Soil Organic Matter under Different Soil Management

Our investigation was aimed to assess impact of different intensity tillage systems, straw and green manure combinations on soil organic matter quantity and quality. The data based on long-term field experiment established since 1999 in the Experimental Station of the Aleksandras Stulginskis University, Kaunas district at 54°52'50 N latitude and 23°49'41 E longitude. The soil of the experiment site is Endohypogleyi-Eutnc Planosol. The obtained results after 14 years from the beginning of field experiment indicated a positive effect on soil organic carbon (SOC) in plots where straw were incorporation or minimized tillage. Significantly highest amount of SOC (2.39 %) was obtained in topsoil layer (0-10 cm depth) after straw chopped and spread at harvesting. In comparison, the lowest content of SOC (2.13 %) was found in soil where straw was removed. The mobile humus susbstances depends on tillage practise, straw and green manure management and were different among treatment. Analysing the straw effect on the content of mobile humus susbstances in toplayer (0-20 cm) the higher amount (7.52 C g kg" i mobile humus substances was found on treatment with straw. Tillage systems had no significant effect on mobile humic acids but tended to increase SOM quality. Mobile humic acids in treatments with conventional ploughing, shallow ploughing, shallow loosening without straw amounted 35.5-37.7 % or with straw - 42.3- 43.6 % from total amount of labile humus substances. The different tillage systems had positive impact on soil organic carbon poc.; in 0-10 cm soil layer. The shallow loosening (32.7 Mg ha"1), green manure incorporation (35.9 Mg ha"1) and no-tillage (35.9 Mg ha"1) significantly increased poo J to compare with conventional deep ploughing (25.5 Mg ha"1). Shallow ploughing and shallow loosening have no effectLietuvos agrarinių ir miškų mokslų centro filialas Žemdirbystės institutasVytauto Didžiojo universitetasŽemės ūkio akademij