IMPACT OF DIFFERENT TILLAGE PRACTICES ON DISTRIBUTION OF SOIL ORGANIC CARBON AND TOTAL NITROGEN IN CLAY LOAM SOIL

摘要

Reduced tillage is one of strategies for mitigat-ing 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 Lithu-ania before. Research was carried out during 2016-2018 at the Joniskelis Experimental Station of the Lithuanian Research Centre for Agriculture and For-estry on a clay loam(siltic, drainic), Endocalcary-Endohypogleyic Cambisol(CMgn-w-can) in the ex-periment, established in 2006. The studied treat-ments included: deep ploughing (DP)at 21-23 cm depth(control),ploughless tillage at 10-12 cm depth (PT), as well as ploughless 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 an-nually 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(0-10 cm) soillayerby 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 treat-ments 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 re-duced tillage systems, amount of TN in the upper(0-10 cm) soil layer increased significantly only under NT+WM.High correlation coefficients were ob-served for the relationship of SOCvs 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.