Foliar N on Wheat

Background:

Fertiliser inputs represent a significant proportion of total variable costs in grain production. A common question that arises in the cropping season is how much nitrogen is lost when fertiliser is applied and follow-up rain does not occur immediately after application? Growers relate to this because they recognise the link between volatilisation and the effect this has on reducing the amount of nitrogen available to their crop and the consequent ‘waste of money’. One method adopted by growers to reduce the likelihood of volatilisation is to use UAN. There is a perception that a large portion of the nitrogen when applied as UAN is taken up by the crops leaves and that there is a reduced need for follow up rain.

Aim:

To quantify nitrogen leaf uptake when applying UAN. To determine if follow up rain is required when using UAN for maximised nitrogen uptake. To assess the effect of streaming vs standard nozzles in Nitrogen leaf uptake.

Methods:

The project will comprise a wheat field trial and a pots experiment. There will also be a pot experiment undertaken to complement the results from this field experiment.The trial and the pots experiment will utilise five treatments and two variates.

Table 1: Field trial and pots experiment variates and treatments

Variates/Treatments	Treatment Description
A	With followup rain
B	Without followup rain
1	No applied N
2	UAN sprayed in interrow only
3	UAN spayed with standard nozzles
4	UAN sprayed with streaming nozzles
5	Urea top dressed

Plant nitrogen uptake will be assessed through tissue sap testing at set intervals before and after nitrogen application, plant nitrogen percentage at peak biomass (flowering) and NDVI (greenseeker) assessments at regular intervals throughout the growing season.