Impact Of Different Tillage Practices On Distribution Of Soil Organic Carbon And Total Nitrogen In Clay Loam Soil

Reduced tillage is one of strategies for mitigating climate change in agriculture. Enhancement of soil organic matter content by reduced or no -tillage practice and Ca-amendment application has been recognized as important strategies to combat soil degradation. Possibilities to reduce tillage clayey soil have not been sufficiently investigated in Lithuania before. Research was carried out during 20162018 at the Joniskelis Experimental Station of the Lithuanian Research Centre for Agriculture and Forestry on a clay loam (siltic, drainic), EndocalcaryEndohypogleyic Cambisol (CMgn-w-can) in the experiment, established in 2006. The studied treatments included: deep ploughing (DP) at 21-23 cm depth (control), ploughlcss tillage at 10-12 cm depth (PT), as well as ploughlcss tillage and aftereffect of lime sludge last incorporated in 2014 (PT+aLS) and no -till in the autumn with a cover crop for winter mulch (NT+WM). Soil samples were collected annually after the main crop harvest from three soil depth 0-10, 10-20, and 20-30 cm.Reduced tillage systems significantly increased soil organic carbon (SOC) content in the upper (010 cm) soil layer by order PT+aLS > NT+WM > PT > DP and shows SOC stratification in reduced tillage systems. Water extractable organic carbon (WEOC) content was higher under PT and NT+WM treatments at 0-10 and 10-20 cm layers, however under PT+aLS the WEOC content was lower compared to DP. Cations from lime sludge stabilized mobile and labile forms of SOC, reducing WEOC content. Total nitrogen (TN) in soil was less affected by applied reduced tillage systems, amount of TN in the upper (010 cm) soil layer increased significantly only under NT+WM. High correlation coefficients were observed for the relationship of SOC vs TN, indicating a close relation between SOC and TN accumulation in soil; lower correlation coefficients were observed for the relations of SOC vs WEOC, and TN vs WEOC.