Organic carbon sequestration and nitrogen content in forest soils versus arable soils within a heavy-clay Phaeozem landscape: a Romanian case study

Abstract

This paper tests the hypothesis that the soil organic carbon (OC), total nitrogen (Nt), nitrate-N and ammonium-N in forests are significantly different from the same properties in arable soils, under similar relief, geology, climate and heavy-clay soil conditions (phaeozioms). Such soils are largely spread in the world. Four pairs of soil profiles 1.5 m deep were carried out in both forest soils and arable soils. The different environmental conditions produced modifications in OC, Nt and other related properties. OC content and Nt content for the first 0.5 m depth soil strata are distinctly significantly higher in forest soils versus arable soils. Soil NO3–N and NH4–N contents present non-significant differences for the same depths in the two land uses. OC, Nt and NH4–N contents are directly and highly significantly correlated for all soil layers. Measurements of OC and N from topsoil are not sufficient for a thorough evaluation of the environment. Afforestation is a measure to increase soil carbon sinks. The findings might be extrapolated to countries with similar environment.