In Germany, the number of biogas plants has increased to 5900 plants with 2240 MWel over the past years. As a result, rye is becoming more and more popular as a fermentation substrate in biogas plants stabilising the gas formation process. In addition, rye provides advantages for a consecutive biogas-crop rotation-arrangement combined with an optimal utilization of the plant, a broader scope for the application of fermentation and continuous ground coverage through the winter months.

For ensiling, both hybrid rye-whole plant silage (WPS) and forage rye are used. They differ in the variety type and in harvest times. Forage rye is a specially bred conventional rye with a very early start of growth and biomass development prior and after winter. Hybrid rye-WPS varieties are hybrids, which tend to have a higher population density and high dry matter yields.

Hybrid rye-Whole plant silage

Features and Recommended Application:

  1. Superior to other cereal species with regard to yield quantity, yield reliability and production costs on dry locations.
  2. Provides as supplemental substrate for the year-round supply of the biogas plant – in particular in dry years.
  3. Harvesting at the time of the milky stage (30-35 % DM in the entire plant) requires the use of a fungicide. A single application is recommended in order to keep costs to a minimum.
  4. With hybrid rye-WPS a high mass of dry matter (up to 150 quintals DM/ha) can be achieved.
  5. The nutrient supply for the bacteria in the biogas plants is supplemented by Hybrid rye-WPS, which leads to a stable gas formation.
  6. Hybrid rye-WPS in combination with maize silage provides for a higher gas and methane yield.
  7. Hybrid rye-WPS used in a biogas crop rotation relaxes peak activities and extends the period for applying the manure remaining after fermentation to the growing crops.

Hybrid rye-WPS in practice:

It is reported from practical application that the use of maize-hybrid rye-silage mixes increases the gas yield compared to a pure maize feed and enhances the stabilisation level. A trial showed that monofermentation of maize or hybrid rye did not yield the amount of biogas per DM that was yielded with a mix of both components. A trial with a mix ratio of 75% maize and 25% hybrid rye-WPS resulted in the highest gas yield.

Normal mixes consist of 70-80 % maize and 20-30 % hybrid rye-WPS.

Hybrid rye-WPS enhances the amount of biogas

Mean 100 = 577 l Biogas / kg DM yielded from maize silage, fermentation time 56 days
(IBS GmbH, Bremen; KWS LOCHOW GMBH, 2011, extract)

Forage Rye (FR)



Features and Recommended Application:

  1. Forage rye is a winter catch crop. Special green mass-winter rye types are bred for an early forage harvest.
  2. Forage rye forms a very high mass of dry matter early in spring.
  3. Due to its high and early tillering ability, a high mass of dry matter can be yielded ( 40 to 70 quintals DM/ha ) at harvest when ears emerge.
  4. Due to its poor resistance to lodging, forage rye must be harvested by mid May at the latest. We recommend choosing varieties with a good resistance to lodging. Storage of forage rye leads to yield losses and contamination of the fermenter (e.g. sand, stones).
  5. Forage rye is best used as maize catch crop on locations rich in water.
  6. Used as maize catch crop forage rye must be harvested early enough (End of April – Beginning of May) to allow for timely sowing of maize or sorghum that will follow.

Additional Information

Practical Experience with Rye Whole Plant Silage as a Source of Biogas – A Farmer Reports (Source: Gut Karow) (517 KB)

Econmic use of rye in the biogas production (Source: Treurat und Partner) (1,1 KB)

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