NSW growers are encouraged to get into the paddock now to understand what their crop nutrition needs are likely to be in 2018.
International Plant Nutrition Institute regional director Rob Norton said it was important that growers test for nitrogen, phosphorus and, in some cases, potassium following what was a predominately low rainfall season.
‘‘Growers need to be approaching their nitrogen management in a way which is both strategic, that is developing management approaches for nutrients where there is little or no other options for intervention, and tactical, where nutrient interventions can be implemented effectively,’’ he said.
‘‘When I say tactical, I mean mapping nutrients, but also understanding what can change.’’
Dr Norton advised growers to tackle ‘‘the known knowns’’ which are what has been removed from your paddocks (yield), what are your nutrient concentrations and what is your likely nutrient supply, which is where soil testing comes in.
‘‘This then helps you to make decisions and offset the ‘known unknowns’ which are what will be the demand of your next crop and what are the likely losses of supplied nutrients due to seasonal conditions, and then there is the unknowns which includes things like frost, bugs and late heat.’’
He said with nutrients the first and most important thing to consider was removal (what’s going out the gate) and soil testing.
‘‘A 5tonne/ha 12 per cent protein yield of wheat is likely to remove 100kg/ha of nitrogen, 15kg/ha of phosphorus, 18kg/ha of potassium and 5kg/ha of sulphur.’’ Canola figures for a 3tonne/ha yield will be 90kg/ha N, 15kg/ha P, 20kg/ha K and 15kg/ha S.
These numbers will change in the case of a frosted wheat crop being cut for hay and stubble burning.
■More information on soil testing is available in the GRDC Southern and Northern Fact Sheets, as well as the GRDC crop nutrition extension hub and the IPNI website.