Compost Calculator

12th December 2016

The calculator allows those creating and selling compost to see the financial values of key nutrients in compost and digestate when compared to inorganic fertilisers. The values are based on current market prices for fertilisers and the typical readily available nutrient content of composts and digestates.

Key points
Data on readily available nutrient content is taken from RB209, for compost, and the DC-Agri project for digestate
Compost is an excellent source of organic matter, which can offer significant improvements to soil quality in the medium and long term – providing further financial savings
Additional tools, such as the MANNER-NPK tool to integrate digestate and compost use into your fertiliser planning

Overview

Overview

The values used as part of the compost calculator are based on current market prices for fertilisers and the typical readily available nutrient content of composts and digestates. 

It is worth remembering that, in addition to the readily available nutrients, organic materials contain nutrients in more complex forms which will become available for crop uptake in future seasons.

For example, composts have a low readily available nitrogen content (5%), but a high total nitrogen content (11kg/tonne of green/food compost) which will contribute to soil nitrogen supply.

Using the table below – you can calculate the values for your particular types of compost:

 

Nitrogen
(N)

Phosphate
(P2O5)

Potash
(K2O)

Total

Market price of fertilisers (£/kg) 0.74 0.59 0.44  
         
Green Compost        
Readily available nutrient content (kg/tonne compost) 0.00

1.50

4.40  
Financial value of readily available nutrient content (£/tonne compost) 0.00 0.88 1.95 2.83
Green/Food Compost        
Readily available nutrient content (kg/tonne compost) 0.55 1.90 6.40  
Financial value of readily available nutrient content (£/tonne compost) 0.40 1.12 2.84 4.36
Digestate (Biofertiliser)        
Readily available nutrient content (kg/tonne digestate) 4.00 0.25 1.60  
Financial value of readily available nutrients (£/tonne digestate) 2.94 0.15 0.71 3.80

Related

Related

MANNER-NPK Tool

The difference between readily available and total nutrient contents could make fertiliser planning complicated, but the free to use MANNER-NPK tool can help you integrate digestate and compost use into your fertiliser planning.

Go to the MANNER-NPK website >>

Related WRAP resources

Specifying compost for the landscape industry >>
Compost use in landscape and regeneration projects >>
Landscape compost specifications >>
Compost use in horticulture >>
Compost case studies >>
Why compost is good for mulch >>

Where next?

Want to know more about composting in Resource Management? Take a look at our reports, guides, tools and case studies for further information:

Reports >>
Guides >>
Tools >>
Case studies >>