Silage19: Timing is Everything!

As silage season is fast approaching, cutting date is vital. The date of cutting has a significant impact on both silage yield and quality. As the crops start to bulk up and yield increases, this will have a negative impact on the quality as the crop will begin to produce stems and heads which will decrease digestibility than leafy growth. Dry Matter Digestibility (DMD) declines by 2.5-3 units for every week delay in harvest between late May and mid June. 

Optimal Silage 

The target digestibility value of 67-70, which means cutting in early-to-mid May for most regions. During first good spell of dry, consistent weather grass should be cut. A bright day is ideal to increase the sugar content of the grass as this results in improved fermentation. The sugar content of a grass is now more important than the nitrogen content, as grasses with relatively high nitrogen contents will preserve as long as the sugar content is 3% or higher. 

It is essential to mow grass dry. Mowing wet grass results in increases wilt time and reduces nutrients. Time of day also has an impact; cutting later in the day is preferable than starting early in the morning when dew may still be on the swards

To ensure an optimal wilting process it is advised to spread the cut grass all over the field to speed up the wilting process. A rapid wilt prevents excessive sugar and protein losses. In optimal wilting conditions, the grass is ready to lift within eight hours if it has been spread out. The aim is for a grass dry matter (DM) of 30% at harvesting.

Good Clamp Management

Proper chop length promotes good consolidation in the clamp (pit) and yields enough fibre for the cow to ruminate.  Set the chop length at 25mm for grass with a DM of 30%. A chop length of 50mm is recommended if grass is wetter (less than 20% DM).

Silage fermentation is divided into two phases. Phase 1 dispels oxygen through proper grass chop length, even distribution, and filling at appropriate dry matter levels. Phase 2 is where lactic acid is produced by micro-organisms in grass, which lowers the grass pH and stabilises the silage.

The clamp needs to be as air-tight as possible so eliminating air is vital. Ensure the ensiled grass is spread in shallow layers, rolled constantly and always covered at night. Apply a suitable cover and weight the cover effectively. Silage additives can be used in the silage pit, which includes bacterial inoculants, non-protein nitrogen sources, acids, enzymes and sugar sources.

Regarding the second cut, it is essential to ensure that soil nutrients are right – soil analysis should be carried out regularly on silage fields. Soil testing predicts mineral requirements, optimises inputs resulting in increased production. Mineral testing comprises of all major trace elements testing for grass and crop growth  (Sulfur, Iron, Manganese, Zinc, Copper, Molybenum, Boron). Slurry will also provide much of the nutrients needed in silage ground. Evenly-spread slurry will improve silage fermentation and minimise sward damage.

To get your soil analysed contact your local Homeland store or Aurivo Farm Commercial Specialist.

Top Tips- check if they’re alright

  1. Cutting date 
  2. Cut when the sugars are highest
  3. Mow when the weather is dry
  4. Airtight cover- Quality wrap
  5. Soil analysis for the second cut 


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