DIGIT Resource Management are at the forefront of recycling and environmental management services specifically tailored to agriculture.

Our aim is to recycle suitable organic materials to agriculture lessening farms reliance upon imported chemical fertilizer. Benefits include a reduction in growing costs and the lessening of your enterprises carbon footprint.

DIGIT has earned a reputation for offering sound technical expertise and providing sustainable, cost effective solutions that empower clients to manage their businesses in compliance with the increasing burden of environmental legislation.

Lime Cake

Our product is the lime stabilised solid fraction from sewage treatment works. The material is a slow release fertilizer, high in Nitrogen, Phosphorous, Sulphur and organic matter with the added benefit of an acid neutralising capacity up to the equivalent value of 15% normal agricultural limestone.

It has undergone an enhanced treatment process recognised by the Water Industry and legislators to enable its recycling to agriculture. (see Table 1)

Lime cake's status as a recognised slow release fertilizer can benefit most cropping enterprises. It is commonly used on cereals, OSR, grassland and fodder crops.

Benefits following the use of Lime Cake on Agricultural Land are:

  • An increase in crop yield and quality.
  • An improvement in the physical and chemical properties of the soil.
  • Improvement of water holding capacity of soil.

Lime Cake is a useful source of major plant nutrients which increase crop yield and quality. A crop will benefit from these major nutrients directly after spreading and over a much longer period than conventional "bag" fertilizer.

The nutrients from Lime Cake will not alone be sufficient to support plant growth. The farmer may add to these to provide the crops total requirements.

Advice to Farmers & Growers

The Safe Sludge Matrix below shows a table of crop types and the minimum acceptable level of treatment for Sewage Sludge based product that can be applied to that crop or rotation (Table 2).

  • Chemical Analysis of lime cake and receiving soil as per Sludge (Use in Agriculture) Regulations.
  • Matching crop requirement with soil type, soil nutrient status and previous crops.
  • Assessing appropriate application method, type, spread rate and timing (as per relevant codes of practice).

The application of lime cake is regulated by the Sludge (Use in Agriculture) Regulations (As amended), along with the Waste Management Licensing (Scotland) Regulations 2011 and the Environmental Permitting (England & Wales) Regulations 2010.

Guidance in Scotland is provided by the PEPFA Code, CoGAP's in the rest of the UK, Code of Practice for the Agricultural Use of Sewage Sludge and finally the BRC Safe Sludge Matrix.

A combination of the latest technology and equipment ensures that DIGIT provides a service that operates and functions at the highest level of Quality Management Systems enabling full compliance with all the relevant legislation and statutory requirements.


Table 1 - Typical Nutrient Levels in Lime Cake (for guidance only)

 Total Nutrients kgAvailable Nutrients (Year 1)
Lime Cake N P2O5 K2O N P2O5 K2O
Kg/t (up to) 9 8 0.5 2 4 0.5

Table 2 - The Safe Sludge Matrix

Crop TypeSludge Type
  Untreated Conventially Treated Enhanced Treated
Fruit 10 month harvest
interval applies
Combinable & Animal Feed Crops
Grass & Forage 3 week no grazing
harvest interval
Grass & Forage
Harvested (Silage Maize)