ИСТИНА

The collapse of the Soviet Union in 1991 caused a serious crisis in agriculture. Part of the arable lands were abandoned and some changes in crop rotations occurred. In addition, global warming has led to changes in the proportion of soil losses from cultivated lands during snow-melt events or rain storms. Different indicators can be used for evaluating the trends in soil erosion rates, as there is a lack of monitoring data. Indicators can be split into two groups. The first group includes hydro-meteorological and agricultural parameters, namely: recurrency of extreme rains during the warm part of the year, maximum water discharges and duration of spring floods, type of crops and/or crop rotations, and area of arable lands. The second group includes characteristics of gully retreat, and sediment deposition rate dynamics in the different sediment sinks along pathways from cultivated slopes to the river channel. Four transects were selected within different landscape zones of the southern half of the Russian Plain for evaluation of contemporary trends of erosion rates on the arable lands, based on application of different indicators (Figure 1A). Each transect crossed both upland and lowland areas of the different landscape zones, and was contained within the administrative region of Russia. Typical soil types and crop rotations were represented within each transect. Maximum reduction of the agricultural land area was observed in 2003