Proceedings

The implementation of the Nitrates Directive has driven the replacement of digested liquid with bio-solids cake in the agricultural recycling market. However, the change has not been universally welcome, particularly by grassland farmers. Whereas the liquid contains readily available nutrients, which produce a rapid response from the crops, the effect from a cake product is less visible. The logistics of moving and storing cake is also fraught with difficulties. In recent years Organo-mineral fertilisers (OMF) have been developed in order to overcome such drawbacks. By incorporating designer formulations into bio-solids granules, the new OMF product provides a means for rapid delivery of the nitrogen component during the high demand period while at the same time replenishing the reserve of other nutrients such as P, K, S and other micronutrients that would be available for the following crops. OMF will be a farmer friendly product that may be bagged, transported stored easily and conveniently applied with a common fertiliser spreader. OMF could provide a novel end-of-waste solution, a step-change in the practice of bio-solids recycling. This paper will take into account the importance of securing the sludge to land recycling route, making comparison between sludge cake and OMF and their prospective places in future agricultural practice. Factors to be considered will include:

• Logistics
• Impact on land bank
• Agronomics
• Nutrient management
• Supply-demand balance
• Sustainability

Keywords: End-o-waste, Bio-solids, Nutrient management, Organo-mineral fertiliser, Sustainability