Animal welfare is more of a priority than ever, and pig farming is undergoing a transformation. Organic enrichment materials are now a legal requirement, and structural developments are leading to more deep-litter pigsties, increasingly with outdoor runs as well. In order to implement the increased use of bedding in practice, farms require sufficient storage facilities for hay and straw, suitable manure removal techniques and proper manure storage. Various aspects must be taken into account to ensure good quality hay and straw and to store manure in an environmentally sound manner. Various points should also be taken into account during manure removal, which on the one hand make day-to-day work easier and on the other hand protect the environment. The ‘Construction: Sows and Fattening’ working group of the Animal Welfare Competence Centre for Pigs from the Fokus Tierwohl network has summarised the most important points.

The question of how much storage space is required must be answered on a case-by-case basis, depending on the farm. The amount of storage space needed depends, for example, on the type of housing and the associated amount of bedding, but also on the shape of the bales. Round bales are less compact than square bales, so more space is required for storage. An average round bale weighs approx. 250 kg. The weights and dimensions of various bales can be found in Table 1 and used to determine the required storage space.

One advantage of round bales is that they are less demanding in terms of storage conditions. Whilst the more finely cut straw in square bales can soak up rainwater (like a sponge), the water tends to run off the long sides of the wrapped straw in round bales. As a result, a square bale exposed to water can rot completely, whereas with a round bale, only a small outer layer spoils. 

It should be noted that hay and straw from areas affected by African swine fever must not be used, or must be stored for at least six months. Therefore, provided there is sufficient storage capacity, it is advisable to store a year’s supply from a single harvest in advance. Although this is more costly, the existing straw-based housing system can continue to operate even in the event of an outbreak. Furthermore, with ample storage capacity, sufficient high-quality material can always be kept in stock, even in rainy years when a good-quality harvest cannot be obtained.

The bale stack should not be covered with plastic sheeting, as condensation can form underneath, increasing the risk of mould growth. If plastic sheeting is used for short-term temporary storage, adequate ventilation must be ensured. Small openings near the ground are suitable for allowing condensation to escape. Straw fleece is better suited for covering stacks, as it is air- and vapour-permeable yet water-repellent when laid at an angle of at least 45 degrees. It is tear-resistant even in strong winds and is also UV-stable for several years. In the case of a square bale stack, the topmost bale should be placed upright on one of its long sides.¹ If round bales are stored on their flat side, this has the advantage that the bales do not deform. It is important to ensure that no more than three round bales are stacked on top of one another to form a cylindrical pile. Taller stacks should be stacked in a staggered pattern to achieve greater stability through the interlocking structure. This serves occupational safety and is required by the employers’ liability insurance association.
After each bale is removed, the stack should be completely covered again to protect it from rain. If the bales are protected from moisture and from wild boars by a fence, and if rodent control measures are in place, the key basic requirements for outdoor storage are met. However, stacks stored outdoors are not as well protected as they would be in a closed building. Table 2 outlines the advantages and disadvantages of storage in a building and outdoors.

Dry materials such as hay and straw can catch fire quickly. This can be caused by external factors such as engines, sparks or open flames, or by the spontaneous combustion of freshly stored bales. In addition to the risk to human and animal life, fires cost a great deal of money and labour, and may also lead to problems with insurance companies. Insurers provide relevant guidelines for damage prevention in the VdS 3453 brochure ‘Fire Protection on Agricultural Holdings’. Fires can be prevented by avoiding the parking of motor vehicles in storage halls and stables.² If this is not possible, a distance of at least 2 metres from combustible materials must be maintained.⁴ Work involving machinery that can produce sparks must also be avoided² in the vicinity of flammable materials, as must, of course, the use of open flames. Having electrical installations inspected by a qualified electrician can identify hidden faults at an early stage. For example, supply cables, light fittings and switches in all buildings and rooms should be checked.² For safety reasons, the maximum size of a storage area should not exceed 10,000 m³.⁵

The following distances should be maintained from various areas:

• 25 m from high-voltage power lines, livestock buildings and residential buildings with brick walls and tiled roofs²
• 50 m from forests, moors, railway tracks, thatched-roof and timber buildings²
• 300 m from schools and similar facilities²
• 100 m from other hay and straw storage areas⁴

It is advisable to check with your own insurance provider or review your policy to ascertain which fire safety measures must be observed to ensure the insurance covers the damage in the event of a fire. For example
, are you aware that dried crops must be checked regularly for spontaneous combustion immediately after storage? If this cannot be proven to have been carried out, insurance cover may be withdrawn in the event of a fire. The measurements should be recorded in writing, stating the date, the measurement points, the temperatures and the measurement depths within the bales. A sketch of the storage location can supplement the documentation.⁵ For measuring the crops, at least one measurement point per 20 m² should be selected. Temperatures in the bales up to 45 °C are safe (Table 3).⁵ Suitable devices are those tested by the DLG, insurance companies or the fire service, where the measuring sensor is inserted deep into the bale.

Further information on fire safety

Contingency plans (drawn up by the Construction Working Group: Sows and Fattening)

Guideline on building regulations for livestock housing

Fire safety on farms – guidelines on damage prevention from German insurers

Alarm systems in livestock housing (DLG leaflet 422)

Preventive fire safety in agricultural construction (KTBL booklet)

Manure storage areas with slurry tanks do not have a roof, which is why they require a drainage system through which the slurry is channelled into a separate tank (Fig. 14). A 2% gradient towards the slurry channel helps the liquid to drain into the slurry storage area.^12,14 Trough-type channels, which are also frequently used at petrol stations, are suitable for this purpose.¹⁴ Care must be taken to ensure that these are always clear so that drainage is guaranteed. A submersible pump can pump slurry from the collection tank into the slurry storage facility. This reduces costs and the required size of the collection tank.¹⁴

An advantage of the covered solid manure slab is that no storage capacity needs to be set aside for slurry. A sufficient roof overhang provides adequate protection against driving rain and prevents slurry from leaking out of the manure.¹² It is nevertheless advisable to ensure the floor slab has a 2% gradient towards the rear or back wall. A disadvantage of the roofing is that, in the absence of moisture, the decomposition process is slower, meaning the manure cannot be utilised as quickly in crop production.¹² 

In exceptional cases where storage on paved surfaces is not possible, the turned manure may be temporarily stored in the open field. A dry matter content of at least 25% prevents the formation of leachate and must therefore be maintained.¹³ If the dry matter content is less than 25%, storage sites compliant with slurry, liquid manure and leachate treatment systems (JGS systems) are required. Temporary storage is only permitted on agricultural arable and grassland areas, which should be level to prevent leachate from running off.¹³ The soil must be clayey or loamy. Otherwise, on sandy soils, for example, an under-surface barrier is required, which may consist of a layer of straw or clay minerals.¹⁵ If manure heaps in the open field are covered with a waterproof covering, they may remain in place for a maximum of six months. If uncovered, only four weeks. You can find further information on storage in the open field here. 

If the manure is to be fed into a biogas plant, it may be placed in containers or trailers on the farm and transported to the biogas plant. Otherwise, no special storage facility is required. It must be borne in mind that the transport of manure is not permitted in the event of an outbreak of disease, and in such cases sufficient storage capacity must be available on the farm. This is regulated by the Swine Fever Ordinance (as of 2020).

If the construction of a new manure storage area is planned, a planner should be consulted who can demonstrate experience in the construction of manure storage facilities. You can also seek support from the agricultural authorities of the federal states when planning manure storage areas. In addition to advising on storage capacity, the experts can also provide guidance on matters such as the required distances from sensitive areas, for example water bodies.

Nutrient assessment sheet: Basis for planning the size/storage capacity