Rake or Merger?

For those of you who only grow maize or whole crop for silage, then it’s time to put the kettle on, or do something else, as this is not the article for you. This piece is all about the machine choice for grouping, merging or rowing up of grass crops into a swath. This series doesn’t usually look at the machines used in silage production so this is a bit of a departure isn’t it?

In my defence, the underlying theme in all the articles from the silage series remains. They are all about making great silage and reducing waste – and how you present the material to the harvester is all part of this.

Back in the 70’s and 80’s rowing up wasn’t anywhere near as popular as it is today. In those times, nine foot of grass was enough of a meal for a Jaguar 75 with little more than 100hp on the end of the PTO shaft. Today a Jaguar has a far more healthy appetite so you, or your contractor, need to serve up a much larger helping to utilize all that horsepower.

The solution in the UK has always been a rake, from one to six rotors gathering over 60’ (for the biggest rakes) of crop into a single swath. Or that’s what we thought for years, but now there is another way. Mergers used to be something to do with the stock market but today they are more to do with the machinery market. These machines were popular in parts of the world growing alfalfa or lucerne. This is due to their gentle action of lifting the crop into a cross belt that delivers the crop to a swath. This is ideal for delicate leafy crops like lucerne where much of the feed value is in those easily lost leaves.

But why would you use a merger in rye grass?

Well the leaf loss advantages of the belt merger are still relevant to grass crops, particularly in higher dry matter crops as leaf shatter becomes more of an issue, but there is more to it than that. A well setup rake is an efficient and effective machine to produce a forage swath. Soil and stone contamination of the swath are minimised on level ground but there is an inherent risk once the rake tackles undulating ground. This comes from the fact that the raking height is set on the bogie or dolly wheels that sit some distance behind the leading edge of the rake. So as you approach a slope, the tines hit the deck before the wheels have reached the slope. The distance between the height control (wheels or skids) and the lowest part of the crop tines is always shorter in a merger than a rake.

So should the rakes stick to flat ground?

Not entirely, rakes are still a cost effective solution for many. So we now need to think about the crop you hopefully didn’t cut, the dead and dying leaves very close to the ground. These leaves host and can introduce all sorts of microbial life forms that you really don’t want in the clamp. So you really don’t want to rake them into the swath and surely a merger will be better at leaving these behind? It will, as long as these leaves haven’t been picked up and mixed in by the actions of a tedder.

A merger has the capability to reduce the leaf losses, reduce contaminations by dropping stones and soils and by leaving the unwanted plant matter behind – so is that it? No – not by a long way, not if you speak to the chopper driver.

What are the other advantages of a Merger?

One of the main advantages of a merger is the more consistent nature of the swath it produces. A rake gathers packets of crop together and delivers them into a swath. The forward speed blends these packets together to produce a more consistent swath but there are still some (sometimes invisible) variations in density in the there. Sitting in the seat it’s not so easy to spot, but walking (or running) along side a chopper you can see the top feed roll following the lumps in the crop feed. Sometimes it’s not possible to feel or hear the effect of these but in tests, a chopper following a merger can run 3km/h faster than following a rake in the same crop.

That sounds like a lot, but let’s assume you have a swath gathered from 9m of crop and you spend 10% of the time at the headland turning or changing trailers - that’s over 6 acres an hour more ground cleared!

So a chopper can travel much quicker behind a merger, and so can a baler, in tests 2-3km/h faster. The merger is also a more flexible machine as it can more easily group swaths in light crops than a rake.

Downsides, well mergers are expensive – but then so are big rakes.

There aren’t many second-hand mergers available and we don’t know how the used values will pan out. Long term reliability issues are also yet to be identified but the different elements of the machines are fairly well known – tine pickup reels are hardly new technology are they? So don’t immediately pick up the rake brochure, give the merger careful consideration as well.

If you want to discuss options for rowing your silage swath or any of the other aspects of silage making covered in this series – contact Jeremy Nash @ jeremynash1@btinternet.com