Maximising pit capacity and feed value is a priority for dairy farmers who rely on ensiled crops for winter feed. Alex Heath speaks to contractors who have built pit compactors of differing designs.
The importance of a well compacted silage pit cannot be overstated, with feed value the priority when ensiling forage crops. However, ensuring the most crop is stored for winter supplies as efficiently as possible requires weight.
While loading shovel and tractor-mounted buck rakes are the favoured method of getting grass into the pit, often a spare tractor will be seen crawling across the clamp, consolidating the layers. While weight is important, the area the weight is targeted through is equally important.
Recently, an influx of pit compactors have come to the market, promising the weight and focusing it into a concentrated area, thus increasing the pressure asserted on the crop.
However, not everyone is in the position to buy, preferring to build something more bespoke to their needs. We speak to two such contractors who have designed and built their own pit compactors, using two distinct designs.
Running his own contracting business, Thomas Penrose says he spotted a gap in the area to hire and contract with a pit compactor as there was no-one else in the area providing that service. With a 16,000-hour John Deere 6800 at his disposal, creating flexible ballasting options to allow his own tractor and those of customers to use the machine was a priority.
He says: “I looked at pit compactors with train wheels, but the expense and rarity of the wheels in our area, coupled to the heavy base weight, meant they were just not suitable for what I had in mind.
"Instead, I liked the idea of a central cylinder which could be ballasted, in addition to weights added to the frame. Because we are using a lower base weight, having a smaller surface area which exerts more pressure on the crop is important.”
The compactor’s construction revolves around a 300mm-diameter tube, 2.2 metres in length. Welded to this are 12 discs, spaced 200mm apart. These are made of 15mm plate and measure 800mm in diameter. Initially, they were cut in one continuous disc, however, to reduce wastage, the decision was made to CNC-cut three pieces per disc by Mr Penrose’s friend Matt Halliday, before being welded to form one disc. The framework was mostly constructed out of 150mm by 150mm box section with 6mm walls.
Mr Penrose says before the 25mm thick end plates were welded on, kiln-dried sand was stuffed into the box section, adding another 60kg of ballast. Empty, the compactor weighs in the region of 1,500kg, he says. There is the option of filling the barrel with about 150 litres of water, although going forwards, Mr Penrose says he will fill it with concrete, which will amount to nearly 400kg of weight.
In addition, the compactor was designed in such a way that up to 650kg of wafer weights can be hung on it also, taking the total weight up to 2,550kg. He says the compactor makes a visible difference to the tidiness of the clamp, especially when used on wagon-harvested grass, with its longer chop length. He adds that farmers report a 20 per cent increase in crop ensiled, with a tighter feed face upon opening.
He does have some modifications to make to the compactor, however. “It can dig in too much,” he says. “On maize, we were seeing it dig in by 65mm, which makes it more difficult to pull than it needs to be.”
To counteract this, Mr Penrose proposes to add a ‘donut’ either side of the existing discs, again made of 15mm plate, but 150mm in depth. He says: “Adding a 45mm strip of plate around the circumference of the discs or a smaller donut could work, but I fear those methods could disturb the surface too much, pulling loose crop back up, so a deeper donut is the best idea.”
Mr Penrose says he typically uses the compactor in conjunction with a buck rake on the front of his tractor, which makes use of all 140hp on offer. However, he reasons that it makes better use of the time spent on the pit, with grass spread while travelling up and compacted while reversing down. With a total width of 2,480mm, he says the tractor tyre can be run tight to the wall, pushing crop into the wall and the compactor pressing it down, forming a tight edge.
Louis Hancock has also built a compactor, in collaboration with a local fabrication company. Mr Hancock says after purchasing his first self-propelled forage harvester in 2017 and recently upgrading it for a Krone BigX 700, silage comes into the pit too quickly for a tractor and buck rake to deal with sufficiently.
Throwing another tractor on the pit abated the problem, however, he soon thought more weight was needed to better compact each layer. Mr Hancock says: “We rarely go out on a job without it now. At first, the challenge was convincing farmers that it did a better job than a tractor on its own, but once they saw the results for themselves, they ask for it to come back.
“Whereas before we were getting about 650kg/cu.m, now we are getting about 800kg/cu.m, giving a much denser pit and harder, cleaner clamp face.”
With a large tractor surplus to requirements during harvest, latterly a Fendt 942, weight of the compactor is not an issue, so he set about building a heavyweight version in 2018. Sourcing train wheels from a friend who is in the rail rolling stock business, Mr Hancock says he was lucky to land on a set of 12 unused, equal diameter wheels, each measuring 800mm and weighing 300kg.
The frame was made in-house, weighing about 500kg, while a solid shaft made of EN24 steel, 200mm in diameter and weighing in at one tonne, holds the wheels in place with 20mm spacers sitting in between the wheels. In total, Mr Hancock reckons the compactor weighs in at 5,100kg.
Mr Hancock says the compactor was built with longevity in mind and reckons it should easily have a working life of at least 10 years. For this reason, he machined grease nipples into each of the wheels and says it is greased twice-a-day when working, with no wear evident yet after three busy seasons.
He says it was designed to be slightly wider than a standard tractor. “It is about a train wheel either side wider than our John Deere 6195R, but it is the same width as the 942. The 6195R just lifts it, but needs a 1,800kg weight block in front of it, just to keep the nose down on the road.
“The Fendt has a 2,500kg weight block on the front; the tractor itself weighs about 12t plus the compactor, with the whole set up near 20t.”
Overall, Mr Hancock is happy with how his compactor is performing. He says: “If we can get 200kg/cu.m, more silage packed into the clamp and help reduce the chances of spoilage, our farmers are happy.
“I regularly go around farms in winter and see for myself the difference it makes, so the project was worthwhile in my eyes.”