Mineralinblandning i torv och dess påverkan på koldioxidutsläpp

Abstract: Swedish peat soils are highly productive provided they’re drained and handled with care. However, the peat soils’ lack of buoyancy and their need for constant draining have resulted in them being viewed as less attractive by farmers. The evidence that organic soils also contribute to emission of greenhouse gases (GHG) has sparked discussions about whether organic soils should continue to be cultivated or fallowed. Sweden's national climate goals include reducing the emission of GHG 17% from 2005 to 2020. Emissions from organic soils account for approximately 10% of the total CO2 – emissions from Swedish agricultural activities (Eriksson 1991 see Berglund, Ö. & Berglund, K. 2010 s. 4). As of today, there are no known techniques for reducing CO2 - emissions from peat soils. However, further research on the topic is needed. This essay examines if blending sand into peat soils results in reduced CO2 - emissions. Furthermore, the effect of peat soil depth on emissions has also been examined. Soil cylinders were taken from the field site Broddbo, Björklinge. At the field site, cells with different amounts of mineral admixture were placed. There were parcels without sand, parcels with 2.5 cm sand and parcels with 5 cm sand. The sand was rotary cultivated down into the upper 20 cm of the soil. The experiment was conducted in a lab where the water content and carbon dioxide emissions were measured. The results of the experiment were that the cylinders from the cells with 5 cm sand produced lower CO2 - emissions. The water content decreased with time when the peat dried. However, no difference in water content could be measured between the different treatments. CO2 - emissions from the peat soil did not decrease at the same rate as the water content. CO2 - emissions increased when the water content declined initially, then decreased when the water content approached 50%. The reason for the initial increase and eventual decrease in CO2 emissions is likely a result of increased oxygen supply to the microorganisms in the pores.