Calculate the nutrient input from your fertiliser application.
Use this article to learn how to calculate the amount of nutrient applied from the declared analyses and treatment rates.
The fertiliser declarations are always expressed as % weight by weight, with nutrients being declared in the oxide form in the UK.
Therefore, a 14–5–10 fertiliser contains:
- 14% w/w N
- 5% w/w P2O5
- 10% w/w K2O
For calculating nutrient inputs for granular fertilisers, use the following formula:
Application rate (kg/ha) x (% nutrient/100) = kg nutrient/ha
Example: 14–0–0 @ 35g/m²
Convert application rate from g/m² to kg/ha (i.e. 35g/m² x10 = 350 kg/ha)
Multiply product rate (kg/ha) by % N content (i.e. 14% N = 0.14) = kg N per ha (i.e. 350 x 0.14 = 49kg N/ha)
In order to calculate the nutrient inputs from Greenmaster Liquid fertilisers, you need to use the Specific Gravity (kg/L) of the particular product being used. This information can be found on the relevant product page.
Specific Gravity (SG) of:
- NK 1.23
- High N 1.31
- Spring & Summer 1.18
- High K 1.18
- STEP Liquid 1.15
- Effect Iron Fe 1.25
- Vitalnova Blade 1.36
For calculating nutrient inputs for liquid fertilisers, use the following formula:
Application rate (L/ha) x Specific Gravity (SG) x (% nutrient/100) = kg nutrient/ha
Example: 12–4–6 @ 60 L/ha (SG = 1.18 kg/L)
Convert application rate from L/ha to kg/ha (i.e. 60 L/ha 1.18 = 70.8 kg/ha)
Multiply product rate (kg/ha) by % N content (i.e. 12% N = 0.12) = kg N per ha (i.e. 70.8 x 0.12 = 8.5kg N/ha)