25 January, 2017
Planning nitrogen fertilizer applications
Differences in the optimum rate of nitrogen not only vary from year to year but also from field to field so to optimise nitrogen use this variation has to be managed.
The long-term optimum nitrogen rate for winter wheat is around 230kgN/ha; last season’s results showed that 2016 was a more average year - the average optimum rate across six sites was also 230kgN/ha. Although this ranged from 214kgN/ha on a light soil in Norfolk up to 250kgN/ha on a heavier soil type in Yorkshire.
The differences in yield were also quite varied with one site in Norfolk yielding 13.17t/ha with nitrogen rate of 214kg/ha; and another site in Lincolnshire yielding 9.92t/ha from 230kgN/ha.
Consider fields separately when planning nitrogen applications
This range of results shows the importance of using the optimum amount of nitrogen for your particular fields and crops; one size doesn’t always fit all. The average on farm use of nitrogen on wheat in the UK is currently 184kg/ha (non-milling, BSFP 2015) showing that farmers continue to sub-optimally apply nitrogen, particularly to milling wheats. This difference of 46kg N/ha from the optimum nitrogen rate equated to a yield loss of 0.35t/ha in 2016 using data from this trial series.
Looking forward to this spring there will be variations which will affect the optimum nitrogen rate from one field to the next; soil type, weed/disease pressures, pH to name a few. The only real way to account for field-to-field and in-field variability is to monitor nitrogen uptake in plants using tools such as the Yara N-Sensor, N-Tester and the ImageIT App. Take some time to consider each field separately as the benefits may be greater than you think.
