Pigs – Frequent manure removal to outside storage

Frequent manure removal to outside storage

System: Pigs

Applicability

Mainly applicable for: Low outdoor temperature, liquid manure systems, farms with an anaerobic digester
Not or less applicable for: High outdoor temperature, or low temperature inside the livestock barn

Description

Frequent removal of manure to outside storage with a lower temperature than inside the livestock barn. This can be achieved by a vacuum system, slanted walls, scraper, or backflushing. Frequent removal, or another method of reducing methane emissions from slurry in barns, may be needed to allow anaerobic digestion to operate effectively. See the separate information sheet on anaerobic digestion for pig farms.

Mechanism of effect

The temperature of outside storage is generally lower than inside livestock barns. At lower temperature the methanogenic microbial activity in stored slurry is lower, and hence less methane is produced. In general, slurry temperatures higher than 20 C have shown high CH4 emissions which are reduced significantly under 15 C (Sommer et al., 2007). Lowering the temperature of slurry from above 25 C to less than 15 C results in less or no N₂O emissions due to inactivation of microbial processes in slurry. Removal to an outside storage is only effective when the external storage temperature is cooler than the inhouse pits.

Effects on GHG emissions

Reference situation: Storage of manure inside livestock barns.

Effect on total greenhouse gas (GHG) emissions (LCA)

Mean effect and range in kg CO2-equivalents	per kg product		per farm (absolute)		Level of evidence
	Mean	(min-max)	Mean	(min-max)
Frequent removal to outside storage	●●	●–●●●	●●	●–●●●	Low

Legend

● – Small effect (<5%)	o – No effect	? – Effect unknown
●● – Medium effect (5-20%)	● – Unfavourable effect
●●● – Large effect (>20%)	● – ● – Variable effect (depending on farm characteristics or way/level of implementation)

Effect per emission source

Mean effect on absolute emission from	Manure storage		Animal	Feed and forage production			Barn
	CH₄	N₂O	CH₄	CO₂	N₂O	LUC	CO₂
Frequent removal to outside storage	●●●	●●			?		●

*risk of an adverse effect (see ’cause of variable or unfavourable effect’)

Legend

● – Small effect (<5%)	o – No effect	? – Effect unknown
●● – Medium effect (5-20%)	● – Unfavourable effect
●●● – Large effect (>20%)	● – ● – Variable effect (depending on farm characteristics or way/level of implementation)

Cause of variable or unfavourable effect

Frequent removal to outside storage

The effect of frequent removal is larger with a larger difference between the temperature inside and outside the barn (effects being larger in winter), a higher frequency of slurry removal and a higher removal efficiency (less residual slurry left in the pit). Different methods (e.g. vacuum system, scraper, backflushing) have different effects.

Other Effects

Effects on yield and cost-effectiveness

	Yield		Labor	Costs and revenues
	Animals	Crops	Time	Capital investment	Operational Costs	Revenues
Frequent removal to outside storage	o-●		●●–●	●●–●	●	o

Legend (thresholds differ per indictor and can be found in the tooltip)

● – Small favorable effect	o – No effect	? – Effect unknown
●● – Medium favorable effect	● – Unfavourable effect
●●● – Large favorable effect	● – ● -Variable effect (depending on farm characteristics or way/level of implementation)

Effects on other sustainability aspects

	Risks of trade-offs	Potential synergies
Frequent removal to outside storage	Water use, Water quality, Land use or occupation, Farm labour safety	Ammonia emission, Soil health, Animal welfare, Societal and cultural acceptance

*Literature references*	Frequent removal to outside storage
Ambrose et al., 2023	Additives and methods for the mitigation of methane emission from stored liquid manure
Petersen et al.; 2024	In-vitro method and model to estimate methane emissions from liquid manure management on pig and dairy farms in four countries
Ma et al., 2023	Frequent export of pig slurry for outside storage reduced methane but not ammonia emissions in cold and warm seasons
Hilgert et al., 2022	Methane Emissions from Livestock Slurry: Effects of Storage Temperature and Changes in Chemical Composition
Misselbrook et al., 2016	Greenhouse Gas and Ammonia Emissions from Slurry Storage: Impacts of Temperature and Potential Mitigation through Covering (Pig Slurry) or Acidification (Cattle Slurry).
Wang et al., 2021	NH3, N2O, and NO emissions from digested pig slurry stored under different temperatures: Characteristics and microbial mechanisms