Browsing by Subject "Biosoil"

In Finland, soil classification in forestry has played only a minor role. However several international classification systems exist, one being the World Reference Base for Soil Resources (WRB) used in this study. The criteria used in WRB to identify diagnostic properties, horizons and soil materials which are to classify a soil may not work everywhere. This is one reason why there is a continuous revision of international soil classification systems and a need to test them nationally. In Finland problems have been encountered with the criteria of international soil classification systems for defining a spodic B horizon. Empirical testing of soils classified as Podzols according to international soil classification systems has not been carried out in Finland. It is not known how many soil profiles considered to be Podzols actually have spodic B horizons, the official requirement for a soil to be classified as a Podzol. Soil classification systems provide detailed information of our soils and its properties in soil horizons. These soil properties are indicators of the degree of development in the soil. Podzols, considered to be the most common upland forest soil type in Finland, are formed through a combination of the five soil formation factors: climate, parent material, topography, biotic and time. These factors determine which soil formation processes operate, which properties develop and then which soil type classes are formed. There have been few studies in Finland that have examined the degree of podzolization of podzolized soil profiles in relation to soil formation factors. The aims of this study were therefore to determine the number of profiles (sampled from all over Finland) that were classified in the field as being Podzol that actually have diagnostic spodic horizons according to World Reference Base for Soil Resources (WRB). The diagnostic spodic criteria of WRB have six criteria and these are based on morphological properties (horizon thickness and Munsell dry/moist colours) and chemical properties (pH, organic carbon content and acid oxalate extractable Al and Fe contents) of the E and B horizon samples. In addition, the degree of podzolization of the profiles using a number of podzolization indices (Thickness index, Rubification index, Al+Fe index and Podzolization Development Index) was determinate and importance of various soil formation factors (climate, topography, parent material, biotic, time) on the degree of development of the profiles evaluated. The study was carried out using soil profiles covering the whole Finland. The soil profile data is from the BioSoil project, Natural Resources Institute Finland, Luke. Study showed that field classification of Podzols based on morphological features (colour and thickness of the albic and spodic horizons) works well in Finnish soils. Except of albic colours criteria of morphological soil properties in spodic horizon are fairly equal with criteria of chemical soil properties. Podzolization intensity is poorly explained by individual soil formation factors (variables). Soil processes occur simultaneously and there is much interaction between/among soil formation factors. In certain situations, indexes based on morphological or chemical properties acts in an opposite way to each other. Nevertheless, time and soil texture (parent material) were the most important factors. Topography was noticed to have only a minor effect on podzolization.