The approach to mowing grass has hardly moved on over the last 25 years or so, all that has really changed is that as tractors have got larger, correspondingly wider mowers have been developed to keep pace.

This past year though, has seen a growing challenge to this placid situation as companies producing grassland equipment have started to look at new ways of managing the crop in the field.

Bigger may not be better

One of the major drivers behind this revision is the voracious appetites of modern, self-propelled forage harvesters, machines that require large swaths to make the most of the power available.

Up until now the standard answer was ever larger rotary rakes, but these have the disadvantage of being limited by the speed at which they can operate.

Mowing forage harvester
High output forage harvesters demand that cutting and raking is equally as quick to stay ahead

A four-rotary rake will also be moving the outside grass twice as it sweeps it to the centre of the machine, an obvious source of inefficiency.

These problems have been addressed by the advent of the belt merger, a machine that has been lurking in the shadows for sometime, confined to handling lighter and more delicate crops.

Belts vs. Tines

Kverneland’s much publicised decision to buy an Italian manufacturer specialising in their production has brought them into the limelight and focussed the thoughts of large operators on the issue of swathing the crop.

ROC Italian grass
ROC specialises in heavy-duty belt mergers and its recent purchase by Kverneland will see them arrive in Ireland

Pottinger and Sip are two other companies that have decided not to be left out if this interest in mergers solidifies into a definite demand.

Yet the advantages of swathing by either method have not been independently tested. Research on cutting silage and managing it in the field appears to have stopped around 20 years ago, leaving large investments in new machinery dependent on gut feeling.

Mowing with lighter tractors

Tractors with higher horsepower ratings need not mean that they are bigger and heavier. Power densities are increasing and lighter four-cylinder tractors are moving up the spectrum.

These machines can provide enough power to cut a wide swath, but they may not have the mass to safely handle large mounted mowers, especially if they are fitted with conditioners and mergers.

Swaths grass crop
Krone’s big M is an impressive machine, but at 15t it is also heavy

This has raised the question as to whether conditioning is always necessary as plain mowers are cheaper to buy and run, easier to handle and, by virtue of being lighter, cause less soil compaction.

It might also be added that with the push to incorporate fragile legumes into the sward, mowing without a conditioner is less likely to cause crop loss through degradation of the leaf and stems of these novel species.

To wilt, or not to wilt

If there is a case for plain mowers, then we might look at the need to wilt as well.

Here we are entering the realm of what might be termed lightweight continental crops that are cut in the expectation of dry weather providing a high moisture loss, even from a swath.

wilting grass mowing
Wider machines will mean fewer passes, keeping the weight off the soil

But wilting is not always carried out satisfactorily in Ireland anyway. The cutting window is shrinking on an annual basis and contractors haven’t the luxury of allowing expensive machinery to stand idle, waiting for the weather to knock the moisture content down by a few percentage points.

The temptation to cut and swath in one pass must be growing, and there are mowing machines available to do this. Traditionally, these use belts to move the grass to either side but augers are also available.

Advance of the auger

Krone has recently revamped its Easycut mowers with auger to include full ISOBUS compatibility. This machine has the auger set close to the blades, minimising the overhang and stress on the tractor’s back end.

Whether it would cope with a full Irish sward in May is an open question yet; with the cost of energy for producing fertiliser and powering machines unlikely to drop in the short term, mowing directly to a swath may become viable.

Mowing rakes
Large machines requie a large capital outlay. There needs to be a focus on cost in conjunction with quality

Up until now most of the research going into grass preservation has, quite rightly, concentrated on the quality of the silage. We need now to look more closely at the cost of doing so.

A lot has changed in the last two decades, we have new crops, new machinery, new production incentives and a whole wealth of new digital technology, yet we are cutting and managing forage crops in much the same way.

What is needed is a new way of putting all these together to conserve grass, and the nutrients within it, in the most efficient manner while also conserving the structure of the soil.