlying variability in N processes/cycling within the paddock they “grew” both irrigated and unirrigated maize in the crop simulation model APSIM Next Generation for the 105 sampling locations for 35 growing seasons, using long term weather data.

Adrian will present this work and the results at the LandWISE 2017 Conference in Havelock North.

Onions NZ Research Workshop

Improving the profitability of onions

Wednesday 10 May 2017 1:30pm to 5:00pm
Campbell Tyson Business Centre
Level 2, 1 Wesley Street

Come along to hear and discuss results from the second seasons of the Onions NZ/MPI Sustainable Farming Fund project “Enhancing the profitability and value of NZ onions” presented by LandWISE Inc. and Plant and Food Research. You will also be able to contribute to the research plans for the next season of this project.

In addition, recent research conducted by Plant and Food Research on the impact of soils on soil borne diseases as well as work completed by the industry’s two PhD scholars will also be presented.

This Workshop is free to Onions NZ members but registration is essential.

Please register attendance by emailing James Kuperus with the names of who you are registering (if it is more than just yourself).

Click here for the programme

Report on Australian SPAA Expo 2017

Hugh Ritchie reports from the 2017 Expo


The Society of Precision Agriculture (SPAA) is a non-profit and independent membership based group formed in Australia in 2002 to promote the development and adoption of precision agriculture (PA) technologies.

I attended the SPAA expo in March this year which was a grower focused day to present the latest tools and services available to growers. All speakers were service providers or users of the technology as opposed to researchers presenting their studies. This made for a day of very applied learning.

A common theme of the day was that tools selected had to deliver a positive return; i.e. they had to earn their keep. This was very good to hear as I feared I would be seen as a laggard to comment on the lack of variable rate and prescription maps. Most of the speakers identified a problem and the use of tools to find a solution.

There was also a range of farm types and again the message was any one can use PA concepts and you do not need to have high tech tools to practice PA.

The work with Near Infrared, Infrared and Short Wavelength InfraRed has come a long way and the work being done by Dr Ian Yule from Massey University leads the way. Of special interest was a camera manufacturer who could allow you to choose which bands you required and build a camera to suit at an affordable cost, putting this technology in everyone’s hands.

So, if we can do the research around what we want to sense and which wavelength it requires we could get real time data to enable prescriptions without the need to ground truth. This would be the next major leap forward in PA tools.  

Tree climbing robots in forestry

Richard Parker

Richard Parker is a Senior Scientist at Scion in Christchurch.  His research focuses on difficult, dangerous and essential occupations such as forest harvesting and rural fire fighting from the perspectives of human factors and technology.  

Richard is involved in the development of novel robots for forest operations and the human factors of forest work. He was a tree faller and breaker out in a former life.  He is also leads research on rural fire fighter performance and new technologies for fire detection and suppression and is a volunteer rural firefighter.

Delegates at LandWISE 2017: are we ready for automation? will hear Richard say that robotics is inevitable in forestry as specialised machines for forest tasks are developed.  The mining industry already has a history of robot development and automation and forestry is learning from their experience. However, forestry has particular challenges – much of the commercially forested land in New Zealand is on steep and remote terrain. 

Forest harvesting operations have been traditionally considered physically demanding and potentially dangerous, with forest workers on foot exposed to heavy and fast-moving trees, logs and machinery.  Many tasks in forestry have already been mechanised to reduce hazards to the worker and increase productivity.  For example, the axe was replaced by the chainsaw, which was replaced by the excavator based harvesting machine.  However large machines can damage the sensitive forest soils and cannot work on steep terrain where many forest grow.  This presentation will discuss the next stage of forest machine development which uses the standing trees for support.

Animals have lived in the trees for millions of years and have developed behavioural, structural and physiological adaptations to the arboreal environment.  Some animals move slowly from branch-to-branch like the stick insect.  Others, such as gibbons, can move rapidly using brachiation, engaging in the arboreal equivalent of running through the forest from branch to branch.  An opportunity exists to use this form of locomotion, although more slowly than gibbons, for the movement of forestry machinery. 

The proposed machine could always stay above ground moving from tree-to-tree using the trees for support. The machine would eliminate the problem of soil disturbance and would not be limited by terrain steepness.

Bottle Lake Trial Robot

With funding from Scion, the Ministry for Primary Industries and the Forest Growers Levy Trust, the concept of a tree-to-tree forestry machine became real.  Scion and University of Canterbury Mechanical Engineering and Mechatronics students built a working radio controlled tree-to-tree locomotion machine. Development of a real machine demonstrated that being independent of the ground makes operator control easier because the ground conditions (holes, rocks, loose soil) do not have to be adjusted for.

Supporting digital innovation

We are delighted that Dr Amanda Lynn is confirmed as a key speaker at our Annual AgTech Conference LandWISE 2017: Are we ready for automation?

Amanda’s focus for this event is on moving “change” away from something that happens to us, to something we do as a natural part of our personal, business, economic and social development. This is called “purposive change” and she will explain how we create, adapt and integrate it.

When we talk about change we often do so without a clear idea of what is meant, and without recognition of our own—individual and collective—roles in adapting to change, or even catalysing it. 

We seldom talk about levels of change and processes of development; instead, getting caught in black and white terminology like “disruption” and forgetting that change is natural, incremental and evolutionary. 

Innovation is purposive change.  We can sometimes forget that purposive change is something we—people—are very, very good at.  And there’s a lot of us; resulting in a lot of purposive change. 

The Executive Director of the Innovation Partnership, and Chair of the Innovation Partnership Forum,  Amanda specialises in development. 

The Innovation Partnership is a not-for-profit Trust.  Sponsored by Google, Chorus and InternetNZ, the Innovation Partnership connects businesses, educators and Government entities to support digital innovation. 

In addition to working with the Innovation Partnership, Amanda leads her own contracting enterprise, Mandolin Associates, undertaking public speaking, research and advisory services, and through this has worked closely with some of New Zealand’s leading agriculture and aquaculture innovators. 

Amanda is a member of the New Zealand Association of Economists, and a Professional Member of the Royal Society of New Zealand.

Is the Juice worth the Squeeze?

Chris Roberts

Chris Roberts, Head of Industrial Robotics at Cambridge Consultants UK is confirmed as a keynote speaker for our Annual Conference. LandWISE 2017: Are we ready for automation?

Cambridge Consultants is a world-class supplier of innovative product development engineering and technology consulting with more than 500 staff including scientists, mathematicians, engineers and designers.

Chris was one of the presenters at AgriTech-East’s Robotics Pollinator in October 2016, which Dan attended as part of his Trimble Foundation Study Trip investigating farm robotics.

“I was really impressed with Chris and his presentation. He worked clearly  and methodically through the issues that need very careful consideration.” 

In this presentation Chris will take a look at the prospects for robotic fruit harvesting, an issue of note in New Zealand as production levels rise and labour availability reduces.

Some of Chris’ questions:

  • Automation has existed in agriculture for decades: what’s new?
  • Why hasn’t it happened everywhere already?
  • Which tasks to automate?
  • What has to come together for a  successful harvesting robot?

Chris will address these questions and more at LandWISE 2017.

Refill Scheduling for Agricultural Robots and Other Vehicles

Rob Fitch

Refill scheduling is the problem of deciding when a robot or other agricultural vehicle should pause in its work to replenish a resource, such as herbicide or fuel. This problem is commonly solved in broadcast spraying, for example, by simply running the spray tank dry and then refilling it.

This strategy actually leads to lost time in traveling to the refill location, and we can show that these time losses can be significant. When multiple machines must queue at a refill location, the problem is made worse.

In this talk, Rob will explain the theoretical difficulty of this problem and give examples from robotic spot-spraying and broadcast spraying to illustrate the potential time losses. He will present an optimisation approach that chooses optimal refill times to minimise travel distance and queuing time. These results apply to agricultural robots, human-driven spray rigs, and any other machine that must refill or empty some material at a fixed location during the course of its work.

Rob will conclude the talk by tying these results into the larger research program in agricultural robotics, including novel machine learning methods for fruit/vegetable detection that support selective harvesting.

Rob Fitch is Associate Professor at University of Technology Sydney.He was previously a Senior Research Fellow with the Australian Centre for Field Robotics (ACFR) at The University of Sydney where he retains an honorary position. He is a leading research scientist in the area of autonomous field robotics. He is interested in systems of outdoor robots and their application to key problems in agriculture and environmental monitoring.

Robert received his PhD in computer science from Dartmouth (USA). He has led research in planning and collaborative decision-making for both ground and aerial robots in a variety of government and industry sponsored projects including those in broad-acre agriculture, horticulture, bird tracking, and commercial aviation.


Field day – mesh crop covers for insect and blight control on potatoes

Tuesday 14 March 9.00 am – 11.00 am

FAR field site, North West corner of Springs and Ellesmere Junction Roads, Lincoln Google map.  Access off Springs Road, 300 m north of Roundabout.

Join FAR, Potatoes NZ, and the BHU Future Farming Centre for a roundup of results to date on the use of mesh crop covers for potato pest & disease control and the findings from the current field trial. 

  • How mesh covers are controlling blight
  • Mesh and tomato potato psyllid TPP control
  • Aphids and mesh
  • Potential yield boost from mesh due to improved microclimate

Get reports from the first two years trials here

Tomato potato psyllid (TPP) (Bactericera cockerelli) arrived in New Zealand in 2006 and has proved to be a important pest in a number of solanaceae crops, including potatoes.  While insecticides have proved effective for its management, this has caused a large increase in agrichemical use which is undesirable, and this option is not available to organic growers.  A ‘non-chemical’ means of controlling TPP is therefore desirable.  Mesh crop covers are such a non-chemical control: they are akin to fly screen for crops. They are extensively used in Europe for controlling a wide range of pests on an equally wide range of crops by both organic and mainstream growers. 


Prior research by the FFC made the serendipitous discovery that mesh crop covers are not only an effective barrier to TPP but they are also achieving significant potato blight (Phytophthora infestans and/or Alternaria solani) control.  A correlation has been shown between a reduction in UV a & b light levels and blight and also TPP symptoms. 

As mesh can keep out a wide range of potato insect pests, including those that are resistant to insecticides, such as tuber moth, it has the potential to be a single non-chemical solution to both insect pests and blight on potatoes.  As potatoes are the 4th most important food crop globally, with more grown in the developing world than the developed world, the potential global impact in terms of reduced agrichemical use is considerable.

However, potato aphids, mostly Myzus persicae, are penetrating the mesh, even mesh that has sufficiently small holes to exclude winged (and wingless) adults.  Once inside the mesh, their populations can explode due to the absence of beneficial insects, in effect, it is an unintentional experiment on the level of biological control of aphids. 

Mesh with sufficiently small holes to exclude immature aphid instars has been tested and resulted in a second serendipitous that the fine mesh appears to be modifying the under mesh micro-climate resulting in increased yields, while also improving blight control. 
Such very fine mesh has the potential therefore to completely control all potato insect pests, as well as blight and increase yield through entirely physical means. 

The field day will provide an opportunity to hear more about the research as well as viewing mesh on potatoes.


Benchmarking Onion Variability 2016-17

Now in year two of our OnionsNZ SFF project, we have trials at the MicroFarm and monitoring sites at three commercial farms in Hawke’s Bay and three more in Pukekohe.


A summary of Year 1 is on our website. A key aspect was testing a range of sensors and camera systems for assessing crop size and variability. Because onions are like needles poking from the ground, all sensors struggled especially when plants were small. This is when we want to know about the developing crop, as it is the time we make decisions and apply management.

By November our sensing was more satisfactory. At this stage we captured satellite, UAV, smartphone and GreenSeeker data and created a series of maps. 

We used the satellite image  to create canopy maps and identify zones. We sampled within the zones at harvest, and used the raltioship between November canopy and February yield to create yield maps and profit maps.

Yield assessments show considerable variation, limits imposed by population, growth of individual plants, or both

We also developed relationships between photographs of ground cover, laboratory measurements of fresh weight and leaf area and the final crop yield.

In reviewing the season’s worth of MicroFarm plot measurements and noticed there were areas where yield reached its potential, areas where yield was limited by population (establishment), some where yield was limited by canopy growth (development) and some by both population and development.

This observation helped us form a concept of Management Action Zones, based on population and canopy development assessments.

Management Action Zones – If population is low work for better establishment next season. If plants are small see if there is something that can be done this season


Our aims for Year 2 are on the website. We set out to confirm the relationships we found in Year 1.

This required developing population expectations and determining estimates of canopy development as the season progressed, against which field measurement could be compared.

We had to select our “zones” before the crop got established as we did a lot of base line testing of the soil. So our zones were chosen based on paddock history and a fair bit of guess work. Really, we need to be able to identify zones within an establishing or developing crop, then determine what is going on so we can try to fix it as quickly as possible.

In previous seasons we experimented with smartphone cameras and image processing to assess canopy size and relate that to final yields. We are very pleased that photographs of sampling plots processed using the “Canopeo” app compare very well with Leaf Area Index again this season.

Through the season we tracked crop development in the plots and using plant counts and canopy cover assessments to try and separate the effects of population (establishment) and soil or other management factors.

We  built a web calculator to do the maths, aiming for a tool any grower or agronomist can use to aid decision making. The web calculator was used to test our theories about yield prediction and management zones.

ASL Software updated the “CoverMap” smartphone application and we obtained consistent results from it. The app calculates canopy ground cover and logs data against GPS position in real time. Because we have confidence that ground cover from image processing is closely related to Leaf Area Index we are working to turn our maps into predictions of final yields.

Maps of canopy cover created from the CoverMap smartphone application show significant variability across the paddock. Canopy increase is seen over time in two maps created a week apart

The current season’s MicroFarm crop is certainly variable. Some is deliberate: we sat the irrigator over some areas after planting to simulate heavy rain events, and we have a poorly irrigated strip. We know some relates to different soil and cover crop histories.

But some differences are unexpected and so far reasons unexplained.

Wide variation within the area new to onions does not follow artificial rain or topographic drainage patterns. This photo is of the area shown far right in the cover maps above.

Together with Plant and Food Research we have been taking additional soil samples to try and uncover the causes of patchiness.

We’ve determined one factor is our artificial rain storm, some crop loss is probably runoff from that and some is historic compaction.  We’ve even identified where a shift in our GPS AB line has left 300mm strips of low production where plants are on last year’s wheel tracks!

But there is a long way to go before this tricky crop gives up its secrets.

This project is in collaboration with Plant and Food Research and is funded by OnionsNZ and the MPI Sustainable Farming Fund.

We also appreciate the support of growers, seed companies and our MicroFarm sponsors Ballance AgriNutrients, BASF Crop Protection and the Centre for Land and Water.


MicroFarm Update

Ballance AgriNutrients and BASF Crop Protection have continued their sponsorship of the LandWISE MicroFarm for 2016-17 and 2017-18. The MicroFarm is hosted by the Centre for Land and Water which provides fields, sheds, equipment and the Green Shed venue for our meetings and seminars. We greatly appreciate their very significant contributions which make the operation possible.

Mark Redshaw put hours into getting the MicroFarm up and running and spending much of his free-time spraying and monitoring onions for two seasons. Now we have our own small sprayer we have taken that task over, but remain most grateful to Mark.

Special thanks also to Mel at HydroServices for irrigation monitoring, Patrick Nicolle for machinery support, BioRich for lending us a tractor, Hugh Ritchie for his irrigator, FruitFed Supplies for crop protection support, Scott Lawson for seed and machinery, Vigour Seeds and SPS for onion seed and McCain Foods for process crop support.

After a number of years of constant pea crops, we are having a break. Our main focus this season has been on onions, crop variability and its drivers. We have plenty of variability, but which factors are driving still proves elusive.

Aerial view of the MicroFarm taken by DJI Phantom showing replicated soil amendment plots on right, flagged replicated plots in onion zones on left, and at far left drought stressed onion beds, the reason we extended the irrigator

In conjunction with OnionsNZ and Plant & Food,
we held a grower field day in January to discuss the OnionsNZ SFF project.

We do know topography and drainage are critical factors but they do not explain all the variation we are seeing. To assess their impact, we deliberately applied “heavy rain” to some areas and have been comparing these with areas not subjected to a hard40+mm rain event before emergence.

Artificial heavy rain event applied after planting and before emergence

We prepared an OptiSurface plan two years ago but did not implement it as we were keen to explore variation in our onions trials. Perhaps it is time to act on our own advice!

Topomap created from a Trimble RTK GPS survey shows relative elevations. Yellow highest, purple lowest. Surface flow analysis of topographic maps like this show where water can become trapped and pond.
OptiSurface analysis shows where water will pond. In this image, the beds are assumed to be 100mm high. The brown areas will drain, blue and purple areas will have ponding – pale blue least, dark purple most.

The other main crop this season is sweetcorn. We are hosting a series of variety trials and are assessing a soil amendment product to see if it offers an economic advantage to growers.

To assess the soil amendment we set up a six plot replicated trial – with and without the treatment. We randomly split plots to avoid bias, and are taking crop development data through the season. At harvest we will determine paddock yield and the recovery rate of kernels in each plot.

A randomised six plot trial layout for assessing the effect of a soil amendment on a sweetcorn crop. Yellow lines imposed on aerial image from consumer UAV.