ADAS scientists have brought together new and topical information to help farmers make correct nitrogen decisions this Spring. The full text of the advice can be downloaded below this article
Summary
• Crops emerging from the winter are variable so crop inspection of each field is essential to judge the need for early N. Thin or backward crops justify some early N (40 kg/ha to cereals, up to 100 kg/ha for rape) applied between mid/late Feb to early March when ground conditions are suitable.
• The map of winter rainfall (to 27 Jan) indicates that, if there is normal rainfall in February and March, many areas will end up having an average or wetter than average winter. Where this is combined with thin or backward crops with low N uptake, then SNS levels this spring might be slightly lower than average – but every field must be judged individually! An updated map will be issued in late March.
• SNS levels will often be high where organic manures have been used, crops have under-performed or have been over-fertilised; SMNs will usually be low where there have been long runs of combinable crops with no manures applied.
• SMN analysis (before any N is applied) is not a precise measure but is very worthwhile to estimate the SNS ‘ball-park’ in fields where large and unpredictable soil nitrogen residues are suspected (e.g. where there have been regular manure applications).
• SMN samples must reach the laboratory with minimum delay. Ongoing research indicates that results can increase by up to 10% for each days delay between sampling and analysis, even when samples are kept cool.
• The Breakeven ratio (BER) for cereals this year is around 5.5-6, and 2.5 for oilseed rape.
• A table of the NPK content of different types of organic manures is provided with their current financial value. Allowing for these nutrients can result in large financial savings.
• All farms and land inside an NVZ must comply with all the NVZ rules. Key requirements now are to plan nitrogen use in each field (SNS, crop N requirement, crop available manure N, fertiliser N) before applying any N, and keeping the required field records (a common failing). Non compliance can result in a reduction in the Single Farm Payment.
• The NVZ N max limit for spring N applied to oilseed rape is now 250 kg N/ha but including any N applied in the autumn.
• Applications for a derogation to the NVZ Livestock Manure N Farm Limit (170 kg N/ha) must be submitted by 31 March. To be eligible, farms must have 80% or more as grassland.
For the full details of this advice, please download the free document below this article. If you have any queries, please contact the ADAS customer services line on 0845 766 0085.