Guide for making silage
18 October 2016
Silage, particularly wrapped in round or square bales, has increased in popularity over recent years. With this year’s bumper winter and spring over many parts of southern Australia, relatively low cattle numbers and high restocker prices, many producers are considering what to do with the surplus feed in their paddocks. Ongoing rain is making for a dicey hay making season which has more producers considering silage.
The following rough guide to silage making is an extract from Making High Quality Silage for Sheep and Cattle Production, by Frank Mickan, Pasture and Fodder Conservation Specialist, DEDJTR, Ellinbank Centre.
When harvesting early to make high quality silage, temperature may be low (20- 22C), possibly overcast and the ground probably damp. The following guidelines may need to vary according to changing circumstances such as unexpected rain and equipment breakdowns. Accessing local knowledge when seeking to make silage is advisable if you have limited experience with the process.
Mow mid-to-late morning, after the dew has lifted, when the weather forecast or your own experience indicates 2-3 days of fine weather approaching. Mowing an early season crop (3-5 weeks before hay), or one which has a short shut up period (3-5 weeks), usually means that the crop is light (less than 3 t DM/ha). This crop will be about 25-30 cm in height. This ensures a quicker wilt at a time when the ground is still moist and drying weather is warm rather than hot.
Heavy crops or those well in head typically produce high yields but are extremely difficult to wilt quickly, are very low in nutritive value and regrowth is negligible or sparse at best. Mow only the area of the crop that you can safely harvest the next day or so within the limits of factors such as machinery, labour and weather.
Spread (ted) the crop immediately after mowing if you have access to a tedder or tedder rake. This will increase the rate of wilting by 30 to 60 per cent. Travel slowly (5-6 km/hour) for this first tedding to ensure all the mown pasture is spread evenly and to avoid lumps being formed. If mown in late spring/early summer and the first day turns out hot, the grass will wilt very quickly and may enable you to begin harvesting on the same afternoon as mowing.
Early in the season a second spreading, after the dew has lifted, is often required as drying conditions at this time of year are not conducive to fast wilting. The plants will still be quite durable so that losses/damage of leaves will be negligible. This tedding can be carried out at a much faster speed than the first tedding (7-10 km/hour). Tedding can be safely carried out up to approximately 50 per cent DM content without too much leaf loss.
If you do not have access to tedder equipment, consider these options.
1. Mower- conditioner or conditioner only:
If you use a mower-conditioner to drop the crop, it is preferable to leave the swath boards open fully or completely removed. This will promote a substantially faster wilt. If wide cutting widths are conditioned into narrow windrows, only the outer 2-3cm of the windrow will be dry after several hours. Meanwhile the plant in the rest of the thick dense windrow continues to "survive", i.e. respire by using the very nutrients you are conserving for your animals. The longer this occurs, the more quality that is lost.
The abrasive (flail/tyned) type of mower conditioners are better for pastures than the crushing (roller) type because a higher proportion of the stems are left intact, thus promoting a higher, fluffier, more open windrow for sunlight and wind movement. The stems and leaves are abraded or scuffed. The roller type is necessary for legumes (lucerne, clovers, faba beans, peas, etc.) and summer forages (sorghums, sudax, etc.) to crush the succulent stems. There is a danger of nutrient loss due to leaching if rain falls on conditioned crops. This is more than offset by the reduction in the drying period and the reduced risk of rain.
2. Rake only:
If you do not have access to a tedder or a tedder rake, try to use your existing rake to flip the swath over. This will increase the drying rate to some extent. This could be done in the late afternoon of Day 1 or mid-morning of Day 2. Foraging may be possible late on Day 2, but making round (or square) baled silage would be unlikely until at least Day 3. Avoid ropy windrows - this will decrease the drying rate and promote uneven drying.
In the afternoon of Day 2 when the crop is likely to be near the desirable dry matter content, rake the wilted pasture into windrows to suit the forager or baler. Light crops may require raking in one direction and then raking in the reverse direction on the opposite side to produce a good sized windrow. However wide, thin windrows result in more densely compacted bales with less air trapped in the bale.
If you plan to forage (loader wagon or precision chop) the crop, start when the dry matter percentage of the wilting pasture is approaching 28% to 30% DM. You may have to start harvesting before 28% DM if the forecast is for a hot day, bad weather is approaching or you have a lot of pasture on the ground. As the crop dries, you will be able to shift up 1 to 2 gears. You may be able to dispense with the second tedding if the crop is light, the crop had a good wilt the day before or the day of harvest is expected to be hot.
If you plan to bale (round or square), start when the dry matter content is approaching 40% DM. This should be about mid-day or mid-afternoon of Day 2. Occasionally you may need to respread the grass a third time and bale later on Day 2 or on Day 3. This might occur if the weather turns cloudy, misty and/or the crop is very heavy (>4,000 kg DM/ha).
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