An Assessment of Macerating Mowers for Zero Effluent Silage Production

A weather-driven whole system model, previously used to study a range of hay and silage conservation methods, practices and mechanization systems, has been further developed to represent the parameters of a silage system based on macerating (severe conditioning) mowers. Parameters are based on field drying experiments with macerated grass. Weather-driven simulations have been carried out to compare maceration systems with a number of conventional options for wilted silage, at 11 sites with contrasting weather in England, Scotland, Wales and Northern Ireland. Results are presented first in terms of the period required for wilting, secondly as losses and quantities of silage produced, and thirdly as gross value (in terms of cost of bought feedstuffs replaced), costs and net value of silage produced. Results show that it is both technically feasible and potentially economically viable to wilt macerated material to 30% dry matter content to avoid effluent production, whereas with conventional systems it is only feasible to wilt to 25% with the inevitable production of some effluent. With maceration, over 60% of material can be harvested on the same day as it is cut, so it does not remain in the field overnight, whereas this is not possible with conventional methods. It is also possible to reduce the quantity of material rained on during field wilting to 1-4% at most sites, compared with around 25% for conventional material. These results are found both for forage-harvested clamp silage on a large farm and for baled silage on a small farm, and both with farmer-owned machinery and using contractors. Results also suggest potential advantages from technology to clear macerated material off the stubble with low dry matter loss, and to harvest macerated material without chopping. If either of these two further technologies can be implemented, the macerating mower system will have an economic performance superior to that of a conventional system.