The nitrogen conserving, biologically activated covering for tanks and lagoons.

BioCrust™ is a layer of lightweight, expanded clay granules which has been inoculated with a mix of naturally occurring bacteria species. The layer of granules and bacteria minimise the loss of ammonia due to surface evaporation. Research by Silsoe Research Institute (SRI) showed that “the ammonia emission rate is linearly related to air speed over the range of air speeds typically found over the surface of slurries (see Fig 1 below).

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Figure 1 Effect of air speed on losses of ammonia (SRI)

The carefully selected bacteria species convert ammonia into valuable, usable nitrates which are retained within the slurry. The bacterial formulation is adjusted to suit each individual application.

BioCrust™ has proved to be valuable across all areas of farming and biogas plant operation.

Within the pig industry it has been accepted by the environment agency to be IPPC Directive compliant.

BioCrust™ is also of considerable interest to the dairy industry as, due to the increasing cost of fertilisers and pressure on milk price, farmers are increasingly considering how to make the most of their slurry and reduce their use of bought-in fertilisers.

Report from Phil Cooper

Biocrust™ is the ideal covering for digestate stores as it not only helps to minimise odours emitted from stored digestate and may subsequently help to obtain planning permission and keep neighbours happy but it also helps to retain valuable nutrients within the digestate. The nutrient value of digestate (an end result of anaerobic digestion) has been recently examined by ADAS and SAC. The report states “because of the increase in slurry ammonium –N content, usually with increased pH and reduced solids content, there is a risk of increased emissions of ammonia during post-digestion storage. Such increased emissions have been confirmed by Danish research but have been shown to be effectively controlled by a range of store coverings”


Covering the digestate store with BioCrust™ will not only reduce odours and the surface evaporation of ammonia but help to retain ammonia as valuable nitrates within the slurry.

  • Conserves valuable nitrogen within the slurry by converting ammonia to nitrates
  • Bacterial formulation adjusted to suit each application
  • Prevents surface evaporation of ammonia
  • Biologically reduces odour emissions
  • Biologically reduces ammonia emissions
  • Reduces odour at spreading time
  • Reforms after mixing
  • Irregular shaped granules provide good coverage
  • Long lifespan
  • Low carbon footprint
  • 100% UK sourced
  • Environmentally safe
  • Complies with IPPC Directive

The purposeful inoculation of lightweight clay aggregate with aerobic bacteria to form a floating digestion bed is © copyright Ameram Ltd 2011.

Please note: Temporary emission may occur whilst mixing.