Wetenschap - 2 december 2010

New solution for manure problem

Environmental legislation is leading to a rise in the manure surplus in the Netherlands. But livestock and arable farmers will be able to replace their synthetic fertilizers with animal manure if the EU approves the ‘mineral concentrate’.

The Netherlands has a manure problem. Its 12 million pigs and 90 million chickens produce more manure than the livestock and arable farmers are allowed to spread on the land by the European Union Nitrates Directive. The manure surplus has to be exported or turned into a product for which there is demand.
Last week, the European Commission and the Dutch Ministry of Economic Affairs, Agriculture and Innovation organized a workshop in Wageningen on manure processing. This was a good opportunity for the Netherlands to put the spotlight on the latest technological development in the area of manure processing: the mineral concentrate. The mineral concentrate, currently in a test phase, is made from manure but has the same composition as synthetic fertilizer. If farmers are allowed to replace synthetic fertilizer by a product made out of animal manure, that could reduce the manure problem by as much as twenty or thirty per cent. Eight manure processing plants are currently testing the potential of the mineral concentrate.
Liquid fraction
KUMAC, a partnership between a group of pig farmers and a contracting firm, is one of them. The cooperative in Deurne separates pig slurry into a solid fraction (containing organic matter and phosphate) and a liquid fraction (containing water, nitrogen and potassium). The company uses the liquid fraction to make the mineral concentrate. That currently costs the affiliated farmers 17 euros per ton of manure, says Paul Hoeksma of Livestock Research.
KUMAC's problem is that it has to be able to offload manure products continuously, even now when manure cannot be spread on the land. Offloading manure always costs money. At present, farmers who want to offload unprocessed manure pay 25 euros per ton. That means it is currently cheaper to deliver to KUMAC, but the offloading price may fall back down to 15 euros per ton in the spring. In the past, manure processors have gone bankrupt because livestock farmers were only willing to supply manure when offloading costs were high. KUMAC has a guaranteed supply of manure as the farmers are co-owners and have an obligation to deliver, says Hoeksma.
Low tech
There is a rule of thumb for manure processing that says that farmers are best off investing in cheap, low-tech facilities for the farm, such as facilities for extracting biogas from the manure and separating the manure into a solid and a liquid fraction. The main thing is to deliver as little 'water' as possible to the manure processor. On the other hand, the manure processing away from the farm should be high tech and on a large scale,  like the manure processing plant in Moerdijk, which processes 440 thousand tons of chicken and turkey manure every year. This manure processor burns the chicken manure to produce energy. In addition, the plant is able to extract useful components like phosphate and potassium from the ash. This factory in Moerdijk is more or less viable. The poultry farmers supplying the manure pay 7 euros per ton of manure.
More expensive
Manure processing will only become even more important in the years to come, says Gerard Velthof, the person organizing the meeting in Wageningen. The Nitrates Directive will lead to the limits for fertilizing becoming more stringent in the period up to 2015, which will mean more farmers with a manure surplus. On top of that, Germany, an important export market for Dutch manure, is becoming stricter about what it allows in. 'The manure surplus will increase', says Velthof, who works for Alterra. 'It will also probably become increasingly expensive to get rid of the manure.' The Netherlands now wants to convince the European Commission that the experiment with the mineral concentrate will benefit the environment and ensure that the persistent problem with manure will at least not get any worse.

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