A trick to combat rust on your irrigator

Many of us have seen brown or orange irrigators out in the field. If the spans, truss rods, v-jacks and towers are all orange or brown, that’s a sure sign that there is a lot of iron in the water that is being irrigated and in the scheme of things it isn’t generally a big concern. 

Discoloration caused by iron in water supply

What you should be concerned about though is all the moving components that can rust, especially if your irrigator is in a coastal area where the salt in the wind causes rapid corrosion. In these areas some of the first signs and parts to cause problems will be hinges and tower alignment components.

Tower alignment components are vital to keeping your irrigator straight and if any of these parts seize, they can break and the corresponding pivot tower could either get stuck in a moving or still state, or if you are lucky, just safety out the machine before anything bad happens.

Likewise, any hinges that seize will either stop you getting into panels, or simply corrode and snap off. 

We’ve found that fish oil products like the one pictured here are fantastic for preventing rust (or at least slowing it down), making your components last much longer. The frequency that you need to apply it will depend on the climate you are in, but keeping a tin of fish oil based product in the shed and applying it frequently to moving and rust-susceptible parts will go a long way to help extend the life of your system.

ANNUAL VOLUMES NEED TO BE USED JUDICIOUSLY

In an El Niño spring and summer water for irrigation is a precious commodity.  As expected irrigation started earlyish – like September - and with current predictions is likely to continue through to April.  That means irrigation will be required on a regular (aka daily) basis and will likely result in two potential issues for irrigating farmers:

a)     Groundwater users could have self-limiting bores.  This occurs when water levels drop to the point where cavitation (sucking air) occurs and/or the head required to lift water to the surface falls outside the optimum for the pump.  Both circumstances result in a reduction in L/s that can be pumped.

b)     Of greater concern is that the season is likely to be greater than the 9/10 (or 90-percentile) demand season and annual volume could be exceeded.  Therefore it is essential every effort is made to use water judiciously.

Judicious use does not include irrigating hard surfaces (aka roads).  I thought we had left the “cleaning of roads” behind – it is such an obvious waste of water and is a misdemeanour, in some cases “fineable”.  All in all not a bright use of water!

My first example is an old one and is thanks to a colleague in Hawkes Bay.  It dates back to early 2000’s, maybe 2006ish.  We have used this photo endless time to emphasise this is not the wisest use of water, and in this case a dangerous use of water.  Can you imagine riding a motorcycle and being hit by the stream of water from the high pressure gun!!  It will wash your windscreen though you could run off the road by the time you recover from the shock of the water hitting the windscreen and the wipers have been able to clear 25L/s of water.

My second example is very recent – November 2015.  No doubt the lane closest to the hedge has been well washed.  While this irrigator is less likely to result in a deluge of water on a windscreen or affect a motorcyclist as badly. It is nonetheless a waste of irrigation water.

The volume of water irrigated onto the roads is relatively small in the scheme of things.  But in a season where every drop will undoubtedly be worth $$$ in return, cleaning roads is not an effective way to make the water pay.  Quite the contrary, in both examples the water has been pumped from bores (a lost cost) and has not added any value to crop intended.

Dr Anthony Davoren, http://www.hydroservices.co.nz

The 2015 EM Season has come to a close

As we fast approach the end of 2015 it is good to look back at the EM surveying season we have just had. Due to the very dry summer we didn’t get going until nearly the end of April which is about 3-4 weeks later than the season before. Stewart Darling join the team this year and many of you would of met him if we conducted any survey work for you. As Stu’s from Scotland he found the colder winter weather easier to handle than this already hot summer! We also changed our side by side Polaris for a larger capacity machine for greater capability in the field and improved downhill descent which comes in very handy at times in Otago!   We did a lot of testing with the new set up to make sure it was performing well before the season kicked off.

Field testing the EM rig on the new Polaris back in February 2015.

Like every season we have faced new challenges and found solutions and developed our protocols to take them into consideration. So next season we will be another step ahead of the previous year! We have met some varied and interesting new clients as well as continuing to work with our existing clients, helping all to achieve their goals with precision ag. through our services.

With the introduction of our AquaCheck soil  moisture probes this season we have been able to add another dimension to the service we offer, not only surveying  your soil’s variability and moisture holding characteristics but now also providing the means to monitor them very effectively.

Travelling past Mount Cook on one of many trips through the central South Island.

Moving forward to 2016 we will start surveying as soon as conditions allow; that is usually when irrigation has finished and we have had a couple of large rain events to negate the man-made influences of that seasons irrigation on the soil. This is usually anytime from late March to April depending on the year.  Our main concern is that our clients get the best data possible. This only happens when the conditions are right so please bare this in mind. If you want to book a survey in for a particular month to fit in with your on-farm management that is fine or if you just want to complete the  survey as soon as possible just let us know so we can keep in touch and start as soon as we’re able. For all enquiries be it for just more information on our services or a full quote please contact us at Agri Optics.

Wishing you all a fruitful and productive summer for what looks to be a very challenging time ahead. And hopefully you have the tools in place to help manage your water resource as efficiently as possible! Have a Merry Christmas and all the best for 2016 from the team at Agri Optics.

Chris Smith

Agri Optics 2015/16 Xmas Hours:

Closed Wednesday 23^rd December  & re-opening on Tuesday the 5^th of January. For any urgent matters over this time please call Jemma Mulvihill on 021796124. 

Is your irrigator going to perform for you this season?

Most of the country's irrigators should be well into gear by now, so it's a good time to ensure that your system is going to get you through the season with as little hassle possible.

Giving your irrigator a mid-winter service is generally the best way to prevent mechanical breakdowns the following season. A mid-winter service generally involves things like lubricating joints, replacing oil in gearboxes, looking for signs of fatigue, etc. Addressing these points will go a long way in setting you up for a happy irrigation season to come.

Avoid scenes like this!

If you have or have not given your irrigator a winter service, there are several crucial things that you should check at the beginning and throughout the irrigation season. Some of the simple things to check include:

• Riser pipe is greased and well lubricated
• Tower box components are free and not corroded. Depending on the type of alignment your pivot has, there may be points to lubricate. If joints corrode, seize, and fail this will cause your machine to safety out.
• Alignment is good – when the pivot is running the spans naturally have a bow one way or the other depending on whether it is in forward or reverse. If this bow is always one way, that is a sign that the alignment needs adjustment and excess pressure is being put on spans, towers and the centre point. This can also lead to excessive wheel rutting.
• No electrical components are exposed. Loose cable glands can let moisture in to electrical components and lead to premature failure.
• Tyre condition – this one should be pretty obvious
•  No obvious leaks – leaks should be treated early as can often be fixed by simply tightening components. For example, if a flange joint between span-pipes is leaking, that is a sign to immediately get up and check that the nuts and bolts are all tight – a simple way to avoid a disaster!
• Visual inspection – anything that doesn’t look right probably isn’t.

Signs of fatigue such as the crack in this base beam bracket should sound alarm-bells!

If you are not comfortable with repairing any of the issues you find with your machine yourself, it is going to be much cheaper to get a service technician to come out and repair it now than it is going to be when it causes your machine to stop working, causes more damage, and affects whatever crop you are irrigating.

EM values - What the data is telling you

An Electro-magnetic (EM) sensor generates a constant electro-magnetic field that penetrates into the soil profile. It measures the bulk electrical conductivity of the soil profile. As we conduct an EM survey the sensor is taking readings at two different depths simultaneously. These two depths are known as the ‘Shallow EM’ and the ‘Deep EM’. The depths the DualEM reads depends on the height the machine is off the ground. With our EM setup we are reading the soil profile depth of 0-40cm for the shallow EM and the deep EM at a soil profile of 0-125cm. So the deep EM values are the same as the shallow plus another 85cm deeper. This is why the deep EM readings are always higher than the shallow as it is reading that extra 85cm.

Figure 1: Shallow EM of the same area with values from 1.6-27 EM units (mS/m)

Figure 2: Deep EM survey values varying from 16-43 EM units (mS/m)

 In this survey the same features are showing in the shallow EM and deep EM results, however sometimes this is not always the case the deeper profile can have a different underlying soil type that the shallow EM doesn’t pick up but the extra 85cm of deeper soil does and it changes the overall structure.

Generally speaking and depending on what part of the country you are in and the time of year the survey is carried out amongst other things, we would class a range in EM in the shallow profile of 1-3 units as low variability, 4-8 units as moderate variability and over 8 units range as high variability in the shallow layer/soil profile. In the deep EM/soil profile layer a range of 1-6 would be low variability, 6-15 moderate variability and over that high. It is often dangerous to generalise like that, but it gives you an idea of the type of ranges we look at, and as previously stated there are a lot of other factors that determine if the readings are low, medium or high variability. You also have to look at the distribution of the values as well, if the majority of the values are within a certain range and a few rogue values outside that but on a minimal area of the total, then the range in variation may not be as much as it first looks. How much the variability is costing you in terms of blanket irrigation applications compared to variable rate irrigation applications be it water, seed or fertilizer is a subject for another day!

Also of note as an aside; is that with all our readings legend red is the lowest value and dark blue the highest. This does not mean that red is bad and blue is good, there are a number of factors that determine that, and there is also a climatic influence on what is good or bad, in a dry year the heavier EM areas would be better where you don’t have VRI, and in wet years the lighter areas with more free draining soils would be more favourable. Likewise in peaty acidic soils with high organic matter they would show through as the high blue EM areas and clay soils would show up as the lighter red soils on the map. So it is always worth taking samples as you conduct the survey to see what is affecting the readings.

For more information on EM Surveying please contact us at Agri Optics NZ Ltd.

Chris Smith.