PRECIKEM 2010-2014
Chemical precision treatment of acid sulfate soils to prevent acid formation (PRECIKEM)
The duration of the project was from 1 December 2010 until 31 December 2014.
In the PRECIKEM project, the goal was to develop preventive, sustainable and directed chemical methods for inhibiting the oxidation processes and thereby the formation of sulfuric acid in the hydrologically active macropores of the partially oxidized soil at drainage depth.
An experimental field divided into nine subfields, the area of each subfield being one hectare, was constructed at Risöfladan in Vaasa. A plastic sheet between all subfields and between the subfields and the open ditches provided hydrological isolation. By pumping suspensions of treatment chemicals through the subsurface drainpipes, the suspension could easily enter the soil through the cracks and macropores at drainage depth. The goal was to create conditions unfavourable for microbes catalysing the sulfide oxidation and to form protective coatings on mineral surfaces. As the chemical treatment was preventive, the expectation was that the use of chemicals would be small compared to a conventional approach where liming would be used to neutralize already formed acid. In the large-scale field trials, about 100 m3 of river water and 100 – 800 kg of calcium hydroxide or calcium carbonate was used. The ultrafine-grained solid phase made stable suspensions possible and the risk for sedimentation of lime products in the drainpipes thereby greatly reduced. The nine subfields made four different treatments possible, where each treatment was repeated in the subfields. Monitoring of the quality of the drainage water showed that the methods developed in the project contributed to a mitigation of the acid and metal load received by nearby water streams affected by acid sulfate soils in agricultural use.
Prior to the large-scale field experiments, treatment chemicals and methods were tested in the laboratory. For this purpose, an experimental setup was constructed in the laboratory. With this equipment, soil samples could be treated with solutions and suspensions and the solution that passed through the soil could be analysed with respect to several parameters.
The experimental field at Risöfladan was designed and its construction was supervised by Rainer Rosendahl at ProAgria/Österbottens Svenska Lantbrukssällskap.
Funding
The funding for the project was in total 850 000 €, of which 90 % was granted by the Centre for Economic Development, Transport and the Environment in Ostrobothnia, Finland, from the Rural Development Programme for Mainland Finland 2007-2013 as part of the European Agricultural Fund for the Rural Development.
Of the total funding, 10 % was granted by private funders and these were during the first three years of the project: The field drainage research association, Maa- ja vesitekniikan tuki, MTK:n säätiö, Österbottens svenska producentförbund and MTK Etelä-Pohjanmaa. During the fourth project year the private funding was granted by K. H. Renlunds stiftelse and Oiva Kuusisto Säätiö.
Due to limitations in the main funding, separate funding was obtained for instrumentation as well as travel and lodging costs for external experts. This funding was granted by K. H. Renlunds stiftelse, Oiva Kuusisto Säätiö, Aktiastiftelsen i Vasa and Stiftelsen Handlanden Gustaf Svanljungs donationsfond. Companies Nordkalk and KWH Pipe supported the project actively by providing materials and expert advice.
In this project an active cooperation was initiated with Prof. Paweł Nowak at the Polish Academy of Sciences in Kraków, Poland, as well as with Prof. Mark Dopson and his group at Linnaeus University in Kalmar, Sweden.
