Background

Modern agriculture practice is based on chemical fertilisation. Farmers, that apply all the proper managing schemes and quality assurance guidelines and those who don’t, use fertilisers (properly or not) in order to achieve an economically viable production. Millions of tons of these chemicals contain nutrients such as Nitrogen, Phosphorus and Potassium that are produced, transferred and applied all over the globe. At the same time more than seven billion people in the planet are feed (adequately or partly, depending of the area and the state) due to the application of these fertilisers. Inadequate provision of nutrients to the cultivations will result to a world wide famine.  Up to recently, the main environmental issue with chemical fertilisation was the local effect of the (excess) use, such as the leaking to the groundwater (degradation of water quality) and the eutrophycation of rivers, lakes and seas. In the last 10 to 15 years another parameter for observation has been added, that of carbon footprint and global climate change. For example a ton of Nitrogen to be captured (from the air) into a fertiliser, requires at least one (some increase that to 1.5 t) ton of diesel, or respected quantity of any fuel of similar energy capacity. If we add in this amount the energy required for transporting and applying the fertiliser then the overall carbon foot print is increased considerably. And as it was mentioned earlier millions of tons are needed per year. Only the 1,000,000 olive trees located in the Perfection of Ilia, consume – through the fertilisers added to them – more than 600 tons of Nitrogen alone. 

As such any methodology that would allow the provision of nitrogen to plants with reduced carbon foot print (in comparison with the existing methodology or in absolute terms), the proposed process should be considered an improvement and an answer to this environmental problem.

However, the abundance of nitrogen in the atmosphere and the natural / biological nitrogen cycle, reduce the availability problem to that of energy management and balance. As long as we can “produce” energy we will be able to “produce” nitrogen containing fertilisers. The case is not the same with phosphorus, because Phosphorus and Potassium are both MINERALS, and as all minerals in the planet their availability is limited. Both these substances do not have a natural / biological cycle, which bring them back in the original state from which chemical industry captures them to use them as chemical fertilisers. Dead tissue releases phosphorus and potassium in water, which then ends up in the final water receiving body (the sea in most cases) and are considered LOST.

Estimations on Phosphorus and Potassium availability cannot be made with accuracy; however there are some data indicating that by the end of this century both will be limited. In the area of Ilia, the olive trees require also about 600 tons of phosphorus and potassium per year. Only in Greece it is estimated that there are more than 20,000,000 olive trees, which are fertilised chemically every year.      

The carbon foot print of Phosphorus and Potassium fertilisation (from the mineral to the bag and then to the plan) is extremely large, estimated 25 % larger than that of Nitrogen.

Concluding all the above, major environmental problems of nitrogen and phosphorus chemical fertilisers’ production, as they take place now, are the following:

  • Increased energy consumption for capturing / excavation, production, packaging, transferring and application, resulting to a negative carbon foot print (global climate change issue).
  • Continuous utilisation of mineral Phosphorus and Potassium, resulting to an estimated adequacy problem by the turn of the century.
  • Local environmental problems mainly related with leaking of these nutrients in water receiving bodies and the degradation of water quality and eutrophycation.   

NOTE: As a results of the above problems and since: a) we are driving the globe into a carbon credit economy, b) energy cost will increase in an effort to reduce the consumption, as well as its effect in the planet, and c) potential lack of phosphorus / potassium will result in a considerable price increase, probably in the next 20 to 50 years; the poorest and less developed areas in the worlds (as well the poorest people), which also happen to be mainly agricultural depended, will be hit harder and adequate food production will be a major issue for them.     

A solution to all these problems was always considered to be the recycling of organic wastes, into the soil and the agricultural production, after some (or no) treatment. Wastes as manure, sewage sludge, organic fraction of municipal solid wastes (MSW), green wastes (trees branches and leaves) etc, could be a useful tool for a sustainable agriculture. It’s well known that the benefit of organic waste addition to the soils is extremely positive, well beyond a simple nutrient source. They do increase the organic matter in the soil, improve the structure of the soil and increase the microorganisms population and diversity. In all cases there is no reason not to support the recycling of these wastes to the soil. However, issues and problems are also raised regarding the practice.    

The first problem is the quality of the wastes. Manure often contains large amounts of heavy metals (especially Zinc) coming from the animals’ feed, as well as pathogens and antibiotics. Sewage sludge also contains heavy metals, pathogens (including viruses) and a large variety of organic micro-pollutants as for example PAHs and LAS. Finally the organic fraction of the MSW can contain all the above as well as plastic, metal and glass fractions that do reduce significantly its quality. A series of European Legislations do support the recycling of these organic wastes into the soil (Landfill Directive, Waste Framework Directive and Soil Framework Directive), but in all cases with some significant quality related limitations.   

In the quality issue, the problem of managing properly these wastes must also be added. Treatment and transportation issues, application technologies and cost, availability and adequacy problems etc are some of the issues raised.    

Especially adequacy is a large problem in respect with nutrients availability. If an olive tree needs per year about 600 g of Nitrogen, then compost from manure, with a mean nitrogen concentration of 4 % in d.w. (in organic and inorganic form), will bee needed in quantities such as 50 to 60 kg (taking under consideration losses, organic form of nitrogen etc), with a mean moisture content of 50 %. The whole of Ilia olive trees cultivation will require about 50,000 tons of manure compost which to be produced would require approximately 70,000 to 80,000 tons of good quality manure and 15,000 to 20,000 tons of bulking agent (green wastes).

There is NO such quantity available in the region, but even if there was the production and transportation / application cost and logistics, would result to such an increased overall cost that the cultivation could NOT be viable any more. And that only for the olive trees cultivation. 

In simple terms and in relation to the nutrients, organic wastes cannot provide a viable solution to the problem. All efforts must be made to supply our soils (especially in the Mediterranean region) with as much as possible good quality organic matter, from good quality organic wastes, but NOT for the nutrients (at least mainly), but for the improved structure, the organic matter content and the microorganisms ecology. For nutrients supply other solutions must be found.     

In conclusion:

Nitrogen, Phosphorus and Potassium current production and application pattern though chemical fertilisation has a significant local and global environmental effect.

Phosphorus and Potassium availability beyond this century is in question, together with existing agricultural production process, which is based in their abundance and considerable small production / application  cost.

Organic wastes, including manure, especially the way are currently managed and applied, can not provide an adequate solution to the nutrient problem availability.    

What the CONDENSE project is aiming to do is to demonstrate a new managing system for manure as well as olive mill wastewater that could be an answer (in part at least) to all the above mentioned problems.