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How can I obtain energy-rich grass silage?


Working carefully is the main pre-condition for successful silage. The exclusive use of silage additives cannot correct insufficiencies such as poor compaction.

Some significant aspects which affect the silage result and should be given special attention are listed below. Since requirements and conditions at every farm differ, the points above can only serve as general guidelines. Special recommendations can be obtained from our employees.

The grassland

The grassland must be checked regularly and evaluated for its quality and quantity aspects. Determine the composition of grasses, herbs and leguminous plants and determine which plants are dominant, possibly by using aids offered by various industrial bodies. If the grass content is approx. 50-66%, the crop is considered to be well-balanced. As a rule you will find some 20 to 30 different species of plant in grassland.

The contribution to the nutritional value made by the various species is important. High-quality species with a high nutritional value such as Deutsches Weidelgras (Lolium perenne L.) should be predominant in the grassland, whereas lesser quality species should occur correspondingly less. Farmers who have had some practice will be quite capable of assessing the composition of their grasslands themselves.

This identification of the composition of grasslands is usually made in spring because the plant characteristics and differences compared to previous years can easily be identified then.

Damage to the top soil due to drought, overpasturing or winter killing must be taken seriously since the grass / crop composition may change rapidly due to such events. Plant species which have disappeared are rapidly replaced by other plants of a lesser value, e.g. by creeping buttercup (Ranunculus repens) which has high vitality and can grow very aggressively.

Constant care is required to maintain the performance of the grassland. For example, levelling the field in spring to level out the molehills, rolling down the field when the top soil has been lifted by frost etc., helps to create stable grass crops. Groundwater-rich areas must have effective gully drains to enable them to dry fast. And fertilising must be adjusted to the current requirements.

New sowing and re-sowing

sowing Hand

You might consider re-sowing if the grassland has been damaged, is severely affected by weeds, or has the wrong composition.

The grass crop can often be corrected by targeted re-sowing. The existing top soil is sown at the start of vegetation in spring, using special disc-type sowers. Intensive cultivation may require re-sowing once every year, or every two years to ensure a stable and well-balanced grass crop.

'Degraded' crops with lesser quality species, and possibly even toxic plant species, require new sowing. This offers the possibility of adjusting the crop composition to the local conditions in a targeted manner. Chambers of Agriculture and private companies carry out regular trials and compile grassland mixtures consisting of tried and tested and recommended species and types of grass.

The optimum cutting time

Farmer measuring the grass height

To obtain silage with a high energy content, the crop should be harvested at the optimum cutting time. This is when ears are emerging on the dominant grass species. A raw fibre content of 220-250g / kg of dry matter is a guarantee for feed which is rich in sugar and energy. Even if cutting at a later time would carry the promise of higher yields, the highest energy content is achieved through feed harvested at the right time.

Mowing grass

Mowing grass on field

Do not cut grass too short (>7-8 cm). Cutting grass to the right length prevents the inclusion of stalks, dirt and dead plant parts which have no nutritional value, and of bacteria and other elements which negatively affect fermentation. And furthermore, a top soil which has been "shaved" will only regenerate slowly, delaying the subsequent harvest. Cutting the grass too short encourages Clostridia, leading to unwanted butyric acids. And more dangerously, bacteria which can produce botulism may be produced which may also end up in the silo.

Special care must be taken if fields are not flat as the blades of the mowing mechanisms may hit the ground and bring up soil and dead plant parts.


A wilting degree of 30-40% is ideal for grass. Leaving the crop out in the field too long leads to field losses and a decrease in nutrients, so it is vital that the grass is ensiled as quickly as possible.

If weather conditions are such that wilting is not possible, the grass should be ensiled without any delay, adding KOFASIL LIQUID or KOFASIL PLUS GRANULAR. This is an effective solution to prevent butyric fermentation. Excessive wilting is no use either. If the grass is too dry, there is the risk of secondary fermentation where yeasts break down the lactic acids created in the silo; the silo heats up; the pH value increases; mould spores will sprout and the silaged crop will mould. Extra care is required if the weather is hot or if there is a lot of wind.

The chop length

Mowing grass

A short chop length gives lactic acid bacteria better access to the vegetable sugar and makes it easier to compact the silo, to expel the air from the silo, and to prevent moulds spreading. To ensure sufficient compaction, the grass should be cut to a length of 6 - 8 cm, whereas under relatively dry conditions 4 cm is better.  

Introducing silage additives

Silage additives can only be applied in a reliable manner using suitable dosing equipment directly on the self-loading forage wagon or forage harvester. For the dosing amounts, see the specifications for the product in question.

Turning and swathing

Turning and swathing grass on the field

In principle, the cut grass should be moved as little as possible to prevent field losses. The tines of the turning units / swathes must be adjusted so that they do not unnecessarily scrape over the top soil, preventing them from bringing up earth and dead plant parts, which will be introduced into the silo afterwards. Swathing should take place immediately before chopping / ensiling.

The shape of the silo


The silo must be laid out such that a feed-out speed of approx. 1.5 metres a week is guaranteed in the winter months (a feed-out speed of up to 3 metres a week is required in the summer). When in doubt, a long silo is to be preferred over a wide silo, or two silos can be filled.

The silo face should be in the opposite direction to the prevailing wind direction. This prevents the wrap being "pumped up" by the wind, which might lead to an excessive introduction of air into the silo, resulting in aerobic deterioration (see above).

Filling / compacting the silo

Silo with farmer and tractor

To initiate lactic acid fermentation as quickly as possible, the silo must be filled as fast as possible. Filling the silo evenly and properly compacting the silaged crop are important to expelling atmospheric oxygen from the silo. The silo filling speed must not be determined by the forage cutters or the forage wagons, but by the tractor compacting the silo. If the roller tractor is relatively light, it should be fitted with narrow tires and drive slowly to increase the pressure per surface unit and extend the time during which the pressure is exerted.

The dimensions of the roller tractor should always be adjusted to the ensiling chain to ensure smooth and trouble-free operations and to avoid bottlenecks. Agricultural contractors nowadays work very efficiently and also have large-volume tippers. A silage spreader attached to the tractor can be very useful to spread the heaps of grass into thin layers.

Ensiling must take place expediently and in a well-planned manner; ensiling for more days must be avoided if possible.

Covering the silo

People covering a silo

After compacting the silo it must be sealed airtight immediately by covering it with suitable silage wrap which is weighted down by spreading tyres, sand bags or earth over its entire surface. Avoid damaging the wrap since this would allow air to enter. When selecting the silage wrap, also consider its UV stability.

For horizontal silos a strip of lining wrap must be drawn in between the silo and the silo wall. The use of an additional thin wrap under the silo has been proven to be valuable and should be standard practice.

Lay the wrap such that precipitation water is fed away from the silo. Use reinforced mesh wrap to cover up the silo and protect the silage wrap against being damaged e.g. by small animals.