Thinking of more slurry storage? Here are your options and costs
The winter of 2017/2018 is one that will stick with farmers for all the wrong reasons for years to come. Not only did farmers struggle with a lack of fodder, they also had to deal with full slurry tanks with no where to spread.
It’s very important to have enough slurry storage on farms from a weather and Nitrates Directive point of view. This was the key message from Teagasc’s environmental specialist Tim Hyde at a recent farm buildings walk in Co. Galway.
On the day, Tim discussed different options available to farmers and the advantages and disadvantages of these options; costings were also brought to the attention of the farmers in attendance.
Slatted tanks are the most common slurry storage option on farms in Ireland. Due to the expansion of the dairy herd, and the need for additional storage, many farmers have opted to install these tanks without constructing a roof over them; this may be done at a later stage.
- Better for small quantities;
- Can be built in new sheds;
- No rainfall as they are normally roofed;
- Fit into existing building developments.
These tanks are normally installed where a smaller capacity is needed, but they can be added to existing tanks.
Over-ground slurry stores and lagoons
These options are available to farmers where space is plentiful. Farmers can install concrete lagoons, earth-lined lagoons or over-ground round towers.
Over-ground round towers require a receptor tank from where slurry can be pumped to the tower. If a flow channel is installed from a slatted tank to a lagoon, this will eliminate the need to move slurry manually at busy times of the year.
Rainfall is another issue with lagoons and round towers. However, Tim noted that this can work well for farmers using an umbilical system to spread slurry; it also leaves agitation easier.
“Approximately 130,000 gallons of rainfall/year enters tanks; however, 30% evaporation can be expected. Slurry lagoons can be covered, but this idea is not widely practised,” he explained.
- Cheaper for large quantities;
- Site dependent;
- Reduced labour when flow channels are installed;
- Over-ground stores are an option where space is limited;
- Rainfall is allowed into lagoons.
Cost of these options
Below shows the different costings for slatted tanks at different capacities (50,000 gallons and 250,000 gallons). It also indicates the cost of open concrete lagoons, earth-lined lagoons (3m deep) and over-ground slurry storage towers at volumes of 50,000 gallons and 250,000 gallons.
Tim outlined that these costs are based on estimates from some builders and these may vary in some circumstances. Deals can be done with different concrete companies.
The environmental specialist also noted that a 16.6ft slat (10ft deep) tank will allow 70% more slurry storage per bay when compared with a 12.6ft (8ft deep) tank.
“Lagoons or towers are cheaper for larger volumes of slurry. As farmers increase volumes, the cost/1,000 gallons decreases.
“There is additional cost at planning permission when it comes to earth-lined lagoons, as farmers have to dig trial pits. If the clay content is not high enough, farmers can’t use compacted clay; it must be lined,” he added.
The round towers and the lined lagoon were not considered at 50,000 gallons because they would be too expensive to construct for their capacity.
However, once you get up to 250,000 gallon stores, the cost/1,000 gallons varies between €160-200, depending on the amount of digging that has to be done and on whether you meet rock; these costs are site dependent.
Targeted Agricultural Modernisation Scheme (TAMS) specifications
Tim highlighted that if a certain capacity tank or lagoon was approved by the Department of Agriculture under TAMS, and the farmer runs into difficulty when digging it out due to rock, he/she may increase the length or width of the tank so that it reaches the desired capacity.
“Farmers just can’t decide to put in a shallower tank; you must go longer or wider to reach the capacity that is stated on the planning permission,” he explained.
For example, if you apply for 100,000 gallons of slurry storage and you put in 120,000 gallons of slurry storage; this is OK. The department do not look at extra slurry space as a bad thing.
However, if a farmer applies for 100,000 gallons – and hits rock – and only puts in 80,000 gallons, this is a penalty somewhere in the region of 20% of the total TAMS grant, Tim concluded.