WATER SOIL EROSION IN RIGHT-BANK UKRAINIAN FOREST-STEPPE ZONE

Abstract

Problem Statement and Purpose. A water soil erosion is one of the most important ecological problems of the world because in the result of it the soil cover completely destroys and is not able to renew for a long time. In opinion of dr. Montgomery D., the loses of agricultural soils even limited the lifetime of ancient civilizations and the same problem closely touches today human being. Following to the information of scientists in 1970-s, about 430 million ha of lands were destroyed in different countries because of water soil erosion. Annual loses of product lands on our planet equal 5–7 million ha. In Ukraine at the end of first decade of 2000s following to National report (2010) the square of eroded agricultural lands equaled 15.954 million ha or 38.4 per cent of their common territory including 12.940 million ha of arable lands or 39.9 per cent. On average the soil loses about approximately 15 t/ha/year. Thereby the purpose of the study is a spatial distributed quantitative assessment of the intensity of erosion soil loses in the right-bank forest-steppe zone of Ukraine and definition of arable squares with different rates of erosion load considering present climate changes and land use peculiarities. Data &Methods. For the estimation of average soil wash off three typical slope plots (К1-р, К2-р, К3-р) were used. The plots are situated within the territory of Educational and Scientific Stationary of the Odesa I. I. Mechnikov National University that is in Podilsk district of the north part of Odesa region. This territory is on south hills of Podolska upland in forest-steppe zone. The plots are the different parts of small valleys slopes which are annual plowed up and used for growing of the most profit-making crops – wheat, corn, barley and sunflower. No any scientifically based crop rotation uses there at least for the last twenty years. The spatial distributed physical and statistical model of soil wash off and accumulation was used as a working model for the estimation of average annual soil loses consideringthe peculiarities of land cultivation and anti-erosion crops properties. The model was developed in Department of Physical geography, Nature Management and Geoinformation Technology of Odesa I. I. Mechnikov National University and realized in GIS‑package PCRaster (Utrecht University, Netherlands). Results. The quantitative assessment of today erosion soil loses on typical plots considering land use demonstrates very high rate of soil erosion degradation which is obviously representative for the most territories of the right-bank forest-steppe zone of Ukraine. Areas of more than 20 t/ha/year wash off equal 23–27 per cent. Areas of less than 2 t/ha/year wash off where the intensity of soil erosion equals to soil restoration are about one third of all arable lands. The average values of wash off for plots К1-р, К2-р, К3-р are 14.2; 26.3 and 14.8 t/ha/year respectively. However, these values are not above the same ones obtained earlier, but even some less. This is due to the decreasing of soil erosion because of snow melting in the spring which is connected with global warming. But simultaneously the hydrometeorological conditions of rainstorm erosion have not change. And essential decreasing of wash off has not happened because the part of snow melting erosion is only 15–20 per cent in the right-bank forest-steppe zone of Ukraine. The huge values of average wash off and significant areas with high and very high wash off (about one third of arable lands) evidence about decreasing of economic and ecological worth of lands commonly. Applying of soil protection crops rotation well influence on soil decreasing the rate of erosion. The plowing of lands with great slopes (6–7° and more) and using them for row crops without rotation leads to catastrophic wash off and increasing of areas with high erosion danger. Such lands need to be exclude of plowing up.