THE STATE OF SOIL ORGANIC MATTER IN DIFFERENT PHYSICAL FRACTIONS DEPEND ON LAND USE TYPE

UDK 631.417(497.6) Known fact is that arable soils compared with correspondent native soils differ in the state of soil organic matter (SOM) and that agricultural practices halved content of soil organic carbon in last decades. Further, soil structure or aggregation mediates many biological and chemical processes in soil and influence on protecting of SOM. The objectives of this paper is to analyze how the different land use (forest, grassland and arable soil) effects on quality and quantity of SOM in different physical fraction. In particular, it is important to determine what pool (physically separated fraction) of SOM is most sensitive on cultivation and what pool is more resistant to mineralization. The research is carried out on two soil type with different texture, Pseudogley and Terra rossa, in condition of different climate and soil management. Two groups of SOM analysis are singled out: 1) quantify SOC and N storage, and δ13C by horizons; and 2) quantify the SOC and N in the following physically separated fractions of SOM: a) coarse and fine particulated organic matter (POM) density <1.8 gcm-3; b) occluded POM in stable microaggregates 53-250 µm; and c) SOM in small microaggregates <53 µm.