Category Archives: Drainage

14th Annual Symposium on Precision Agriculture in Australasia

Albury NSW, 2-3 September 2010

Hosted by the Australian Centre for Precision Agriculture and SPAA Precision Agriculture Australia

Summary Report by Dan Bloomer and James Powrie, LandWISE Inc.

Presentations at the symposium tended to refer to practical applications of Precision Agriculture technologies with a research focus.  They ranged across topics from grains, to remote sensing, and from livestock to viticulture.

The opening by outgoing SPAA President Mark Branson, referred to population increases, tightening oil supply and environmental regulation, crop losses through climate change and future restrictions on synthetic fertilisers.   Precision Agriculture was offered as an opportunity for the farming industry to invest in technologies to address these challenges.

Note:  The names credited here are those of the speakers.  Other authors also contributed to most of the papers presented. We assume full papers will be made available through SPAA or ACPA websites.

Assessment of sugar cane yield monitoring technology

Troy Jensen- National Centre for Engineering in Agriculture

Systems were trialled for monitoring sugar cane yield.  Significant variation was noted between yield monitor types.  While we don’t grow sugar cane in NZ there may be implications for forage harvesters.

Are passive sensors passé

Eileen Perry- DPI Victoria

Passive sensors rely on sunlight as the source that is reflected, so there are issues dealing with readings as light conditions change. Active sensors have their own light source, so they get a stable result in changing light conditions – and can be used at night if desired. Passive sensors have a place in remote sensing. Satellites, for example, cannot supply active light so remain passive. Passive sensors are also being used in permanent positions to monitor temporal changes in crop status.

Some links to other information: Tetracam.com and headworkphotonix.com and Quantalab in Spain may be interesting to review.  The FLIR handheld imaging sensors for carotenoids and chlorophyll looks interesting: www.psi.cz/products/pocket-sized-instruments/plantpen.

Precision pastures

David Lamb- Precision Agriculture Research Group, University of New England

Experiments have been using GPS information to track pasture quality and grazing behavior.   By tracking what animals are doing when, i.e, moving, still or eating, they are gaining insight into which areas are most productive.  This enables improved understanding for integrated landscape management.  Tracking animals shows places where they are not grazing at all.  Pasture quality patterns show up, with different pastures preferred morning to afternoon.

RFID animal tags are also being trialled to enable automatic walkover weighing and fleece weight recordings to assess growth achieved in relevant parts of the paddock.  RFID eartags with GPS (estimated 3 year battery life) are about 2 yrs from market.

Other studies have investigated training animals to allow remote control using sirens. This will potentially enable isolated stock to be managed and encouraged to move to new paddocks by a farmer  anywhere on the globe.

UNEPARG research has now shown that Cropcircle sensors with enhanced LEDs can now be used up to 50m above the ground for improved (and safer) aerial biomass measurement.

Once biomass variability has been mapped using, for example, optical sensors or CDAX pasture meter they believe you can define transects within a field that give you a shortcut to getting whole paddock biomass estimates (truncated biomass transects).

David Lamb also noted LIDAR may augment the use of sensors by adding more detailed knowledge of biomass.  David Manktelow’s Hawke’s Bay work with orchard canopies was mentioned.

Why do grapevine yield and quality vary in time and space?

Andrew Hall- National Wine and Grape Industry Centre, Charles Sturt University

Andrew reported that their research showed there are big annual deviations in yield.  Data from a normal year predicts variability in other years better than same-season sampling in an off-year.  Spatial variation was found to be greatest early and late in season.   Understanding the effects on weather induced change on reproductive processes and carbohydrate dynamics within the plant appears to be the key to making accurate productivity forecasts. [See also Rob Bramley’s report]

Remote sensing applications for the Australian cotton industry.

Andrew Robson- Queensland Department of Employment, Economic Development and Innovation.

Much of this focused on review of different resolutions of available remote imagery. Some satellite imagery is relatively coarse but is cheap for large areas so may prove appropriate in the cotton industry.  Strategic purchase of imagery at only necessary resolution can save cost.

UAV technology with PA to improve productivity and sustainability of macadamia orchards

Leasie Felderhof- Skyview Solutions Pty Ltd.

Regulations are holding back use of UAVs (model aircraft with cameras) in Australia and in US.    A commercial pilot licence is required for UAVs!  A macadamia orchard of 100ha was mapped in 4 hours flying time.  Wind can limit flight potential.

Image quality can be very high (3cm pixel size) and can be used to show individual leaves and identify early stages of pest attack.  This is possible using relatively easily available cameras.  New photo stitching technology makes it possible to easily and rapidly create mosaics from individual images.

Preliminary cost analysis suggests that nutrition maps derived from aerial images can lower production inputs and increase profits in the macadamia sector.

Fixing low pH soils and solving drainage problems with PA in NSW and Victoria

Tim Neale- precisionagriculture.com.au

Farmers can gain more value from their GPS purchase by using their guidance system to create farm topography maps.    Drainage analysis and cut and fill maps can then be created from these.  Software advances allowed them to reduce soil moved to ensure drainage by 90% compared to traditional laser levelling techniques.

High resolution satellite images were being used to identify areas suspected of low pH.  They compared targeted sampling to grid sampling and decided that zones drawn from satellite imagery were a good intermediate step to start on variable rate liming.  A targeted approach to pH can reduce the number of samples required.

John Deere Industry Update

Andrew Bremner John Deere AMS

A number of new John Deere PA products are being launched for 2011.  Remote access to tractors equipped with new communications features, will allow for fleet management, diagnostics and online backup.

An Automated system for rapid in field soil nutrient testing

Craig Lobsey- Australian Centre for Precision Agriculture

This work is bridging the gap between conventional lab sampling and lab analysis and current proximal soil sensors.  Wet chemistry is desirable for measuring soil nitrate, and potassium and sodium.  But rapid processing is essential for on-the-go in-field analysis. The research goal was to get wet chemistry sample processing done in 30 seconds to make in-field processing economic.  They found (the cunning bit) that by carefully measuring the rate of change of the chemical reaction at early stages they were able to predict a result that would be gained by the reaction going to completion (which takes 30+ minutes).

SPAA Precision Ag Association Grower group project

Leighton Wilksch- SPAA Precision Agriculture Association

The Grower Group project is focusing on site specific crop management. SPAA has 16 farm discussion groups running, with three meetings a year are held per group.

SPAA also ran their first annual Advanced Training Courses in PA for advisors and key farmers (70 attendees).  People we spoke to said this was stunningly good. We’ll find out if we can arrange a New Zealand course if there is interest.

Wireless Sensor Networks

Rakesh Devadas- RMIT University, Melbourne

Effective calibration of remote sensing by satellites, aeroplanes etc needs ground based data.  A system was set up to capture continuous ground based measurements, to give data that coincides exactly with aerial and satellite observations.  To collect that data, the researchers built an in-paddock sensor network that was wirelessly connected to a base computer, so that when satellite image received they had the necessary data to calibrate the image.  This cost $2K per node.

Identifying scales at which yield and soil attributes are related

Brett Whelan- Australian Centre for Precision Agriculture

This statistical presentation looked at the resolution (density of sampling points) of data collection, and the analysis of that data to explain the causes of variability. The amount of variability seen in data can relate more to the amount of sampling than the actual variability present.  Some analyses can show highly correlated results, but only explain a little of the variability. By changing the scales, you may have lower correlation but explain more of the variability.

Integrating temporal variation into the management of spatial variability of Precision Viticulture

Rob Bramley- CSIRO

Work was completed at Stoneleigh Squires vineyard in Marlborough.  This was led by Marlborough Wine Research Centre’s Mike Trought with John Paul Praat also involved in the project.  They analysed spatial vineyard information gained over several years to quantify relationships.  EM appeared useful for describing soil variation but detected very low EC values over a very narrow range due to shallow stony soils.  EC was closely correlated with trunk circumference.

They used an array of Cropcircle sensors from side of canopy to derive the Plant Cell Density (PCD) index. This uses the same wave bands (near infrared and red) as NDVI, but is a simple ratio rather than the difference ratio used for NDVI index. In contrast to Australian work, vine vigour assessments did not correlate with yield.  The researchers believe this is due to the high degree of bud selection at hand pruning.  Australian vines are typically machine pruned.

With assistance from a panel of winemakers they determined a juice score based on soluble solids, juice pH and titratable acidity.  They then predicted the change in juice score through time using the proximally sensed vine vigour data.  This gave a spatial fruit quality and maturity map of the vineyard changing over time.  This allowed them to create a map showing the date on which optimum harvest score was attained.

“Identifying those parts of the vineyard that produce the best fruit, and the date for best balance of flavour and aroma is the holy grail of viticulture research” (Mike Trought)

Onion Precision Agronomy

Trevor Twigden- National Onion Labs

Trevor’s team has been working on nutrient and plant stress impacts on onion pungency, sweetness and shelf life. There is a significant price premium for “mild onions” (called “sweet onions” in USA) which are actually low pungency rather than sweet.

To avoid pungency growers must avoid plant stress as the chemical involved (pyruvic acid) results from a stress response. There is “Mild Onion Certification” in Australia – Australia’s only flavour certified fresh horticultural product on the market. The research has demonstrated that precision agronomy e.g. GPS mapping and GPS generated sample sites with infield onion pungency testing makes it feasible to isolate areas with low pungency onions.  The marketing system is fully traceable, so the industry can assure quality is not degraded by untested onions being represented as mild.

A very large amount of spatially referenced sampling has enabled the researchers to identify soil, nutrient and nutrient combination effects on pungency and on storage quality. Pungency and sugars are independent.  Industry belief was that higher yields caused low storability, but this work shows good nutrition (at all points across the full site) allows high yields (100+ t/ha) and good storability.

TopCon Update

Martin Keye- Topcon

The CropSpec optical sensor has been through numerous upgrades.  It is currently being widely used in Montana to manage protein levels in wheat, because protein premiums are at record highs.

New TopCon products have remote communications ability allowing on-line service and support. Farmers can see exactly where each machine is and where it has been, from the office computer. They can send prescription maps directly to the tractor and equipment.  Martin sees great future for such connectivity allowing access to weather data etc from the cab. The move to wireless connectivity avoids the need for USB data sticks (thumb drives) or swapping data cards to transfer data – this is seen by many as a vital improvement.

Developing capacity via paddock learning – growers and groups

Simon Craig- Birchip Cropping Group (BCG)

Simon reported that use of PA technology for guidance is widespread among BCG farmers, but use of PA information for input decisions has been rare. Barriers of initial investment and aging gear are being displaced by drivers of reduced input costs and risks. A major limitation is software compatibility between office system and various different equipment protocols.

The BCG has been working with farmers to reduce inputs where possible, delay inputs such as nitrogen until later in the season when seasonal forecasts and yield potential predictions are more reliable. They have taught farmers to use paddock strips: e.g. leaving out an input in a pass that crosses over representative zones then monitoring yield at harvest time. These are very effective for building confidence to push the boundaries with little risk to production. An example relevant to NZ maize, would be leaving out P in starter fertiliser. They noted the benefits of running inter-seasonal nutrient budgets, reflecting previous crop extraction and anticipated yields.

PA education and training modules

Brett Whelan- Australian Centre for Precision Agriculture

Brett and colleagues have prepared a series of training modules based on the 2006 GRDC PA Training Manual. They identify different levels of knowledge sought, and structure the material accordingly. Each module covers a separate aspect of PA, and starts with a general introduction, allows an interested person to access more detailed information, and includes references to very details references should those be wanted. This information is intended to be made freely available, downloadable or CD, and open for use by educators and advisors as they wish to generate their own resources.

Future Trends in PA

James Hassall- Farmer and Nuffield Scholar in Precision Agriculture

James is a very long term PA farmer who built his own auto steer system years ago, and other pieces of equipment since. James presented a view of the future of PA, based on his experience, his Nuffield research and hours sitting in his tractor thinking.  He says ISOBUS communication between tractor and equipment is coming. However some manufacturers think it is already becoming redundant as it won’t cope with the required volume of data moving between multiple sensors on the tractor and equipment.  He says manufacturers are sharing information and testing compatiblity between gear by holding ‘plugfests’.

James is building a robot to move through his fields. He suggested that in terms of technology, the 80s introduced the personal computer, the 90’s the internet. We are currently seeing miniaturisation, and the next decade will see widespread introduction of robotics.  He believes he’ll be able to use his robot for many applications, including soil sampling, protein monitoring, weed spraying and more.

He noted work by David Slaughter using a robot to drop micro-doses of herbicide onto weed leaves. The Danish researchers have combined optical colour and shape technology to identify weed species and apply different chemicals at specific rates using bubble jet printer technology.

James is convinced that wireless data transfer and diagnostics will change farm management. No more having data cards slip out of your top pocket into the spray tank. He is keen to upload maps from office to tractor to manage equipment. He employs a lot of casual labour and remote access can assist the farmer ensure correct operation, and help inexperienced operators easily.

Trade Displays (a sample)

Apogee

Apogee is a defence company which has moved into agriculture, bringing a different spin on technology. They are highly specialised in satellite radar which penetrates cloud and works at night and can provide a lot of information not available through standard light sensing from satellites.  Radar allows identification of different materials, through polarizing of signals. http://www.apogee.com.au

Trimble

Trimble was marketing their equipment range and their base station network services.

Leica

Leica had a display of their ag products along with video on their mining and construction products with laser driven drafting of existing structures and earthworks.

Crop-Optics

Crop-Optics had a display of Weedseeker and Greenseeker sensors (formally manufactured by Ntech, now owned by Trimble).  The display included a moving banner of maize plants being scanned by Greenseeker and showing calculated variable rate against the NDVI score changing as the plant images passed.  Contact Scott Jameson

PrecisionAgriculture.com.au

Tim Neale and Andrew Whitlock had their imaging, training packages and consulting services on display.

Outline Imagery

This is a South African firm now in Australia.  They have an easily mounted multi-spectral camera for aircraft.  Contact Andrew Coleman

Going High Tech at Holton Farm

As Published in ‘Grower’ Magazine February 2010.

Like many farmers who have adopted precision agriculture, Tim Macfarlane is using GPS to control his machinery.  This gives savings in time, fuel, labour, machinery and other input costs.

Tim farms Holton Farm near Kaiapoi.  He grows sweetcorn and pumpkin for the fresh market and seed crops including cabbage, clover, ryegrass and radish.  Peas, wheat and barley are grown for feed.

The first steps into precision agriculture came to the farm in the 1990s. A hired hand-held GPS was used to map paddock boundaries. Knowing true paddock sizes allowed for accurate ordering of seed and chemicals.

Now, GPS guides the tractor providing for more efficient cultivation, planting, fertilising and inter row cultivation.  It controls his spray boom too, switching nozzles on and off, section by section at exactly the right time.  Spraying is more precise and less overlapping of herbicide applications reduces chemical waste and yield reduction.

Leica RTK GPS is now used for all high accuracy guidance, with corrections coming from an on-site base station. This gives season to season accuracy of better than 2 cm. Farm operations are routinely logged with GPS and transferred into an integrated farm mapping and management program.

New technology keeps coming to Holton

GPS and auto steering is allowing a shift towards Controlled Traffic Farming (CTF) which Tim thinks will increase yields by reducing overall compaction.  CTF is also expected to provide other efficiencies. “As we grow in confidence with Precision Ag, endless possibilities are opening up to us,” says Tim.

GPS allows various types of captured data to be precisely located and mapped on the farm.  EM38 soil conductivity sensing is being used to map relative water holding capacity across the farm.  Greenseeker crop sensors are capturing differences in greenness across paddocks, helping decisions about weed control.  Yield maps are clearly showing how much crop was harvested from each part of a paddock.

EM38 scanning and mapping was conducted in 2009.  The intention is to gain understanding of soil depth, quality and water holding capacity.  This information will be used to plan rotations and decide whether to irrigate more of the property.

EM38 mapping also helps determine location and depth of old, forgotten drains, identifying areas where inversion and ripping might be practical.

Weeds and technology

Weed challenges are now focusing Tim’s attention on GPS based weed management practices. These offer alternative options for control and can increase efficiency in the use of chemical, fuel and other inputs.

Tim wants systems that allow him to determine weed type and density using sensing and GPS mapping tools.  Once the target is well understood, chemical rates and application methods can easily be varied. Already, GPS controlled boom switching is reducing overlap, providing accurate record keeping and proof of placement, and easy recording of chemical trial data.

When chemical tools are unavailable, the improved accuracy of RTK allows very efficient mechanical weeding. The accuracy lets Tim go later with the final inter row weeding pass and go closer to the planted crop. And RTK inter row weeding means less hand weeding in radish, sweetcorn, cabbage and pumpkin row crops.

The future of technology at Holton

Technology is giving gains at Holton.  Tim says, “As we learn more about technology, we learn more about our farm and how we can keep making progress. Over time and with good planning, precision ag ensures that huge benefits are gained in production, efficiency and economics for the entire operation”

Tim is an agent for Leica Geosytems Precision Ag products, Raven GPS and spray control equipment, and Farm Data software. These technology products are integrated into the farming system.  The GPS feeds operations and yield data into the farm software.  Farm software feeds data and map files back to the GPS.

If you would like to keep making progress on your farm and to understand Precision Agriculture better, you may like to join LandWISE and to attend the LandWISE conference in Havelock North on May 12th and 13th.  This year’s conference will be called ‘Know your farm – with Precision Ag’.

See www.landwise.org.nz for more information.

Guest Post: Dr Paul Johnstone (Plant and Food Research) on Improving Profits by Reducing Surface Ponding

Ponding of surface runoff from rainfall and irrigation can reduce crop production. The ‘Holding it together’ project addresses this.

Plant & Food Research and LandWISE are working with growers on ways to reduce surface ponding, improve soil quality and increase returns.

MAF Sustainable Farming Fund, Fresh Vegetable Product Group, Potatoes NZ, Hawke’s Bay Regional Council, Horizons Regional Council, Auckland Regional Council, Environment Waikato and Ballance Agri-Nutrients have funded the project.

Runoff occurs when water infiltration is slower than application of rain or irrigation. In some soils, slow infiltration is due to texture, in others it is reduced by frequent tillage or compaction. Whatever the cause, runoff can pond for extended periods, in low-lying dips or field edges. This ponding can be damaging to crops.

Trials with onions have shown that even temporary ponding can reduce yields. Yield loss ranged from 60-80%.  Ponding also reduced the proportion of yield within the most profitable size range.

In one field, a leaky pipe resulted in ponding during irrigation. This area of 0.2 ha cost the grower $1,700 in lost income. The cost of fixing the pipe was $10.

A  similar-sized area was affected by ponding during spring rainfall. Resulting crop loss totalled $3,500 in lost income.

Other crops dislike wet feet too, especially during germination, emergence and early growth, when ponding can affect establishment and final yield outcomes.

Weeds and soil-borne diseases can also flourish in affected areas.  Mobile nutrients, such as nitrogen, are easily leached beyond shallow root zones, resulting in potential deficiency. In worst cases, crops require replanting.

The project also looked at the grower’s greatest asset – their soil. Soil condition proved to be poorer in ponded areas. In particular, aggregates became clumpy, and soils heavily compacted.  When aggregation and structure collapse, soils become poorly drained and aerated, access to nutrients and water is restricted, and this reduces yield.

Nutrients and productive topsoil also concentrate in ponded areas after runoff.  In ponded areas, soil Olsen P levels were as much as 75% higher than adjacent unponded areas. Organic matter levels were higher too. This can contribute to variability and input inefficiency over time.

Furrow diking is a tool to reduce surface runoff. Small soil dikes (dams) are formed in wheel tracks by a towed implement. Controlling runoff largely eliminates the impacts of ponding, meaning better returns.

Horowhenua grower, John Clarke has seen how effective diking can be. In the past, ponding has reduced yields in low-lying areas. Where they tested diking there was no standing water after heavy rain, this is a major improvement.

Hawke’s Bay grower Scott Lawson of True Earth Organics, is also an advocate. “Diking eliminates ponding damage and can reduce disease incidence. It’s standard practice now”.

Growers may also harvest more rainfall with diking installed, as water has more soaking time and so more storage in the soil.

Scott Lawson notes that soils need to have good drainage. “sustainability of farming operations includes promoting good soil structure, by building organic matter levels, reducing cultivation and working to eliminate compaction”.

For more information on ‘Holding it Together’ projects or on implementing practices on-farm please contact Paul Johnstone (Plant and Food Research) or Dan Bloomer (LandWISE).

2010 LandWISE Conference

2010 LandWISE Conference

Know Your Farm – With Precision Ag, Havelock North, 12th & 13th May.

The LandWISE conference aims to be to the leading Precision Agriculture event in New Zealand each year.

You will get to meet other farmers, growers and industry people with an interest in Precision Agriculture.  And  hear world class speakers on these topics:

  • Precision Ag and the Big Wide World – MAF Director of Strategy Development – James Palmer, Professor David Lamb (UNE) and Dr Charles Merfield, will address the challenges and changes driving advances in Precision Ag. in NZ and worldwide.
  • Making Your Data Valuable – New ways farm data is enhancing farm profitability.  See how it is being collected and used to farm better.
  • Knowing and Growing Your Soil – Ways you can preserve and improve soil quality.
  • Managing Traffic in the Field – Updates on managing soil compaction, a technical session on tyre inflation and successful Controlled Traffic Farming in NZ.
  • Managing Variability – Demystifying crop sensors, agronomy tools and Variable Rate Technology to improve effectiveness with fertiliser and other inputs.
  • Precision Irrigation – How some NZ  farmers are managing water smarter to reduce the cost and environmental impacts of irrigation.

Members enjoy a discount, so if you are coming to the LandWISE conference, consider signing up, you will be in excellent company.

This year the LandWISE Conference will be followed by a one day Crop Sensor Workshop on 14th May 2010.  Places limited.

To receive a conference schedule, to register or to learn more about our activities, contact LandWISE for more information at info@landwise.org.nz

Evans Farm Precision Agriculture Field Walk, Canterbury

On Monday 16 November 2009, a field walk was held in conjunction with FAR, at John and Jack Evan’s farm in Dorie. This is an Advanced Farming Systems Project farm and includes a strip tillage trial.

James Powrie and Dan Bloomer spoke about the LandWISE Advanced Farming Systems project, what the various farmers are achieving with Precision Ag and the benefits of Controlled Traffic. About 35 visitors attended and saw John’s Trimble GPS guidance at work in mechanical weeding of beetroot seed. And then viewed the strip tillage trial which is in carrot seed production.

John spoke frankly about the warts and all of adopting Precision Agriculture. The principle benefits to him are in reducing overlaps and wasteage and in being able to solve weed control and herbicide efficacy challenges by mechanically weeding. As he becomes more precise with planting, he finds that his demand is lifting for still further precision, so that he can weed closer and faster.

Thanks to John and Jack Evans and FAR.
For further information: Call James on 06 6504531 or 0272 757757, email james@landwise.org.nz or see www.landwise.org.nz for updates.

Auckland Region Precision Agriculture Field Walks

On Thursday 19 November a LandWISE field day started at 10am at NZ Fresh Cuts at Mangere, South Auckland.
Chris Butler described the adoption of a permanent bed system in their salad growing operation.

GPS use and Controlled Traffic Farming have evolved there, to the point where fuel savings of about 50% are being gained over conventional practices. A reduction in the number of cultivation operations has been made possible and this has the benefit of allowing more crops per season on this property.

The next challenge is in optimizing Nitrogen fertiliser efficiency, which will enhance their profitability dramatically.

The use of NDVI sensing will be explored as part of the LandWISE project at this site. This will be with the support of Agri Optics from Canterbury.

Lunchtime Presentations on the Advanced Farming Systems and Holding It Together projects were given by James Powrie- LandWISE and Paul Johnstone- Plant and Food Research at the Franklin Centre in Pukekohe.

In the afternoon about 20 visitors saw the AS Wilcox and Son permanent bed trial in Pukekawa. Wilcox’s are trialling controlled traffic and permanent beds in a 3 year trial in potatoes, onion and oats. They aim to gain in soil quality, efficiency and a reduction in harvest cost by reducing compaction. They also talked about their journey in adopting and now expanding the use of GPS in their cropping operation.

Thanks to Plant and Food Research, AS Wilcox and Sons and NZ Fresh Cuts.
For further information: Call James on 06 6504531 or 0272 757757, email james@landwise.org.nz or see www.landwise.org.nz for updates.

Precision Ag in Vegetables – November Field Walk in Levin

On Tuesday 24 November 2009 an Advanced Farming Systems and Holding It Together Project update was given by James Powrie- LandWISE and Paul Johnstone- Plant and Food Research. The update was held at Levin RSA following on from a HIT project team meeting.

In the afternoon this was followed by a field walk to Woodhaven Gardens where Antonia Glaria showed 15 visitors their trials in Controlled Traffic farming and Permanent beds for Fresh vegetables.

Early improvements in soil structure are encouraging as soil structure recovers with a reduction in wheel traffic and cultivation. Furrow diking was also observed and HIT project sediment traps were visited by the group with discussion on amelioration of the effects of soil loss in intensive vegetable cropping.

Furrow diking is having the effect of reducing ponding and enhancing infiltration at this farm.

Thanks to Plant and Food Research and Woodhaven Gardens.
For further information: Call James on 06 6504531 or 0272 757757, email james@landwise.org.nz or see www.landwise.org.nz for updates.

FAR and LandWISE Precision Ag field day at Lawson’s Organic Farms in Hastings

On 8 December FAR and LandWISE co-hosted a Precision Agriculture and Advanced Farming Systems session at the Centre for Land and Water. Jim Wilson from Soil Essentials in the UK, gave a presentation on crop sensors and variable rate management to a group of 28 farmers and industry representatives.
Case IH sponsored lunch for the group at the Centre for Land and Water.

After lunch the group reconvened at Lawson’s Organic Farms to view Scott Lawson’s high tech organic operation in Ngatarawa road. Scott is using GPS to guide his cultivation in a seasonal controlled traffic operation in fresh and process vegetables.

Thanks to CASE IH, FAR for support of this event and True Earth Organics for hosting the field walk.

For further information: Call James on 06 6504531 or 0272 757757, email james@landwise.org.nz or see www.landwise.org.nz for updates.

Guest Post: Dr. Craig Ross on Levelling Sand Dunes To Improve Crop And Irrigation Performance

By Dr Craig Ross, Landcare Research, Palmerston North

These are my observations on re-contouring sand dunes to improve crop and irrigation management on the sand dune country of the Dalrymples’ Waitatapia Station, Bulls.

Hew and Roger Dalrymple have recently started levelling low sand dunes for farm improvement. Paddocks in sand dune country have very variable soil patterns, with generally shallow topsoils over raw sands on the upper parts of the dunes, deeper topsoils on the lower dune slopes, and often peaty soils, sometimes with underlying iron pans and silty layering in the inter-dunal hollows. The aim of re-contouring is to even out the soil pattern and change the contours to gently rounded or more flattened slopes that follow the natural lie of the land.

Why re-contour low sand dune country?

• Re-contouring the land to flat or gently rounded slopes improves the operation of centre pivots
• A more uniform soil pattern improves irrigation efficiency (water use) and crop performance, and particularly can provide a more even pattern of when crops mature
• Plus the obvious improvements to farm management (drainage, fencing, vehicle access, cultivation, sowing, and harvesting, etc.).

The Process

The Dalrymples use imported tractor-towed scrapers (pictured) to remove and replace topsoils. The equipment has high accuracy GPS and geo-referenced mapping for controlling the stripping and re-spreading operations.

 Topsoil (and peaty material in hollows) is stripped from an area of paddock and stockpiled for later re-spreading. Sand from the low dunes is removed using the same equipment, leaving them flattened or rounded. A bulldozer, which has lower ground pressure than the wheeled tractor and scrapers is also used in some areas.

The sand removed from the dunes is re-spread in the hollows to provide the flat to gently rolling contours. Topsoil is then returned to the re-contoured area, spread more evenly than before, mostly to about 100–200 mm depth. Final seedbed cultivation (using closely spaced discs and tynes) precedes sowing. 

The final stage is to ensure good drainage. Open drains are dug to about 2 m depth at about 100 m spacings after the re-contouring.

Potential Problems

Topsoil damage

Topsoil in the core of stockpiles becomes temporarily anaerobic and may have patches of grey or greenish-grey colours with a pungent odour. However, research has shown that the topsoil recovers quickly when re-spread, although there may be a small flush of ammonium.

Earthworm populations can also temporarily diminish but populations are usually low in sand dune soils and should recover in time.

The main damage from topsoil stripping and re-spreading is soil structural damage from machinery compaction, burial in the stockpile, and mechanical handling. The sandy topsoils on Waitatapia Station tend to have not well aggregated, single-grained structures and thus structural degradation is not really an issue. Compaction can be a problem but seedbed cultivation relieves this.

Hew Dalrymple is planning to minimise topsoil handling and damage through operations planning. Topsoil stripped from an initial area will be stockpiled. After re-contouring, topsoil from the second area will be spread on the first. This pattern will continue, with the initial stockpile being spread on the last re-contoured area.

Nutrient availability

Some of the re-contoured area is being converted to cropping from pine plantation. Stumps are removed (they could also be ground using appropriate machinery) and the wood slash is minimal.  It will soon become broken down by natural decomposition.

Because decomposition of woody carbonaceous slash uses up some of the soil nitrogen, higher than usual nitrogen fertilizer is required. Mulching the slash is an option, if the appropriate machinery is available. 

Soil type implications

Sands

Normal cropping on re-contoured sand country should work well because soil structural damage is minimal and easily remedied by cultivation. However, soil structural damage on re-contouring silty or clayey soils is generally more severe, requiring a period of restorative pasture before cropping is recommended.

Silts and clays

A common problem in re-contoured land, especially on silty and clayey soils, is layering at the interface between natural and re-spread soil materials. Compaction at the interface inhibits soil drainage and root penetration. It can be remedied by scarification (cultivation) before adding re-spread soil, or by subsoiling after re-spreading.

Buried soils

Sudden textural changes and buried topsoils or silty layers also create these problems,  but can be overcome by cultivating before re-spreading sand or topsoil or subsoiling. Buried topsoils should be stripped and added to the topsoil re-spreading.

Waitatapia

Most of these problems were not observed in the sand country at Waiatatapia. There were, however, small patches of underlying iron pans, silty layers and buried humic topsoils.

Patchy iron pans in the underlying sands occurred in some small areas. Ripping to break up these pans will help drainage and root penetration. In effect, ripped iron pans will behave rather like a stony layer.

Ripping may not work as well for buried silty layers because they will re-consolidate. Instead, cultivation (ripping) of the silty layer may be beneficial by mixing it with sand.       

It is early days for the Dalrymples’ re-contouring of low sand dune country in the Manawatu. The cost-benefits of levelling the dunes will become known after two or three seasons.   

.pdf version of this report available here:

Dr. Craig Ross Report on Levelling Sand dunes

Guest Post: John McPhee, on Maintaining Wheel Tracks for CTF #1

If you are into CTF, you will know your paddock has two distinctly different soil conditions – loose and friable for growing crops, and hard and compacted for driving on. You will also realise that each area requires different management. A successful CTF system is more than just getting the wheels in the right place.

To a large extent, your cropping soil will look after itself once you keep the wheels off it. However, managing wheel tracks is very important and introduces some civil engineering to your farming enterprise.

The ideal CTF wheel track is hard, dry and wide enough to support wheels without sliding off. In vegetable production, wheel tracks tend to be narrow to maximize the crop area and are often wet, either from rainfall or irrigation. A wet wheel track may be greasy and hard to stay on, but an underwater wheel track will have lost a lot of its strength. This can lead to deep ruts from essential passes, such as from unavoidable harvest traffic.

So what to do about it, and do I have all the answers? No, I don’t have all the answers – but here are some ideas, some based on experience, others as yet untried.

First and foremost; correct paddock layout and effective surface drainage are essential to good wheel track performance. Some slope (and farming above sea level!) is a good start. Wheel tracks should run up and down slope for positive drainage. In undulating topography, there are probably places where you travel across slope to some degree, but positive drainage is the key. Strategic drainage might be necessary if there are low spots in the paddock.  Upslope diversion drains to prevent run-on, and down slope drains to collect run-off, are key elements. These should take water away as fast as possible, and may be broad-based and grassed so they can be driven over. They may be incorporated into paddock headlands.

Flat (or very low slope) paddocks present particular challenges. Laser grading may be an option. Consider laser grading just the base of the wheel track. The bed height may vary a little, so you will have to judge what is acceptable.
Will this solve all your problems? Probably not. Track erosion is one potential issue, depending on slope, although with improved infiltration in the bed, there should be a lot less water running down the tracks.

Daily harvest pressures for fresh produce are a challenge. You don’t always have the freedom to wait for tracks to dry, but at least if they are drained, they will regain their strength faster. Greasy tracks test the system – steerage discs on tractors and other equipment may help.

Despite your best efforts, there will be times when it all turns to custard. Maintenance of wheel tracks will be part of your CTF work program. After all, they are roads, and roads need maintenance. And it’s a fair bet you will spend less time maintaining them, than you would otherwise spend cultivating.

Pictures: Trafficability impacts on a heavy clay soil after rain (lots of it – 150 mm in 2 days).

This is a conventional tillage area 2 days after rain

Conventional post rain red

And here, a well drained CTF wheel track 2 days after rain

CTF post rain red

John McPhee

John is a Controlled Traffic Farming researcher at the Tasmanian Institute of Agricultural Research and the Department of Primary Industries.