PROJECT DESCRIPTION
BACKGROUND
Agriculture based on the use of fertilisers accounts for 40-60% of the world’s food supply. The main nutrients – nitrogen (N), phosphorus (P) and potassium (K) – are elements that occur naturally in the environment but are removed with the harvesting of crops. Fertilisers replenish the soils with N, P, K and other nutrients, thereby helping to sustain ongoing food production. The world market of chemical fertilisers is extremely large, but it has a heavy impact on the environment.
The need to protect the biological characteristics of the soil has to be considered as an important environmental challenge. The scale of this challenge increases according to the length of the time (usually years) that chemical fertilisers have been applied. Chemical fertilisers are very effective in the short term, but need a suitable supplement of natural organic substances. Often, the factor that limits the wider use of organic fertilisers is the difficulty in correctly managing the maturing process of the raw materials. As a result, the final product has a poor agronomic quality.
OBJECTIVES
The main objective of the LIFE RESAFE project was to demonstrate the production and effective use of reduced salinity fertilisers (RSF) as a step towards replacing chemicals and mineral fertilisers through a technological route based on urban organic waste (UOW), bio-char and farm organic residues (FOR).
Based on this approach, it is expected to be possible for farmers and urban waste managers to reduce costs and benefit economically from material recovery (e.g. reduced quantities of waste sent to landfill and the related costs saving). They would also benefit financially from the use of these organic fertilisers. The environmental impact would also be significant, due to the decrease in greenhouse gas emissions from landfills and to the benefits for soil structure and fertility.
The use of the RSF is expected to have the following advantages:
- A significant reduction in the systematic use of chemical fertilisers;
- A consistent improvement in soil health and fertility;
- Increased availability of nitrogen and phosphorus for plants;
- Increased “suppressive soil potential” against soil pathogens.
RESULTS
Life RESAFE demonstrated the production and effective use of innovative reduced-salinity fertilisers as a step towards replacing conventional chemical and mineral fertilisers. This was done using a technology based on urban organic waste (UOW), bio-char (BC), and farm organic residue (FOR).
The project team achieved this objective by means of the following activities:
- Raw materials (UOW, BC, FOR) and technologies (pyrolysis, composting, etc.) were selected to obtain the necessary material for fertiliser production, while VAP (vegetable active principles) quantities and quality was defined.
- Raw material samples were fully characterised and "recipes" to be used at the laboratory scale were defined for suitable candidates (10 overall: 3 for Italy, 3 for Spain, and 4 for Cyprus). This allowed the team to produce fertilisers, containing different proportions of UOW, FOR, BC and VAP.
- Pilot-scale plants in the three countries were set up and 18 tons of HQ-ORBP (High Quality Organic Matter Based Product), with different raw material proportions, were produced to be used for agricultural tests and full characterisation.
- Finally, the HQ-ORBP was applied in the field in the 3 countries, with harvesting of crops and vegetables. In particular, 6 different fertilisation treatments on 16 different crops were assayed in Italy (7), Spain (5) and Cyprus (4), and some 170 samples of harvested crops and treated soil (at the beginning and end of crop cycles) were characterised.
The project team identified the main environmental benefits of the new proposed fertiliser as:
- The production process allows maximising nitrogen retention in the fertiliser, resulting in higher nitrogen, phosphorus and potassium content in the soil (N content in fertiliser was maintained in almost 100% of the pilot plants in Spain and Cyprus, and in 75% in Italy).
- Reduced or controlled salinity, depending on raw materials characteristics (in presence of poultry manure, final values decreased to 4 mS/m).
- Composting enhances sanitation and strengthens humification, benefitting the soil.
- The fertiliser facilitates good water retention capacity (about 28-33% in soils where the RESAFE fertiliser was applied).
- Reduced use of mineral fertilisers and chemicals in agriculture (between 50-100%), leading to reduced pollution.
- Use of urban organic waste, organic farm residues and bio-char in the fertilisers (mixed with complex enzymatic mixtures) reduces the amount of waste to be disposed of.
Adding organic substance to soils prevents soil sealing, by enhancing water filtration and field capacity; prevents the removal of soil surface layer such as dust, together with carbon and organic fraction; prevents mineralisation and pre-desertification, which can reduce soil function.
The use of the HQ-ORBP fertiliser also made the soil softer and more absorbent, ensuring better retention of heavy rains, and could reduce agricultural water consumption by up to 30%.
The production cost of the new fertiliser was estimated to be below €100/t. A crop fertilisation plan based on the RESAFE product may have higher costs compared to mineral fertilisers (especially due to transport and spreading), but it provides more micro-nutrients. In particular, the RESAFE fertiliser increased yields for vegetable crops, matching the higher costs.
