Test: Marshall ST2550 Slurry Tanker

By: Jaiden Drought, Photography by: Jaiden Drought

marshall st2550 slurry tanker Hertell 10,000L pump is standard on all ST2550 tankers marshall st2550 slurry tanker
marshall st2550 slurry tanker Six-inch outlets both front and rear allow you to alter filling position as the pond goes down marshall st2550 slurry tanker
marshall st2550 slurry tanker Double baffle system helps protect the pump if the tank is overfilled marshall st2550 slurry tanker
marshall st2550 slurry tanker Simple and effective drawbar suspension marshall st2550 slurry tanker
marshall st2550 slurry tanker Integrated tank and chassis reduces the risk of premature fatigue while increasing strength marshall st2550 slurry tanker
marshall st2550 slurry tanker Inverted spreading plate reduces both smell and nitrogen losses marshall st2550 slurry tanker

Here’s a no frills slurry tanker that’s easy on the wallet, easy on your power requirements and will have you cleaning up your operation in no time.

Test: Marshall ST2550 Slurry Tanker
The large recessed wheels allow lower ground compaction without affecting machine width

If you've been living with your head in the sand lately hoping the drought will go away, then you'll have failed to notice the local regional councils in partnership with Fonterra handing out abatement notices left, right and centre, to clean up the countries streams. The latest findings from a Fonterra study found "we could do better" as a whole, and therefore it's an issue not soon going away.

To follow the theme of cleaning streams, this month I am testing a machine able to help you out in the dry by applying water from you ponds to your fields. This is not only beneficial to the dry ground but also keeps the pond down and out of the creek, killing two birds with one stone. I can already hear you asking, "Where do I sign?!"

The Marshall slurry spreader has been manufactured in Aberdeen, Scotland for over 60 years by Marshall Engineering, so it's by no means new to the market. However, these tankers are fairly new to New Zealand, having been imported by Robert Pooler of Atlas Agriculture just over two years ago and already proving a hit with the locals.

This machine is what I would describe as a very good tanker for farmers. A 100hp tractor will pull this on the flat, meaning you can purchase a cheap tanker without having to upgrade the farm tractor, so cost savings all around. With this tanker you'll benefit from recessed mudguards to accommodate the large 750/60 - 30.5 tyres, providing fantastic floatation in the wet but also allowing the majority of the weight to be held over the axle, again reducing power requirements.

The Marshall ST2550 is the largest tanker in the range, with a total capacity of 2550 gallons or 11,600 litres, which may limit the appeal to contractors wanting to move large volumes in one go, although having said that, Pooler runs these machines in his contracting business with great success.

Design and build

It's built tough, with the tank quality as good as anything on the market, but the features are kept simple, keeping the price down.

The Marshall tankers have an integral chassis design to reduce stress on the tank and prevent premature cracking. In addition, the tank is constructed from six-millimetre steel, and painted with two-pack paint, improving durability and increasing the lifespan of the tanker. The ST2550 comes standard with a six-inch side valve, interchangeable with another rear-mounting position so you can alter this depending on your loading position.

Double baffles are fitted with two slurry traps, reducing the risk of effluent reaching the pump if the tanker is overfilled. One is located inside the main tank while the second is located in the siphon box mounted on the front of the tanker. The valve at the bottom of the siphon box should be opened regularly to allow any slurry to escape before it overflows the trap and reaches the pump.

The machines also come standard with a simple leaf spring drawbar suspension which works well and is much cheaper and easier to replace than spring setups.

Parts and backup

When it comes to parts and backup, some may initially be a little apprehensive about these tankers as you're not buying from a dealer but directly from Atlas Agriculture. Of course, on the flip side there's no dealer clipping the ticket, but as far as backup support goes, where does the owner stand? Well, firstly, very little can go wrong with these machines - they're that simple. Unless you run the pump out of oil or the hoses eventually perish and need replacing, you're not going to have any problems. To offer you even more peace of mind, Pooler also runs them in his own fleet and did so before he started selling them to the New Zealand market. He also stocks a lot of parts for his own fleet, as well as customers' fleets, and can have most parts on a 24hr, overnight courier to anywhere in the country.

The pump

Our test tanker had the Hertell 8000L pump on it, although now all ST2550s come with the 10,000L pumps, providing quick and efficient loading of the tanker, all in around four minutes.

Now, it's often assumed the bigger the pump in slurry tankers, the faster the tanker will fill. This is somewhat true, although you need to think of these pumps more like vacuum cleaners as opposed to a normal pump. Unlike a most, this pump builds up pressure inside the tank, sucking the liquid up into it like your vacuum cleaner. On some vacuum cleaners you can put the pipe on the back and use this to blow up an air bed, for example, and this is exactly the same as switching the pump from 'suck' to 'blow' to apply the effluent to the paddock. Because of this principal, the pump doesn't take much to run in terms of power as it is simply creating a vacuum. This actually means running the pump flat out will only ruin it. Three hundred and fifty revs is all it will need and running it higher than this will not decrease the filling time of the tanker. Like any PTO-driven machine, aggressive start-up will only wear the machine out faster so by running in 540 rather than 1000 to save a little bit of fuel, in terms of tractor revs, is probably costing you more in the long term.


With the Marshall Slurry tanker, what you see is what you get. It's built well and Marshall's no-frills approach to its standard machine will appeal to a lot of farmers. If you want the extras, you simply add them to the price rather than paying for specs which you may never use. Speaking of price, the cost of these machines is on the website, along with details from the manufacturer explaining how the cost is broken down and the cost of additional extras. Farmers like transparency, so this clear price indicator will appeal to the majority. Knowing exactly how the price is made up and being able to choose the features you require is rare, but very appealing, and will only add to the success of this brand here in New Zealand.

Standard equipment

  • A 10,000L Hertell pump
  • Six-millimetre pressed steel tank with integrated chassis, reducing stress fractures
  • Standard six-inch side valve (with interchangeable rear mounting position)
  • Pressure gauge is easy to read from the cab
  • Fully integrated lights
  • 11,600L capacity, even with the recessed mudguards
  • All cut-in tanks have dropped axles to lower the centre of gravity but it also allows the tank to be on a backward lean, ensuring all material is deposited
  • Standard sprung drawbar
  • 750/60 - 30.5, 90mm, 10-stud axle standard
  • Hydraulic jack
  • Skid plate (this is used for tractors with pick-up hitches - few and far between in New Zealand)
  • Six metres of six-inch pipes

Optional extras

  • Autofill - this system has been patented and is quite unique as it is like a little metal speed bump, where the tractor drives over the bump and, once the machine is lined up, drops the slide arm straight down into the pod. This is at ground level - a great idea as ground contour makes no difference due to the pod staying straight and true while the pipes move, the pond level dropping. The other advantage of this design is the filling arm's short reach. This stops it from moving around when driving over rough tracks and causing unnecessary fatigue on the welds and pivot points.
  • Hydraulic pump change over
  • Tyre options, either larger or smaller depending on your requirements

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