Dairy Australia has released a new calculator that aims to help farmers make better use of the nutrients contained in dairy effluent and sludge and save money in the process.
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 were 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 dependent 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.
“Knowing how much nutrient is in the effluent or sludge is an important part of fertiliser planning. The calculator helps me to target the areas of the farm that need the nutrients and also understand when too much effluent on a paddock may be detrimental,” he said.
Early autumn is typically a time of maintenance around effluent ponds in southern dairy regions.
Drawing down the effluent storage pond to its minimum level going into the autumn break and also removing sludge that has accumulated in the primary pond are key maintenance requirements to support a functional effluent pond system.
The Nutrients from Effluent and Sludge Calculator’ calculator is available for free download from Dairy Australia’s Dairying for Tomorrow website www.dairyingfortomorrow.com.au.