Concentrations of nitrogen and organic carbon in different uses of Terric Histosol
Keywords: Terric Histosol, organic carbon, total nitrogen, mineral nitrogen, C:N
AbstractIn 2016–2019 in Eastern Lithuania, in Naujienos Terric Histosol (HSs-d), where natural and cultural meadows are grown and areas of cereal crops are annually cultivated, monitoring sites were installed. There at different times of the year at different Histosol depth – 0–30, 30–60 and 60– 90 cm layers, organic carbon (Corg.), total nitrogen (Nsum.) and mineral nitrogen (Nmin) concentration and their relationship were investigated. The studies have shown that the highest Nmin concentration was found in natural meadows areas, followed by cultural meadows areas, and finally cereal crops areas; in Terric Histosol at the 0–30 cm depth, mean concentrations were obtained, 100.7, 88.3 and 79.0 mg kg–1, respectively. The highest Nmin concentration was observed in the first days of July. It was 137.6 and 105.4 mg kg–1 in natural and cultural meadows areas, respectively. In deeper Terric Histosol layers, the Nmin concentration in cereal crops areas was slightly different. At the 30–60 cm depth, it ranged from 45.6 to 102.2 mg kg–1 over the years, and at the 60–90 cm depth from 55.1 to 87.2 mg kg–1. Nitrate formed the major part of mineral nitrogen in the studied Terric Histosol – 49.7–91.0%. Corg. concentration at the 0–30 cm depth in natural meadows areas was 41.2%, in cultural meadows areas it was 35.6% and in cereal crops areas 19.4%. The same sequence of Nsum. concentration was found – 3.04, 2.18 and 1.97%, and C:N ratio – 13.6, 16.3 and 9.8%. At deeper Terric Histosol layers the values of these indicators differed slightly between the crops areas. The Nmin concentration at 0–30 and 30–60 cm depth correlated best with the C:N ratio (r0–30 cm = 0.872**, r30–60 cm = 0.562*), Nsum. concentration (r0–30 cm = 0.618*, r30–60 cm = 0.568*) and to a lesser extent with the Corg. concentration (r0–30 cm = 0.341, r30–60 cm = 0.564*).