Slurry & Manure Nutrient Value Calculator

Typical 6% dry matter cattle slurry contains about 2.6 kg total N, 1.2 kg P₂O₅ and 2.5 kg K₂O per cubic metre. How much of that you can count on depends on when and how it is spread — far more of the nitrogen reaches the crop from a spring trailing shoe application than from autumn splash plate. Enter your own fertiliser prices above to see the value per m³ and per field.

Much of the nitrogen in slurry and manure is in organic forms that release slowly, and some of the ammonium is lost to the air as ammonia or washed out over winter. Band-spreading, injection and spring application reduce those losses, which is why they give a higher crop-available figure.

For Northern Ireland, the total nitrogen and phosphorus contents and nitrogen availability set in the Nutrient Action Programme Regulations (NI) 2019 — the figures used for NAP compliance — with potash from AHDB RB209. For England, AHDB RB209 Section 2 (updated March 2026), including its crop-available nitrogen tables by timing, soil and application method.

RB209 advises using the available figures where the crop is expected to respond — soil P or K index 0 or 1 — and the total figures where the soil is at its target index or above, because then the nutrients are building up soil reserves. The soil index option above switches between the two.

Yes, if you can. Standard figures are averages and real slurry varies a lot with diet, dilution and storage. A simple dry matter test (with a hydrometer or by a lab) lets you pick the closest dry matter band, and a full analysis gives you exact figures. Digestate must be analysed before spreading in Northern Ireland.

In Northern Ireland, no more than 50 m³/ha of slurry (30 m³/ha in February and from 30 September to 15 October) or 50 t/ha of solid manure per application, at least three weeks apart. In England’s NVZs, no more than 30 m³/ha of slurry or 8 t/ha of poultry manure at a time between the end of the closed period and the end of February, and no more than 250 kg N/ha of organic manure on any hectare in 12 months.