THE topic of fertiliser decisions after dry and low-yielding years was presented by Summit Fertilizers research manager Mark Gherardi at the Grains Research and Development Corporation’s Research Updates, Perth, last week.
Mr Gherardi explained the importance of a crop’s nutrition after low-yielding seasons, and assessing input decisions for best returns, based on field trial data.
“Soil testing and analysis is important to identify responsiveness but benchmark values are not as critical as their name suggests,” Mr Gherardi said.
Residual nutrients, like fertiliser, are difficult to ascertain at general input rates, therefore even after a low-yielding season, the application remains seasonal.
Mr Gherardi said there was a false economy in cutting back or neglecting nutrients, especially phosphorus, at seeding time to save costs, or even shifting to more in-season nitrogen spending.
Summit Fertilizer conducted many trials on the value of soil nutrients without additional fertiliser applications, with the results proving that seasonal application is the only way to guarantee nutrients in the soil.
“Crop trial data shows providing fertiliser application strategies will generate the best return to growers,” he said.
Mr Gherardi said grower strategies needed to focus on the plant being able to receive nitrogen at all points in its growth.
Trial evidence showed that adequate Phosphorus is necessary for crops to gain maximum benefit from nitrogen.
“In conclusion there is more downside than upside potential in altering nutrient inputs after low yielding seasons,” he said.
