Farmers may need to apply more nitrogen to crops this year, as the exceptionally wet winter across most of the UK has reduced soil levels, warns the AHDB.

The levy board reports that the extent of moderate and high excess winter rainfall (EWR) zones across the UK is already much wider this year compared with the long-term average. This means that the historically drier areas of the country – the middle and eastern parts of England – are most likely to see a lower than normal soil nitrogen supply (SNS) index.

Based on mid-season (October 1st 2019 – January 31st 2020) estimates, the AHDB says that 83% of the UK’s cropped regions fall in the high rainfall category of 250 mm EWR, equivalent to an annual rainfall of over 700 mm.

AHDB crop nutrition specialist Sajjad Awan observes that this is a stark contrast to the relatively dry 2018/19 winter which allowed some farmers to cut back on the total amount of nitrogen applied to crops. “This winter has been phenomenally wet – currently, only about 3% of cropped regions remain in the low-rainfall category of less than 150 mm EWR or annual rainfall under 600 mm. Long-term average data would put the typical low-rainfall figure closer to 25%.

“As several weeks of the EWR period remain, it would not be a surprise if all low-EWR regions are washed off the UK map by the end of March. In fact, without the drying effects of crops, no regions would fall into the low category at all. With many farmers forced to leave land bare this winter, it is even more important to consider a lack of evapotranspiration.”

The AHDB advises growers and their advisers to use the RB209 Nutrient Management Guide SNS tables to determine the precise impact of the wet conditions on their spring nitrogen management strategy.