Winter has come early for many farms this year with the incessant bad weather meaning that there will be increased pressure on both slurry and soiled water storage on many farms.
A difficult September led to untrafficable field conditions and slurry sitting in tanks unspread. Meanwhile, the minimum volume of soiled water storage on farms will increase again this year due to a tightening of spreading rules.
For a dairy cow, a minimum of 0.33m³ slurry storage is required, the equivalent of 74 gallons. A typical 100-cow herd requiring 16 weeks minimum storage will therefore need 528m³ of storage (116,143 gallons).
However, having 528m³ of storage is not enough. In addition, 200mm of freeboard – a gap between the top of the slurry and the bottom of slats – is required to allow for agitation and to prevent animal welfare issues in covered tanks and 300mm in uncovered tanks.
The recommendation is to have 20% of a buffer for dairy farms and a 10% buffer for drystock past the minimum requirement.
Suckler cows require a minimum 0.29m³/head/week, with a full list of requirements listed in Table 1.
Soiled water storage
Where tanks are located outdoors, the rainfall entering the tank will have to be subtracted from the slurry capacity.
To do this, the mean rainfall for the closed period in your county (for example, 450mm over the 16-week period) will have to be subtracted from the tank depth when calculating capacity.
Soiled water storage has increased to three weeks of a minimum requirement, with a closed period for spreading soiled water running from 10-31 December this year.
This requirement will jump to four weeks storage next year (1-31 December of a closed period) bar those producing winter milk who have until 2025 to increase their storage to four weeks.
Current recommendations from Teagasc are to allow for 30l/cow for every cow in the herd when calculating requirements, though work is currently underway to get a more accurate figure on this through use of flow meters in parlours.
Lessening the load
While these requirements are in place, there is scope to help ease the pressure on storage.
Firstly, run-off from clean yards should not be entering slurry tanks as capacity can quickly be reached, as was unfortunately seen with some recent flooding in farm yards.
Effluent channels from clean silage pits should be diverted as clean water run-off and not directed towards tanks.
To avoid pollution of nearby watercourses, the pit floor should be regularly cleaned to prevent nutrients (muck from tyres, dropped silage etc.) from contaminating the water run-off.
Leaks in roofs and gutters that are allowing rainwater in to tanks should be fixed immediately.
Where cattle are using a slatted or solid floor as a feeding area, then the collected waste will be classed as slurry. This is an important point for farmers who may be using collection yards as buffer feeding areas at this time of the year.
Soiled water is classed as having 1% of a dry matter concentration or less, so small volumes of dung going in to soiled water tanks will quickly lead it to being classed as slurry with the increased holding period of 16 weeks plus.
Tillage farmers have been hit hard this year by the poor weather conditions. This has caused a poor straw harvest or a large volume of straw being chopped due to low dry matter.
The table charts the requirement of straw for each livestock type, as recommended by the Department, although many farmers will use significantly more than this. For reference, a typical 4x4 bale of straw weighs 150kg.
Skimping on straw is a high risk, low reward game, as disease and infection can quickly appear where bedding has been skimped on. Using a good quality straw will have greater absorption and will reduce straw requirements.
Chopping straw with a bedder, or purchasing bales that were chopped when baling, will lead to increased absorption and lower volumes used.
Sloping floors towards effluent channels to remove excess urine will also aid in keeping bedding drier for longer. Bedding should be topped up as necessary, with high traffic areas, such as along feed barriers, most prone to wetting.
This can cause a build up of bacteria, leading to scours in calves or foot ailments in sheep.