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Double crop (Bi-crop) silage

Bi-cropping combines a spring-sown cereal crop and a spring-sown legume crop. The cereal crop provides energy in the form of starch while the legume crop provides protein. This cropping system has been around for many years. Today, advances in harvesting machinery allow the crops to be taken at a later stage, when nutrients — such as starch and protein — are at their optimum level.

The advantage of using bi-crops is that they potentially ease fermentation by offering: water-soluble carbohydrates (WSC) and starch; they can reduce lodging issues; and they also offer a different harvest window.

There are multiple potential mixtures of crops. Typical bi-crop combinations include:

  • Spring triticale and lupins
  • Spring wheat and lupins
  • Spring barley and peas
  • Spring oats and peas

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Maturity

In bi-cropping situations, harvest decisions are even more important because different crops do not always mature together. Both crops should be carefully selected to ensure they reach maturity at a similar time. If one crop is faster maturing than the other, it makes harvesting increasingly difficult. One crop could be mature with hard seeds or grains, while the other crop could be very immature, resulting in low dry matter (DM) forage. Both situations should be avoided in an attempt to make the best possible bi-crop forage.

The rule of thumb is that harvest timing, chop length and other recommendations are based on the dominant variety at time of harvest. Consult with a seed or forage specialist regarding the best time to harvest based on your geographic region and the crops to be harvested.

Dry Matter and Harvest

Bi-crops should be direct cut with a self-propelled forage harvester fitted with a combine reel header or specialist wholecrop header at around 30% dry matter (DM). Chop length will be about 1 inch or 2.5 cm. This will aid in clamp consolidation and provide effective fiber for livestock. If the bi-crop is undersown, it can be cut using a mower (without a conditioner) to limit grain or seed loss. The crop should be picked up immediately using a forage harvester, preventing excessive drying out.

Challenges

Bi-crops have higher protein levels than conventional wholecrop cereals, which can buffer the pH drop in the fermentation process. Use an effective, crop-specific forage inoculant to promote a rapid acidification and preserve nutrients.

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