JOURNAL OF ENVIRONMENT AND HUMAN Effects of Soil Sample Preservation Methods on Dissolved Nitrogen and Dissolved Organic Carbon Content in Grassland Soils Fertilized With Cattle Slurry Manure

The research was carried out to investigate the effect of soil sample preservation methods on dissolved nitrogen and dissolved organic carbon contents in Dutch grassland soils fertilized with improved cattle slurry manure quality by comparing the analytical results of soil samples preserved moist at-4oC in cold room and the same soil samples preserved after oven dried at 40oC for 48 hours. The results revealed that soil sample preservation methods influenced dissolved mineral nitrogen, dissolved organic nitrogen and dissolved carbon contents of the soils. Dissolved mineral nitrogen (nitrate-N and ammonium-N), organic nitrogen and dissolved organic carbon contents were higher in soil samples preserved after oven drying. Moreover, the initial field soil moisture contents affected the dissolved mineral and organic nitrogen as well as dissolved organic carbon contents of the soils. Therefore, the analytical result of soil sample preservation on oven dry basis does not represent the soil population from which the soils samples were originally taken from. Hence, it is not recommended to dry soil samples before analysis as alternative to moist soil samples preservation for analysis. Keywords