The Big X 800 has two DaimlerChrysler power units, one producing about 500hp and the other about 330hp.

Krone says clean and economical running is one of the selling points of the new model, with engine emissions fully meeting the 1 January 2007 TIR 3 exhaust requirements and a rated 823hp achieved at a moderate1950rpm.

Economy is further helped by the Krone electronic engine control, which automatically shuts down one of the power units when not required, for instance during roadwork at up to 25mph.

The transport drive system also automatically matches engine rpm to requirements thus markedly reducing fuel use and drive train wear and tear, says Krone.

In the field, the Big X 800 chops with an 800mm wide 28-knife drum. For a finer chop, particularly desirable for biogas silage, Krone offers a 40-knife drum.

The new Krone is “little brother” to the 980hp twin 12.8-litre engined Big X 1000 introduced in 2005 and now one of the stars in a booming German market for self-propelled harvesters, which has brought total sales of all makes to over 500 during 2006.

One of the main reasons for this boom is a massive rise in on-farm biogas production from whole-crop fermenting.

More than half the 5000 biogas fermenters on German farms are now fuelled partly or completely with grass, whole-crop cereals or maize, says the country’s Ministry of Agriculture.

The crops are first ensiled and then fed in regular batches into the fermenter.Electricity produced is sold to the national grid at a f0.06/kWh (4p) bonus under a government regenerative power incentive scheme.

The German machinery manufacturers association (VDMA) reports that 504 new self-propelled forage harvesters were sold in the year to October 2006, the highest annual number for nine years. At the same time the average power of the machines has also increased, with one-third of annual sales now rated at over 530hp.

fwmachinery@rbi.co.uk