Epsilon Archive for Student Projects

Abstract

The background of this work is the media discussion about the effect of cultivation on peat
soils on greenhouse gas emissions. It has been argued that row sown and intensively
cultivated crops such as carrots are more likely to emit carbon dioxide than for example grass
leys. The association KRAV (an association promoting organic farming) shall, from this year
adapt their environmental policy to be more climate smart and have asked the question if the
cultivation of some crops is more climate smart than others? Carbon dioxide emissions from
soil are due to degradation of organic material and the rate is controlled by microbial activity.
The microbial activity is determined by a variety of factors such as temperature, soil organic
matter quality and water content. I have measured the carbon dioxide emission from four
different crops at two different farms. At Åloppe which is an organic farm, I have compared
carbon dioxide emission from grass leys and carrot grown on peat soil. At Ekhaga which is
SLU's experimental farm for organic farming; I have compared spring wheat and potatoes
grown on gyttja soil. The results show no significant difference in carbon dioxide emissions
when growing these crops on organic soils. The emission levels where the same on both soil
types. The amount of water in the soil and the temperature affect the carbon dioxide emission
but the results are very uncertain. Biological systems usually have a peak activity range when
all environmental factors are optimized, and so does this system. A moderate amount of water
and air in the soil and a high enough soil temperature resulted in the highest carbon emission.
I also studied how the above-ground biomass reflects the underground biomass, knowledge
that can be used to get an idea of the crop root respiration. Because carbon dioxide emissions
depend on many factors, you need to have a comprehensive view on cultivation practices.
With an open mind you can go far in today's environmentally conscious society.