Organic carbon and nitrogen content in Estonian erosion-affected soils

Abstract

The work is dedicated to the characterization of erosion-affected soils' (EAS) humus status (HS) in pedo-ecological conditions of South-Eastern Estonia. For understanding HS of EAS their organic carbon (OC) and total nitrogen (NT) sequestration capacities and the ratio C:N was studied by separate soil layers. The average data about soil OC and NT contents (g kg–1) and superficial densities (Mg ha–1) are given by arable soil species. The analysis of reflecting EAS HS on four research areas (Valgjärve, Otepää, Haanja and Mooste) was carried out on the basis of four different origin databases. The analysis of OC content is done by Tjurin and NT by Kjeldahl. In soil associations of erosion-affected areas' the following groups of soils were distinguished: eroded (E), deluvial (D), neutral (N) and non-eroded (En) soils. The HC thicknesses of research area Valgjärve E soils are in limits 18–23 cm, D soils 30–65 cm and of En soils 22–27 cm. The medians of same soils OC concentrations are accordingly 9.4, 11.2 and 10.9 g kg–1 and ratios C:N accordingly 9.8, 9.4 and 10.2. The OC stocks given in the limits of quartiles are in E soils 24–36, D soils 51–143 and En soils 32–49 Mg ha–1. Therefore on eroded areas the perpetual continuums of soil properties' (among these HS) changes may be followed and it is very complicated to separate soil contours on 1:10 000 soil maps. In this work the transitional areas between E and D soils are characterized via N soils. On erosion-affected areas the E and D soils form different soil associations with auto- and hydromorphic normally developed non-eroded soils, where very commonly as well the fluvial (abnormal) soils are presented. The relatively high pedodiversity caused by the areas high geodiversity, is the requisite to the high biodiversity. In erosion-affected regions is extremely important to maintain agricultural activity, as with this is ensured the persistence of naturally beautiful landscapes. The soil cover with EAS acts as accumulator of formed on the same area soil OC.

Keywords

• erosion-affected soils
• water and tillage erosion
• total nitrogen
• soil organic carbon
• humus status
• sustainable soil management
• soil association