Windrower at work
Introduction
Most crops and pastures cut for silage have to be mown and windrowed so that the forage can be harvested by machinery fitted with windrow pick-up attachments.
This includes all balers, most fine and precision chop forage harvesters, and double chop and flail harvesters operating in Australia.
Direct harvest (e.g. ‘Kemper’) fronts are available for some forage harvesters, but they are not common and are only suitable for harvesting certain crops when the DM content of the standing crop is already at the desired level.
The DM content of most standing crops and pastures is low (<20%) when they are at the growth stage recommended for silage cutting. The forage must be wilted prior to ensiling to ensure a good silage fermentation and to eliminate effluent losses.
Wilting occurs between mowing and harvest, and describes the process of plant moisture loss prior to the forage being harvested or baled. Crops and pastures should be wilted as quickly as possible to the desired Dry Matter (DM) content, to minimise loss of DM and quality.
The period of wilting required will depend on the original (DM) content of the crop, extent of wilting required, quantity of material (yield), time of day when cut, prevailing weather conditions, wetness of the ground surface and mechanical treatments used to enhance the speed of wilt.
The Key Issues
Crops and pastures are mown and wilted to increase the DM content of the ensiled forage. Wilting should occur as rapidly as possible to minimise the loss of DM and quality in the field. Monitor weather forecasts to decide when to mow.
- Mow in the morning after the dew has lifted, later if harvest is possible within 24 hours.
- Ensure mower blades are sharp and set to cut at the correct height.
- Ensure tractor power is sufficient to maximise mower output.
- Wilt to the correct DM content as quickly as possible:
- Low-yielding crops wilt more quickly than high-yielding crops.
- Vegetative (leafy) plants wilt more rapidly than more mature (stemmy) plants.
- Increase wilting rate by: conditioning the plants at mowing, maximising the surface area of the swath, leaving the mown swath as wide and thin as possible, OR spreading or tedding immediately after mowing, AND respreading or tedding when and if necessary after the dew lifts.
- If possible, harvest no later than 48 hours after mowing.
- The fastest wilt is achieved with a thin swath, warm temperatures, low humidity, long periods of sunshine, and with a breeze.
Safety First
- Operate all equipment to the specifications laid down in the manufacturer’s manual and/or warning stickers on the machinery.
- Never approach machinery until all mechanical motion has completely stopped.
- All PTO shafts, belts, chains, etc, must have strong, tamper-proof coverings that are only removed for servicing and repair work after machinery has been turned off and all moving parts are stationary.
What it means
- Swath – the material left by a mower or mower-conditioner.
- Tedded swath – mown material that has been spread or respread by a tedder.
- Windrow – the mown material that has been raked in preparation for harvest.
- Harvesting – the picking up and baling or forage harvesting of the mown material from a windrow.
- DM loss – the quantity of material lost during the conservation process, e.g. for every tonne of forage cut, present in each unit of forage.
- Quality loss – the reduction in the content of nutrients (e.g. ME, crude protein) during the conservation process. if DM loss is 10 % , then 100 kg of DM has been lost.
Ideally, forage should be cut and harvested under good drying conditions, without risk of rain damage. Before mowing, use weather forecasts to select a ‘harvest window’ when weather conditions are likely to be favourable for silage making. As well as local and regional weather forecasts, the Internet provides up-to-date forecasts.
