Muck or Magic?
As farmers seek to reduce reliance on imported fertiliser, many are now looking closely at actual nutrient values of home-produced Farmyard Manure (FYM), by having nutrient analysis carried out on muck middens. This article provides an overview of nutrients available from FYM, current fertiliser prices and looks at anticipated Carbon Border Adjustment Mechanism (CBAM) rates.
Since the start of the conflict in the Middle East, AHDB has reported a significant price rise in fertiliser, with imported Ammonium Nitrate up 20%, Triple Super Phosphate (TSP) up 22%, while Murate of Potash (MOP) has remained stable.
Nutrients in FYM
Table 1 below illustrates the difference in nutrient value when comparing analysis results from a muck midden sampled in August 2026 to Technical Note 736.
Table 1: Actual cattle FYM results vs FAS Technical note (TN736)
| TN736 (Kg/tonne) | Actual results (Kg/tonne) | Difference | |
|---|---|---|---|
| Total N | 6.0 kg/t | 7.9kg/t | +32% |
| Available N | 0.6 kg/t | 0.79 kg/t | +32% |
| P₂O₅ | 3.2 kg/t | 5.16 kg/t | +61% |
| K₂O | 8.0 kg/t | 23.28 kg/t | +191% |
The nutrient analysis of the FYM, will largely be determined by the diet of the cattle and the amount of bedding used. The high potassium value in the above results can be explained by a high inclusion of silage and straw.
Fertiliser Prices
Table 2: Fertiliser price (AHDB Oct 2026)
| Fertiliser | Nutrient Content | Price (£/t) | Value per kg nutrient |
|---|---|---|---|
| Ammonium Nitrate | 34.5% N | £484 | £1.40/kg N |
| Triple Superphosphate (TSP) | 46% P₂O₅ | £643 | £1.39/kg P₂O₅ |
| Muriate of Potash (MOP) | 60% K₂O | £370 | £0.61/kg K₂O |
When comparing the actual FYM results against the fertiliser prices above, 1 tonne of this FYM will provide over £18 of fertiliser value, whereas standard figures from technical note TN736 would suggest a value of only £8/tonne (Assuming 60% P₂O₅ will be available in year of application and 90% of K₂O available in year of application).
It is worth noting that a proposed tax on imported fertiliser is due to come into force on the 1 January 2027, under the UK’s Carbon Border Adjustment Mechanism (CBAM). Under current proposals it will affect imported Nitrogen fertiliser, as well as steel, concrete and plastics.
On the 16 October 2026, HMRC issued an estimated rate of £1.45/t C02e, which suggests an initial charge of £3.77/t Ammonium Nitrate, however this is illustrative only and it is expected that the actual CBAM rates will be published before the end of 2026, with rates updated and published on a quarterly basis thereafter.
In summary, it is worth analysing your FYM and using the results alongside farm soil analysis results and a cropping plan to accurately calculate application rates and determine inorganic fertiliser requirements. This may highlight opportunities within your system to reduce reliance on imported fertilisers.
George Gauley, SAC Consulting
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