Storage of cattle slurry is a significant source of ammonia (NH3) emissions. Emissions can be reduced by covering slurry stores, but this can incur significant costs, as well as practical and technical difficulties. In this pilot-scale study, slurry was stored in small tanks (500 L) and the effectiveness of natural crust development for reducing NH3 emissions was assessed in a series of experiments. Also, factors important in crust development were investigated. Measurements were made of crust thickness and specially adapted tank lids were used to measure NH3 emissions. Slurry dry matter (DM) content was the most important factor influencing crust formation, with no crust formation on slurries with a DM content of <1%. Generally, crusts began to form within the first 10 to 20 d of storage, at which time NH3 emission rates would decrease. The formation of a natural crust reduced NH3 emissions by approximately 50%. The type of bedding used in the free stall barn did not influence crust formation, nor did ambient temperature or air-flow rate across the slurry surface. There was a large difference in crust formation between slurries from cattle fed a corn (Zea mays L.) silage-based diet and those fed a grass silage-based diet, although dietary differences were confounded with bedding differences. The inclusion of a corn starch and glucose additive promoted crust formation and reduced NH3 emission. The maintenance of a manageable crust on cattle slurry stores is recommended as a cost-effective means of abating NH3 emissions from this phase of slurry management.

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The aim of the study was to investigate the decontamination of pig slurry containing exotic viruses of pigs, foot and mouth disease virus (FMDV), Aujeszky's disease virus (ADV) and classical swine fever virus (CSFV). Laboratory‐scale decontamination experiments showed that FMDV, ADV and CSFV were heat inactivated in slurry within 3 min at 67 °C, 3 min at 62 °C and 3 min at 60 °C and in Glasgow Eagles medium within 5 min at 67 °C, 4 min at 65 °C and 2 min at 65 °C, respectively. At pilot scale, FMDV was heat inactivated at 66 °C in water and 61 °C in slurry, ADV at 61 °C in water or slurry and CSFV at 62 °C in water and 50 °C in slurry. Treatment of pig slurry for the inactivation of exotic viruses may be achieved through the use of a thermal pilot plant operating in continuous mode. The work demonstrates the suitability of thermal treatment in ensuring the safety of pig slurry following a disease outbreak.