EFFECT OF LIMING ON THE DYNAMICS OF WATER-STABLE AGGREGATES AND ORGANIC CARBON IN MORAINE LOAM SOIL.

The paper summarises the data of field and laboratory trials made in Lithuania (Vezaiciai Branch of Lithuanian Research Centre for Agriculture and Forestry) during the period of 1996-2013. The effect of liming with different intensity (at a rate 0.5 every 7 years and 2.0 every 3-4 years) was investigated in the topsoil of acid moraine loam Bathygleyic Dystric Glossic Retisol on the dynamics of water-stable aggregates and organic carbon. Data showed that systematic liming over 56 years (1949-2005) affected the structure of moraine loam soil. The largest amount (68.4-72.1%) of water stable aggregates (>0.25mm) was determined in the relatively most intensively limed soil when perennial grasses and winter wheat were grown in 2002-2003. During the study period the decrease of water-stable aggregates was appointed in both soil backgrounds: acid (from 57% to 25%) and limed (from 72% to 29%) soil. These data suggest that the climatic conditions (swelling clay under warm and wet conditions in autumn-winter periods and drying and rewetting cycles in springsummer periods) have a substantial negative effect on the aggregates formation. The effect of systematic soil liming on the distribution of soil organic carbon and it's fractional composition was evaluated. Study showed that periodical liming decreased the amount of organic carbon in the soil. Soil organic carbon amount was approximately by 0.11-0.18 persentage points lower compared to the unlimed plots (1.44%). Periodical liming significantly decrease the content of humic and fulvic acids and dissolved organic carbon content, as one of labile fractions of soil organic carbon. Fulvic acids was dominated in the soil in all treatments, that could be associated with a slow humification processes in the soil. [ABSTRACT FROM AUTHOR]