Effect of different land use (forest-grassland-cultivated sites) on soil carbon and nitrogen stocks in Kastamonu region

Land use strongly influences soil properties and unsuitable practices lead to degradation of soil and environmental quality. The aim of this study was to assess the impact of different land uses (forest, cultivated and grassland sites) on some soil chemical properties, carbon (C) and nitrogen (N) stock rates in Kastamonu, Turkey. Uludag fir stands and adjacent grassland and cultivated sites were used to study the differences in some soil properties and soil C and N stock rates. Mineral soil samples were taken from 0-10 cm and 10-20 cm soil depths, and analyzed for texture, pH, water holding capacity, salt, lime, organic matter, P and K concentrations, total soil carbon and total nitrogen. The total soil carbon and total nitrogen pools were then calculated by multiplying soil volume, soil bulk density, and the total soil carbon or total nitrogen content. Results showed the cultivated site had lowest soil carbon and nitrogen contents, carbon/nitrogen ratios and stock rates compared to the forest and grassland which had similar results. In general, when 0-20 cm soil depth was considered, mean soil carbon stock rate was the highest under fir (47,7 Mg C ha-1) followed by grassland (47,0 Mg C ha-1) and cultivated site (28,2 Mg C ha-1), whereas mean soil nitrogen stock rate was the highest under grassland (6,90 Mg N ha-1) followed by fir(6,82 Mg N ha-1) and cultivated site (5,53 Mg N ha-1). There was also significant relationship between soil carbon stock capacity and soil C/N rations of soils.