This calculator estimates the minimum land area required for sustainable application of nitrogen, phosphorus, and potassium (NPK) in wastewater. It supports compliance with national guidelines and helps prevent nutrient accumulation that could harm soil or water quality.
For nitrogen, the tool uses crop uptake and volatilisation losses to determine sustainable loading, based on NSW Department of Local Government (1998) and ANZECC/ARMCANZ (2000) guidelines. It also accounts for the potential nitrogen lock-up in high-carbon wastewater, such as from beverage production.
For phosphorus, the calculator incorporates the total phosphorus content of wastewater and the soil’s phosphorus retention index (PRI), favouring soils with higher phosphorus-holding capacity to reduce irrigation area and maintenance costs.
For potassium, the tool allows for site-specific adjustments using operational monitoring data. It helps manage potassium through crop uptake and highlights risks of soil structural issues from excess potassium, especially in winery wastewater.
This tool enables tailored nutrient management strategies that align with environmental best practices.
Refer to Water quality protection note no. 22 for further guidance.
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