Crusting of Stored Dairy Slurry to Abate Ammonia Emissions

Abstract

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.

Ammonia losses from the storage and application of raw and chemo-mechanically separated slurry

“…This may be explained by the lower TS content of the liquid fraction (Table 1), which did not allow the development of a consistent crust layer on the slurry surface (Amon et al, 2006;Dinuccio et al, 2008;Fangueiro et al, 2008). The TS content was found to influence the formation of natural surface crust (Misselbrook et al, 2005a;Smith et al, 2007) which could limit the ammonia diffusion from the slurry to the atmosphere. During our storage trials, a consistent crust layer (up to about 1.0 -1.5 cm) was observed to develop only on the raw slurry surface.…”

Farm-Scale Applicability of Three Covers (Peat, Polystyrene Balls and Synthetic Sheet Roof) to Reduce Ammonia Emissions from Pig Slurry Storage

“…This difference in results could be due to the damage caused to the peat cover during the farm experiment compared to no damage in the laboratory experiment. Moreover, as pointed out by [37], laboratory studies are usually conducted with limited volumes and depths of slurry, which may cause differences in the gas generation and emission processes. In our study the higher carbon emissions from the peat cover on some occasions could be the result of the reactive organic matter content of peat which can decompose when wet.…”

BMP Optimization to Improve the Economic Viability of Farms in the Upper Watershed of Miyun Reservoir, Beijing, China

“…Top-loaded manure storage appears to be the most common manure storage in the Miyun Reservoir region. The crust that forms on bottom-loaded manure storages has been found to decrease N volatilization losses [42]. Thus, had a bottom-loaded manure storage system been used in place of a top-loaded storage system, total farm N volatilization would likely have decreased with increasing manure storage time.…”