Spatial characteristics of carbon and nitrogen reserves in the black soils of China

Abstract

AbstractSoil total carbon (STC) and total nitrogen (TN) play important roles in providing essential nutrients for vegetation growth, improving soil structural properties, dissipating organic pollutants, and reflecting the fertility of black soils. Based on 1,057 soil samples collected 0 to 20 cm below the surface, geostatistical analysis was used to explore the spatial distribution and factors influencing STC, TN, and C/N ratios in the study area, which is a typical black soil area in northeast China measuring 83,439.04 km2. The soil sampling points were based on randomness and accessibility, spaced 1.25 km apart. The average STC and TN contents and C/N ratios in typical black soil areas of northeast China were 19.25 and 1.88 g kg–1 and 10.07, respectively, and the STC and TN were significantly higher than the national averages (13.26 and 1.32 g kg–1, respectively). The spatial distribution showed a decreasing trend from northeast to southwest, and the nucleation density of STC and TN was highest in the central part and decreased to the north and south. The STC and TN contents and C/N ratio were highest in clayey soil and were 46.11 and 4.23 g kg–1 and 11.39, respectively. The sandy soils had the lowest STC, TN, and C/N ratios. The distribution of STC and TN content is governed by multiple factors, such as human activities, soil type, climate, topography, soil acidity and alkalinity, and land use changes. This study provides the benchmark needed for the development and conservation of China's black soil resources.