There is a lot more nutrient cycling taking place than just what is put into the soil through fertiliser, and taken out in grass and eventually milk. In order to develop a more efficient nutrient cycling system, farmers have to take into account the various losses and sources of nutrients.
Nutrients are brought into the farm through the farm gate, and nutrients are removed through the farm gate. The question that needs to be asked is, are there more nutrients brought into, or removed from the farm system?
As to whether effluent is a waste or a benefit, depends entirely on how you, the farmer, use it.
A supply of nutrients and minerals to soils which is greater than the amount needed to maintain soil health and fertility actually endangers the soil and can negatively impact on surface and ground water sources.
Many nutrients are wasted on dairy farms due to oversupply through inputs from fertilizers and feeds. A great deal of nutrients, and therefore money, can be saved by recording and monitoring what nutrients are removed from the farm and what nutrients are brought onto the farm.
Two of the prominent aspects of sustainability are long-term profitability and environmental protection. Limiting chemical nitrogen fertiliser use to only what is very necessary contributes to both of these aspects.
Excessive use of chemical nitrogen fertiliser has a negative effect on soil life and soil structure. Yet there still seems to be a trend of farmers wanting, or feeling the need, to apply excessive chemical nitrogen fertiliser to pastures.
Here is an example of how improved soil life and good soil structure can unlock unavailable nitrogen into a form that is readily available for pasture uptake. You can possibly reduce your nitrogen fertiliser costs.