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AG News: 06/08/09

Includes: No Short Cuts For Good Silage; Farming Diary; And Climate Change Forum

By Department of Primary Industries - 12th August 2009 - Back to News

NO SHORT CUTS FOR GOOD SILAGE

Silage bales are often incorrectly wrapped resulting in substantial losses of dry matter (DM) and quality.

There are no short cuts when wrapping round or square baled silage. Nor are there any cost savings by scrimping here and there on plastic – for example by not applying the last one or two turns of plastic; or stretching the film more than the machine is designed to do by swapping cogs.

Forage ensiled into bales at the correct DM content, densely compacted and wrapped with the correct number of layers over the entire bale, should have a pleasant smell with negligible mould when opened up 12 months later.

The amount of mould and its location can indicate how well bale wrapping was done and the quality of film used. Baled silage has six to eight times the surface area in contact with the plastic film compared to conventional stack silage, and about half of the silage volume is within 15 cm of the plastic film. Therefore, it is important that the film’s integrity is not compromised in any way.

The points below discuss some of the reasons for failures in baled silage.

Plastics ain’t plastics!

Films can vary in permeability to air, consistency in their stretching capacity, degree and longevity of adhesiveness or ‘tackiness’. They can also contain irregularities from the production line, have unevenness of colour integration, and most importantly, the quality and amount of ultra-violet (UV) light inhibitor impregnated into the plastic film can vary substantially between products.

Some overseas films for example from Scandinavia are manufactured for low-level light intensity and contain very little UV inhibitor. At the end of their harvest season, excess film can arrive on our markets which are often cheaper because the Australian product has a high concentration of UV inhibitor. Although much less frequent now, the result can be a very quick break down of some imported plastic films in our high solar radiation climate. However, most of our own products and several overseas products are well manufactured and meet our needs.

Stretch rate

Many people assume that all plastics will prevent all air from passing through the film and entering the bale. However, most stretch warp films have a thickness 25 microns before application to a bale. If stretched at 55 per cent and four layers are applied, per common Australia practice, the final thickness will be about 18 to 20 microns. If stretched to 70 per cent, as is common in New Zealand, thickness is further reduced - hence their recommendation to apply six layers versus our four.

Most wrapping machines sold in Australia are designed to stretch the stretch-wrap plastic to 55 per cent. However, some older machines stretch the plastic to 70 per cent, which as mentioned previously is too thin with only four layers. Consequently, thinner layers of wrapping can allow substantial entry of air into the bales resulting in mould. Wrapping in high ambient temperatures (over about 25 degrees Celsius) may also affect the properties of some plastics, particularly the stretch rate.

To check that the correct stretch is occurring, mark small distance on the unwrapped roll, eg 10 cm or roughly the length of a pocket knife. Once applied to the bale, the mark should now measure about 15.5 cm or just over 1.5 pocket knife lengths.

Some Australian manufactured films are pre-stretched at the factory before being stretched again at bale application on the farm, usually requiring a separate set of gears to achieve the correct stretch ratio.

The film arrives on the farm in a range of pre-determined thicknesses (12, 14 to 16 microns) and different recommended stretch ratios. This technology was developed to reduce the cost of the film per bale.

Bale Coverage

Every round or rectangular bale that is being individually wrapped must have at least four layers of plastic over the entire bale. This is very difficult to achieve with slightly odd shaped bales resulting in underlapping and only three layers will be applied at that section. This means that plastic coverage is reduced to 25 per cent on a seal where 100 per cent coverage is a must.

Overlap for each layer should be at least 50 per cent and no less. Mature or stemmy crops should have six layers applied to reduce puncturing of the film.

Number of layers

Bales that have had four layers of stretch wrap film applied at 55 per cent stretch, a 50 per cent overlap and guaranteed to last 12 months before degrading can sometimes lasts several months longer. Practical experience in the field has shown that applying six layers at the above stretch will generally ensure bales will last another 12 months. Assuming a bale weighs about 250 kg DM, the extra cost is about $3 to $5 per bale, ie $12 to 15 tonne DM or 1.2 to 1.3 cents/kg DM.

Overseas research comparing two, four, six and eight layers, at 70 per cent stretch, has shown that two layers will result in huge losses of DM and nutritive value due to mould and yeast growth, and aerobic deterioration due to air entering the bale through insufficient layers.

Both six and eight layers are superior to four layers, but greater than six layers does not result in economical gains when baling grass silage for dairy cattle. However, six to eight layers may be necessary if wrapping drier or more mature pastures, especially for sheep and horses which have low tolerance to mouldy feeds. Extra layers are recommended if bales are to be transported after wrapping.

Plastic Colour

Lighter colours have been shown to be more suited to the hotter areas of Australia compared to black due to less surface heating. Black is more absorbent of solar radiation. However, in the more cool temperate areas such as southern Victoria and Tasmania, black wrap is equally effective and usually less prone to UV break down.

Centre the bale

The centre of the bale must be in line with the centre of the film reel. Larger diameter bales (1.35 cm) are becoming more common and if the reel is not lifted, wrapping will be uneven on the bale.

Holes

Warm weather, a drier bale, stemmy material, plus a large hole and elapsed time before its repaired will all create an environment for DM and quality losses, and increased mould growth for each problem. Apply similar coloured specific silage repair tape to clean, dry and cool/warm plastic.

For more information, please contact Frank Mickan at DPI Ellinbank on 03 5624 2222.

FARMING DIARY

Bushfire Recovery Workshop

Topic: Erosion control and weed management

When: Saturday, August 15, 2009

Where: Labertouche Hall, Cnr Labertouche and Forest Road, Labertouche.

Time: 9:30 am to 12:30 pm.

This workshop focuses on property owners who want to learn more about identifying and managing weeds including a practical introduction on the use of farm chemicals; and how to manage erosion areas on their properties.

It will be presented by Nicole Driessen from Melbourne Water, Tyson Dennis from Baw Baw Shire Council and David Stewart from the Department of Primary Industries.

All landholders are welcome, in particular those whose properties have been fire affected.

For more information, contact Carolyn Ferguson on 5624 2409.

Learn to use farm chemicals safely

A two day veterinary and agricultural chemical course for farmers will be held in Heyfield on August 24 and 25, 2009.

Topics to be covered in the ‘Chemcert’ accredited training course include:

• Applied chemicals under supervision.
• How to prepare and apply chemicals.
• Transport, handling and storage of chemicals.

The accredited course allows participants who successfully complete the course to apply to the Department of Primary Industries for an Agricultural Chemical Users Permit (ACUP). Further training for a Pest Animal Bait 1080 endorsement is also available upon request.

For more information or to register, please contact Neville Prowse-Brown on 5157 7575.

Climate Change Forum

The Victorian Government will be holding a public forum to discuss the recently released Victorian Climate Change Green Paper on Friday, August 28, 2009 in Morwell.

The Government is seeking community feedback on the ideas and strategies put forward in the Green paper towards the development of an effective, long-term response to Climate Change for Victoria.

The event will be hosted by Minister for Climate Change, Gavin Jennings, at Kernot Hall, Cnr Princes Drive and Monash Way, Morwell from 10:00 am to 12:00 pm (refreshments included).

To register for this event, or for further information, call 1800 463 684 or visit www.climatechange.vic.gov.au

Source: http://gippsland.com/

Published by: news@gippsland.com

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