Peatlands in their natural state accumulate organic matter and bind large quantities of carbon (5 - 50 g C/m²/year). The drainage and cultivation of peat soils increase the aeration of the soil, which increase the brake down of the organic matter. The degradation of the organic material release greenhouse gases such as CO₂, N₂O and CH₄. CO₂ emissions dominate when the soil has high oxygen levels, while CH₄ mainly is released under anaerobic conditions. The organic soils (8% of the arable land in Sweden) are the dominant greenhouse gas emitters from arable land in Sweden and these soils contribute as much as 10% of the total anthropogenic emissions (in which fossil fuels accounts for most) and greatly affect the agricultural sector's contribution of greenhouse gases to the atmosphere. Greenhouse gas measurements from fields are often done on few points per field using chamber measurements. A lysimeter study conducted 2002-2005 showed large variations in CO₂ emissions between different places, peat type and drainage depth, and field trials during the same period showed a very large spatial variation within the same field. This may be due to the fact that organic soils have very large variation in physical and chemical properties, often larger than on mineral soils. One way to obtain information about the spatial variation is to measure the electrical conductivity (EC) of soil with an EM38 (Geonics Ltd), which is sensitive to differences in the amount of organic matter and water holding capacity. Another way to estimate the moisture content variation is to measure the natural gamma radiation from ⁴⁰K, which is released from rock/mineral soil and blocked by water. Peat soils often contain large amounts of water resulting in no or very low readings in the gamma-ray spectrometer measurements. CO₂ emissions from cultivated peat soils show a large spatial variation, which gives uncertain estimates of greenhouse gas emissions. The aim of these investigations was to find better methods and models to estimate the greenhouse gas emissions from cultivated peat soils.

Hypotheses:

 

The results show that there are correlations between EC and water content, EC and penetration resistance, and CO₂ emission and penetration resistance. The structure of the spatial variation of EC shows clear zones that can be used to design the measurement scheme for CO₂ measurements.