Foliar N on Wheat

A common question that arises from growers is about the best N source to apply to cereals and canola in-season. To address this, a field experiment was established at Birchip, Victoria to assess the relative efficiency of UAN, liquid urea and granular urea, particularly when rain does or does not occur. Comparisons were also made between streaming and hollow-cone nozzles for the application of fluid N sources.

Wheat yields from plots where soil-applied fertilizers were added were not significantly different from yields where liquid urea or UAN was applied with standard nozzles. There was no significant difference in yield or protein concentration between standard nozzles and streaming nozzles. The results show that granular urea and UAN were equally effective when applied to the soil. There were no significant differences on grain yield between between N applied as fluid or granular sources if rain occurred soon after application, although on average rainfall after application increased grain protein concentration.

Based on these results, it was concluded that there is little agronomic benefit from using different N forms, and growers should select the N source that most suits their farming system in terms of logistics and costs. Fluid N sources are more expensive than granular sources, but the former do offer some significant logistic benefits including improved application accuracy.