The ‘Nutrients from Effluent and Sludge Calculator’ assists dairy farmers to determine a suitable application rate for effluent as well as the value of the nitrogen, phosphorus and potassium that is applied during reuse.
Users can also calculate a value for their effluent or sludge based on equivalent fertiliser prices.
Dairy Australia Land Water and Carbon Consultant, Scott Birchall, said farmers are often told to sample their effluent and to then get a lab to analyse the amount of N, P & K it contains.
“The calculator was developed to answer the usual question that followed about working out how much to put on,” he said.
“The question is critical if it is pond sludge that is being spread as the contractor’s cost is partly dependant on the application rate, and more importantly, the distance to the paddock that you’ve chosen for reuse.
“The temptation to apply heavy rates of sludge in paddocks close to the pond is understandable but if you can match the amount of nutrient available to what the soil or crop needs and then substitute for purchased fertiliser, desludging becomes a cost effective part of the fertility program rather than just another cost.”
Kerang-based agronomist, Matt Page, has been using the calculator while preparing Fert$mart nutrient management plans for his clients.