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  • Writer's pictureKPM Partners

Time to start planning the grass silage

The end is in sight – the end to the lockdown (hopefully) and the end to winter routine. Better times are ahead so it’s time to be positive and start thinking about the first cut silage. Chances are you already have a rough idea of the fields, the fertilizer rates and where you are going to put it, maybe even who is going to be cutting it. But it’s also time to plan the detail, the target dry matter, chop length and additive selection.

The dry matter you achieve at harvest should dictate the chop length, the drier the silage the shorter it must be chopped to ensure good consolidation and good fermentation. Longer chop lengths will increase the chances of aerobic instability and lead to massive increases in losses once the clamp is opened so getting the chop length right is vital to make the most of your grass harvest.

Some of the latest forage harvesters have the ability to automatically adjust the length of chop to suit the real-time dry matter measured by the on-board NIR sensor. Whilst this is really useful for the guys working long days harvesting maize in the autumn, its not so important if you’re lucky enough to be making grass silage in the sunshine. The ideal would always be to pickup grass once the dew has lifted and the sun is out – or at least a breeze has moved some air through the swath.

So how do you choose a target dry matter?

As with so many things, it’s a balancing act to some degree. On one hand, achieving high dry matter means leaving the mown grass for longer in the field, so increasing the rain risk. The cut grass is also respiring and burning up that energy rich sugar that you need in the forage. Unfortunately getting silage in the clamp quickly doesn’t solve the problem of losses. Low dry matter silage will produce higher losses in effluent run off and the resultant silage will limit the forage intake by cattle. Basically the cow is stuffed full of low value silage and just can’t eat any more. So how can you get a higher dry matter silage without the risks and losses?

Reaching higher dry matter quickly needs some help, so conditioning whilst mowing and tedding or spreading the grass really speeds the process. In good drying conditions running though with the tedder again will also have a positive effect. The spreading of the crop should not lead to excessive physical losses such as leaf shatter if the dry matter is below 40%. The tedding and conditioning will reduce the time the grass is sitting in the field but there will still be some respiration losses.

Tackling respiration losses

You need to remember that respiration losses will start as soon as the grass is mown and don’t stop once the grass goes through the chopper. The crop continues to lose value until a stable, lactic acid fermentation is achieved, so by choosing the right additive or inoculant, you can improve the silage dry matter and reduce losses. This is because not all inoculants are equal and there are test and trial results to prove this. In Germany the DLG certification process tests most of the leading inoculants and none out perform BIO-SIL® when it comes to rapid pH drop and stable silage fermentation. Achieving a stable fermentation at around pH 3.8-4.0 in just 48hrs after ensiling, BIO-SIL® outperforms most inoculants by 1 to 2 days. This ability means high dry matter silage can be produced with no increase in losses. BIO-SIL® is also certified for use on forage with dry matters right up to 35% so there is no risk of using the wrong inoculant if you’re blessed with an unexpected heat wave whilst the grass is on the ground.

Aerobic stability

Higher dry matter brings a risk of aerobic instability; losses that occur once the clamp is opened and oxygen can get to the silage. There are traditionally two ways to tackle this problem, physical and chemical. Physical actions are by far the most effective solution; getting the chop length and the consolidation right at ensiling and then moving through the silage at 2m per week once the clamp is open.

Some additive producers tackle the issue by including acetic acid producing, hetero-fermentative bacteria or adding potassium sorbate can aid aerobic stability (although trial results are mixed) but come at a cost. Higher levels of acetic acid can make silage unpalatable to livestock reducing forage intakes whilst potassium sorbate kills bacteria, including the lactobacillus plantarum required to produce a stable fermentation. Luckily BIO-SIL® inoculant is proven to aid aerobic stability without resorting to these unwanted side effects.

It is no wonder BIO-SIL® inoculant is the market leader in its home country, and it is now available here too – at prices that are as welcome as a warm sunny day.

If you want to discuss how BIO-SIL® can help you make high dry matter, low loss silage – contact


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