Category Archives: Agronomy

In our final year of “Benchmarking Onions” we have again planted a crop at the MicroFarm. It went into a suitably moist soil, emerged reasonably evenly but has shown increasing variation. We now have very good areas and very disappointing areas.

We’ve mapped the crop with our CoverMap system again this season so we can compare 2015-16, 2016-17 and 2017-18 growth patterns. Are there areas that consistently perform better or worse? What is driving the variation we see?

We also have a few different varieties we are tracking to see how canopy development fits our web calculator. We want to know if the same calculations can be applied to phone images or if variety-based tweeks are necessary.

In a couple of fertiliser application trials we comparing standard and late application because we understand most nitrogen is taken up at or after bulbing. And based on our mapping, we are comparing the effects of full and half rates on areas where canopy cover is low. Maybe we can cut back, save fertiliser and leaching and get the same yield with improved bulb quality.

Come along and see for yourself!

Note: This field walk follows the HotGrass electric weeding demonstration, see more here>

Our Onion Research is in conjunction with Plant and Food Research. It is funded by Onions NZ and the Sustainable Farming Fund. This season we are being aided by Apatu Farms who are helping with field operations and harvest and we are very grateful for their support.

Nitrogen fertiliser is used extensively to maximise productivity across a range of vegetable, arable and forage crops in New Zealand. Matching crop N demand with supply from residual soil mineral N, N mineralisation from organic matter and fertiliser N is central to economic and environmental outcomes in these sectors.

To improve nitrogen use efficiency, effective tools and approaches are required to help guide nutrient management decisions. One potential method is the ‘quick test’ soil nitrate (NO3-N) approach. This in-field approach uses a ‘test strip’ impregnated with a NO3-N sensitive alert zone which, with a simple colorimetric scale, may be used to measure soil solution NO3-N concentrations. Measured NO3-N concentrations can then be compared with critical threshold limits that have been established for a number of crops.

The quick test strips have already been used for a number of years overseas to support growers in making N fertiliser decisions. Depending on NO3-N levels at sampling, a test strip reading may indicate the need for fertiliser to be applied, withheld for a period or eliminated entirely. The test can therefore provide more certainty in decision making. In addition to being cost effective and simple to use, the quick test approach provides the user with rapid information thus enabling decisions to be made at short notice.

In 2013–14, Plant & Food Research undertook a series of proof-of-concept trials to examine the ‘quick test’ soil nitrate (NO3-N) approach under NZ conditions. The aim of the work was to:

substantiate the relationship between test strip nitrate values and laboratory-determined mineral N (the ‘gold standard’) and

Since April 2017 we’ve been hosting a Field Connect weather station at the MicroFarm.

The station offers a set of weather readings comparable to our Plant and Food HortPlus weather station. The main advantage to us is easy access to (nearly) current conditions as the FieldConnect station is updating regularly during the day.

Being web-based we can view the data from anywhere, anytime. This has been helpful in checking wind conditions when irrigation or spraying is due and for our records after spray applications.

The online dashboard is easily customised, selecting the date range and sensors reported with a few clicks. That lets us compare soil moisture, PET and rainfall for example as shown below.

Over winter the station has been monitoring soil moisture in our access strip between cropped areas, but we can shift the sensor into crops to monitor those as we want.

Do you have an interest in field scale electrothermal weeders and being part of a project to make that happen?

Charles Merfield is leading a proposal to develop equipment in conjunction with Ubiqutek, a UK company who originally designed electric weeders and have weeders in use in the UK and HotGrass, the NZ agent.

The current commercial machines are ‘only’ hand held weeders aimed at the urban weed control market, e.g., councils, and their contractors. However, the handheld machines can clearly demonstrate the potential of electrothermal, and Kazel Cass of Hotgrass, is doing a series of demonstrations around the country which you may be interested in attending.

In any normal situation, Ubiqutek and Hotgrass as the owners / suppliers of the weeders would be developing field weeders themselves, however, both are very small business startups with limited funding and people resources, so they are unable to start work on a field machines for several years. They also lack expertise in what is required from field machines especially for the different sectors, e.g., pasture, cropping, viticulture and other permanent crops, and therefore how to design them.

The aim of Charles Merfield’s project is to accelerate the development of a field scale weeder so that NZ farmers & growers get access much sooner. To do this he is seeking farmers and growers who are interested in the technology and willing to contribute some funding.

This season we are linking with regional agronomists and farmers in Pukekohe/Pukekawa, Hawke’s Bay and Canterbury to further test the Management Action Zone tools.

One of the Pukekawa crops is most advanced and our mapping there starts very soon. Our aim is to map crops at 3 leaf stage, use that to identify canopy zones and take photos in each zone for detailed analysis.

The ground area calculated from the photos is added to plant population counts and run through a crop development model on SmartFarm.co.nz to predict final yield in each zone. The model also identifies if population of plant growth rate are causing lower than expected development, and therefore yield.

This field is almost ready for the first mapping exercise. We are somewhat nervous because the weeds can cause errors: green is green! Sometimes we can filter the weeds out of the images, but if there is very little difference between weed and onion, it is not yet possible.

The MicroFarm crop has started to emerge in recent days. We are keeping an eye on this to see what impact emergence has later.

Approaches to the non-chemical / sustainable management of weeds

Full House at Weed Control Workshop.

With the increasing and well know issues surrounding herbicides, such as resistant weeds, ‘resistant’ consumers and increased regulation, non-chemical/herbicide weed management is becoming increasingly important.

Growers are well aware of the limitations of current weed management tools and practices. They recognise simple chemical solutions are increasingly limited and more sophisticated management is essential.

In response to this need, the BHU Future Farming Centre, NZ’s leading specialist sustainable agriculture research centre, and LandWISE with its focus on sustainable production through technology ran a non-chemical weed management workshop to give attendees the knowledge and tools they need to make significant enhancements to the long-term sustainability of their on-farm weed management practices.

Dr Charles Merfield, Head of the Future Farming Centre, said “the aim of this practically focused course was to give attendees a sound overview of the whole of non-chemical weed management as well as providing practical details about how to implement the ideas once they get back to the farm.”

The feedback from attendees was very positive and we anticipate running this again next winter. We already have a wait list so contact us if you are keen info@landwise.org.nz

We have a comprehensive programme. We’ve gone a bit outside the box to bring a variety including from outside the horticultural and arable sectors. We find cross-pollination and hybrid vigour valuable!

So register, come along and listen to excellent presenters, discuss the ideas with colleagues and go away with new understanding and plans.

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.

Improving the profitability of onions

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).

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