June 8, 2012
Many milling wheats may need late foliar N this Season
High yield potential crops coupled with significant spring nitrogen losses from the wettest April on record mean late foliar nitrogen may be particularly important for many milling wheats to make the required protein specification this season, warns Agrii crop nutrition technical manager, David Langton. And additional sulphur could also be well worthwhile.
“With most wheats looking set to yield particularly well this year, grain proteins are likely to be diluted to a far greater extent than last season,” he points out. “At the same time, more than 200 mm of spring rain will almost certainly have led to noticeable losses of applied nitrogen in many cases. Leaching will have been the main culprit on light and shallow soils, while heavier ground that suffered water-logging could have seen N losses of up to 25% through denitrification by soil bacteria.
“These factors are behind the clear trend for reduced grain proteins with increasing levels of spring rainfall shown in wheat quality records, suggesting more N than usual will be required to achieve the full milling specification. Especially so where higher sulphur losses through leaching also reduce the efficiency of nitrogen utilisation.”
If sufficient extra ammonium nitrate was not applied at the flag leaf or foliar N with the T3 spray, David Langton strongly advises growers to consider around 40kg N/ha as liquid urea by the end of the milky ripe stage wherever late foliar nitrogen is permitted by end-users.
“Our trials and others have typically shown a protein boost of 0.75-1.00% from a 200 l/ha application of Protol liquid urea delivering 40 kg N/ha,” explains David Langton.
“A more reliable protein lift than we see with either solid AN or earlier-applied urea, this is likely to be particularly cost-effective in a season in which high protein milling wheats could well be in far shorter supply than of late.
“Combining this with an extra 11 kg/ha of SO3 as Protol-S may also be advisable to maximise the efficiency of protein improvement if there is any doubt about the crop’s sulphur status,” he adds.
“Application through standard spraying equipment and nozzles, together with a variety of delivery options, makes these products suitable for farms not equipped for liquid fertiliser storage as well as those already geared-up for it.
“For the greatest effectiveness, applications need to be made when the crop is at the milky ripe stage. Early evening spraying is always preferable to minimise N losses through volatilisation in the heat of the day. And tank-mixing should be avoided to minimise scorch risk.”
David Langton stresses that the extent to which late nitrogen will be valuable this season will depend on the particular protein efficiency of the varieties being grown as much as the specific crop circumstances.
“Our extensive milling wheat systems trials highlight major differences between modern varieties in the efficiency with which they build grain protein,” he notes.
“This and the care that needs to be taken to ensure applications comply with NVZ restrictions in addition to end-user production protocols makes it vital to plan applications carefully with our agronomists who are armed with the most up-to-date research and recommendations.”