Other sources represent non-block total losses from raceways and lanes, leaching or runoff from unlined pads and effluent storage systems.
For raceways and lanes, a proportion of the animals excreta is estimated to be deposited on lanes and races and then lost as leaching. For Nitrogen, the proportion of N that is leached varies with rainfall. For Dairy enterprises, the rate of transfer of excreta to lanes is adjusted to account for variation on lactation length and number of milking's per day (i.e. reduced for once-a-day milking as there is only one trip to the shed per day which means less time on lanes).
Excreta is estimated as intake less nutrients required for products removed from the farm that are produced with a calendar year (milk, wool, velvet), and nutrients associated with live weight gain during the year (product nutrients). As such the amount of excreta will be affected by enterprise type, number of animal, production, amount and type of feed etc.
Lane areas are estimated as 1.5% of the sum of all pastoral blocks grazing dairy animals and 1% of the area of other pastoral blocks except those grazing merino (in which case lanes are assumed to be non-existent)
These Other sources can be influenced by reducing dietary intake of P (by reducing animal numbers or diet P content), or by making changes to the farm system, for example, lining standoff pads or changing Once A Day Milking options.