Slurry storage solutions pros and cons
EFFECTIVE management of slurry is essential for environmental sustainability and efficient farm operations. Various types of slurry stores exist with each offering distinct advantages and disadvantages. Understanding the characteristics and factors for each type is important for farmers looking to optimise their storage systems depending on specific requirements and constraints.
Earth-banked lagoon
Earth-banked lagoons offer a cost-effective solution for slurry storage, suitable for areas with impermeable soil. They require soils with a low permeability, typically with a clay content of 20-30%, and a thick impermeable layer. A 750mm freeboard is also necessary.
Pros:
■■ Economical to construct.
■■ Versatile and easily extendable.
■■ Long structural lifespan with proper maintenance.
Cons:
■■ Vulnerable to rainwater collection.
■■ Difficult to agitate large volumes.
■■ Susceptible to damage from vegetation and machinery.
Lined earth-banked lagoon
Lined earth-banked lagoons using synthetic liners or imported clay to overcome permeability limitations. A 750mm freeboard is required.
Pros:
■■ Suitable for permeable soils.
■■ Expandable with concrete flooring.
■■ Relatively lower construction costs.
Cons:
■■ Vulnerable liner prone to damage.
■■ Limited lifespan of synthetic liners.
■■ Susceptible to structural damage and leaks.
Above-ground tanks
Above-ground tanks provide storage solutions in areas unsuitable for lagoons, offering minimal land use and protection against high water tables. Though more expensive than lagoons, they offer efficient capacity and rainfall protection.
Pros:
■■ Compact footprint with minimal land use.
■■ Suitable for high water table areas.
■■ Relatively simple to extend structurally.
Cons:
■■ Reliant on pumps, prone to mechanical failures.
■■ Unsuitable for high dry matter content manures.
■■ Higher initial costs compared to earth-banked lagoons.
Concrete stores
Concrete stores, typically made of reinforced concrete panels or mass-poured, offer durability and adaptability. They can be constructed above or below ground, with various filling methods available.
Pros:
■■ Minimal land use with tall structures.
■■ Suitable for high water table areas.
■■ Long lifespan with regular maintenance.
Cons:
■■ Vulnerable to mechanical failures with complex pumping systems.
■■ Unsuitable for high dry matter manure.
■■ Higher initial costs compared to earthen reservoirs
Underfloor slatted stores
Underfloor slatted slurry stores are positioned beneath livestock housing, primarily receiving manure from housed animals under
feeding or circulation areas. They offer a low maintenance option and a range of construction materials. A 300mm freeboard is necessary.
Pros:
■■ Minimal above-ground footprint.
■■ Little maintenance required.
■■ Compatible with various bedding types except chopped straw and sand.
Cons:
■■ Health and safety concerns during access of store.
■■ Potential requirement for solids removal.
Weeping wall stores
Weeping wall stores offer
both separation and storage capabilities. They utilise concrete flooring with semi-permeable walls for draining liquids, with easy access for solids removal.
Pros:
■■ Customisable size and shape.
■■ Separates liquid and solid components.
■■ Low maintenance costs.
Cons:
■■ High construction costs.
■■ Vulnerable to concrete panel damage.
■■ Limited to amount of dry matter in slurry.
Slurry bags
Slurry bags offer an alternative storage option
with impermeable artificial membranes, for example PVC.
They’re effective at containing ammonia emissions but require careful maintenance.
Pros:
■■ Effective at preventing ammonia emissions.
■■ Minimal maintenance required.
■■ Option to incorporate stirrers.
Cons:
■■ Limited lifespan of synthetic liner (approximately 20 years).
■■ Vulnerable to damage by animals or machinery nearby.
■■ Moderate to high land use required.