How to Plan a Silage Season: Chopping, Packing and the Machines That Matter

Silage is how a dairy farm survives the dry season without buying feed at panic prices. The principle is simple — ferment green fodder without air — but the failure mode is brutal: one air pocket or one wet batch and a season of feed becomes a pit of mold. Good silage is made in the field with the right machines, not in the pit with luck.

1. Harvest at the right stage — this is half the battle

• Maize: at milk-to-dough stage, 30–35% dry matter. Too young and the silage is sour and watery; too mature and it will not pack.
• Napier / elephant grass: cut at 1–1.5 m height; older grass is all fibre and no feed value.
• Legumes (alfalfa, cowpea): wilt to 30–35% dry matter before chopping — legumes ensile poorly when wet.

2. Chop length and the machine that sets it

Chop length decides packing density, and packing density decides air — the whole game. Target 10–20 mm for cattle. A chaff cutter with adjustable discharge and sharp, heat-treated blades is the core machine; for big silage days, a high-spray chaff cutter blows chopped material directly into the pit or bags, removing the double-handling that loses you a day at exactly the wrong time.

Size the cutter so a full day's chopping fits comfortably in daylight — silage cannot wait for tomorrow once cut.

3. Pack tight, seal fast

1. Fill in thin layers (15–20 cm) and compact each layer — by tractor weight on a pit, or by machine pressure in bales.
2. Fill and seal the same day. A pit left open overnight reheats and spoils from the top down.
3. Seal airtight: pit plastic weighted with soil or tyres, or bales wrapped within 4 hours of baling.

For farms without a pit, silage bales are the flexible option — see our baler and wrapper ranges. Bales let you make silage in small daily batches instead of one make-or-break week, and unopened bales keep for a year.

4. Feeding out without waste

Silage spoils on contact with air — open only what the herd eats in 2–3 days, keep the pit face tight and clean, and discard any moldy layer completely. For daily feeding, chopped silage mixes evenly with concentrates in a feed mixer — mixed rations reduce sorting and raise milk response measurably.

5. The five mistakes that ruin silage

1. Chopping too long. 40 mm stems leave air channels no amount of packing fixes.
2. Ensiling wet grass without wilting. Below 25% dry matter you get butyric fermentation — cows refuse it.
3. Slow filling. A pit filled over a week ferments layer by layer, unevenly.
4. Poor sealing. "Mostly airtight" is not airtight. Check plastic daily for the first month.
5. Blunt blades. A dull cutter tears instead of cutting, heating the crop before it even reaches the pit. Keep a spare blade set — see our chaff cutter buying guide for blade specs.