When effluent is stored on farm pond solids are created. Ponds are emptied out and solids are either applied to selected blocks or exported off farm. The frequency the pond is emptied out has an effect on the nutrient content of the solids. The model assumes that if pond solids are added to a block, the amount of nutrient applied is the amount that settles each year times the number of years between pond emptying.
Pond Solid nutrient content = annual pond solid accumulation x years between pond emptying
There are two ways frequency of years can be entered:
- Enter 1 year - add pond solid application to selected block. This would apply an average amount of pond solids nutrients that are created each year to the allocated block.
- Enter number of years between emptying pond eg 3 years – allocate ponds solids to a block ONLY if it is being applied in the year that is being modelled.
If the number of years the pond is emptied is greater than one year, pond solids do not have to be allocated to a block each year the farm is modelled.
The change in N from accumulation of emptying of ponds is shown in the organic pool section of the farm nutrient budget.