SOIL NITROGEN levels could be higher than normal this spring following below average winter rainfall in many areas, predicts ADAS.
Apart from Western areas, rainfall up to mid-January has been below average and similar to 2004, when spring soil N supply (SNS) turned out to be higher, said ADAS‘ Peter Dampney.
“Many farmers did reduce fertiliser N use because of higher SNS levels and others regretted that they did not, as crops became too lush.”
Crops that have received an autumn/winter manure application or those following a break crop are likely to show the largest effects of higher soil N, he said.
In contrast, the dry winter is likely to have less impact on sandy or shallow soils, where soil N is more readily lost through leaching, he noted.
Where crops have high shoot populations, February/early March N applications should be omitted or delayed in cereals or reduced for winter oilseed rape, Mr Dampney added.
Further information on the general SNS situation this spring will be available in March, he said.
Information on fertiliser recommendations is available in a computerised version of DEFRA‘s ‘Fertiliser Recommendations (RB209)‘ book, www.planet4farmers.co.uk.