Maximising the Value of Irrigation

The H2Grow Team are excited to introduce Carolyn Hedley as our guest contributor, it is with great pleasure that we can share with you her valuable expertise. Carolyn is a Soil Scientist with Manaaki Whenua, based in Palmerston North, and lives on a small Kairanga farm with husband, Mike. Carolyn has combined her interests in soil science, proximal soil sensing and precision agriculture with on-farm studies of precision irrigation and soil carbon mapping. She has led several nationally funded projects in irrigation and soil carbon, including current leadership of the MBIE funded programme “Maximising the Value of Irrigation”.

Maximising the Value of Irrigation  -  Carolyn Hedley

Early in the new millennium I found out about EM mapping and in 2004 published a method in the Australian Journal of Soil Research to rapidly EM map soil variability on a basis of soil texture. I realised that EM mapping was a really useful new technology to rapidly survey soil variability. The EM map had picked the difference between a Kairanga silt loam and a Kairanga clay loam, and this had management implications for the farmer because the heavier textured soil would compact sooner when grazed in wet conditions.

I could see great potential in this new technology and so embarked on a PhD in proximal soil sensing and this is when I started to relate the EM map to soil available water holding capacity and realised how useful this could be for irrigation scheduling. But critics commented that irrigation systems cannot irrigate to such a complex pattern (example shown in Figure 1 below). Enter Stu Bradbury and George Ricketts, who had worked with me on some EM mapping projects when they were students at Massey University. There was an engineering solution to this problem – control the sprinkler system on a pivot to irrigate to any pattern – which led to the development of the Precision VRI system. Precision VRI, the world’s first true variable rate irrigation system, turned the heads of the global irrigation giants and as a result Lindsay Corporation acquired the technology development company founded by Stu and George.

Figure 1: Available Water-holding Capacity map derived from an EM map for a 100-ha area irrigated by a VRI linear move irrigation system

There was still work to be done though and a proposal put to the Ministry for Business Innovation and Employment received six years funding in 2013 to further research methods to improve management of irrigated land. Now in its final year, the “Maximising the Value of Irrigation” programme has been able to refine methods to use proximal sensor data to create prescription maps for precision irrigation. It has developed soil and crop sensing methods that can inform in near real time the prescription map, and a prototype scheduling tool has been tested with participating farmers as a smart phone app. The in-field sensor monitoring methods have been used to support Lindsay further refine the software control features for the Precision VRI system, which is remotely managed through the FieldNET platform.

Ekanayake, J. and Hedley, C. (2018) Advances in Information Provision from Wireless Sensor Networks for Irrigated Crops. Wireless Sensor Network, 10, 71-92. 

Research into different soil management methods has identified correct tillage and soil surface management methods to store more water in the soil and reduce irrigation requirement and water losses. A spatial framework to run the APSIM model has been created to test the effect of different irrigation scenarios on yield, drainage and water use efficiency. Spatial-APSIM simultaneously runs the model for up to 1,400 grid cells for one irrigation system to compare results of different irrigation scenarios at spatial resolution < 50 m, over several decades.

The MBIE Programme “Maximising the Value of Irrigation” is now working closely with its industry advisory group to ensure that its findings are communicated effectively and to find ways to integrate new tools and support improved management of irrigated land in New Zealand.

PAANZ Workshops - Technology to Reduce N Leaching

If you are a farmer or involved in the primary sector and wanting to further understand the issues around N leaching and the potential solutions available to better manage nutrients on farms then the "Technology to Reduce N Leaching" workshop may be of interest to you.

These workshops are being run by Precision Agriculture Association NZ in the North Island on the following dates:

1st September - Palmerston North
2nd September - Hastings 

For more information visit precisionagriculture.org.nz

Irrigation – Grow with the Flow

Next week the historical Waitaki region will be host to the 2016 IrrigationNZ conference, IRRIGATION – GROW WITH THE FLOW. There is a variety of keynote speakers from all around the world and a jam-packed programme of interesting presentations and workshops. I have picked out a few presentations and workshops of mention that may be of interest to the H2Grow followers. For the full programme click here.

We all know information is key and many of the posts that you may have read on H2Grow share the many different sources of data that you can gather, monitor and measure in relation to irrigation. But with so many options for irrigation management you may be left wondering which are going to give you the greatest benefit. I’m hoping that this workshop may shed some light…

WHAT TO MEASURE MONITOR AND HOW TO MANAGE DATA FOR IMPROVED IRRIGATION PERFORMANCE – ENERGY, PRODUCTION & ENVIRONMENT presented by Ian McIndoe (Aqualinc) & Steve Breneger (INZ)

And…

REGEN WATER – USING SCIENCE, INFORMATION AND SOFTWARE TO MANAGE IRRIGATION presented by Bridgit Hawkins (Regen)

And furthermore…

REAL-TIME SOIL MOISTURE MONITORING IRRIGATION DECISION SUPPORT SYSTEMS presented by Pierre Roudier, Carolyn Hedley, Jagath Ekanayake, and Joseph Pollacco (Landcare Research)

Coincidentally the team presenting this later topic from Landcare Research have been involved in many variable rate irrigation and electromagnetic surveying studies.

Once you have monitored, measured and made an informed decision of when, where and how much to irrigate you may be after a tool that allows you to implement your irrigation schedule. This next workshop should enlighten you on the latest options to do so…

COMPLETE CONTROL FROM YOUR MOBILE DEVICE presented by Stu Bradbury (Lindsay NZ)

And lastly, one of the most topical irrigation related discussions at present (second to the tough economic conditions for many) is…

HOW REGULATORS AND FARMERS ARE DEALING WITH IRRIGATION AND NUTRIENT USE EFFICIENCY – THE CHALLENGES AND THE OPPORTUNITIES

Once we’ve been educated by the educators and experts I thought interesting food for thought would come in the form of…

OUR FUTURE – WHAT WILL IRRIGATION LOOK LIKE IN 2050? This will be presented by Christopher Neale (Director of Research, Robert B. Daugherty Water for Food Institute, University of Nebraska). Currently development of remote irrigation management technologies and pinpoint irrigation control systems seems to be the focus but what will be next? And what will an irrigator look like when my son is the age that I am now?

I hope that provides a small taster of some of the information that will be on offer. As well as the presentations there is a exhibition with over 35 stands where you are able to talk to those in the irrigation industry including irrigation designers, engineers, suppliers and support companies.

Lindsay NZ are at site 17, we will be unveiling two exciting new product releases (which I will share more information on next week), but we look forward to seeing you all there.

If you are not able to make it to the entire conference there is a Farmer’s Trade Afternoon, on Tuesday 5th April from 3:30pm–5:30pm.

Today's post has been written by Sarah Elliot from Lindsay NZ.

A guide to S-Map

What is S-Map?

S-Map is a map containing information of the soils across the country. It is being developed by Landcare Research and information is continually being added to it. The project was started to collaborate and update information on New Zealand’s soils into one easily accessible map of the whole country with different layers of information for different applications and to support land management at different scales.

Anyone can access the information freely. Mapping is carried out by Landcare scientists who either use old soil maps or go to the area and undertake traditional soil surveying. This is where soil core samples are taken to determine the soil type and this information, alongside the history of the area, is used to present what they think the pattern of soils will look like. The most detailed information available is currently on the lowlands while the uplands of the country are being mapped using digital modelling based on the soils having similar characteristics to other known soil types.

How to use it

In the previous blog (identifying soil textures) you see how the content of sand, silt and clay determines soil physical properties such as WHC, porosity and bulk density and how there are different horizons in a soil profile with different quantities of these three particle sizes. S-Map also uses soil horizons to determine soil characteristics.

You can search for your location on S-Map and select to see polygon layers to view the soil types present on your farm as shown below for Methven, Canterbury.

S-Map Online is freely accessible for anyone; smap.landcareresearch.co.nz

You can then select the ‘Soil information’ tab at the top of the screen and click on a point on the map. S-Map will show you the percentage of each soil type present around this point and you can select to view the factsheet of the dominant soil type (and the other soil types present). In the figure below the Greenvale farm near Methven is shown by S-Map to have three dominant soil types: 50% is a shallow, well drained Eyre, 25% is a shallow Darnley and the final 25% is a moderately deep Mayfield.

The soil will have been given a series of names using the New Zealand Soil Classification System however don’t worry about this too much, the information contained further down in the factsheet has more practical applications. The fact sheet tells you:

• ·         How stony the soil is which relates to its drainage class
• ·         The amount of water expected to be held at different depth increments
• ·         The clay content
• ·         Potential rooting depth
• ·         Soil phosphorus retention
• ·         Water management such as the potential for waterlogging and drought
• ·         Nutrient management such as nitrogen and phosphorus leaching vulnerability. 

Page 1 of an S-Map report for an Eyre soil, downloaded from smap.landcareresearch.co.nz

You can also select different layers to view on the map, on the left hand side of the screen: soil drainage, depth to hard soil/ gravel/ rock and soil moisture. The map will then update using the colour scheme from the legend for this layer which is shown on the right hand side of the screen. The figure below shows that for the Greenvale farm the soil drainage depth layer has been selected and on the right hand side the legend explains what each drainage class means.

Positives

S-Map brings all information on NZ soils into one database that can be easily accessed and used by all land users and interested parties. It is the largest national resources on soils that NZ has and it contains a range of information that is relevant and useful for all scales of management. However there are also aspects to S-Map that limit its usefulness, especially to farmers.

Drawbacks

According to S-Map the Greenvale farm, shown in the S-Map figures above is a mix of mainly three soil types. However an Electromagnetic map carried out alongside soil sampling showed that there was, in fact, a much more complex pattern of soils present on the farm. The picture below and top is the Electromagnetic map of the property and the different colours represent different textures while the picture below and bottom uses the patterns from the EM map alongside soil sampling to identify the pattern of soil types (families) on the property. 

Top, EM map by Agri Optics Ltd. Bottom map of soil types developed from soil sampling.

These maps provide a substantial amount more information than the map of the farm from S-Map (discussed above). The soil information used by Overseer to determine nitrate leaching is supplied by S-Map and this can result in inaccuracies in N leaching figures when S-Map believes the soil pattern on a farm is more simple or different than it actually is. Furthermore using soil information from S-Map for irrigation scheduling could mean over or under irrigating areas which can decrease yields as well as creating inefficiencies in water and power use.