Browsing by Subject "maanparannus"

The main problems with cultivated peat soil are its weak carrying capacity, high greenhouse gas emissions, coldness, and acidity. There is very little research on using industrial by-products as soil amendments in peat soil. The aim of this thesis was to study the effects of industrial by-products paper mill sludge and gypsum on the sustainability of soil structure, greenhouse gas (CO2 and N2O) emissions and soils heat and gas dynamics in peat soil. The study was performed in the laboratory on samples taken from a field test. The tested treatments were unfertilized, control, gypsum 3 kg m-2, paper mill sludge 3 kg m-2, paper mill sludge 15 kg m-2 and paper mill sludge 15 kg m-2 + gypsum 3 kg m-2. The water-stable aggregates were determined by wet sieving with 0.25 mm mesh and 2 mm mesh at three different moisture contents. The greenhouse gas emissions of the soil were determined by gas chromatography at field capacity. The thermal properties of the soil were determined by measuring the thermal conductivity and diffusivity of the soil at field capacity and at saturation. In addition, soil pH, hydraulic conductivity of saturated soil, and water-holding capacity at matrix potentials pF 0; 0.4; 1; 2 and 4.2 were measured. Soil amendments had no effect on the water-stable aggregates in field moisture. The soils CO2 emissions increased with paper mill sludge treatments and decreased with gypsum treatment. Individual soil amendments had no effect on the N2O emissions of the soil, but the combined effect of paper mill sludge and gypsum increased the N2O emissions. The soils CH4 consumption decreased with gypsum treatment. Soil amendment treatments had no effect on soil thermal conductivity or thermal diffusivity at field capacity. However, in water-saturated samples the thermal conductivity and heat diffusivity of the soil was increased by the combined effect of paper mill sludge and gypsum. Unlike gypsum, paper mill sludge was found to have a clear liming effect. Soil amendments had no effect on the hydraulic water conductivity or water-holding capacity of saturated soil at any matrix potential. Based on the results, the soil amendments used did not have a major impact on the cultivation problems in peat soil, but further research on their use as soil amendments is needed.