Irrigation Evaluations (aka Bucket Testing) - Including tips for testing VRI systems

Spring is here but we are seeing all four seasons rolled into one some weeks which is not an anomaly. The soil moisture levels in our region have had a healthy boost in the last few days but if the media reports are true we may be in for a dry summer - please don't shoot the messenger, I'm only relaying what I have heard.

Should this transpire then that is even more reason to ensure that our irrigation systems are applying water as efficiently as possible so that we are maximising the amount of water applied that is available for plants to grow. An irrigation evaluation is a way to assess the efficiency and distribution uniformity of your irrigation system to ensure it is performing as expected.

An irrigation evaluation will help identify causes of any poor performance and (sometimes with the assistance of a qualified professional) show how these can be resolved. Increasing irrigation effectiveness and efficiency will allow you to grow more for less.

An irrigation evaluation (often referred to as a bucket test) is simple enough to carry out yourself, there are several good guides freely available to walk you through this process. For more information check out:

IrrigationNZ - Bucket Testing Resources
DairyNZ - Irrigation Evaluation Guide

The guides recommended above will walk you through how to carry out a standard bucket test however before you begin you need to consider any additional technologies that enhance your irrigation system. For instance if your system has variable rate irrigation (VRI) technology then you will need to take this into account when planning your bucket test. Lindsay NZ, the developers of the Growsmart Precision VRI system, have created a step-by-step guide that explain these additional considerations in more detail.

Growsmart Precision VRI - Bucket Testing Tip Card

If you are not in favour of the DIY irrigation evaluation option then consider contacting an accredited evaluator, this would also be recommended if your own test identifies potential issues that warrant further investigation. If you have additional technology such as a VRI system then ensure that whoever is carrying out the test is aware of this and that they carry out the recommended additional steps. If you need further help then contact your irrigation dealer, many dealers also have accredited evaluators on hand.

Irrigation system checks and maintenance should be undertaken at scheduled times over the irrigation season (the more hours your irrigator runs for the more regularly these checks should be carried out). Recommended irrigation system maintenance will be covered in more detail in the next H2Grow blog post, this will include a checklist that you can download and print off to help you with this task.

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Today's blog was written by Sarah Elliot from Lindsay NZ - I hope you have found it useful!

Inaugural PAANZ Conference - Summary

Precision Ag in New Zealand is finally starting to gain a bit of traction in NZ & this was seen last Friday by:

1)      the fact that the Precision Ag Association of NZ (PAANZ - www.precisionagriculture.org.nz) ran their first conference

2)      the  number of attendees that came from far and wide to attend & learn

Firstly, I’d like to congratulate the PAANZ committee on organising a well-run event with some thought provoking topics and speakers. I’m going to run through a bit of a summary of the day in terms of what was covered and some ideas to ponder.

Andy Macfarlane from Macfarlane Rural Business kicked the conference off to a start with a general overview of NZ ag and where we’re at in terms of water, nutrients and farming within limits. One of the key points from his presentation was that “Good Management Practice (GMP) is a given – everyone needs to get there NOW!” GMP will evolve and is not a fixed point. ‘Good’ will also not be good enough, farmers will need to be ‘great’ to keep ahead of the game and ensure long term farm viability. Precision Ag is going to be integral going forward to achieving this.

Some Key Principles for mitigating N leaching

1. Measure before you apply – need to know what you’re dealing with so you can make the right input decision.
2. Use nitrogen (& water) interceptors – roots, different crops etc
3. Smaller and often applications are better than large amounts and less often
4. Do not put nutrients where you don’t need them (use targeted application technology – Precision Ag)
5. Apply less urine or less nitrogen concentration in urine
6. Increase nitrogen utilisation in gut to decrease output of nitrogen
7. Less water drained = less nitrogen leached
8. Integrated farm systems approach required to achieve long term desired outcome
9. Validation of science needed both at research level and on farm

Keith Cameron, Professor of Soil Science at LincolnUniversity also posed a sound point that irrigation, even though it might be controversial in some areas and need better management allows increased N uptake as the plants are actively growing and not under stress, therefore less leaching of nitrogen results. Is there a case for environmental irrigation? Especially in summer dry areas? He also pointed out that we need to look at plant uptake as a mitigation strategy for decreasing nitrogen leaching. Catch crops following/during winter grazing is likely a good way to achieve this and studies have shown that this can be by between 20-40%.

While we all know that nitrogen itself is a key part to the nitrogen leaching discussion, in irrigated Canterbury and other parts of the South Island managing soil moisture is key to effective nitrogen management. Dr Tony Davoren from HydroServices spoke on this topic and highlighted the following:

• Measuring and understanding your soil moisture is key to good irrigation management and reduced leaching
• No drainage throughout the growing season from pivots if managed well – the same can’t be said of other irrigation systems with high application rates in particular
• You need to measure soil moisture at and below the root zone. Firstly to understand your plants requirements, and secondly to know and be able to prove that you aren't leaching and wasting water
• It’s also important to measure soil temperature as this is also a factor when scheduling irrigation and brings in the ‘farm systems approach’ that Andy talked about by looking at multiple factors.

As the focus of the day was mostly looking at how nitrogen leaching could be reduced using Precision Ag (PA) techniques there wasn't a lot of emphasis on other areas, however some were slightly touched on. These included Ian Yule (Massey University) talking about the economic impact of poor spreading pattern and that it could cost a farmer on average $45/ha if his spreading CV was at 20%, however CV was likely to be nearer 30% when out in the field. At costs like this we obviously need to get our spread pattern accurate before we start doing variable rate fert. Accuracy is key to everything in Precision Ag. The benefits of ‘All Paddock Soil Testing’ was highlighted for reducing paddock to paddock nutrient variation and pushing pasture yield along on dairy farms.

There were a vast array of topics covered during the day, stretching further than just nitrogen leaching and it was truly encouraging to see such a good turn-out of interested people to this inaugural event as well as the robust debates and discussion that went along with it. It’s truly heartening to see NZ farmers and industry pushing the boundaries and meeting NZ farming targets using tools and technologies that are already out there today. The future is very bright for NZ ag and coupled with all of the emerging technologies and the science to back these up I feel very encouraged about the position of the New Zealand farmer. Now to get everyone dabbling their toe in the water of Precision Ag…

~ Jemma

WHO SAID IRRIGATING WAS EASY?

Being an Irrigating Farmer has many benefits with increased land value and production to less reliance on rainfall events being at the top of the list.

But with these benefits comes responsibilities and duties to ensure success at being an irrigating farmer.  So, what is involved?

1. Regular System Maintenance

1.       Irrigation System checks should be undertaken pre-season and at least twice over the irrigation season.  This involves doing pressure tests, checking sprinklers and nozzles, cleaning out filters, checking and fixing leaks.  Click on the link below for checklists and guides.

http://irrigationnz.co.nz/news-resources/irrigation-resources/irrigation-system-checklist/

2. Irrigation Evalulations

Irrigation Systems need to be evaluated much like getting a vehicle Warrant of Fitness.  Evaluating your system allows you to check that it is working to the design specifications and performing as you would expect.  High distribution uniformity (how evenly the system applies water) is the key to achieving an efficient and effective irrigation system.  

Ideally, irrigation systems should be ‘farmer’ evaluated annually using the ‘Irrig8lite’ guide - http://www.pagebloomer.co.nz/resources/irrigation-calibration/irrig8lite/.  

Should your system show low performance, a full system evaluation should be undertaken by a qualified evaluator: http://www.hydroservices.co.nz/index.php?option=com_content&view=featured&Itemid=271.

3. Measuring Soil Moisture

Measuring your soil moisture is the BEST way to manage and schedule your irrigation efficiently.  If you don’t know what your soil moisture content is, it is likely you are either under irrigating or over irrigating which can be detrimental to your crop and/or the environment.  There are a number of options when it comes to measuring soil moisture whether it be an on farm service or telemetered continuous soil moisture sensors.  

Find out more at: http://www.hydroservices.co.nz/index.php?option=com_content&view=featured&Itemid=268.

The Irrigation Season has already arrived for some and is fast approaching for others.  If you haven’t completed your pre-season system maintenance checks already, now is the time to do it!