Farmers in Britain may need to apply more nitrogen to crops this year, following an exceptionally wet winter across most of the UK, according to the latest advice from AHDB. Charlotte Cunningham of CPM magazine reports.
AHDB says the extent of the ‘moderate’ and ‘high’ excess winter rainfall (EWR) zones is already much wider this year, compared with the long-term average.
Historically drier areas of the country, particularly the middle and eastern parts of England, are the most likely to experience downward shifts in soil nitrogen supply (SNS) indices, it says.
To determine the precise impact on nitrogen management strategies, the advice from the levy board is to follow the guidance published in the recently revised AHDB Nutrient management guide (RB209).
“EWR is the amount of rainfall the land receives after the soil profile becomes fully wetted in the autumn (field capacity) and before the end of drainage in the spring (around the end of March),” says an AHBD spokesperson. “Ideally, the calculations also take account of water lost through any growing crop (i.e. via evapotranspiration) during this period.
“Because nitrate is soluble, any water moving through a field takes nitrate out with it. As this affects soil nitrogen supply (SNS), an understanding of EWR is essential for accurate nutrient management planning.”
The current season is in stark contrast to the 2018/19 winter, which was relatively dry and allowed some farmers to cut back on the total amount of nitrogen applied to crops.
SNS calculations take account of several other critical factors, such as the previous crop and soil type.
To plan nitrogen applications, consult RB209 and access the latest EWR maps via ahdb.org.uk/ewr
