GPS: for simpler operations, savings, and sustainability

As published in Grower, July 2009.

NZ Fresh Cuts is creating new ground in vegetable growing, using RTK GPS guided cultivation.  GPS is used to guide tractors for controlled traffic farming in maize and to form permanent beds in leaf vegetables and carrots.  The goal is to save input costs and to improve sustainability in cropping operations.  This is done by using Trimble GPS to guide tractors down the same wheel tracks, pass to pass, year to year. Repeatable 2 cm accuracy is possible and early trials of permanent beds, show savings in inputs, management and improved yield. 

“Indications are that GPS will pay [for itself] in 3 years on fuel savings alone, and we also expect major savings in labour, land allocation, steel, fertiliser and machine R&M”. Chris Butler- NZ Fresh Cuts.

Sustainability is a company-wide focus at NZ Fresh Cuts, who aim to operate a future focused business that is environmentally responsible and looks after people and profits.
Water use efficiency is also likely to increase with improved infiltration through the beds.  Chris has observed that heavy rain is now resulting in less runoff and that runoff water is tending to be clean, indicating that improved infiltration is already occurring.  Combined with planned electromagnetic sensing (EM38) and mapping, this may lead to optimization of irrigation programs.
“Our soil is our big asset, so seeing that it is staying in place is a big plus from controlling our tractor traffic with GPS”. Chris Butler

Controlled traffic also offers potential for less soil damage in wet weather harvesting, because the permanent tramlines are better able to support traffic.

Farming operations were set up 3 years ago with the intention of moving to full controlled traffic. The operations are still evolving towards a final methodology.  Equipment changes were required and a 225hp tractor with RTK auto steer, 6 meter discs, triple bed hoe and triple bed Lister bar were purchased.  Another tractor has GPS fitted for bed forming.

A major advantage is the increased opportunity to get ground preparation done in narrow windows while minimising the damage to the soil.  Because there are fewer operations in the CTF system there is less total waiting time after wet weather.  GPS also allows for the tractor to turn out of one row and into another three or four rows away which cuts down on turning time.  This is possible because the GPS guides the tractor accurately and so adjacent rows are not required to guide the setting up of beds.  Now that three rows are being cultivated per pass, time savings are even greater.  Loss of downtime may allow more crops per year to be grown.
The market for leaf vegetables, has wide variation in daily demand.  Contracts require 300 harvest days per year to meet agreements.  Quality standards are high and the rotations are short, with up to 8 crops grown per season.  Gains in landuse efficiency and turnaround are an attractive aspect of GPS use.

Dan Bloomer manages LandWISE and has worked with Chris over the past 8 years while controlled traffic farming was pioneered at Opou Station in Gisborne. 
“The early gains from controlled traffic are in the soil recovering from the beatings of conventional cropping.  This can quickly provide for cheaper cultivation, more worms and healthier soils.  It is a no-brainer to care for soil by driving on it less”- Dan Bloomer, LandWISE

Mechanical weeding is already being used to reduce reliance on herbicides.  Chris can see the benefit of auto steer on implements and later will explore what the increased accuracy of GPS guidance will offer for mechanical weeding.   Pest and disease pressure will need to be monitored, as the effect of permanent beds is unknown.  Disease pressure will be a point of study to ensure best possible outcomes.

Controlled traffic trials are being run at both Rangiriri and Mangere sites to compare conventional practice with CTF and cost, yield and soil properties will be monitored.  Short rotations of the crops here, give an opportunity to measure any effects of changes quickly.  LandWISE is hosting field days, at this and 11 other Advanced Farming sites around New Zealand. 

NZ Fresh Cuts are a key sponsor of the LandWISE Advanced Farming Systems project.  LandWISE will monitor trials and report on progress at these farms.

LandWISE is a forum for sharing information on new technology for smarter farming and on farm research.  For more on LandWISE field days, events and membership, go to

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