МОНГОЛ ОРНЫ ТӨВ ХЭСГИЙН ХЭЭРИЙН ХӨРСНИЙ ОРГАНИКИЙН 90 ЖИЛИЙН ДАРААХ ӨӨРЧЛӨЛТ

One of first soil investigation of Mongolia made by Russion famous scientist B. Polynov in 1925, in the Uvur Jargalant area of Central aimag. In 2018 we made soil investigation on the same area with aim of soil organic matter (SOM) change issue. Average drop of steppe SOM after 90 years is following: in the 5 cm soil depth -51.5 %, in 10 cm soil depth is -33.2 % and 30 cm soil depth is about -11.1 %. In the below 30 cm soil of depth no change of SOM. By landscape positions SOM change differed. Mountain top area and valley bottom area SOM is more declining comparing to the footslope area soils. For 0-30 cm top soil layer weighed average change of SOM within 90 year is -30.9 % and SOC stock decline is 16.5% or 15.4 t/hectare. Impact of livestock pressure and climate warming on soil is significant, need to renew pasture management policy.