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Silage deterioration and effluent production - WA0104

WA0104. Non-polluting strategies for forage treatment and silage production

UK agriculture loses several hundred million pounds yearly through aerobic deterioration and effluent losses from silage. In addition, harmful organisms such as Listeria grow in aerobically deteriorated silage. This study will aim to investigate the changes taking place during ensiling and to devise means of reducing aerobic deterioration and release of effluent. A model of aerobic deterioration, based on gas movement by permeation, will be developed and tested against data from silage in an instrumented bunker with 1 face exposed, under known conditions. Rates of deterioration will be examined with varying O2 and CO2 concentrations and the sensitivity of the model to various factors will be evaluated. Mathematical models of silage effluent production and flow will include physical properties, such as dry matter, density and hydraulic conductivity. Physical conditions within silos will also be examined (e.g. pressure distribution), together with key parameters that should be taken into account to enable small-scale silos to be representative of large-scale areas. Small and large-scale, well-instrumented silos will be filled with forage of different dry matter contents, and measurements will be taken of physical phenomena such as forces on the forage and walls during filling, permeability and density; effluent production and flow will be measured and used to used to test the outline models. The project will also aim to investigate possible reductions in the amount of effluent produced during silage making by removal of excess water before ensiling. Retention forces associated with surface and easily released moisture within a grass crop matrix will be investigated; a theoretical study, complemented by laboratory and field measurements, will be used to determine the relevant interactions between droplet size, crop density and absolute moisture content. The optimal approach will be defined by interpreting the effects of various treatments in terms of the dynamics and time dependency of moisture removal; options to be considered will include conventional mechanical methods such as centrifuging, as well as novel processing approaches; such treatments will be evaluated in terms of energy and economic balance predictions with the aid of existing computer models. Further experiments will be conducted to investigate novel harvesting systems that will enable removal of free moisture and preparation of grass for ensiling in a predictable and repeatable form, independent of ambient weather conditions. It is anticipated that this work will lead to an improved understanding of the mechanisms of aerobic deterioration and air exchange in heterogeneous biological matrices and of the mechanisms of water retention and release in harvested forage, before and after ensiling.

Time-Scale and Cost
From: 1991

To: 1993

Cost: £270,000
Contractor / Funded Organisations
Silsoe Research Institute (BBSRC)
Fields of Study
Environmental Protection - Agriculture