ISSN 1392-3196 / e-ISSN 2335-8947
Zemdirbyste-Agriculture, vol. 107, No. 4 (2020), p. 291–300
DOI  10.13080/z-a.2020.107.037

The distribution of organic carbon, its forms and macroelements in agricultural soils



The objective of the present study was to estimate the distribution of soil organic carbon (SOC) and its forms (protected and labile organic carbon) and total nitrogen (Ntot), plant available phosphorus (P2O5) and potassium (K2O) within 0–30 cm layer of a ploughed horizon in agricultural soils as influenced by tillage and fertilisation.

Research was carried out in two regions of Lithuania: in Central (sites I and II) and Northern (site III) parts of Middle Lithuanian Lowland. Tillage systems, including conventional tillage (CT) and no-tillage (NT), straw management methods and mineral fertilisation were investigated on a loam and sandy loam top layer of glacial morain Eutric Endocalcaric Endostagnic Cambisol in site I. Five fertilisation treatments were tested in a grassland with a sandy loam top layer of glacial morain Endocalcaric Albic Brunic Endogleyic Arenosol in site II: without fertilisation and fertilisation with separated liquid and separated solid digestates at rates of 85 and 170 kg ha-1 N. The field experiment on a glaciolacustrine Eutric Endocalcaric Amphistagnic Endogleyic Cambisol with clay loam in site III involved the following tillage systems: conventional tillage (CT), ploughless tillage (PT), ploughless tillage with lime sludge incorporation (PT + LS) and no-tillage with a cover crop for winter mulch (NT + WM). Long-term NT caused pronounced stratification of Ntot, available K2O and SOC within the arable layer of Eutric Endocalcaric Endostagnic Cambisol. The highest accumulation of SOC and chemically protected-humified carbon in the grassland on an Endocalcaric Albic Brunic Endogleyic Arenosol was determined at the highest digestate rate of 170 kg ha-1 N. High SOC accumulation potential was shown by PT + LS in a Eutric Endocalcaric Amphistagnic Endogleyic Cambisol. This significantly increased the share of humified carbon fraction bound with calcium in 0–10 and 10–20 cm soil layers. Reduction of tillage intensity by applying PT and NT + WM increased the concentration of labile organic carbon in the soil, especially in the upper 0–10 cm layer. The lime sludge application reduced the amount of labile organic carbon by its incorporation with Ca in this amendment, while increasing the stability of carbon compounds. In Eutric Endocalcaric Endostagnic Cambisol, the mean results of 0–30 cm layer revealed that the share of F4 carbon fraction, resistant to degradation, in the SOC was significantly higher under NT than under CT.

Key words: digestate, fertilisation, labile and protected carbon, lime sludge, soil, tillage

Full text: 107_4_str37.pdf