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Recycling of agricultural materials as a novel slow release fertiliser

Contract n°: FAIR-CT98-4042
Project n°: 4042
Project type: SC
Starting date: 01/04/1999
Duration: 36 months
Total cost: 1,489,182 EUR
EC Contribution: 1,106,957 EUR
Scientific Officer: Armin MÜNZINGER
Research topic: Speciality products

The overall objective of the proposed work is to recycle agricultural wastes and residues to produce a high added value slow release fertiliser for the horticultural and agricultural industries. The abundance of agricultural and forestry residues with increasing problems of disposal is a problems that is very addressed by this project as the wastes are totally recycled, together with their mineral content, thereby minimising losses of natural nutrients. The slow release fertiliser is a high added value product that also assists with soil conditioning.

The overall objective of the work is to recycle agricultural wastes and residues into a slow release fertiliser by pyrolytic liquefaction with nitrogen addition through ammonoxidation and nutrient blending, to form a high added value slow release fertiliser for the horticultural and agricultural industries. The key feature is the total recycling of agricultural wastes and residues into a unique and valuable fertiliser that can be safely used in a range of agricultural and horticultural applications. This approach, therefore, is a sustainable method of recycling agricultural materials into a useful and valuable non-food, non-fuel product. The product is flexible as a range of nutrients and additives can be included as required, for different applications. The pyrolysis process that liquefies the agro-materials is a well established technology that produces no wastes as all the by-products are either used in the process for energy or contained as essential components of the resultant liquid.

The work programme contains four main elements.

1) Produce slow release nitrogenous fertiliser. Fertiliser production will be carried out by three methods, the first of which has already been successfully demonstrated but the other two may provide a more cost effective processing route:

a) reaction of nitrogen containing compounds with pyrolysis liquid;
b) addition of the nitrogen containing compound to the biomass before pyrolysis,
c) direct reaction of nitrogen containing compounds within the pyrolysis process.

The products from the three routes will be compared to determine the most effective fertiliser product and hence derive the most cost effective process. The addition of other essential nutrients will also be investigated. Solid fertiliser products will be initially produced as a free flowing dark brown powder, but alternative product formulations will be investigated including liquids, granules and pellets. Product samples will be made from different feedstocks, under different reaction conditions and with different ammonoxidation reagents.

2) Test the slow release nitrogenous fertilisers. Growth trials on pot plants will be used to test the fertiliser samples in order to identify the most suitable product for growth using various criteria. These include nitrogen release rate, soil conditioning properties, level of application in the soil media, soil media substitution, release of micro-nutrients and toxicity. The fertiliser product will be extensively characterised. In addition, the fast pyrolysis by-product char can act as a fertiliser support medium and also release the original inorganic elements present in the agro-industrial waste thereby also recycling micro-nutrients. Although the short-term focus is on the specialist slow release, high added value fertiliser market, there are wider opportunities for general fertiliser use in the longer term.

3) Produce and test larger quantities of slow release nitrogenous fertiliser. The most promising slow release fertiliser product from the evaluation tests in Part 2 will be produced in larger quantities of 20-50 kg for larger scale field trials on suitable agricultural crops, including miscanthus in Denmark and wheat in the UK. These results will be used to assess the short, medium and long-term performance of the fertiliser in terms of release rate, degree of mineralisation of nitrogen, crop growth and other criteria.

4) Design, cost and evaluate commercial scale opportunities. The market potential for the product will be evaluated for key market opportunities in Europe. Comparative costs with other conventional slow release nitrogenous fertilisers will be made and potential markets assessed. A fully integrated demonstration/commercial plant will be specified, designed, costed and assessed techno-economically.

Current situation/results:
Samples of solid fertiliser products have been made in all nitrogenolysis configurations. High levels of nitrogen acquisition have been achieved through process development. Preliminary plant testing in pots has been carried out and valuable results obtained. Plant toxicity tests have given encouraging results.

This is under preparation and will available early in 2000.

Aston University
Aston Triangle
UK-B4 7ET Birmingham
Tel.: +44 1213 59 36 11
Fax: +44 1213 59 68 14


  • Mike BULLARD
    Agricultural Development and Advisory Service Consulting Ltd
    Adas Headquarters
    Oxford Business Park
    UK-OX5 1NZ Oxford
    Tel.: +44 1354 69 25 31
    Fax: +44 1354 69 44 88

    Danish Institute of Agricultural Sciences
    Blichers Alle
    DK-8830 Tjele
    Tel.: +45 89 99 17 62
    Fax: +45 89 99 17 19

  • Dietrich MEIER
    Bundesforschungsanstalt fuer Forst und Holzwirtschaft
    Leuschnerstrasse 91
    D-21031 Hamburg
    Tel.: +49 407 396 25 17
    Fax: +49 407 396 22 96

  • Philip WALLACE
    Levington Agriculture Ltd
    Levington Park
    UK-IP1O 0LU Ipswich
    Tel.: +44 1473 27 18 18
    Fax: +44 1473 65 90 25
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